JP6892166B1 - Telescope control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To not see the North Star depending on the situation where an astronomical telescope is installed when aligning the polar axis of an equatorial mount. According to the disclosed technique, from at least three images of the celestial sphere at different positions on the celestial sphere, taken while rotating the equatorial mount around the right ascension axis in a fixed state. A program that identifies the deviation between the true RA axis and the RA axis of the equatorial mount, and causes the computer to execute a process of outputting the adjustment amount in the direction of the RA axis of the equatorial mount so as to reduce the deviation. Is provided. [Selection diagram] Fig. 5

Description

The present invention relates to a program for controlling a telescope.

When observing stars with an astronomical telescope, an equatorial mount is attached to the astronomical telescope in order to track diurnal motion celestial bodies and observe the stars in a stable manner.
The equatorial mount has a mechanism that rotates around the RA axis (also referred to as the "polar axis") and a mechanism that rotates around the declination axis that is perpendicular to the RA axis.
When using an equatorial mount, it is required to align the RA axis of the equatorial mount attached to the astronomical telescope with the north pole of the celestial sphere before starting observation of the celestial body (this is also called "polar alignment"). .).
Generally, polar alignment is performed by using a polar telescope to align the RA axis of the equatorial mount with the celestial pole near the North Star.

In addition, some astronomical telescopes have conventionally been provided with an automatic introduction function of celestial bodies. The automatic introduction function of celestial bodies is a function to put a target celestial body into the field of view of an astronomical telescope based on its coordinates.
With a correction data storage unit that can hold the deviation of the direction of the astronomical telescope with respect to the directional coordinates due to the right angle error of the equatorial mount and the installation error as correction data set for each small airspace formed by dividing the visible airspace into multiple parts. , There is a technique for providing a data correction means for incorporating the correction data into the drive data and correcting the drive data (see, for example, Patent Document 1).

In addition, there is a technique related to an automatic introduction device that automatically introduces a target celestial body by controlling the rotation of the astronomical telescope around at least two axes.
This technique has an imaging means for capturing an astronomical image and an astronomical database, and identifies the captured celestial body by comparing the astronomical image captured by the imaging means with the astronomical information in the astronomical database by the astronomical identification means. .. Further, this technique further includes an image processing means for extracting information on each celestial body from the celestial body image captured by the imaging means in order to reduce the amount of calculation, and the celestial body identification means is extracted by the image processing means. By comparing the information of each celestial body with the celestial body information of the celestial body database, the imaged celestial body is identified (see, for example, Patent Document 2).

Japanese Patent No. 2955489 Japanese Patent No. 4579826

When using an equatorial mount, it is necessary to align the polar axis of the equatorial mount. Polar alignment is the alignment of the RA axis (polar axis) of the equatorial mount with the true North Pole of the celestial sphere. A polar telescope is generally used for polar alignment. When aligning the polar axis, the North Star may not be visible depending on the situation in which the astronomical telescope is installed. The disclosed technique provides a technique for aligning the polar axis of an equatorial mount without using a polar telescope.

A celestial sphere photographed by the telescope by instructing the telescope to rotate around the right ascension axis of the equatorial mount while the equatorial mount connected to the telescope is fixed by the disclosed technique. By performing the step of acquiring at least three images having different positions on the above and matching each of the at least three images with the database of the positions of the plurality of stars on the celestial sphere, each of the at least three images From the stage of identifying the coordinates of at least three points with different positions on the celestial sphere pointed to by the telescope when the image was taken, and from the coordinates of the at least three points , the true RA axis of the celestial sphere and the equatorial mount By identifying the deviation from the RA axis, a program is provided that causes the computer to execute a step of outputting an adjustment amount in the direction of the RA axis of the equatorial mount so as to reduce the deviation.

According to the disclosed technique, it is possible to more easily align the polar axis of the equatorial mount without using a polar telescope.

