JP2014163685A - Celestial body luminance calculation device and celestial body luminance calculation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable observation to be performed at various configurations, and allow luminance of a celestial body to be accurately calculated.SOLUTION: In order to eliminate a position error calculated by a position error calculation section 23, an instruction to move radio wave telescopes 11 and 12 is transmitted to truck control sections 15 and 16, and after the radio wave telescopes 11 and 12 are moved by trucks 13 and 14, a movement observation point mutual correlation value calculation section 24 is provided that calculates a movement observation point mutual correlation value C(τ) between an observation radio wave E(t) of the radio wave telescope 11 and a radio wave E(t) of the radio wave telescope 12, and a stationary observation point mutual correlation value C(τ) calculated by a stationary observation point mutual correlation value calculation section 17 and the movement observation point mutual correlation value C(τ) are integrated.

Description

  The present invention relates to a celestial luminance calculation apparatus and a celestial luminance calculation method for calculating the luminance of a celestial object by observing radio waves coming from the celestial object.

Radio astronomy is a research field that investigates the properties of celestial bodies by observing the behavior of radio waves emitted from, for example, stars, interstellar gases, and plasmas around high-energy celestial bodies.
A radio telescope is used for radio astronomy observation, and an aperture antenna is most often used as an antenna element constituting the radio telescope.
Radio wave observation methods using antennas can be broadly divided into two types: single mirror observation and interferometer observation.

As an example of a radio telescope often used for single mirror observation, a radio telescope using an aperture antenna having a diameter of 45 m described in Non-Patent Document 1 below can be cited. This telescope is capable of observing radio waves with a frequency of 1 to 150 GHz, and has produced many achievements particularly in high-frequency emission line observation.
In the radio telescope using the aperture antenna having a diameter of 64 m described in Non-Patent Document 2 below, many high-energy celestial bodies called pulsars have been discovered.
As in the above two examples, single mirror observation is suitable for celestial emission line observation and pulsar observation. However, in the single mirror observation, due to the problem of the spatial resolution of the antenna constituting the telescope, it is not often used for the purpose of observing and imaging the detailed structure of the celestial body.

When observing the detailed structure of a celestial body, normally, a single mirror observation is not performed, but an interferometer observation is performed in which two or more telescopes are Fourier-synthesized.
The spatial resolution of the interferometer depends on the baseline length vector that represents the distance and directional relationship between the constituent elements. Information obtained by observing a certain baseline length vector corresponds to information on one spatial frequency.
In order to acquire a radio wave image, information on various spatial frequencies is required. Therefore, it is necessary to perform observation by installing radio telescopes at the start and end points of various baseline length vectors. If the number of elements of the telescope is increased, the number of observation data of the baseline length vector obtained at the same time increases, so the number of observation data of each spatial frequency obtained simultaneously by one observation increases.

As an example of such a multi-element radio wave interferometer, there is a radio wave interferometer called VLA (Very Large Array) described in Non-Patent Document 3 below.
This interferometer is composed of 27 radio telescopes with a diameter of 25 m. Each radio telescope moves on a rail with a side length of 21 km and observes various baseline length vectors. The observation data of many spatial frequencies can be obtained simultaneously.
As a general operation method of a multi-element radio wave interferometer such as a VLA, a method of performing observation by installing each radio telescope at a point (configuration) defined on a rail is used. The observation target varies depending on the configuration.

Furthermore, as means for observing a long baseline length vector, a very long baseline radio interference (VLBI) such as VLBA (Very Long Baseline Array) described in Non-Patent Document 4 below is used. Is mentioned.
This method is a technique that obtains ultra-high resolution radio observation by observing one astronomical object by matching the time and frequency timing of two or more radio telescopes installed at a distance of several hundred km or more. is there.
Non-Patent Document 5 below discloses a space VLBI system in which an interferometer is formed by a radio telescope mounted on a satellite and a ground radio telescope.

As a radio telescope that can be installed anywhere, there is a portable telescope “CARAVAN 2400” described in Non-Patent Document 6 below.
Since the aperture antenna used in “CARAVAN 2400” is very small, the light collecting power is low. However, if an interferometer is formed in the vicinity of a large radio telescope, the condensing power can be compensated and a large radio telescope that has been operated as a single mirror can be converted into an interferometer.

Hereinafter, a conventional example of an observation algorithm for acquiring an astronomical image using a movable two-element telescope such as a VLA will be described with reference to a method described in Non-Patent Document 7.
First, a base line length vector necessary for obtaining a radio image of an celestial body to be observed and positions on the earth representing both ends of the base line length vector are calculated, and two radio telescopes are moved.
After install two radio telescope, radio waves E ₁ where two radio telescope arrives from astronomical (t), and receives E ₂ a (t), the radio wave _{E 1 (t), E 2} (t) Voltages a ₁ E ₁ (t) and a ₂ E ₂ (t) proportional to are output. When there is no phase difference between the two radio telescopes, E ₁ (t) = E ₂ (t).

式（１）において、τは位相差である。
位相差τは、下記の式（２）で与えられる。

式（２）において、ｋは波数、Ｄ_λは基線長ベクトル、ｃは自由空間の光速度である。 When two radio telescopes output voltages a ₁ E ₁ (t) and a ₂ E ₂ (t) proportional to the radio waves E ₁ (t) and E ₂ (t), the following equation (1) is obtained. Then, using the voltages a ₁ E ₁ (t) and a ₂ E ₂ (t), a cross-correlation value C (τ) between the radio wave E ₁ (t) and the radio wave E ₂ (t) is calculated.

In equation (1), τ is a phase difference.
The phase difference τ is given by the following equation (2).

In equation (2), k is the wave number, D _λ is the baseline length vector, and c is the light velocity in free space.

式（３）において、Ａ_Nはアンテナパターン、Ｉ_νは天体の輝度、（ξ，η）は天球上の位置、（ｕ，ｖ）はある基線長ベクトルが示す２次元の空間周波数を表している。 Observation is performed with the same baseline length vector for a certain period of time, and high-accuracy observation data is generated by time-integrating the cross-correlation value C (τ).
Then, a radio telescope is placed at the start point and end point of the next baseline length vector, and the above observation is performed again.
Then, when observation is performed for the number of necessary baseline length vectors, the observation data obtained by time-integrating each cross-correlation value C (τ) is Fourier-transformed, and the visibility v ( ω) is calculated.

In Equation (3), A _N is an antenna pattern, I _ν is the brightness of a celestial body, (ξ, η) is a position on the celestial sphere, and (u, v) is a two-dimensional spatial frequency indicated by a certain baseline length vector. Yes.

電波望遠鏡が複数台ある場合は、同時に観測できる基線長ベクトルの数も増える。例えば、全部でＮ台の望遠鏡が存在するならば、Ｎ（Ｎ−１）／２通りの基線長ベクトルを同時に観測することができる。 By observing various baseline length vectors, the spatial luminance distribution I _v (ξ, η) of the celestial body is calculated from the following equation (4).

