JP2003298915A - Celestial body imaging/image distribution system and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a celestial body imaging/image distribution system for controlling an astronomical telescope with high performance having a CCD camera for imaging a celestial body from a remote place so as to image a desired celestial body and acquire a clear image of the celestial body. <P>SOLUTION: The remote astronomical telescope control system is provided with: a server having a database for storing identifiers of the types and/or names of celestial bodies and exposure times for the CCD camera in cross- reference with the identifiers; and a camera controller for acquiring an exposure time for imaging a celestial body from the database and controlling the CCD camera. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an astronomical observation system and an astronomical observation method. In particular, an astronomical object that delivers an astronomical image after remote control of an astronomical telescope installed in an astronomical observation facility via a network, capturing and capturing a desired astronomical object, and making corrections to clarify the captured image. The present invention relates to an imaging / image distribution system and a method thereof.

[0002]

2. Description of the Related Art Astronomical observation facilities are usually installed in places away from urban areas such as in the mountains. In order to perform astronomical observation, you should visit a astronomical observation facility at a remote location, drive the astronomical telescope to capture the desired celestial body, and image the celestial body.
Astronomical observation is performed by keeping the captured image as a record.

However, in order to drive the astronomical telescope, introduce a desired astronomical object, and capture a clear image, not only knowledge about astronomical objects but also astronomical telescopes for imaging astronomical objects, cameras mounted on the astronomical objects, etc. Various specialized knowledge is required such as knowledge about the optical system, correction of image non-uniformity and noise caused by defects of the optical system and elements, and the like.

For example, when a celestial body is imaged using a camera of a charge-coupled device that converts light into an electric signal, if the CCD camera is exposed for a long time, the CCD is exposed.
The generated heat causes noise in the image. Therefore, in order to detect the faint light of a planet or the like with the cooled CCD camera, it is necessary to control the temperature of the CCD camera to be below a certain temperature. Further, there is a case where a part of the chip that constitutes the CCD has a defect, and the correction is necessary.

The amount of light reaching the camera for each wavelength varies depending on the optical system used, and the reflectance for each wavelength varies depending on the material of the plating and the presence or absence of the coating. In addition, the material of the correction lens may have an influence. For this reason,
Correction of these optical systems is also necessary.

In many cases of imaging celestial bodies, the celestial body to be imaged rarely comes to the center of the image. In other words, the celestial body appears in all parts of the image, vertically and horizontally. In order to capture an astronomical object and obtain a clear astronomical image, a high degree of specialized knowledge and a great deal of labor are required.

[0007]

Therefore, the object of the present invention is to enable anyone to easily control a high-performance astronomical telescope from a remote location via a network to image a clear astronomical object.
The present invention provides a system that can be acquired and a method thereof.

[0008]

According to the present invention, there is provided an astronomical telescope having a CCD camera for capturing an image of an astronomical object, a driving device for driving the astronomical telescope so as to supplement the astronomical telescope according to an imaging command, and the imaging command via a network. Means for receiving and transmitting to the drive device, and the C
In an astronomical imaging / image distribution system including means for accumulating images captured by a CD camera and sending the images to a computer that has issued the imaging command, an identifier of the type and / or name of an astronomical object, and the identifier. A server having a database for accumulating the exposure time of the associated CCD camera, and a camera control device for controlling the CCD camera by acquiring the exposure time at the time of celestial image pickup of the CCD camera from the database. A database is created for the optimal imaging time (exposure time of the CCD camera) of the celestial object that is the imaging target for each type and / or name of the celestial object, and the exposure that matches the conditions at the time of imaging is acquired from this database and the CCD camera is controlled. By doing so, anyone can easily image a clear celestial body.

The server further includes means for performing matching processing on the celestial body image. When the celestial body is imaged, it is automatically adjusted so that the celestial body that is the imaging target appears in the center of the image.

The database includes a flat correction management table containing correction values for performing flat correction of the celestial object image captured by the CCD camera. This is for correcting the nonuniformity of light caused by the optical system characteristics of the astronomical telescope.

The database includes a dark correction management table containing correction values when performing dark correction on the celestial object image captured by the CCD camera. This is data for correcting a noise image due to a device defect of the CCD camera, dark current, and the like.

The CCD camera is a cooled CCD camera. As a result, noise such as dark current during exposure can be significantly reduced.

The server flat-corrects the celestial image,
And / or means for dark correction. Flat correction value and dark correction value are extracted from the database and automatically corrected.