Schematic diagram of the astronomical telescope installed on the equatorial mount (1) Schematic diagram of the astronomical telescope installed on the equatorial mount (2) Control hardware block diagram Functional block unit of the control unit (first embodiment) Functional block unit of the control unit (second embodiment) Diagram to explain the calculation of the polar axis User interface to display polar axis deviation (adjustment amount) Flowchart showing polar alignment processing (first embodiment) Flowchart showing polar alignment processing (second embodiment)

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples, and do not limit the scope of claims.

First, the configuration of the equatorial mount 100 will be described with reference to FIG. 1A. An astronomical telescope 130 is installed on the equatorial mount 100.
The equatorial mount 100 also functions as a mount for supporting the telescope 130. The equatorial mount 100 is aligned with the north pole of the celestial pole in the direction of its polar axis (right ascension axis) 101 so as to track the diurnal motion of the celestial body.
As shown in FIG. 1A, the equatorial mount 100 is mounted on a tripod 123. The balance weight 122 is set to balance with the telescope 130. A camera 223 may be attached to the telescope 130.
The RA rotation clamp (not shown) fixes the rotation of the telescope 130 around the RA axis 101 (direction of arrow A). Similarly, a declination axis rotation clamp (not shown) fixes the rotation of the telescope 130 around the declination axis 102 (in the direction of arrow B).
Further, the equatorial mount 100 is provided with a polar axis altitude adjusting screw 111a and a polar axis directional adjustment screw 111b, and the altitude of the telescope 130 (direction of arrow C) can be finely adjusted around the altitude axis 103. In addition, the orientation of the telescope 130 (direction of arrow D) can be finely adjusted around the azimuth axis 104.

When aligning the polar axis 101 with the north pole of the celestial sphere, the polar axis 101 is adjusted by operating the polar axis altitude adjusting screw 111a and the polar axis orientation adjusting screw 111b by the user. In the following, the polar axis height adjusting screw 111a and the polar axis orientation adjusting screw 111b may be collectively referred to as "polar axis adjusting screw 111". The altitude and direction may be controlled by a motor or the like.
When introducing a star, the RA axis and the declination axis rotate so that the optical axis of the telescope 130 matches the target star. If the direction of the polar axis 101 coincides with the north pole of the celestial sphere, the RA axis is controlled to automatically rotate so as to track the diurnal motion of the celestial body.

FIG. 2 shows the hardware configuration of the control unit 200 that controls the equatorial mount 100.
The control unit 200 includes a CPU 211, a memory 212, a motor I / F 213, a memory I / F 214, a camera I / F 215, an operation unit I / F 216, and a display unit I / F 217.
The CPU 211 controls the control unit 200 as a whole. In particular, in the present embodiment, the CPU 211 executes the polar alignment process as described later by using the program read into the memory 212.
The memory 212 is composed of RAM and the like. The memory 212 stores a program for the CPU 211 to execute the polar alignment process.

The motor I / F 213 is an interface with the motor 221 that controls the equatorial mount 100. The motor 221 may have a plurality of stepping motors and the like, and has a motor that controls the direction of the telescope centered on the right ascension axis and the declination axis. Further, the motor 221 may include a motor 221 such as a motor that drives to control altitude and a motor that drives to control azimuth. In this way, there may be a plurality of motors.
The memory I / F 214 is an interface with the external memory 222. The external memory 222 is composed of a hard disk or the like, and is built in a PC or the like (not shown). An astronomical database or the like may be stored in the memory 212 or the external memory 222. The celestial body database may be provided from an external device via a network (not shown).
The camera I / F 215 is connected to the telescope 130 and is an interface with the camera 223 for photographing celestial bodies.
The operation unit I / F 216 is an interface for inputting instructions from the operation unit 224 that accepts various user operations including operations related to the direction of the telescope centered on the RA axis and the declination axis to the control unit 200. ..
The display unit I / F 217 is an interface for outputting the result calculated by the control unit 200 to the display unit 225 of the user interface 500, which will be described later, provided on a PC or the like (not shown).

