KR20220059258A - Method for correcting roll angle of solar coronagraphic image and apparatus thereof - Google Patents

Abstract

Disclosed are a method for correcting a roll angle of a solar coronagraph observation image and a device thereof. In the method, first, an observation image is converted into an image of the motion of the star according to the change in azimuth, and the Fourier power for the phase speed is calculated by performing the discrete Fourier transform on the motion image of the star according to the change in azimuth. Then, using the calculated Fourier power, the speed of the star according to the azimuth is calculated. Finally, by rotating the observation image based on the azimuth angle at which the speed of the star is minimum, roll angle correction for the observation image can be performed accurately.

Description

Method and apparatus for correcting roll angle of solar coronagraph observation image

The present invention relates to a method and apparatus for correcting roll angle of a solar coronagraph observation image.

In order to observe faint light near the sun, such as a corona, light from the sun must be blocked. An optical system for implementing this is referred to as a coronagraph.

In order to accurately analyze the observation data, especially the observation image, by using the corona graph, it is necessary to know the position of the sun and the direction of the rotation axis (or the Earth's orbital plane). However, when observing through a coronagraph, it is difficult to determine the exact coordinates and polar axis of the sun because the observation is performed while the sun is covered.

As a method to overcome this, a method such as a comparison of the relative positions of a star and the sun whose coordinates are known in detail is being used. However, according to this method, for hundreds of thousands of images, it is necessary to detect a star, and it is necessary to determine the coordinates of the star at the corresponding time and observation point. However, not only is it difficult to detect stars using coronagraph observations, including signals from galaxies, planets, and high-energy particles, but efforts are also being made to match the detected stars to known stars. And, these tasks are limited in batch processing, which is essential for large-scale data analysis.

Accordingly, various problems such as missetting of the north direction of the sun may occur due to a large-capacity solar coronagraph image having uncertainty of coordinate information, for example, a solar coronagraph image having an inaccurate roll angle.

The problem to be solved by the present invention is to provide a method and apparatus for correcting the roll angle of a solar coronagraph observation image that can be batch-processed and can determine the north direction of the sun even when the roll angle of the solar coronagraph image is uncertain.

The characteristic configuration of the present invention for achieving the object of the present invention as described above and for realizing the characteristic effects of the present invention to be described later is as follows.

According to one aspect of the present invention, there is provided a method of correcting the roll angle of an observation image of a solar coronagraph, the method comprising:

Converting an observation image into an image of a motion of a star according to an azimuth change, performing a discrete Fourier transform on the image of a motion of a star according to the change of azimuth to calculate a Fourier power for a phase velocity, the calculated Fourier power calculating the speed of the star according to the azimuth using

According to another aspect of the present invention, there is provided an apparatus for correcting the roll angle of an observation image of a solar coronagraph, the apparatus comprising:

a processor, a memory, a communicator and an input/output device, wherein the communication device communicates with an external device, the input/output device displays information or outputs a voice to the outside, receives information or commands input from the outside, the memory is configured to store a set of codes, wherein the code is a process for converting the observed image into an image of a motion of a star according to an azimuth change, and a discrete Fourier transform on the image of a motion of a star according to the change of azimuth by performing a discrete Fourier transform a process of calculating the Fourier power with respect to the phase velocity, a process of calculating the speed of a star according to an azimuth using the calculated Fourier power, and a process of rotating the observed image based on the azimuth at which the speed of the star is minimized; used to control the processor to execute.