When there are multiple radio telescopes, the number of baseline length vectors that can be observed simultaneously increases. For example, if there are a total of N telescopes, N (N-1) / 2 different baseline length vectors can be observed simultaneously.

K. Kawaguchi, Y. Kasai, S. Ishikawa, and N. Kaifu, “A spectral-Line Survey Observation of IRC +10216 between 28 and 50 GHz”, Publ. Astron. Soc. Japan, vol 47, pp. 853- 876 (1995) R. N. Manchester, A.R. G. Lyne, F.A. Camilo, J. F. Bell, V. M. kaspi, N. D'Amico, NPF McKay, F. Crawford, IH Stairs, A. Possenti, M. Kramer, and DC Sheppard, “The Parkes multi-beam pulsar survey-I. Observing and data analysis systems, discovery and timing of 100 pulsars ”, Mon. Not. R. Astron. Soc., vol. 328, pp. 17-35 (2001) J. J. Condon, W. D. Cotton, E. W. Greisen, and Q. F. Yin, R. A. Perley AND G. B. Taylor, AND J. J. Broderick, “The NRAO VLA Sky Survey”, The Astronomical Journal, vol. 115, pp. 1693-1716 (1998) ML Lister, HD Aller, MF Aller, MH Cohen, DC Homan, M. Kadler, KI Kellermann, YY Kovalev, E. Ros, T. Savolainen, JA Zensus, and RC Vermeulen, “MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VI. Kinematics Analysis of a Complete Sample of Blazar Jets ”, The Astronomical Journal, vol. 137, pp. 3718-3729 (2009) H. Hirabayashi, et al., “The VLBI Space Observatory Program and the Radio-Astronomical Satellite HALCA”, Publi. Astron. Soc. Japan, vol. 52, pp. 955-965 (2000) Yuri Ishii, Yasuhiro Koyama, Ryuichi Ichikawa, Hiromitsu Kubuki, Kazuhiro Takashima, Junichi Fujisaki, “VLBI Observation with CARAVAN 2400 Small Radio Telescope”, 2005 Space Research Symposium with VLBI Technology, 5th IVS Technology Development Center Symposium National Astronomical Observatory, “Interferometer Summer School 2005 Textbook”, 2005 Interferometer Summer School Materials

  Since the conventional celestial luminance calculation apparatus is configured as described above, the spatial luminance distribution of the celestial object can be calculated without securing a large space by using a small portable telescope. However, since the portable telescope has poor positional accuracy as compared with the installed telescope, there is a restriction that the place where it can be installed is limited to the vicinity of the place where the position on the earth is accurately measured. Due to this restriction, it is difficult to perform observations in various configurations, and even if observation is performed with a large position error, the correlation of the obtained observation data is reduced, so an accurate luminance distribution is calculated. There was a problem that could not be done.

  The present invention has been made to solve the above-described problems, and is capable of performing observations with various configurations and calculating celestial luminance with high accuracy and celestial luminance calculation. The purpose is to obtain a method.

  An astronomical luminance calculation apparatus according to the present invention includes a first radio telescope that observes radio waves coming from a celestial body, a second radio telescope that observes radio waves coming from a celestial body, and a radio telescope that changes over time. The base line length vector indicating the installation position of the base line is input, the first radio telescope is transported to the start point of the base line length vector corresponding to the current time, and the second radio telescope is moved to the end point of the base line length vector. After the first and second radio telescopes are transported by the telescope transport means and the telescope transport means, the cross-correlation value between the observation radio waves of the first radio telescope and the observation radio waves of the second radio telescope is calculated. First cross-correlation value calculating means, receiving a signal transmitted from the satellite, specifying the installation positions of the first and second radio telescopes, the installation positions of the first and second radio telescopes, Vs time A position error calculating means for calculating an error between the start point and the end point of the baseline length vector to be moved, and an instruction to move the first and second radio telescopes so as to eliminate the position error calculated by the position error calculating means And a second cross-correlation value calculating means for calculating a cross-correlation value between the observation radio wave of the first radio telescope after movement and the observation radio wave of the second radio telescope after the movement, An observation data output unit that integrates the cross-correlation value calculated by the correlation value calculation unit and the cross-correlation value calculated by the second cross-correlation value calculation unit, and outputs observation data that is the cross-correlation value after integration; The astronomical luminance calculation means calculates the luminance of the celestial object from the observation data output from the observation data output means.

  According to the present invention, after the first and second radio telescopes are transported by the telescope transport means, the cross correlation value between the observed radio waves of the first radio telescope and the observed radio waves of the second radio telescope is calculated. 1 cross-correlation value calculating means, position error calculating means for calculating errors between the installation positions of the first and second radio telescopes, and the start and end positions of the baseline length vector corresponding to the current time; Instructions for moving the first and second radio telescopes are output to the telescope transport means so that the position error calculated by the calculation means is eliminated, and the observed radio waves and the second radio waves of the first radio telescope after the movement are output. Second cross-correlation value calculating means for calculating a cross-correlation value between the observation radio waves of the telescope is provided, and the observation data output means is connected to the cross-correlation value calculated by the first cross-correlation value calculating means and the second cross-correlation value Calculated by the correlation value calculation means Since the cross-correlation values are integrated and the observation data, which is the cross-correlation value after the integration, is output to the celestial brightness calculation means, observations can be performed in various configurations, and the celestial brightness can be accurately measured. There is an effect that can be calculated.

It is a block diagram which shows the astronomical luminance calculation apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing content (celestial luminance calculation method) of the celestial luminance calculation apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing content (celestial luminance calculation method) of the celestial luminance calculation apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the simulation result of drift tracking observation. It is a conceptual diagram which shows the parallel process of the astronomical brightness | luminance calculation apparatus by Embodiment 1 of this invention.

Embodiment 1 FIG.
1 is a block diagram showing an astronomical brightness calculation apparatus according to Embodiment 1 of the present invention.
In FIG. 1, when calculating the luminance of the celestial body 2, the baseline length vector calculating unit 1 calculates the baseline length vector m indicating the position where the radio telescope is installed (the radio telescopes 11 and 12 with respect to the celestial body 2 as time passes). Since the relative installation position changes, the base length vector m changes with time), and the base length vector m is transmitted to the astronomical luminance calculation device 3 by radio or the like. If the number of necessary baseline length vectors m is M, M baseline length vectors m (m = 1, 2,..., M) are calculated.
In the first embodiment, it is assumed that the baseline length vector calculation unit 1 is configured by a computer or the like external to the celestial luminance calculation device 3 and the baseline length vector m is given to the celestial luminance calculation device 3 from the external computer or the like. However, the astronomical luminance calculation device 3 may be equipped with the baseline length vector calculation unit 1.