3A and 3B are block diagrams for realizing various functions included in the control unit 200 according to each embodiment.
FIG. 3A is a block diagram according to the first embodiment. The first embodiment is an embodiment in which the final polar alignment is performed by rotating the polar axis adjusting screw by the operation of the user who is viewing the live view image, as will be described later in the flowchart of FIG. 6A. ..
The three image acquisition units 301 acquire three images of the celestial sphere in order to calculate the deviation between the direction of the RA axis 101 of the equatorial mount 100 and the direction of the true north pole of the celestial sphere.
The three-point coordinate identification unit 302 specifies the coordinates of the center point by plate matching using the astronomical database for each image acquired by the three image acquisition units 301. In the first embodiment, the coordinates of the center point are specified, but it goes without saying that the coordinates of other positions in the image may be specified.
The polar axis deviation (adjustment amount) calculation unit 303 is based on the coordinates of the three center points specified by the three-point coordinate identification unit 302, and is the direction of the RA axis 101 of the equatorial mount 100 and the direction of the true north pole of the celestial sphere. Calculate the deviation from. The adjustment amount of the polar axis adjustment screw for adjusting the direction of the polar axis is calculated so that this deviation is adjusted to zero.
The display unit 306 may display the adjustment amount based on the deviation between the RA axis 101 of the equatorial mount 100 and the true north pole of the celestial sphere calculated by the polar axis deviation (adjustment amount) calculation unit 303. Further, the live view image acquired by the live view acquisition unit 305 may be displayed. Here, "display" is an example of "output".
The deviation amount determination unit 304 determines the amount of deviation between the direction of the RA axis 101 of the equatorial mount 100 calculated by the polar axis deviation (adjustment amount) calculation unit 303 and the direction of the true north pole of the celestial sphere. That is, when the introduction instruction of the target star is given in a state where the polar axis is deviated, it is determined whether or not the target star is within the live view area of the camera. This judgment is made by calculating whether or not the target star to be introduced enters the imaging surface based on the angle of view determined by the combination of the telescope and the camera and the size and shape of the imaging surface of the camera. You may. Alternatively, when the introduction instruction of the target star is given in a state where the polar axis is deviated, the image of the five view of the camera is played and matched, and it is determined whether or not the star to be introduced is included in the image of the camera. You may.
The live view acquisition unit 305 acquires a live view image of the camera.

FIG. 3B is a block diagram showing a second embodiment. In the second embodiment, as will be described later in the flowchart of FIG. 6B, the adjusting unit automatically aligns the polar axis by controlling the rotation of the polar axis adjusting screw with a motor or the like based on the calculated adjustment amount. It is an aspect.
The three image acquisition units 311, the three-point coordinate identification unit 312, and the polar axis deviation (adjustment amount) calculation unit 313 have the image acquisition unit 301, the three-point coordinate identification unit 302, and the polar axis deviation described in FIG. 3A, respectively. (Adjustment amount) It has the same function as the calculation unit 303.
The star introduction unit 314 performs an operation of introducing a star that serves as a mark for polar alignment.
The adjustment unit 315 adjusts the polar axis with an adjustment amount calculated by the polar axis deviation (adjustment amount) calculation unit 313 so that the deviation between the RA axis 101 of the equatorial mount 100 and the true north pole of the celestial sphere becomes zero. The direction of the polar axis 101 may be adjusted by controlling the screw 111. The adjustment unit finely adjusts the direction of the polar axis 101 by rotating the polar axis adjustment screw 111 so that the star to be introduced is located at the center of the image while referring to the live view of the camera. You may try to do it.
The completion notification unit 316 notifies the user that the adjustment of the polar axis 101 by the adjustment unit 315 is completed.
The display unit 317 may display the adjustment amount based on the deviation between the RA axis 101 of the equatorial mount 100 and the true north pole of the celestial sphere calculated by the polar axis deviation (adjustment amount) calculation unit 313. Alternatively, the live view may be displayed to display the star that the star introduction unit 314 tried to introduce. If the amount of deviation is large, the star to be introduced may not be displayed in the live view. Further, the completion notification unit 316 may notify by displaying or the like that the polar alignment has been completed. Sound information other than visual information may be used to notify that the polar alignment is completed.