According to another aspect of the present invention, there is provided an apparatus for correcting the roll angle of an observation image of a solar coronagraph, the apparatus comprising:

A coordinate transformation unit that converts an observation image of a Cartesian coordinate system into an observation image of a corresponding polar coordinate system, converting the observed image of the polar coordinate system converted by the coordinate transformation unit into an observation image displayed by time and height based on an azimuth An azimuth reference coordinate transform unit, a discrete Fourier transform unit that performs a discrete Fourier transform on the image transformed by the azimuth reference coordinate transform unit, and the phase velocity using the discrete Fourier transform result performed by the discrete Fourier transform unit A Fourier power calculator for calculating Fourier power, a speed calculator for calculating a speed of a star according to an azimuth using the Fourier power calculated by the Fourier power calculator, a minimum among the speeds of the stars calculated by the speed calculator and a minimum azimuth calculation unit for calculating an azimuth corresponding to the speed of a star, and an image rotation processing unit for rotating the observed image based on the azimuth calculated by the minimum azimuth calculation unit.

According to the present invention, the amount of work can be reduced by using polar coordinate system transformation, discrete Fourier transformation, etc. that can be batch processed without requiring tasks that are difficult to batch process, such as star detection and relative position comparison, and are excellent in practical aspects.

In addition, even when the roll angle of the solar coronagraph image is uncertain, it is possible to set the northern direction of the sun, thereby contributing to the production of more accurate scientific knowledge.

1 is a schematic flowchart of a method for correcting a roll angle of a solar coronagraph observation image according to an embodiment of the present invention.
2 is a diagram illustrating an example of an observation image on a Cartesian coordinate system obtained through solar coronagraph observation.
3 is a diagram in which the observation image shown in FIG. 2 is converted into an observation image in a polar coordinate system.
FIG. 4 is a view in which motion parts of some stars among the observed images shown in FIG. 3 are time-accumulated.
5 is a view illustrating an image after converting the observation image shown in FIG. 3 into an observation image displayed by time and height based on an azimuth.
FIG. 6 is a diagram illustrating an example of an image showing a result of calculating a Fourier power with respect to a phase velocity from a 2D discrete Fourier transform performed on the observed image of FIG. 5 .
7 is a diagram illustrating a speed graph of a star according to an azimuth change calculated using the Fourier power shown in FIG. 6 .
FIG. 8 is a view illustrating an observed image after rotating the observed image of the Cartesian coordinate system shown in FIG. 2 by a difference of 180 degrees from an azimuth at which the speed of a star is the minimum.
9 is a diagram illustrating a schematic configuration of an apparatus for correcting a roll angle of a solar coronagraph observation image according to an embodiment of the present invention.
10 is a diagram illustrating a schematic configuration of an apparatus for correcting a roll angle of a solar coronagraph observation image according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be implemented in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, terms such as “…unit”, “…group”, and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software. there is.

The devices described in the present invention are composed of hardware including at least one processor, a memory device, a communication device, and the like, and a program to be executed in combination with the hardware is stored in a designated place. The hardware has the configuration and capability to implement the method of the present invention. The program includes instructions for implementing the operating method of the present invention described with reference to the drawings, and executes the present invention in combination with hardware such as a processor and a memory device.

In the present invention, for the image of the observation data observed by the coronagraph, when the image that is well aligned according to the Cartesian coordinate system is converted to the polar coordinate system, the azimuth to the rotation axis of the sun is 90 degrees, and the The motion moves from left to right of the image in the horizontal direction, based on the fact that the motion of the star has a minimum velocity at 180 degrees in azimuth.

Hereinafter, a method of correcting the roll angle of a solar coronagraph observation image according to an embodiment of the present invention will be described.

1 is a schematic flowchart of a method for correcting a roll angle of a solar coronagraph observation image according to an embodiment of the present invention.

Referring to FIG. 1 , first, an observation image in a Cartesian coordinate system obtained through solar coronagraph observation is converted into an observation image in a polar coordinate system ( S100 ). For example, an example of an observation image on a Cartesian coordinate system obtained through solar coronagraph observation is shown in FIG. 2 .

2 , the observation images on the Cartesian coordinate system obtained through solar coronagraph observation are images for representing the movement of stars in the Cartesian coordinate system, and in these images, the solid line 10 displayed parallel to the x-axis is y It is a line marked parallel to the direction of the equator at any position on the axis, and the portion indicated by a circle 20 represents the stars in the Pleiades cluster that are approximately 400 light-years away from the Sun 30 .