The radio telescope 11 is mounted on the platform of the truck 13, the observation position is moved, the radio wave E ₁ (t) arriving from the celestial body 2 is observed, and the observation result of the radio wave E ₁ (t) is transmitted by radio or the like. Perform the process. The radio telescope 11 constitutes a first radio telescope.
The radio telescope 12 is mounted on the platform of the truck 14, the observation position is moved, the radio wave E ₂ (t) coming from the celestial body 2 is observed, and the observation result of the radio wave E ₂ (t) is transmitted by radio or the like Perform the process. The radio telescope 12 constitutes a second radio telescope.
Here, an example is shown in which the radio telescopes 11 and 12 transmit observation results of the radio waves E ₁ (t) and E ₂ (t). The observation results of ₁ (t) and E ₂ (t) may be transmitted.

The track control unit 15 is composed of, for example, a semiconductor integrated circuit mounting a CPU or a one-chip microcomputer, and receives the baseline length vector m transmitted from the baseline length vector calculation unit 1 and corresponds to the current time. A process of controlling the track 13 is performed so that the radio telescope 11 is conveyed to the position of the starting point of the baseline length vector m to be performed.
The track control unit 16 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted or a one-chip microcomputer, and receives the baseline length vector m transmitted from the baseline length vector calculation unit 1 and corresponds to the current time. A process of controlling the track 14 is performed so that the radio telescope 12 is transported to the position of the end point of the baseline length vector m to be performed.
When the track control units 15 and 16 control the tracks 13 and 14, the positions of the tracks 13 and 14 need to be measured. As a positioning method, for example, positioning by a GPS signal, triangulation, or the like is used. Can be considered.
The trucks 13 and 14 and the track controllers 15 and 16 constitute a telescope conveying means.

The fixed observation point cross-correlation value calculation unit 17 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer or the like, and after the radio telescopes 11 and 12 are conveyed by the tracks 13 and 14, the radio waves The observation results of the radio waves E ₁ (t) and E ₂ (t) are received from the telescopes 11 and 12, and the fixed observation point cross-correlation value that is the cross-correlation value between the radio waves E ₁ (t) and the radio wave E ₂ (t) A process of calculating C ₀ (τ) is performed. The fixed observation point cross-correlation value calculation unit 17 constitutes a first cross-correlation value calculation unit.

The artificial satellite 18 is a satellite that transmits a signal including position information, time information, frequency reference information, and the like, for example, a GPS satellite that transmits a GPS signal.
The artificial satellite 19 is a satellite that transmits a signal including position correction information and the like, for example, a quasi-zenith satellite that transmits a LEX signal.
The satellite signal receivers 20 and 21 perform processing for receiving signals transmitted from the artificial satellites 18 and 19.

The position time specifying unit 22 is constituted by, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like, and the radio telescopes 11, 12 are detected from the signal of the artificial satellite 18 received by the satellite signal receiver 20. While positioning the installation position, a process for specifying the current time is performed.
Further, since the position time specifying unit 22 does not reach the position accuracy for performing astronomical observation only with the signal of the artificial satellite 18, the satellite position / speed error, clock error, ionospheric delay, The position of the radio telescopes 11 and 12 and the current time / frequency standard accuracy are improved by correcting the influence of the tropospheric delay.

The position error calculation unit 23 is composed of, for example, a semiconductor integrated circuit mounted with a CPU or a one-chip microcomputer, and receives the baseline length vector m transmitted from the baseline length vector calculation unit 1 to specify the position time. A process of calculating an error between the installation positions of the radio telescopes 11 and 12 measured by the unit 22 and the positions of the start point and the end point of the baseline length vector m corresponding to the current time specified by the position time specifying unit 22 is performed. .
The satellite signal receivers 20 and 21, the position time specifying unit 22 and the position error calculating unit 23 constitute position error calculating means.

The moving observation point cross-correlation value calculation unit 24 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, or a one-chip microcomputer, so that the position error calculated by the position error calculation unit 23 is eliminated. An instruction to move the radio telescopes 11 and 12 is transmitted to the track control units 15 and 16 by wireless or the like. After the radio telescopes 11 and 12 are moved by the tracks 13 and 14, the radio telescopes 11 and 12 transmit the radio waves E ₁ (t ), E ₂ (t) observation results are received, and a mobile observation point cross-correlation value C ₁ (τ) that is a cross-correlation value between the radio wave E ₁ (t) and the radio wave E ₂ (t) is calculated. carry out. The moving observation point cross-correlation value calculation unit 24 constitutes a second cross-correlation value calculation unit.

The cross-correlation value accumulating unit 25 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted or a one-chip microcomputer, and the fixed observation point cross-correlation value C calculated by the fixed observation point cross-correlation value calculating unit 17. A process of accumulating ₀ (τ) and the moving observation point cross-correlation value C ₁ (τ) calculated by the moving observation point cross-correlation value calculation unit 24 is performed.
The observation accuracy determination unit 26 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like, and the observation accuracy of the observation data E that is a cross-correlation value integrated by the cross-correlation value integration unit 25. If the observation accuracy is equal to or higher than the predetermined accuracy, the observation data E is output to the celestial luminance calculation unit 28. On the other hand, if the observation accuracy does not satisfy the predetermined accuracy, the position error is recalculated. The command is output to the position time specifying unit 22 and the command for accumulating the mobile observation point cross-correlation value C ₁ (τ) calculated again by the mobile observation point cross-correlation value calculation unit 24 to the observation data E is calculated. Processing to be output to the unit 25 is performed.

The correlation strength determination unit 27 is composed of, for example, a semiconductor integrated circuit mounted with a CPU or a one-chip microcomputer, and the fixed observation point cross-correlation value C ₀ calculated by the fixed observation point cross-correlation value calculation unit 17. The correlation strength R between (τ) and the mobile observation point cross-correlation value C ₁ (τ) calculated again by the mobile observation point cross-correlation value calculation unit 24 is calculated, and the correlation strength R is equal to or greater than a predetermined strength. For example, a command for accumulating the mobile observation point cross-correlation value C ₁ (τ) recalculated by the mobile observation point cross-correlation value calculation unit 24 to the observation data E is output to the cross-correlation value integration unit 25, while the correlation strength is increased. If R does not reach the predetermined intensity, a command for recalculating the position error is output to the position time specifying unit 22, and the moving observation point cross-correlation value C ₁ (τ) by the moving observation point cross-correlation value calculating unit 24 is output. Repeat the calculation process To be carried out.
The cross-correlation value accumulating unit 25, the observation accuracy determining unit 26, and the correlation strength determining unit 27 constitute observation data output means.

The astronomical luminance calculation unit 28 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like, and calculates the visibility v (ω) from the observation data E output from the observation accuracy determination unit 26. At the same time, a process of calculating the spatial luminance distribution I _v (ξ, η) of the celestial body 2 is performed. Note that the celestial luminance calculation unit 28 constitutes celestial luminance calculation means.