FIG. 4 is a diagram illustrating the principle of the method of performing polar alignment of the equatorial mount in the present embodiment.
First, the user adjusts the installation direction of the tripod 123 or the polar axis adjusting screw 111 to direct the RA axis 101 of the equatorial mount 100 toward the north pole direction of the celestial sphere. At this stage, it is extremely difficult to accurately align the RA axis 101 with the north pole of the celestial sphere. Therefore, as already mentioned, the direction of the RA axis 101 is deviated from the direction of the true north pole of the celestial sphere. Most of the time.
By rotating the telescope around the declination axis 101 (direction of arrow A) and around the declination axis 102 (direction of arrow B) with the equatorial mount 101 facing the vicinity of the north pole direction. It is desirable to point the telescope 130 as close to the zenith as possible (see FIG. 1B). Next, with the rotation around the declination axis 102 fixed, the telescope is rotated around the right ascension axis 101 at an arbitrary angle, and images of the celestial sphere in three directions are taken by the camera 223. When taking an image in three directions, the equatorial mount 100 may be automatically rotated around the right ascension axis 101 by, for example, 10 degrees by a program, and the image in three directions may be taken by the camera 223.
Then, for each of the three captured images, for example, the equatorial coordinates (right ascension, declination) of the center of the image are calculated by plate matching. Plate matching is the comparison of a star in a captured image with a database of star positions. In calculating each coordinate, it is desirable to make corrections for the influence of the atmosphere. This is because on the surface of the earth, the position of the apparent star observed by the telescope is deviated from the original position of the star due to the refraction of light by the atmosphere. By correcting for the influence of the atmosphere, three more accurate coordinates can be obtained. Since it is a technique well known to those skilled in the art to obtain more accurate equatorial coordinates of a star in consideration of the influence of the atmosphere, the description thereof is omitted in the present specification.

Here, the equatorial coordinates (right ascension, declination) of these three points are P ₁ (α ₁ , δ ₁ ), P ₂ (α ₂ , δ ₂ ), P ₃ (α ₃ , δ ₃ ), respectively. To do.
As shown in FIG. 4, since _{the declination of the three points P 1} , P ₂ , and P ₃ is the same, if the polar axis (right ascension axis 101) of the equatorial mount 100 correctly points to the north pole of the celestial sphere. , The declination of these three points should be the same, and the normal of the plane passing through these three points should point to the true north pole direction of the celestial sphere.
However, at this stage, the polar axis 101 of the equatorial mount 100 does not accurately face the true north pole of the celestial sphere, so it is necessary to correct the polar axis 101.

First, the _{vector P 12} (x ₁₂ , y ₁₂ , z _{13 ) from P 1} (α ₁ , δ ₁ ) toward P ₂ (α ₂ , δ ₂ ) is obtained by Eq. (1).

Similarly, the _{vector P 13} (x ₁₃ , y ₁₃ , z _{13 ) from P 1} (α ₁ , δ ₁ ) to P ₃ (α ₃ , δ ₃ ) is obtained by Eq. (2).

The vector P ₁₂ and the vector P ₁₃ are vectors existing in the triangle formed by the three points P ₁ , P ₂ , and P _3. Therefore, by calculating the outer product of _{P 12} and P ₁₃ , we can obtain the vector in the direction of the normal of the triangle formed by _{P 1} , P ₂ , and P _3. This outer product Q (x _q , y _q , z _q ) is calculated by the following equation (3).

ここで、α_qの象限は、x_q,及びy_qの符号により判断する。
外積Qは、３点P₁,P₂,P₃が作る三角形の法線ベクトルであり、赤道儀１００の極軸１０１の方向を示すベクトルである。極軸１０１が正確に天球の北極に向いていればδ_q=90°（なお、αは不定）となるはずだが、実際には極軸１０１は天球の北極からズレが存在する。したがって、赤道儀１００の極軸１０１を天球の北極に正確に向くように修正することが必要である。 Next, the outer product Q (x _q , y _q , z _q ) obtained by the equation (3) is converted into _{the equatorial coordinates Q (α q} , δ _q ) of the polar coordinate representation using the equation (4).