Referring to FIG. 2 , it can be seen that the motions of the stars in the circle 20 are not parallel to the solid line 10 in the observation images. That is, this shows that the roll angle of the observed image is incorrect, and correction of the roll angle should be performed. Therefore, the above-described step S100 is preceded for correction of the roll angle, and an example of the observed image after converting the observed image on the Cartesian coordinate system shown in FIG. 2 into a polar coordinate system is shown in FIG. 3, and FIG. An enlarged view of some observation images of FIG. 3 is shown. 3 and 4 , it can be seen that the observation image of the polar coordinate system is displayed by the azimuth and the height.

Meanwhile, converting the observation image of the Cartesian coordinate system into the observation image of the polar coordinate system in step S100 may be performed, for example, through [Equation 1].

[Equation 1]

Here, x and y represent the x-axis and y-axis, respectively, in the Cartesian coordinate system, t represents time, θ represents azimuth, and r represents distance.

Since the transformation of the Cartesian coordinate system into the polar coordinate system as in Equation 1 is well known, a detailed description thereof will be omitted.

Next, the motion of the star in the observation image of the polar coordinate system is converted into the motion of the star according to the azimuth change (time accumulation) (S110). That is, an observation image of the polar coordinate system indicated by the azimuth and height is converted into an observation image indicated by time and height based on the azimuth. For example, an image after converting the observation image of the polar coordinate system indicated by the azimuth and the height shown in FIG. 3 into the observation image indicated by the time and height based on the azimuth will be referred to in FIG. 5 .

Thereafter, a two-dimensional discrete Fourier transform is performed on the motion image of a star according to the change of the azimuth (S120). That is, the 2D discrete Fourier transform is performed on an image according to time and height at each azimuth.

Here, the two-dimensional discrete Fourier transform may be performed, for example, through [Equation 2].

[Equation 2]

는 주어진 임의의 방위각에서의 거리와 시간에 따른 영상을 나타내고, k, w는 각각 파장과 주파수를 나타내며,

및

는 해당 영상의 2차원 푸리에 변환을 나타내고, 푸리에 변환 결과는 복소수로서 실수부는 진폭, 허수부는 위상에 대한 정보를 담고 있다. 이러한 과정이 방위각 1도부터 360도까지 수행되므로 편의상

와 같이 방위각의 함수로 나타낼 수 있다.here,

represents the image according to the distance and time at any given azimuth, k and w represent the wavelength and frequency, respectively,

and

represents the two-dimensional Fourier transform of the image, and the Fourier transform result is a complex number, and the real part contains information about the amplitude and the imaginary part contains information about the phase. Since this process is performed from 1 degree to 360 degrees in azimuth, for convenience

It can be expressed as a function of azimuth as

Thereafter, the Fourier power for the phase velocity is calculated using the result of the two-dimensional discrete Fourier transform in step S120 (S130).

The Fourier power with respect to the phase velocity can be calculated using, for example, Equation (3).

[Equation 3]

와 같이 정의된다.Here, the phase velocity is

is defined as

6 is a diagram illustrating an example of an image showing a result of calculating a Fourier power with respect to a phase velocity from a 2D discrete Fourier transform performed on the observed image of FIG. 5 .

Referring to FIG. 6 , it can be seen that the Fourier power due to the movement of the star appears in the 2nd and 4th quadrants at 0 degrees of the azimuth, and gradually appears in the 1st and 3rd quadrants, and then again in the 2nd and 4th quadrants as the azimuth angle is changed.

Thereafter, the speed of the star according to the change in the azimuth is calculated using a weighted average of the Fourier powers for the calculated phase speed ( S140 ).

The speed of such a star may be calculated through [Equation 4], for example.

[Equation 4]

In this way, the speed of the star can be calculated as a function of the azimuth through [Equation 4].