The present invention receives an astronomical image pickup command from a client computer connected via a network, drives an astronomical telescope equipped with a cooling CCD camera so that the celestial body of the image pickup command can be introduced, and picks up an image. A celestial body imaging / image distribution method for transmitting the captured celestial body image to the computer via a network, wherein the cooling C
From the database in which the exposure time of the CD camera is stored in association with the celestial type and / or name identifier,
A correction value for acquiring the exposure time at the time of astronomical imaging, imaging the astronomical object by the cooled CCD camera, and correcting the non-uniformity of the image due to the characteristics of the optical system of the lens mounted on the astronomical telescope, and CCD camera element defect and /
Alternatively, a flat correction value and / or a dark correction value is acquired from a correction value and a database that is accumulated for correcting noise caused by dark current, the captured image is corrected by the correction value, and the correction is performed by the computer. The celestial body image. Thereby, anyone can easily operate a high-performance astronomical telescope installed at a remote place to clearly capture a desired celestial body and acquire the celestial body image.

The designation of the imaged celestial body in the computer is performed by designating a desired celestial body as an XY coordinate value from the all-astronomical chart reproduced on the monitor of the computer by a web browser, and the introduction of the celestial body is performed by the XY coordinate value. Is converted into declination / right ascension data by the equirectangular projection method and / or the equirectangular projection method. This allows anyone to easily image a celestial object from a computer connected to an open network.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an astronomical image capturing system 1 which is an embodiment of the present invention. The astronomical telescope 3 includes an equatorial mount 10, a cooled CCD camera 11,
Equipped with a boundary cylinder and a stand. The astronomical telescope 3 is usually installed in the astronomical observation dome 2.

The astronomical observation dome has a structure that rotates by power. There is a slit for astronomical observation on the roof, and astronomical observation is performed through this slit. The slit has a structure that opens and closes by power.

The astronomical telescope 3 moves in the direction of the supplementary celestial body by the RA and declination drives of the equatorial mount 10. The client computer 21 shown in FIG. 1 is connected via an open network such as the Internet,
It is connected to the astronomical observation server 14 having functions such as acceptance of astronomical imaging commands and distribution of captured images. The astronomical observation server 14 is connected to the dome opening / closing control device 12 and the astronomical telescope control device 13 through the network in the astronomical observation dome 2, and gives control commands to these.

In the astronomical image pickup system shown in FIG. 1, the astronomical telescope 3 can be controlled from the client computer 21 to image the astronomical object. When the client computer 21 accesses the astronomical observation server 14, the all-astronomical map is displayed on the monitor of the client computer 21 by the web browser.

FIG. 2 shows an example of the astronomical observation menu displayed on the monitor of the client computer 21. The user selects an celestial object from the all-astronomical map reproduced on the monitor by clicking the celestial object to be observed with the mouse. You can select the celestial object from the pull-down menu.

FIG. 3 is a flow chart of the celestial object imaging reservation. When the celestial body is selected and the date and time when the celestial body is imaged are input (S1), the XY coordinates of the celestial body designated on the monitor are converted into declination / right longitude data of the celestial body in the celestial body observation server 14 (S2).

The conversion from XY coordinates to declination / right ascension data is performed using the equirectangular cylindrical projection method, x = (α-α ₀ ) + A
y = (δ−δ ₀ ) + B, or an equation using the equirectangular projection, x = C (π / 2−δ) COS (α−α ₀ ) + D y
= E (π / 2−δ) SIN (α−α ₀ ) + F (S2). In the formula, α is the star's right longitude, δ is the star's declination, α ₀ is the value corresponding to the center of the star chart on the monitor, and δ ₀ is the center declination of the star chart on the monitor. It is a corresponding value.

When the coordinate conversion is completed, the celestial object to be imaged and the imaging date and time are confirmed (S3). If there is no mistake, the observation date and time, the observation purpose, the name of the observer, etc. are input and the imaging of the celestial object is reserved. Is completed (S4).

The astronomical observing server 14 moves the astronomical telescope 13 in a direction to capture the celestial body, based on the declination / right longitude data of the celestial body which is the object of imaging designated by the client computer 21. Along with this, the dome opening / closing control device 12 moves the slit of the dome so as to match the direction of the astronomical telescope.

When the celestial body is imaged, the celestial body to be imaged rarely comes to the center of the image, and the celestial body image is often photographed at all positions in the vertical and horizontal directions with respect to the entire image.
Since parts other than the celestial body image are unnecessary, matching processing is performed so that the celestial body image is located at the center of the image (S6).

FIG. 5 shows a flowchart of the matching process. Astronomical telescope 3
When is captured (S20), the image is compared with the star map (S21). Next, the center coordinates of the image are determined (S22),
The correction value is calculated so that the celestial body is at the center of the image (S2
3), the correction command is issued to the astronomical telescope control device 13, and the astronomical telescope 3 is driven to correct the position (S24).

In FIG. 1, the astronomical telescope 3 is a cooling CC.
A D camera 11 is provided. The cooled CCD camera 11 is a camera that images the celestial body captured by the astronomical telescope. In the embodiment of the present invention, the camera for astronomical imaging is a cooling C
Use a CD camera.