In the example of FIG. 1, radio telescopes 11 and 12, tracks 13 and 14, track control units 15 and 16, fixed observation point cross-correlation value calculation unit 17, satellite signal receiver 20, which are constituent elements of astronomical luminance calculation device 3. 21, a position time specifying unit 22, a position error calculating unit 23, a moving observation point cross-correlation value calculating unit 24, a cross-correlation value accumulating unit 25, an observation accuracy determining unit 26, a correlation strength determining unit 27, and an astronomical luminance calculating unit 28, respectively. Is assumed to be configured with dedicated hardware, but a part of the astronomical luminance calculation device may be configured with a computer.
For example, the fixed observation point cross-correlation value calculation unit 17, the position time specifying unit 22, the position error calculation unit 23, the moving observation point cross-correlation value calculation unit 24, and the cross-correlation value integration unit 25 that are part of the celestial luminance calculation device 3. When the observation accuracy determination unit 26, the correlation strength determination unit 27, and the astronomical luminance calculation unit 28 are configured by a computer, the fixed observation point cross-correlation value calculation unit 17, the position time specification unit 22, the position error calculation unit 23, the mobile observation A program describing the processing contents of the point cross-correlation value calculation unit 24, the cross-correlation value integration unit 25, the observation accuracy determination unit 26, the correlation strength determination unit 27, and the astronomical luminance calculation unit 28 is stored in the memory of the computer. A computer CPU may execute a program stored in the memory.
FIG. 2 (FIGS. 2A and 2B) is a flowchart showing the processing contents (celestial luminance calculation method) of the celestial luminance calculation apparatus 3 according to Embodiment 1 of the present invention.

Next, the operation will be described.
When calculating the luminance of the celestial body 2, the baseline length vector calculating unit 1 calculates the relative length of the radio telescopes 11 and 12 with respect to the celestial body 2 as time passes. Since the installation position changes, the baseline length vector m changes with time), and the baseline length vector m is transmitted by radio or the like (step ST1 in FIG. 2).
When generating the radio wave image of the celestial body 2, if the number of necessary baseline length vectors m is M, M baseline length vectors m (m = 1, 2,..., M) are calculated.
When M baseline length vectors m are calculated, the astronomical luminance calculation device 3 repeats the processes of steps ST1 to ST23 M times.
Note that the calculation process of the baseline length vector m is a known technique, and thus detailed description thereof is omitted.

The track control unit 15 receives the baseline length vector m transmitted from the baseline length vector calculation unit 1, and moves the track 13 so as to carry the radio telescope 11 to the position of the starting point of the baseline length vector m corresponding to the current time. Control (step ST2).
That is, the baseline length vector m transmitted from the baseline length vector calculation unit 1 includes the starting point position of the baseline length vector m corresponding to the time t ₀ , the starting point position of the baseline length vector m corresponding to the time t ₁ , and the time Since the position of the starting point of the baseline length vector m corresponding to t ₂ is recorded, the position of the starting point of the baseline length vector m corresponding to the current time is specified, and the position of the track 13 is the baseline length vector m The track 13 is controlled so as to coincide with the position of the starting point. In practice, control such as guiding the route to the position of the starting point of the baseline length vector m with the navigation device of the track 13 can be considered.

The track control unit 16 receives the baseline length vector m transmitted from the baseline length vector calculation unit 1, and transports the track 14 so as to carry the radio telescope 11 to the position of the end point of the baseline length vector m corresponding to the current time. Control (step ST2).
That is, the baseline length vector m transmitted from the baseline length vector calculation unit 1 includes the end point position of the baseline length vector m corresponding to the time t ₀ , the end point position of the baseline length vector m corresponding to the time t ₁ , and the time Since the end point position of the baseline length vector m corresponding to t ₂ is recorded, the end point position of the baseline length vector m corresponding to the current time is specified, and the position of the track 13 is the baseline length vector m The track 14 is controlled so as to coincide with the position of the end point. In practice, control such as guiding the route to the position of the end point of the baseline length vector m with the navigation device of the track 14 can be considered.
Here, an example in which the trucks 13 and 14 carry the radio telescopes 11 and 12 is shown, but the means for carrying the radio telescopes 11 and 12 is not limited to the trucks 13 and 14, and for example, a freight car or a truck. It may be a ship or a ship.

When the radio telescope 11 is transported by the track 13 to the position of the start point of the baseline length vector m corresponding to the current time, the radio telescope 11 observes the radio wave E ₁ (t) coming from the celestial body 2 and changes the radio wave E ₁ (t) to the radio wave E ₁ (t). A signal indicating a proportional voltage a ₁ E ₁ (t) is transmitted.
When the radio telescope 12 is transported by the track 14 to the position of the end point of the baseline length vector m corresponding to the current time, the radio telescope 12 observes the radio wave E ₂ (t) coming from the celestial body 2 and changes the radio wave E ₂ (t) to the radio wave E ₂ (t). A signal indicating a proportional voltage a ₂ E ₂ (t) is transmitted.
In this example, the radio telescopes 11 and 12 transmit signals indicating voltages a ₁ E ₁ (t) and a ₂ E ₂ (t) proportional to the radio waves E ₁ (t) and E ₂ (t). Although shown, a radio device (not shown) may transmit signals indicating the voltages a ₁ E ₁ (t) and a ₂ E ₂ (t).

式（５）において、τは位相差である。
位相差τは、下記の式（６）で与えられる。

式（６）において、ｋは波数、Ｄ_λは基線長ベクトルｍ、ｃは自由空間の光速度である。 The fixed observation point cross-correlation value calculation unit 17 includes voltages a ₁ E ₁ (t) and a ₂ E ₂ (t that are proportional to the radio waves E ₁ (t) and E ₂ (t) transmitted from the radio telescopes 11 and 12. ) Is received, using the voltages a ₁ E ₁ (t) and a ₂ E ₂ (t) as shown in the following equation (5), the radio waves E ₁ (t) and E ₂ (t) The fixed observation point cross-correlation value C ₀ (τ) that is the cross-correlation value is calculated (step ST3).

In Expression (5), τ is a phase difference.
The phase difference τ is given by the following equation (6).

In Equation (6), k is the wave number, _Dλ is the baseline length vector m, and c is the light velocity in free space.

The satellite signal receivers 20 and 21 receive signals transmitted from the artificial satellite 18 (for example, signals including position information and time information / frequency reference information such as GPS signals transmitted from GPS satellites).
Further, the satellite signal receivers 20 and 21 receive a signal transmitted from the artificial satellite 19 (for example, a signal including position correction information such as a LEX signal transmitted from the quasi-zenith satellite).
When the satellite signal receivers 20 and 21 receive the signals from the artificial satellite 18, the position time specifying unit 22 determines the installation positions of the radio telescopes 11 and 12 from the received signals and specifies the current time (step ST4). .
However, since the satellite 18 signal alone does not reach the position accuracy required for astronomical observation, the satellite position / speed error, clock error, ionospheric delay, tropospheric delay, etc. Correction is made to improve the position of the radio telescope 11 and the current time / frequency standard accuracy.