For example, a graph of the speed of a star according to an azimuth change calculated using the Fourier power versus the phase speed in FIG. 6 described above is shown in FIG. 7 . 7, the speed of the star according to the azimuth is shown in the form of a histogram 40, and for comparison, the speed of the star according to the orbital motion of the earth is shown in the form of a solid curve 50 for comparison. In particular, the vertical dotted line 41 represents an azimuth representing the minimum speed among the speeds of stars according to the azimuth calculated in step S140 , and the vertical solid line 51 is an indicator representing an azimuth angle of 180 degrees. As shown in FIG. 7 , it can be seen that the azimuth angle representing the minimum speed of a star calculated from the observation image observed by the solar coronagraph does not coincide with the azimuth angle representing the minimum speed of the star, theoretically, 180 degrees, and there is a difference. In addition, it can be seen that the motions of the stars in the observation images are not parallel to each other as in FIG. 2 , due to the difference in the azimuth angles. Therefore, it indicates that this difference in azimuth should be corrected.

Next, the azimuth at which the speed of the star is the minimum is calculated ( S150 ).

For example, as in [Equation 5], the azimuth angle at which the speed of the star is the minimum may be calculated using a weighted average.

[Equation 5]

Referring to the example of FIG. 7 , it can be confirmed that the azimuth angle at which the speed of the star is the minimum is calculated as 186.1 degrees, indicating a difference of 180 degrees and 6.1 degrees, which is the azimuth angle at which the theoretical speed of the star is the minimum.

This azimuth difference can be calculated through [Equation 6].

[Equation 6]

Finally, by rotating the observed image by the calculated azimuth difference, the roll angle correction of the solar coronagraph observation image is performed (S160).

For example, when the observation image is an observation image of a Cartesian coordinate system, the image is rotated by the difference in the azimuth calculated in step S150 based on the roll axis, that is, the x-axis, and the observation image is the observation image of the polar coordinate system. In the case of , by moving the azimuth axis, ie, the θ axis, by the azimuth difference as described above, it is possible to correct the roll angle of the solar coronagraph observation image, ie, correct the direction of the rotation axis of the sun.

As described above, an example of the observed image after being rotated by the azimuth at which the speed of the star is the minimum with respect to the observed image of the Cartesian coordinate system shown in FIG. 2 is as shown in FIG. 8 . Referring to FIG. 8, in the above example, the observed image of the Cartesian coordinate system shown in FIG. 2 is rotated by 6.1 degrees, which is the difference between the azimuth angle at which the speed of the star is the minimum and the azimuth angle at the minimum of the theoretical star by 6.1 degrees. Later, it can be seen that the motions of the stars in the circle 21 are parallel to the solid line 11 . Therefore, it is confirmed that the roll angle correction of solar coronagraph observation according to the embodiment of the present invention has been accurately performed through the image of FIG. 8 .

Hereinafter, an apparatus for performing the method of correcting the roll angle of the solar coronagraph observation image described above will be described.

9 is a view showing a schematic configuration of an apparatus for correcting a roll angle of a solar coronagraph observation image according to an embodiment of the present invention.

As shown in FIG. 9, the roll angle correction apparatus (hereinafter referred to as 'roll angle correction apparatus') 100 of the solar coronagraph observation image according to an embodiment of the present invention includes at least one processor 110, a memory ( 120 ), a communicator 130 , an input/output device 140 , and a communication bus 150 .

The processor 110 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling program execution in the solution of the present application.

The memory 120 stores information related to the roll angle correction of the solar coronagraph observation image according to an embodiment of the present invention.

Specifically, the memory 120 is further configured to store a set of codes, and the codes are used to control the processor 540 to execute a process as follows. This process includes a process of converting an observation image in a Cartesian coordinate system into an observation image in a polar coordinate system, a process of converting a star motion in an observation image of a polar coordinate system into a motion of a star according to an azimuth change, and a star movement according to an azimuth change A process of performing a two-dimensional discrete Fourier transform on an image, a process of calculating the Fourier power for a phase velocity using the result of a two-dimensional discrete Fourier transform, The method includes a process of calculating a velocity, a process of calculating an azimuth at which the speed of the star is minimized, and a process of rotating an observation image by an azimuth at which the velocity of the star is minimized.