Here, the quadrant of _{α q} is determined by the signs of _{x q} and y _q.
The outer product Q is _{a normal vector of a triangle formed by three points P 1} , P ₂ , and P ₃ , and is a vector indicating the direction of the polar axis 101 of the equatorial mount 100. If the polar axis 101 is accurately oriented toward the north pole of the celestial sphere, δ _q = 90 ° (α is indefinite), but in reality, the polar axis 101 is deviated from the north pole of the celestial sphere. Therefore, it is necessary to modify the polar axis 101 of the equatorial mount 100 so that it faces the north pole of the celestial sphere accurately.

_{Now, when the right ascension α q} and declination δ _q in the equatorial coordinate system of the outer product Q indicating the direction in which the polar axis 101 of the equatorial mount 100 is facing are obtained, these are the directions A _q and the altitude h of the horizontal coordinate system. Convert to _q. The direction A _q represents the south as 0 ° and the westward direction up to 360 °, and the altitude h _q represents the horizon as 0 ° and the zenith as 90 °. The following equation (5) is used for this calculation.

Here, φ is the latitude of the observation site, and θ is the local sidereal time at the observation time. Local sidereal time is equivalent to the right ascension of a celestial body seen in the direction of the south at the observation site, and is an amount that increases with time as the earth rotates. This can be calculated, but the Greenwich sidereal time at 0 o'clock is posted every day in calendars such as the science chronology.
By adding the longitude of the observing site to this, the local sidereal time at 0 o'clock at the observing site can be obtained. Furthermore, since sidereal time advances by about 24 hours 03 minutes 57 seconds a day, the local sidereal time at the observed time can be obtained by proportional calculation from here. Since the local sidereal time increases with the passage of time in this way, the polar axis of the equatorial mount 100 is calculated from the time when the polar axis of the equatorial mount is calculated using the coordinates of three points in the equation (6) described later. _{By the time to calculate the difference (ΔA, Δh) between the directions A q} and altitude h _q in the horizontal coordinate system of 101 and the true north pole direction of the celestial sphere (true north) and altitude (latitude φ of the observation site). , If time has passed, it is desirable to make corrections in consideration of the passage of time.

ここまでの計算を経ることで、天球の真の北極方向（例えば、北極星）を観測せずに、赤道儀１００の極軸１０１のズレの量を算出することができる。 _{Difference (ΔA, Δh) between the orientation A q} and altitude h _q in the horizontal coordinate system of the polar axis 101 of the equatorial mount 100 and the true north pole direction orientation (true north) and altitude (latitude φ of the observation site) of the celestial sphere. Is calculated by the following equation (6).

By going through the calculations up to this point, it is possible to calculate the amount of deviation of the polar axis 101 of the equatorial mount 100 without observing the true north pole direction of the celestial sphere (for example, the North Star).

FIG. 5 is a user interface 500 that displays the amount of deviation of the polar axis 101 of the equatorial mount 100, which is the result calculated as described above, as a graph-like screen 510 and a numerical value 513.
In the screen 510 of FIG. 5, the origin 511 where two orthogonal coordinate axes intersect indicates the true north pole direction of the celestial sphere. Also, the cross 512 indicates the "shifted" North Pole direction the telescope 130 is currently facing, and the amount of shift is displayed on the screen 510. The scales of the X-axis and the Y-axis of the screen 510 may be changed according to the amount of deviation. By changing the scale, the cross 512 may be displayed on the screen 510. Further, the numerical value 513 in FIG. 5 indicates the deviation of the orientation and the deviation of the altitude of the polar axis 101 of the equatorial mount 100 with respect to the true north pole direction of the celestial sphere.
This deviation is an adjustment amount for adjusting the polar axis 101 of the equatorial mount 100. In the example of FIG. 5, the deviation of the direction and the deviation of the altitude are shown as the angles as the adjustment amount. As the adjustment amount, the operation amount of the polar axis altitude adjustment screw 111a and the polar axis orientation adjustment screw 111b may be displayed (or output).
In the user interface 500, the user refers to the directional deviation and the altitude deviation, and operates the polar axis adjusting screw 111 in the horizontal and vertical directions so that these values approach 0. By this operation, the difference between the direction of the polar axis 101 and the direction of the north pole of the celestial sphere is reduced. Alternatively, referring to the displayed position of the cross 512, the polar axis adjusting screw 111 may be turned horizontally and vertically so that the position approaches the origin 511.