The CCD camera uses a charge-coupled device capable of converting light into an electric signal. A CCD camera used for astronomical observation needs to have high efficiency of conversion from light to electricity in order to capture faint light.

When exposed at ordinary temperature for a long time,
Noise occurs and the image quality deteriorates. Noise can be reduced by cooling the CCD element. Therefore, cooled CCD
Use camera 11

The cooling CCD camera controller 15 is a cooling C
The exposure time (shutter opening / closing) of the CD camera 11 is controlled. To image a celestial body, it is necessary to change the exposure time according to the characteristics of the celestial body that is the imaging target (type of celestial body, class, etc.). The exposure time is closely related to dark current, which is one of the causes of noise. Therefore, the characteristics of the celestial body that is the imaging target,
The exposure time and the cooling temperature are interrelated. This is one of the reasons that a great deal of time and specialized knowledge are required to obtain a clear celestial image.

The exposure time controlled by the cooled CCD camera controller 15 is obtained from the database of the camera control / image server 16. The database stores, for each type of the cooled CCD camera 15 mounted on the astronomical telescope 3, the type and name of the celestial body, the date and time when the image is taken, and the optimum exposure time and cooling temperature corresponding to binning.

FIG. 6 shows an example of a database structure provided in the camera control / image server.
Each cooled CCD camera has solid characteristics. Therefore, a database is constructed for each cooled CCD. FIG. 6 shows an example of two CCD cameras, but the present invention is not limited to this.

Further, the exposure time varies depending on the type of celestial object to be imaged, for example, nebula, star cluster, planet, date and time of image pickup, and the like. Therefore, the database structure corresponds to these combinations. Further, binning may be performed depending on the celestial body that is the imaging target, and this can be dealt with.

In FIG. 3, the cooled CCD camera 1 is operated by the database of the camera control / image server 16 described above.
The imaging conditions such as the exposure time of 1 are determined (S7), and the cooling C
The cooling of the CD camera is started (S8). The object is cooled to a predetermined temperature (S9), and when the imaging time comes, the celestial object is imaged (S10).

FIG. 4 shows a flowchart for correcting a captured celestial body image. The captured celestial image is subjected to image processing (dark correction, flat correction) (S1
1) is registered in the camera control / image server (S12),
Transferred to the client computer 21 (S1
3). The image taken by the CCD camera has noise and CC
There is an unnecessary component due to uneven sensitivity of D or dust attached to the lens. The processing for removing this is the dark correction in the image processing (S11).

In general, a CCD camera sold on the market generates noise at each cooling temperature. This noise will appear the same if the exposure time and cooling temperature are the same. In order to subtract this noise, the dark frames taken with the shutter closed and the same exposure time and the same cooling temperature as the astronomical object taken are made into a database. By removing such unnecessary components, the captured astronomical image can be made clear.

The dark frame database may be calculated from this theory since the way dark noise appears depends on the exposure time and the cooling temperature. Alternatively, the exposure time and cooling temperature may be determined in advance and a large number of dark frames may be photographed and stored in a database. In addition, different CCD cameras produce different noises from different manufacturers, and even the same manufacturer varies from lot to lot. Therefore, a dark frame correction value is stored in a database for each CCD camera. FIG. 7 shows an example of the database structure of the dark correction described above.

Flat correction is a process for performing sensitivity calibration. This is a process for correcting the difference in sensitivity between pixels of the CCD chip, the difference in light amount on the chip due to vignetting (peripheral dimming), and the difference in sensitivity for each wavelength. In the case of spectroscopic observation, a spectroscopic standard star (a star whose spectrum is already known)
Or use the internal light source (halogen lamp) to build a flat correction database. The flat correction depends on the entire optical system such as the type of lens mounted on the astronomical telescope. FIG. 8 shows an example of a database structure of flat correction values for each optical system.

FIG. 9 shows a method of correcting an astronomical image captured using a dark frame. From the captured celestial body image (A), a dark frame image (B) that matches the photographing condition is extracted from the database, and the celestial body image (A) is subtracted from the dark frame image (B) to correct it.

FIG. 10 shows a method for correcting an astronomical image captured using a flat frame. From the captured celestial body image (A), a flat frame image (C) that matches the photographing condition is extracted from the database, and the flat frame image (C) is subtracted from the celestial body image (A) to correct.

FIG. 11 is a block diagram of the cooling CCD camera control device 15 for controlling the exposure time, temperature and the like of the cooling CCD camera 11. The control circuit 43 receives a celestial object imaging command from the CCD camera control / image server 16.

The control circuit 43 controls the opening and closing of the shutter 31 so as to match the exposure time. In addition, the Peltier element 34 allows the CCD to pass through the heating plate 33 to a predetermined temperature
Cool 32.