Here, the observation image on the Cartesian coordinate system is an image obtained through solar coronagraph observation using a coronagraph.

In addition, this process is a process of receiving a coronagraph observation image from the outside through the input/output device 140, and the input/output device 140 It further includes a process of externally marking through.

Memory 120 can be read-only memory (ROM) or other type of static storage that can store instructions, or random access memory (RAM) or other type of dynamic storage that can store information and instructions; or Electrically Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM), or other compact disc storage device or optical disc storage device (compressed optical disc, laser disc, optical disc, digital versatile disc, blue ray disk, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can carry or store expected program code in the form of instructions or data structures and that can be accessed by a computer; This is not limited. The memory 120 may exist independently and is coupled to the processor 110 by a communication bus 150 .

The communicator 130 communicates with other devices or communication networks, and may be implemented using various communication technologies. That is, Wi-Fi (WIFI), WCDMA (Wideband CDMA), HSDPA (High Speed Downlink Packet Access), HSUPA (High Speed Uplink Packet Access), HSPA (High Speed Packet Access), Mobile WiMAX (Mobile WiMAX), WiBro (WiBro) , LTE (Long Term Evolution), Bluetooth (bluetooth), infrared data association (IrDA), NFC (Near Field Communication), Zigbee, wireless LAN technology, USB (Universal Serial Bus), etc. can be applied. . In addition, when a service is provided by being connected to the Internet, TCP/IP, which is a standard protocol for information transmission on the Internet, may be followed.

The input/output device 140 specifically includes an input device 141 and an output device 142 , and the input device 141 may communicate with the processor 110 and receive user input in a plurality of ways. . For example, the input device 141 may be a mouse, a keyboard, a touch screen, or a sensing device. The output device 142 may communicate with the processor 110 and display information or output voice in a plurality of ways. For example, the output device 142 may be a liquid crystal display (LCD), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, a speaker, or the like.

The communication bus 150 is configured to couple all the components of the roll angle correction device, that is, the processor 110 , the memory 120 , the communicator 130 , and the input/output device 140 .

10 is a diagram illustrating a schematic configuration of an apparatus 200 for correcting a roll angle of a solar coronagraph observation image according to another embodiment of the present invention.

As shown in FIG. 10 , the apparatus for correcting the roll angle of the solar coronagraph observation image (hereinafter referred to as 'roll angle correction apparatus') 200 according to another embodiment of the present invention includes a coordinate conversion unit 210, an azimuth reference It includes a coordinate transformation unit 220 , a discrete Fourier transformation unit 230 , a Fourier power calculation unit 240 , a velocity calculation unit 250 , a minimum azimuth angle calculation unit 260 , and an image rotation processing unit 270 .

The coordinate conversion unit 210 converts an observation image in a Cartesian coordinate system obtained through solar coronagraph observation into an observation image in a polar coordinate system. Since this transformation corresponds to the step S100 of the method for correcting the roll angle of the solar coronagraph observation image described above, a detailed description thereof will be omitted. In addition, this conversion may be performed through the above-mentioned [Equation 1].

The azimuth reference coordinate conversion unit 220 converts the motion of the star in the observed image of the polar coordinate system converted by the coordinate conversion unit 210 into the motion of the star according to the change in the azimuth. Since this transformation corresponds to the step S110 of the method for correcting the roll angle of the solar coronagraph observation image described above, a detailed description thereof will be omitted.

The discrete Fourier transform unit 230 performs two-dimensional discrete Fourier transform on the motion image of a star according to the azimuth change transformed by the azimuth reference coordinate transform unit 220 . Since this two-dimensional discrete Fourier transform corresponds to step S120 of the above-described method for correcting the roll angle of the solar coronagraph observation image, a detailed description thereof will be omitted. In addition, such a two-dimensional discrete Fourier transform may be performed through the above-mentioned [Equation 2].