However, to accurately correct the deviation of the polar axis 101 by referring only to the deviation of the orientation and the deviation of the altitude, or the position of the displayed cross 512, the user can adjust the polar axis by referring to the numerical value of the operation amount. Since the operation of turning the screw 111 is performed, an adjustment error may remain. Therefore, it is often necessary to repeat the above-mentioned adjustment operation a plurality of times.

Therefore, it is required to be able to more easily correct the deviation of the polar axis 101 by an operation that is intuitively easy for the user to understand. Therefore, when instructing to introduce a star as a marker, the above adjustment operation is required once or until the star can be introduced into the live view of the camera 223 connected to the telescope 130. Have the user execute it multiple times depending on the situation. If the star can be introduced into the live view of the camera 223 connected to the telescope 130 when the instruction to introduce the star is given here, use the introduced star as a marker as follows. The deviation of the polar axis 101 can be corrected.
After instructing to introduce a bright star as a marker, the user sees a live view image of the camera 223 connected to the telescope 130.
At this stage, the bright star, which serves as a marker, is projected at a position deviated from the center of the screen due to the deviation of the polar axis. In this case, the center position of the live view is a virtual position where the star is introduced into the imaging range of the telescope if the deviation is zero. The user can rotate the polar axis adjustment screw 111 horizontally and vertically so that the introduced star is located in the center of the screen, and align the bright star as a mark with the center position of the screen to align the polar axis. Can be achieved.

The principle of polar alignment using the introduced stars is as follows.
_{When the coordinates of P 3} which is the last third point described above are measured by plate matching, the coordinates are calculated as _{P 3} (α ₃ , δ ₃ ) based on the orientation of the telescope 130 at the time of measurement. Here, by rotating the polar axis 101 of the equatorial mount 100 and correcting the polar axis 101 correctly, the coordinates of _{P 3 calculated when the direction in which the telescope 130 is facing moves by the amount of the rotation.} There _{P '3 (α' 3,} δ '3) and the.
Coordinate _{P '3 (α' 3,} δ '3) can be calculated in the following order.

First, the coordinates P ₃ (α ₃ , δ ₃ ) are converted into horizontal coordinates by Eq. (7) to obtain _{P 3} (A ₃ , h _3).

Next, the calculated horizontal coordinates P ₃ (A ₃ , h ₃ ) are converted into _{Cartesian coordinates P 3} (x ₃ , y ₃ , z ₃ ) by Eq. (8).

When the polar axis 101 is correctly corrected, the positions of all the celestial bodies on the celestial sphere are the coordinates calculated by the equation (6) moved to the coordinates rotated in the opposite direction. The position of P, the coordinates P rotated by the correction amount of displacement _{'3 (x' 3, y} '3, z' 3) is obtained by the following expression (9).

ここで、A’₃の象限は、x’₃及びy’₃の符号によって判断する。 This, by converting the horizontal coordinate by the following equation (10), P _'3 of azimuth A' _3, highly h _'3 is determined.

Here, A _'3 quadrants, x' is determined by the sign of the ₃ and y _'3.

ここで、式（１１）の右辺はすべて既知であることから、左辺のα'₃及びδ'₃を求めることができる。 Next, this was converted to the equatorial coordinate system by the following equation _{(11), P '3 (} α' 3, δ '3) Request.