The position error calculation unit 23 receives the baseline length vector m transmitted from the baseline length vector calculation unit 1 and acquires the installation positions and current times of the radio telescopes 11 and 12 measured by the position time specifying unit 22.
When the position error calculation unit 23 acquires the installation position of the radio telescope 11 and the current time, the position error calculation unit 23 calculates an error between the installation position of the radio telescope 11 and the position of the start point of the baseline length vector m corresponding to the current time (step ST5). ).
That is, the baseline length vector m transmitted from the baseline length vector calculation unit 1 includes the starting point position of the baseline length vector m corresponding to the time t ₀ , the starting point position of the baseline length vector m corresponding to the time t ₁ , and the time Since the position of the starting point of the baseline length vector m corresponding to t ₂ is recorded, the position of the starting point of the baseline length vector m corresponding to the current time is specified, and the position of the starting point of the baseline length vector m is An error with respect to the installation position of the radio telescope 11 (for example, an error in latitude and longitude) is calculated.
Even if the radio telescope 11 is installed at the position of the start point of the baseline length vector m in the process of step ST2, since the baseline length vector m changes with time, the position of the start point of the baseline length vector m and the radio telescope An error occurs between the 11 installation positions.

Further, when the position error calculation unit 23 acquires the installation position of the radio telescope 12 and the current time, the position error calculation unit 23 calculates an error between the installation position of the radio telescope 12 and the position of the end point of the baseline length vector m corresponding to the current time ( Step ST5).
That is, the baseline length vector m transmitted from the baseline length vector calculation unit 1 includes the end point position of the baseline length vector m corresponding to the time t ₀ , the end point position of the baseline length vector m corresponding to the time t ₁ , and the time Since the end point position of the baseline length vector m corresponding to t ₂ is recorded, the end point position of the baseline length vector m corresponding to the current time is specified, and the end point position of the baseline length vector m is An error with respect to the installation position of the radio telescope 12 (for example, an error in latitude and longitude) is calculated.
Even if the radio telescope 12 is installed at the end point position of the baseline length vector m in the process of step ST2, the baseline length vector m changes with time, so the end point position of the baseline length vector m and the radio telescope An error occurs between the 12 installation positions.

When the position error calculator 23 calculates an error between the installation position of the radio telescope 11 and the position of the start point of the baseline length vector m corresponding to the current time, the moving observation point cross-correlation value calculator 24 eliminates the position error. Thus, an instruction to move the radio telescope 11 is transmitted to the track control unit 15 by radio or the like (step ST6).
Thereby, the track control unit 15 moves the track 13 in a direction in which the position error is eliminated, thereby transporting the radio telescope 11 to the position of the starting point of the baseline length vector m corresponding to the current time (step ST7).

In addition, when the position error calculation unit 23 calculates an error between the installation position of the radio telescope 12 and the position of the end point of the baseline length vector m corresponding to the current time, the movement observation point cross-correlation value calculation unit 24 calculates the position error. In order to eliminate this, an instruction to move the radio telescope 12 is transmitted to the track control unit 16 by radio or the like (step ST6).
Thereby, the track control unit 16 moves the track 14 in the direction in which the position error is eliminated, thereby transporting the radio telescope 12 to the end point position of the baseline length vector m corresponding to the current time (step ST7).

When the radio telescope 11 is transported by the track 13 to the position of the start point of the baseline length vector m corresponding to the current time, the radio telescope 11 observes the radio wave E ₁ (t) coming from the celestial body 2 and changes the radio wave E ₁ (t) to the radio wave E ₁ (t). A signal indicating a proportional voltage a ₁ E ₁ (t) is transmitted.
When the radio telescope 12 is transported by the track 14 to the position of the end point of the baseline length vector m corresponding to the current time, the radio telescope 12 observes the radio wave E ₂ (t) coming from the celestial body 2 and changes the radio wave E ₂ (t) to the radio wave E ₂ (t). A signal indicating a proportional voltage a ₂ E ₂ (t) is transmitted.

なお、電波望遠鏡１１，１２を移動してから、電波望遠鏡１１，１２が天体２から到来する電波Ｅ₁（ｔ），Ｅ₂（ｔ）を観測しているが、この観測は、常に移動し続けるトラッキング観測であってもよいし、移動、停止、観測を繰り返すドリフトトラッキング観測のどちらであってもよい。 The moving observation point cross-correlation value calculation unit 24 uses voltages a ₁ E ₁ (t) and a ₂ E ₂ (t that are proportional to the radio waves E ₁ (t) and E ₂ (t) transmitted from the radio telescopes 11 and 12. ) Is received, using the voltages a ₁ E ₁ (t) and a ₂ E ₂ (t) as shown in the following formula (7), the radio waves E ₁ (t) and E ₂ (t) The mobile observation point cross-correlation value C ₁ (τ), which is the cross-correlation value, is calculated (step ST8).

Although the radio telescopes 11 and 12 observe the radio waves E ₁ (t) and E ₂ (t) coming from the celestial body 2 after moving the radio telescopes 11 and 12, this observation always moves. It may be tracking observation that continues, or drift tracking observation that repeats movement, stop, and observation.

In the cross-correlation value integrating unit 25, the fixed observation point cross-correlation value calculating unit 17 calculates the fixed observation point cross-correlation value C ₀ (τ), and the moving observation point cross-correlation value calculating unit 24 is moving the moving observation point cross-correlation value C. _{When 1} (τ) is calculated, the fixed observation point cross-correlation value C ₀ (τ) and the moving observation point cross-correlation value C ₁ (τ) are integrated as shown in the following equation (8), and the integration result is obtained. Is output to the observation accuracy determination unit 26 (step ST9).
E = C ₀ (τ) + C ₁ (τ) (8)

When the observation accuracy determination unit 26 receives the observation data E from the cross-correlation value integration unit 25, the observation accuracy determination unit 26 calculates the observation accuracy of the observation data E.
That is, the observation accuracy determination unit 26 calculates the signal-to-noise ratio SN of the observation data E as an index indicating the observation accuracy of the observation data E (step ST10).
Specifically, the observation data E output from the cross-correlation value accumulating unit 25 is used as the cross power spectrum x (t) at time t, and the cross power spectrum x (t) is Fourier-transformed. By substituting (k) into the following equation (9), the signal-to-noise ratio SN of the observation data E is calculated.