The Fourier power calculator 240 calculates a Fourier power with respect to the phase velocity using the result of the second-order discrete Fourier transform performed by the discrete Fourier transform unit 230 . This calculation corresponds to the step S130 of the method for correcting the roll angle of the solar coronagraph observation image described above, and thus a detailed description thereof will be omitted. In addition, this calculation may be performed through the above-mentioned [Equation 3].

The speed calculator 250 calculates the speed of the star according to the azimuth change by using the Fourier power calculated by the Fourier power calculator 240 . Since this calculation corresponds to the step S140 of the method for correcting the roll angle of the solar coronagraph observation image described above, a detailed description thereof will be omitted herein. In addition, this calculation may be performed through the above-mentioned [Equation 4].

The minimum azimuth calculation unit 260 calculates an azimuth at which the speed of the star calculated by the speed calculation unit 250 is the minimum. Since this calculation corresponds to the step S150 of the method for correcting the roll angle of the solar coronagraph observation image, a detailed description will be omitted here. In addition, this calculation may be performed through the above-mentioned [Equation 5].

The image rotation processing unit 270 rotates the observed image by the azimuth angle at which the speed of the star calculated by the minimum azimuth angle calculation unit 260 becomes the minimum. Since this rotation corresponds to the step S160 of the method of correcting the roll angle of the solar coronagraph observation image described above, a detailed description thereof will be omitted. Also, this rotation may be performed through the azimuth difference calculated through Equation 6 above.

The roll angle correction apparatus 200 includes a coronagraph observation image input to the coordinate conversion unit 210, an observation image converted by the coordinate conversion unit 210, an image converted by the azimuth reference coordinate conversion unit 220, Displaying the image representing the Fourier power calculated by the Fourier power calculator 240 , the image representing the speed of the star calculated by the speed calculator 250 , and the observed image after being rotated by the image rotation processor 270 . It further includes a display for. This display may be the same device as the above-described output device 142 .

On the other hand, the height in the polar coordinate system may be different from the actual height due to the uncertainty of the heliocentric coordinates, but this does not affect the Fourier power (The Fourier power of a signal with well coordinated alignment is the same as the Fourier power of a signal with misaligned coordinates. ). Accordingly, the roll angle correction method according to the embodiment of the present invention described above can operate regardless of the uncertainty of the heliocentric coordinates.

The embodiment of the present invention described above is not implemented only through the apparatus and method, and may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium in which the program is recorded.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improved forms of the present invention are also provided by those skilled in the art using the basic concept of the present invention as defined in the following claims. is within the scope of the right.

Claims (14)