Here, since all the right-hand side of equation (11) are known, it is possible to determine the left side of the alpha _'3 and [delta]' _3.

Here, it is assumed that the telescope 130 is currently pointing in the direction _{of P 3 at the third point by the operation at the beginning.} Here, with respect to Tadashi Akamichi 100, the direction facing currently performing synchronization as a _{P '3 (α' 3,} δ '3). Synchronization means instructing the control unit 200 that the telescope 130 is currently pointing in a designated direction. By synchronizing, the telescope 130 will operate based on this thereafter.

Then, the telescope 130 introduces a _{suitable bright star P 4} (α ₄ , δ _4).
As the star to be introduced, for example, a bright star (for example, Sirius, a first-class star) that is visible within an altitude range of 30 to 60 ° is preferable.
At this stage, the polar axis 101 of the equatorial mount 100 has not been adjusted correctly, causing a shift, and the introduced star is not located in the center of the screen 410 (the virtual introduction position of the introduced star). .. Specifically, the introduced star is projected at a position deviated from the center of the screen by the amount of the polar axis deviation as shown in the equation (6). Therefore, if the polar axis is corrected by using the polar axis adjusting screw 111 so that this star is located at the center of the screen, the polar axis can be aligned accurately.

From the above, it is possible to align the polar axis of the equatorial mount even if the north pole of the celestial sphere is not visible.
In addition, since the polar axis adjustment screw 111 may be adjusted so that the introduced star is located in the center of the screen in the live view image, the polar axis can be adjusted as if looking into a pseudo polar axis telescope. it can.

The above is the method of polar alignment, but the position where the stars can be seen on the actual celestial sphere is the fluctuation of the rotation and revolution of the earth, the precession and nutation, the atmospheric refraction where the starlight is refracted by the atmosphere, etc. Affected by various factors. As a result, the actual star appears in the direction of the coordinates called "visual position", which is slightly different from the coordinates represented by "J2000", which is the coordinate system generally used for star charts at present. Since the above-mentioned measurement by plate matching is performed with reference to the stellar position represented by J2000, the obtained coordinates are in the J2000 system. However, since the actually visible direction is the "visual position" in consideration of the above-mentioned deviation, it is possible to perform the above-mentioned polar alignment more accurately by appropriately correcting these. ..

The polar alignment process described above will be described with reference to the flowcharts of FIGS. 6A and 6B. FIG. 6A shows a flowchart according to the first embodiment. Further, FIG. 6B shows a flowchart according to the second embodiment.
The following processing can be executed by the CPU 211 in the control unit 200 using a program read into the memory 212 or the like.

FIG. 6A shows a flowchart according to the first embodiment.
The CPU 211 takes a three-direction image of the celestial sphere captured by the camera 223 while rotating the telescope 130 toward the zenith and fixing the right ascension axis 101 of the equatorial mount 100 around the right ascension axis 101. Obtained via I / F215 (S601).
Next, the CPU 211 calculates the equatorial coordinates of the center point for each of the coordinates in the three directions acquired in S601 by plate matching using the celestial body database stored in the external memory 222 (S602). As described above, it is desirable to make corrections for the influence of the atmosphere when calculating each coordinate.

Next, the CPU 211 calculates the deviation of the celestial sphere of the polar axis 101 from the true north pole from the polar axis 101 calculated in S603 (S603). At this time, first, the CPU 211 calculates the polar axis (right ascension axis) 101 of the equatorial mount 100 from the three equator coordinates calculated in S602. Here, as described above, the polar axis 101 of the equatorial mount 100 is calculated as a vector in the direction of the normal of the triangle formed by the three points. Next, the CPU 211 calculates the deviation between the calculated direction of the polar axis 101 and the direction of the true north pole of the celestial sphere of the polar axis 101.
As described above, if time has elapsed from the time when the polar axis 101 of the equatorial mount 100 is calculated in S602 to the time when the deviation from the true north pole of the celestial sphere is calculated, the deviation is calculated. In this case, the correction is made in consideration of the difference between the two times.
Then, based on the deviation calculated in S603, the CPU 211 displays an adjustment amount in the polar axis direction that cancels the deviation as a screen 510 or a numerical value 513 on the user interface 500 (S604).