ここで、ｋは時刻ｔにおけるフーリエ周波数を表し、ある天体２を観測した際に得られる相互相関値の振動周期（フリンジ周期）は赤緯によって一定であるから、周期成分は常に１つのフーリエ周波数に集中するため、信号対雑音比ＳＮは、上記の式（９）で定義することができる。
この実施の形態１では、信号対雑音比ＳＮを式（９）で定義しているが、信号強度と雑音強度の関係性を表せる指標であれば、式（９）に限るものではない。

Here, k represents the Fourier frequency at time t, and since the oscillation period (fringe period) of the cross-correlation value obtained when observing a certain celestial body 2 is constant according to declination, the periodic component is always one Fourier frequency. Therefore, the signal-to-noise ratio SN can be defined by the above equation (9).
In the first embodiment, the signal-to-noise ratio SN is defined by the equation (9), but it is not limited to the equation (9) as long as it is an index that can represent the relationship between the signal strength and the noise strength.

The observation accuracy determination unit 26 calculates the signal-to-noise ratio SN of the observation data E as an index indicating the observation accuracy of the observation data E, and compares the signal-to-noise ratio SN with a predetermined threshold level T ₁ ( Step ST11).
If the signal-to-noise ratio SN is higher than the threshold level T ₁ (SN ≧ T ₁ ), the observation accuracy determination unit 26 has a sufficiently high observation accuracy of the observation data E. Output to.
On the other hand, if the signal-to-noise ratio SN is lower than the threshold level T ₁ (SN <T ₁ ), the observation data E has not reached the required accuracy, so a command for recalculating the position error is given as a position time specifying unit. (Step ST12).

When receiving the command to recalculate the position error from the observation accuracy determination unit 26, the position time specifying unit 22 determines the installation positions of the radio telescopes 11 and 12 from the signals of the artificial satellites 18 and 19 as in the process of step ST4. While positioning, the current time is specified (step ST13).
When the position time specifying unit 22 specifies the installation positions of the radio telescopes 11 and 12 and the current time, the position error calculation unit 23 installs the radio telescope 11 and the base line corresponding to the current time, as in the process of step ST5. An error between the start point and the end point of the long vector m is calculated (step ST14).
When the position error calculation unit 23 calculates the position error, the moving observation point cross-correlation value calculation unit 24 gives an instruction to move the radio telescopes 11 and 12 so that the position error is eliminated, as in the process of step ST6. It transmits to the track control parts 15 and 16 by radio | wireless etc. (step ST15).
Accordingly, the track control units 15 and 16 move the tracks 13 and 14 in the direction in which the position error is eliminated, similarly to the process of step ST7, so that the start point and the end point of the baseline length vector m corresponding to the current time are obtained. The radio telescopes 11 and 12 are transported to the position (step ST16).

The moving observation point cross-correlation value calculation unit 24 transmits the radio waves E ₁ (t) and E transmitted from the radio telescopes 11 and 12 after the radio telescopes 11 and 12 are transported to the start point and end points of the baseline length vector m. _When voltages a ₁ E ₁ (t), a ₂ E ₂ (t) proportional to ₂ (t) are received, the voltages a ₁ E ₁ (t), a ₂ E ₂ ( Using t), the mobile observation point cross-correlation value C ₁ (τ), which is the cross-correlation value between the radio wave E ₁ (t) and the radio wave E ₂ (t), is calculated again (step ST17).

固定観測点相互相関値算出部１７により算出された固定観測点相互相関値Ｃ₀（τ）が最も正確な観測値であり、移動精度の問題から移動観測点相互相関値Ｃ₁（τ）が正確に算出されていないと、相関強度Ｒが低下する。 When the moving observation point cross-correlation value calculation unit 24 recalculates the moving observation point cross-correlation value C ₁ (τ), the correlation strength determination unit 27 calculates the fixed observation point cross-correlation value as shown in the following equation (10). The correlation strength R between the fixed observation point cross-correlation value C ₀ (τ) calculated by the calculation unit 17 and the moving observation point cross-correlation value C ₁ (τ) is calculated (step ST18).

The fixed observation point cross-correlation value C ₀ (τ) calculated by the fixed observation point cross-correlation value calculation unit 17 is the most accurate observation value, and the moving observation point cross-correlation value C ₁ (τ) is calculated from the problem of movement accuracy. If it is not accurately calculated, the correlation strength R decreases.

After calculating the correlation strength R between the fixed observation point cross-correlation value C ₀ (τ) and the moving observation point cross-correlation value C ₁ (τ), the correlation strength determination unit 27 calculates the correlation strength R and a predetermined threshold level T _2. Are compared (step ST19).
If the correlation strength R is equal to or higher than the threshold level T ₂ (R ≧ T ₂ ), the correlation strength determination unit 27 has calculated the moving observation point cross-correlation value C ₁ (τ) sufficiently accurately. A command for integrating the moving observation point cross-correlation value C ₁ (τ) to the observation data E is output to the cross-correlation value integrating unit 25 (step ST20).
As a result, the cross-correlation value accumulating unit 25 accumulates the moving observation point cross-correlation value C ₁ (τ) to the observation data E as shown in the following equation (11), and the observation data E that is the result of the accumulation. Is output to the observation accuracy determination unit 26 (step ST21).
E = E + C ₁ (τ) (11)

Thereafter, the process returns to step ST10, the observed data E signal-to-noise ratio SN is calculated, its signal-to-noise ratio SN by a predetermined threshold level T ₁ is compared (step ST11).
If the signal-to-noise ratio SN is equal to or higher than the threshold level T ₁ (SN ≧ T ₁ ), as described above, the observation data E is output to the astronomical luminance calculation unit 28, but the signal-to-noise ratio SN is If it is lower than the threshold level T ₁ (SN <T ₁ ), a command for recalculating the position error is output to the position time specifying unit 22 again (step ST12).

If the correlation strength R is lower than the threshold level T ₂ (R <T ₂ ), the correlation strength determination unit 27 has not accurately calculated the moving observation point cross-correlation value C ₁ (τ), and therefore the correlation error R A command for performing recalculation is output to the position time specifying unit 22.
Thereby, the processing of steps ST12 to ST19 is repeatedly performed.

式（１２）において、Ａ_Nはアンテナパターン、Ｉ_νは天体の輝度、（ξ，η）は天球上の位置、（ｕ，ｖ）はある基線長ベクトルｍが示す２次元の空間周波数を表している。 When the astronomical brightness calculation unit 28 receives the observation data E with high observation accuracy from the observation accuracy determination unit 26, the astronomical luminance calculation unit 28 performs Fourier transform on the observation data E to obtain the visibility v (ω) represented by the following equation (12). Calculate (step ST22).

In Expression (12), A _N represents an antenna pattern, I _ν represents the brightness of the celestial body, (ξ, η) represents a position on the celestial sphere, and (u, v) represents a two-dimensional spatial frequency indicated by a certain baseline length vector m. ing.