As a method of correcting the roll angle for the observation image of the solar coronagraph,
converting the observation image into an image of movement of a star according to an azimuth change;
calculating the Fourier power for the phase velocity by performing discrete Fourier transform on the image of the motion of the star according to the change in the azimuth angle;
calculating the speed of the star as a function of azimuth using the calculated Fourier power, and
rotating the observed image based on the azimuth at which the speed of the star is minimized;
A roll angle correction method comprising a. According to claim 1,
Before converting the observation image into an image of the movement of stars according to the change of azimuth,
When the observation image is an image of a Cartesian coordinate system, converting it into an image of a corresponding polar coordinate system
Roll angle correction method further comprising. According to claim 1,
The step of converting the observation image into an image of the movement of a star according to the change in azimuth includes:
A step of converting the observation image of the polar coordinate system indicated by the azimuth and height into an image according to the distance and time from the sun,
How to correct roll angle. 4. The method of claim 3,
The step of calculating the Fourier power for the phase velocity by performing a discrete Fourier transform on the image converted into the motion of the star according to the change in the azimuth includes:
performing a two-dimensional discrete Fourier transform on the image converted to the motion of a star according to the change in the azimuth, and
calculating a Fourier power for the phase velocity using the result of the two-dimensional discrete Fourier transform;
Including, roll angle correction method. According to claim 1,
In the step of calculating the speed of the star according to the azimuth using the calculated Fourier power,
The speed of the star along the azimuth is calculated using a weighted average of the calculated Fourier powers,
How to correct roll angle. According to claim 1,
Rotating the observation image based on the azimuth at which the speed of the star is the minimum comprises:
calculating an azimuth at which the speed of the star is minimized using a weighted average of the speed of the star;
calculating an angular difference between an azimuth at which the speed of the star is minimized and an azimuth at which a preset theoretical speed of the star is minimized; and
rotating the observed image by the angle difference
Including, roll angle correction method. 7. The method of claim 6,
In the step of rotating by the angle difference with respect to the observation image,
When the observed image is an image of a Cartesian coordinate system, the observed image is rotated by the angle difference with respect to a roll axis, or
If the observation image is an image of a polar coordinate system, moving the azimuth axis by the angle difference,
How to correct roll angle. 8. The method according to claim 6 or 7,
The azimuth at which the preset theoretical speed of the star is minimized is 180 degrees,
How to correct roll angle. As a device for correcting the roll angle for the observed image of the solar coronagraph,
including processors, memory and input/output devices;
The input/output device displays information or outputs voice to the outside, and receives information or commands input from the outside,
the memory is configured to store a set of codes;
The code is
A process of converting the observation image into an image of the movement of a star according to an azimuth change;
A process of calculating the Fourier power for the phase velocity by performing a discrete Fourier transform on the image of the motion of the star according to the change in the azimuth;
the process of calculating the speed of the star as a function of azimuth using the calculated Fourier power, and
The process of rotating the observed image based on the azimuth at which the speed of the star is minimal.
used to control the processor to execute
Roll angle compensator. 10. The method of claim 9,
The processor is
a process of receiving the observation image from the outside through the input/output device; and
A process of externally displaying the observed image and the rotated observed image through the input/output device
To run more, roll angle correction device. 10. The method of claim 9,
The processor is
When the observation image is an image of a Cartesian coordinate system, a process of converting it into an image of a corresponding polar coordinate system
To run more, roll angle correction device. 10. The method of claim 9,
The process of rotating the observed image based on the azimuth at which the speed of the star is the minimum,
a process of calculating an azimuth at which the speed of the star is minimal using a weighted average of the speed of the star;
a process of calculating an angular difference between an azimuth at which the speed of the star is minimized and an azimuth at which a preset theoretical speed of the star is minimized; and
The process of rotating the observed image by the angle difference
Including, roll angle correction device. As a device for correcting the roll angle for the observation image of the solar coronagraph,
a coordinate transformation unit that converts an observation image of a Cartesian coordinate system into an observation image of a corresponding polar coordinate system;
An azimuth reference coordinate conversion unit for converting the observation image of the polar coordinate system converted by the coordinate conversion unit into an observation image displayed by time and height based on the azimuth;
a discrete Fourier transform unit that performs a discrete Fourier transform on the image transformed by the azimuth reference coordinate transform unit;
a Fourier power calculator for calculating a Fourier power for a phase velocity using a result of the discrete Fourier transform performed by the discrete Fourier transform unit;
a speed calculator for calculating the speed of a star according to an azimuth using the Fourier power calculated by the Fourier power calculator;
a minimum azimuth calculation unit for calculating an azimuth corresponding to the minimum stellar speed among the stellar speeds calculated by the speed calculation unit; and
An image rotation processing unit for rotating the observed image based on the azimuth calculated by the minimum azimuth calculation unit
A roll angle correction device comprising a. 14. The method of claim 13,
The image rotation processing unit,
Calculate the angular difference between the azimuth at which the speed of the star calculated by the minimum azimuth calculation unit is the minimum and the azimuth at which the preset theoretical speed of the star is the minimum of 180 degrees, spinning,
Roll angle compensator.

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