The astronomical image captured by the CCD 32 is
After being converted into digital data by the AD conversion circuit 41 and once stored in the image buffer 42, it is sent to the camera control / image server 16. In the camera control / image server, the celestial object image is subjected to the above-described image processing, registered, and transferred to the client computer 20.

【The invention's effect】

As described above, according to the present invention, even a person having no specialized knowledge about astronomy can observe astronomical objects and obtain clear astronomical images by using a high-performance astronomical telescope installed at a remote place. Can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram showing an astronomical imaging / image distribution system according to the present invention.

FIG. 2 is an example of a top menu of astronomical observation that appears when a server is accessed from a client computer.

FIG. 3 is a diagram showing a flowchart of astronomical imaging reservation.

FIG. 4 is a diagram showing a flowchart of image processing of a captured celestial object and transfer of an image to a client computer.

FIG. 5 is a diagram showing a flowchart of matching processing.

FIG. 6 is a diagram showing an example of a structure of a database provided in a camera control / image server.

FIG. 7 is a diagram showing an example of a database structure for dark correction.

FIG. 8 is a diagram showing an example of a database structure of flat correction.

FIG. 9 is a diagram showing a method of correcting an astronomical image captured using a dark frame.

FIG. 10 is a diagram showing a method of correcting an astronomical image captured using a flat frame.

FIG. 11 is a block diagram of the cooled CCD camera controller 15.

[Explanation of symbols]

1 Astronomical imaging system 2 astronomical dome 3 Astronomical telescope 11 Cooled CCD camera 12 Dome opening and closing control device 13 Astronomical telescope control device 14 Astronomical observation server 15 Cooling CCD camera controller 16 Camera control / image server 20 Internet 21 client computer

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C022 AB17 AB37 AB62 AB65 AC42                       AC43 AC69                 5C024 AX01 BX04 CX03 CX24 CX27                       CX33 CX54 EX26                 5C054 CD03 CE16 DA09 HA00

Claims (8)

[Claims] 1. An astronomical telescope equipped with a CCD camera for capturing an image of an astronomical object, a drive device for driving the astronomical telescope so as to complement the astronomical telescope according to an imaging command, and the imaging command being accepted via a network and sent to the driving device. Means and
A celestial body image pickup / image distribution system including means for accumulating an image picked up by the CCD camera according to the image pickup command and sending the image to a computer that issued the image pickup command, wherein an identifier of a kind and / or a name of the celestial body And a server having a database that stores the exposure time of the CCD camera associated with the identifier, and a camera control device that controls the CCD camera by acquiring the exposure time when an astronomical object is imaged from the database. An astronomical imaging and image distribution system characterized by being equipped. 2. The celestial body image pickup / image distribution system according to claim 1, wherein the server further comprises means for performing a matching process on the photographed celestial body image. 3. The database according to claim 1, wherein the database includes a flat correction management table including a correction value for performing flat correction of a captured celestial image. Celestial body imaging and image distribution system. 4. The database according to claim 1, further comprising a dark correction management table including a correction value when performing dark correction on a captured celestial image. Celestial body imaging and image distribution system. 5. The astronomical imaging / image distribution system according to claim 1, wherein the CCD camera is a cooled CCD camera. 6. The astronomical imaging system according to claim 1, wherein the server includes means for flat correction and / or dark correction of the astronomical image. 7. An astronomical imaging command from a computer connected via a network is received, an astronomical telescope equipped with a cooling CCD camera is driven so that the astronomical object of the imaging command can be introduced, and the astronomical object is imaged. A celestial body imaging / image distribution method for sending the photographed celestial body image to the computer via a network, wherein a database in which the exposure time of the cooling CCD camera is accumulated in association with the celestial body type and / or name identifier From the above, the exposure time at the time of celestial body imaging is acquired, the celestial body is imaged by the cooled CCD camera, and the flatness correction for correcting the nonuniformity of the image due to the characteristics of the optical system of the lens mounted on the astronomical telescope is performed. Accumulation of a correction value and a correction value of dark correction for correcting noise caused by a defect in the CCD camera and / or dark current A correction value for flat correction and / or dark correction is acquired from a stored database, the captured celestial image is corrected with the correction value, and the corrected celestial image is sent to the computer. Imaging and image distribution method. 8. The designation of the imaged celestial body in the computer is performed by designating a desired celestial body as an XY coordinate value from an all-astronomical chart reproduced by a web browser on a monitor of the computer, and the introduction of the celestial body is performed in the XY coordinate system. 8. The celestial body image pickup / image distribution method according to claim 7, wherein the value is converted into declination / right ascension data by an equirectangular projection and / or an equidistant azimuth projection.