基線長ベクトルｍ（ｍ＝１，２，・・・，Ｍ）の個数Ｍ分だけ、ステップＳＴ１〜ＳＴ２３の処理を繰り返し実施することで、天体２の構造を詳細に捉えることができる。 After calculating the visibility v (ω), the celestial luminance calculation unit 28 calculates the spatial luminance distribution I _ν (ξ, η) of the celestial body 2 from the visibility v (ω) as shown in the following equation (13). Calculate (step ST23).

The structure of the celestial body 2 can be captured in detail by repeatedly performing the processes of steps ST1 to ST23 for the number M of the baseline length vectors m (m = 1, 2,..., M).

式（１４）において、Ｄは一次元方向の基線長、λは観測波長、Ωは地球の回転角速度（２π／８６１６４）、δは観測赤緯を表している。 Here, the applicant of the present application performs a simulation in order to grasp how much the signal-to-noise ratio SN is improved by compensating the position error.
FIG. 3 is an explanatory diagram showing a simulation result of drift tracking observation.
The vertical axis of FIG. 3 shows the signal-to-noise ratio SN of the integral data E defined by the equation (9), and the horizontal axis is corrected for the position error when the position error is not corrected. The case where there is no position error.
In this simulation, the baseline length at the time of observation is 1 km, the wavelength is 20 cm, the observation declination is 37 °, the noise given to the observation data is “Gaussian noise according to Normal Distribution N (0, Σ2), and the fringe amplitude is 1σ. It is said.
In the case of drift tracking observation in the one-dimensional direction of the red meridian, the fringe period T is expressed by the following formula (14).

In equation (14), D is the baseline length in the one-dimensional direction, λ is the observation wavelength, Ω is the rotational angular velocity of the earth (2π / 86164), and δ is the observation declination.

Normal GPS measurement accuracy is about 10 m. Assuming measurement accuracy of 10 m, the fringe cycle error is about 0.034 seconds. When the position error is not corrected, it is considered that the moving observation point cross-correlation value C ₁ (τ) includes such an error at random.
Assuming that 10 sets of moving observation point cross-correlation values C ₁ (τ) are obtained by moving observation in a state where the position error is not corrected, the signal-to-noise of the integration data E defined by equation (9) The ratio SN is about 10.9 dB.
On the other hand, when the position error is corrected by the method of the first embodiment, it is considered that the position error that can occur randomly at the time of movement is about 3 cm, and the error of the fringe period is about 0.0001 seconds. .
Therefore, when the position error is corrected, the signal-to-noise ratio SN of the integration data E of the 10 sets of moving observation point cross-correlation values C ₁ (τ) becomes 12.9 dB, and the position error is corrected. The signal-to-noise ratio SN is improved compared to the case where there is no signal.
In addition, it can be seen that the observation data E of the signal-to-noise ratio SN almost equal to the signal-to-noise ratio SN13.0 dB when there is no position error is obtained.

As apparent from the above, according to the first embodiment, after the radio telescopes 11 and 12 are transported by the tracks 13 and 14, the radio waves E ₁ (t) and E ₂ (t) are transmitted from the radio telescopes 11 and 12, respectively. The fixed observation point cross-correlation value calculation unit 17 calculates the fixed observation point cross-correlation value C ₀ (τ) that is the cross-correlation value between the radio wave E ₁ (t) and the radio wave E ₂ (t). A position error calculation unit 23 that calculates an error between the installation positions of the radio telescopes 11 and 12 measured by the position time specifying unit 22 and the start point and end point positions of the baseline length vector m corresponding to the current time; An instruction to move the radio telescopes 11 and 12 is wirelessly transmitted to the track control units 15 and 16 so that the position error calculated by the error calculation unit 23 is eliminated, and the radio telescopes 11 and 12 are transmitted by the tracks 13 and 14. After moving Telecommunications E ₁ (t) from the telescope 11, observations receives, moving the observation point the cross-correlation value is the cross-correlation value of the radio wave E ₁ (t) and Telecommunications E ₂ (t) of E ₂ (t) A moving observation point cross-correlation value calculation unit 24 for calculating C ₁ (τ) is provided, and the cross-correlation value accumulating unit 25 calculates the fixed observation point cross-correlation value C ₀ calculated by the fixed observation point cross-correlation value calculation unit 17. Since (τ) and the moving observation point cross-correlation value C ₁ (τ) calculated by the moving observation point cross-correlation value calculation unit 24 are integrated, observation can be performed in various configurations, There is an effect that the brightness of the celestial body can be calculated with high accuracy.
That is, according to the first embodiment, since integration for a long time is possible, a small aperture antenna having a lower light collecting power than a large aperture antenna is used as an element of a radio telescope. However, highly accurate observation data E can be acquired. Further, it can be realized with a small aperture antenna, and there is no restriction on the installation position, so that there is an advantage that a large space is not required.

Further, according to the first embodiment, the observation accuracy determination unit 26 calculates the observation accuracy of the observation data E that is the cross-correlation value integrated by the cross-correlation value integration unit 25, and the observation accuracy is a predetermined accuracy. If it is above, the observation data E is output to the celestial luminance calculation unit 28, and if the observation accuracy does not satisfy the predetermined accuracy, a command for recalculating the position error is output to the position time specifying unit 22. Since the command for integrating the mobile observation point cross-correlation value C ₁ (τ) recalculated by the mobile observation point cross-correlation value calculating unit 24 with the observation data E is output to the cross-correlation value integrating unit 25, There is an effect that the integration can be performed until the observation data E having sufficiently high observation accuracy is obtained.

Further, according to the first embodiment, the correlation strength determination unit 27 calculates the fixed observation point cross-correlation value C ₀ (τ) calculated by the fixed observation point cross-correlation value calculation unit 17 and the moving observation point cross-correlation value. The correlation strength R with the mobile observation point cross-correlation value C ₁ (τ) calculated again by the calculation unit 24 is calculated. If the correlation strength R is equal to or higher than a predetermined strength, the mobile observation point cross-correlation value calculation unit 24 is calculated. A command for accumulating the mobile observation point cross-correlation value C ₁ (τ) calculated again by the observation data E is output to the cross-correlation value accumulating unit 25, and if the correlation strength R does not satisfy the predetermined strength, the position A command for recalculating the error is output to the position time specifying unit 22 so that the moving observation point cross-correlation value C ₁ (τ) is repeatedly calculated by the moving observation point cross-correlation value calculating unit 24. So move is calculated accurately enough Survey point correlation value C ₁ (τ) will be able to integrate only the observed data E, an effect that can increase the observation accuracy of observation data E.

  In the first embodiment, when the satellite signal receivers 20 and 21 receive the signal from the artificial satellite 18, the position time specifying unit 22 determines the position of the installation of the radio telescopes 11 and 12 and the current time from the received signal. However, the current time information may be sent as a frequency standard to a device that requires synchronization between the radio telescopes 11 and 12 such as “Phase Lock Oscillator”.

Embodiment 2. FIG.
In the first embodiment, the calculation of the spatial luminance distribution I _v (ξ, η) of the celestial body 2 from the radio waves observed by the two radio telescopes 11 and 12 has been described. A plurality of 12 sets may be prepared, and the spatial luminance distribution I _v (ξ, η) of the celestial body 2 may be calculated from the radio waves observed by the multiple sets of radio telescopes 11 and 12. For example, when M sets of radio telescopes 11 and 12 are prepared, the number of radio telescopes is 2 × M.
In this case, for example, the constituent elements (the radio telescopes 11 and 12, the tracks 13 and 14, the track controllers 15 and 16, the fixed observation point cross-correlation value calculating unit 17, the celestial luminance calculating unit 28 of the celestial luminance calculating apparatus 3 are excluded. Satellite signal receivers 20 and 21, position time specifying unit 22, position error calculating unit 23, moving observation point cross-correlation value calculating unit 24, cross-correlation value accumulating unit 25, observation accuracy determining unit 26, and correlation strength determining unit 27). As many as M pieces of baseline length vectors m may be prepared, and N components may perform processing in parallel as shown in FIG. 4 (see FIG. 2A, FIG. 2 only for the number M of baseline length vectors m). 2B steps ST2 to ST21 are processed in parallel). M celestial luminance calculation units 28 may be prepared, and the M celestial luminance calculation units 28 may perform processing in parallel.
Thus, if the M baseline length vectors m are simultaneously observed, the effect of suppressing the time variation factor of the system that may affect the mosaicing observation can be suppressed.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Baseline length vector calculation part, 2 Astronomical object, 3 Astronomical brightness calculation apparatus, 11 Radio telescope (1st radio telescope), 12 Radio telescope (2nd radio telescope), 13,14 track, 15,16 track control part ( Telescope transport means), 17 fixed observation point cross-correlation value calculation section (first cross-correlation value calculation means), 18, 19 artificial satellite, 20, 21 satellite signal receiver (position error calculation means), 22 position time specifying section (Position error calculation means), 23 Position error calculation section (position error calculation means), 24 Moving observation point cross correlation value calculation section (second cross correlation value calculation means), 25 Cross correlation value integration section, 26 Observation accuracy determination 27, correlation strength determination unit (observation data output means), 28 celestial brightness calculation unit (celestial brightness calculation means).

Claims (5)

A first radio telescope that observes radio waves coming from celestial bodies;
A second radio telescope that observes radio waves coming from celestial bodies;
A baseline length vector indicating the installation position of the radio telescope that changes over time is input, the first radio telescope is transported to the position of the start point of the baseline length vector corresponding to the current time, and the baseline length Telescope transport means for transporting the second radio telescope to the position of the end point of the vector;
After the first and second radio telescopes are transported by the telescope transport means, a first mutual correlation value for calculating a cross-correlation value between the observation radio waves of the first radio telescope and the observation radio waves of the second radio telescope is calculated. Correlation value calculating means;
A signal transmitted from a satellite is received, the installation positions of the first and second radio telescopes are specified, the installation positions of the first and second radio telescopes, and the baseline length vector corresponding to the current time A position error calculating means for calculating an error between the start point and the end point of
An instruction to move the first and second radio telescopes is output to the telescope transport means so that the position error calculated by the position error calculation means is eliminated, and the first radio telescope after the movement is observed. Second cross-correlation value calculating means for calculating a cross-correlation value between the radio wave and the observation radio wave of the second radio telescope;
The cross-correlation value calculated by the first cross-correlation value calculating means and the cross-correlation value calculated by the second cross-correlation value calculating means are integrated, and observation data that is the cross-correlation value after the integration is output. Observation data output means;
An astronomical luminance calculation device comprising: astronomical luminance calculation means for calculating the luminance of an astronomical object from observation data output from the observation data output means. Observation data output means
When the observation accuracy of the observation data is calculated and the observation accuracy is equal to or higher than a predetermined accuracy, the observation data is output to the celestial luminance calculation means,
If the observation accuracy is less than the predetermined accuracy, a command for recalculating the position error is output to the position error calculation means, and the cross-correlation value calculated again by the second cross-correlation value calculation means is used as the observation data. The astronomical brightness calculation apparatus according to claim 1, wherein Observation data output means
The correlation strength between the cross-correlation value calculated by the first cross-correlation value calculation means and the cross-correlation value calculated again by the second cross-correlation value calculation means is calculated, and the correlation strength is not less than a predetermined strength. For example, while the cross-correlation value calculated again by the second cross-correlation value calculating means is added to the observation data,
If the correlation strength does not reach the predetermined strength, a command for recalculating the position error is output to the position error calculation means, and the cross correlation value calculation processing by the second cross correlation value calculation means is repeatedly performed. The astronomical brightness calculation apparatus according to claim 2.   When a plurality of baseline length vectors are provided, a plurality of first and second radio telescopes, telescope transport means, first and second cross-correlation value calculation means, position error calculation means, and observation data output means are prepared, The first and second radio telescopes, the telescope transporting means, the first and second cross-correlation value calculating means, the position error calculating means, and the observation data output means are processed in parallel. The celestial brightness calculation apparatus according to claim 1, wherein the celestial brightness calculation apparatus is implemented. The telescope transport means inputs a baseline length vector indicating the installation position of the radio telescope that changes with time, and transports the first radio telescope to the position of the start point of the baseline length vector corresponding to the current time. A telescope transport step for transporting the second radio telescope to the position of the end point of the baseline length vector;
After the first and second radio telescopes are transported in the telescope transporting step, the first cross-correlation value calculating means determines between the observed radio waves of the first radio telescope and the observed radio waves of the second radio telescope. A first cross-correlation value calculating step for calculating a cross-correlation value;
The position error calculation means receives a signal transmitted from the satellite, identifies the installation positions of the first and second radio telescopes, and determines the installation positions of the first and second radio telescopes and the current time. A position error calculation step of calculating an error between the start point and the end point of the corresponding baseline length vector;
The second cross-correlation value calculation means outputs an instruction to move the first and second radio telescopes to the telescope transport means so that the position error calculated in the position error calculation step is eliminated. A second cross-correlation value calculating step of calculating a cross-correlation value between the observation radio waves of the first radio telescope and the observation radio waves of the second radio telescope later;
The observation data output means integrates the cross-correlation value calculated in the first cross-correlation value calculation step and the cross-correlation value calculated in the second cross-correlation value calculation step. An observation data output process for outputting certain observation data;
An astronomical luminance calculation method, comprising: an astronomical luminance calculation step in which astronomical luminance calculation means calculates the luminance of an astronomical object from the observation data output in the observation data output step.

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