Here, the adjustment amount may be displayed as a numerical value 513 on the user interface 500. Alternatively, the adjustment amount may be displayed as the position of the cross 512 in the screen 510.
Due to the deviation calculated in S603, the cross 512 still has the angle of view of the camera 223 on the screen 510 (the angle of view of the short side when the imaging surface of the camera is rectangular, that is, the field of view of the short side). If it does not fit inside the circle 514 as the radius (S605 is No), the user is urged to operate the polar axis adjusting screw 111 so that the deviation becomes smaller (S608). Then, after the polar axis adjusting screw 111 is used for adjustment, the process returns to S601 and the above-mentioned series of steps is repeated.
It is desirable to repeat the above series of steps until the cross 512 is inside the circle 514 on the screen 510.

Then, when the cross 512 enters the inside of the circle 514 on the screen 510 (S605 is Yes), the CPU 211 switches the screen 510 of the user interface 500 to the live view image from the camera 223, and the introduced star. Can be displayed as a live view image (S606). This is because the cross 512 is now inside the circle 514 on the screen 510, so that the introduced star is projected in the live view image.
At this time, assuming that the deviation calculated in S603 is zero, the introduced star is projected on the origin 511 (virtual introduction position of the star) of the screen 510 which is the center of the live view image. However, in most cases, the deviation remains, so that the introduced star is projected at a position away from the origin 511 in the live view image corresponding to the deviation.

In this state, the user is urged to operate the polar axis adjusting screw 111 so that the introduced star is projected on the origin 511 of the screen 510 while viewing the live view image (S607).
Since this user's operation is performed while looking at the screen 510, the user can more easily adjust the polar axis adjusting screw 111 so that the star is located at the origin 511 of the screen 510. When the introduced star is projected on the origin 511 of the screen 510, the direction of the polar axis 101 of the equatorial mount 100 is substantially toward the north pole of the celestial sphere.

FIG. 6B shows a flowchart according to the second embodiment.
In the first embodiment described above, the polar alignment screw is operated by the user, but in the second embodiment, the polar alignment screw 111 is adjusted by, for example, attaching a motor to the polar alignment screw 111. Is performed under the control of the CPU.
Since the processes from S611 to S613 in FIG. 6B are the same as the processes from S601 to S603 in FIG. 6A, detailed description thereof will be omitted.

When the polar axis deviation is calculated and output in S613, the equatorial mount 100 is synchronized with the calculated polar axis state.
Next, the CPU 211 introduces a star (S614). The introduced star may be displayed as a live view image (S614). Here, the introduced star is projected at a position away from the origin 511 in the live view image corresponding to the deviation (adjustment amount) (in some cases, the introduced star may not be projected in the live view. possible).
In the second embodiment, as described below, the CPU 211 rotates the polar axis adjusting screw 111 based on the amount of the output deviation. Therefore, if the introduced star is pattern-recognized by the CPU 211. Often, it does not necessarily have to be displayed as a live view image.
Next, the CPU 211 rotates the polar axis adjusting screw 111 by a certain amount based on the adjustment amount calculated in S613 so as to cancel the deviation. The fine adjustment of the polar alignment screw 111 is controlled so that the introduced (or to be introduced) star is located in the center of the image in the live view (S615).
Then, when the polar axis adjusting screw 111 is rotated by a certain amount, the CPU 211 calculates how much the star introduced into the imaging range of the camera 223 deviates from the center of the image by pattern recognition (plate matching) (S616). Even if the star to be introduced is not projected in the imaging range, the CPU 211 should be introduced by pattern recognition (matching with play) the image in the imaging range using the database. The amount of deviation can be calculated by estimating the position of the star.

If the deviation is not yet within the predetermined value (S617 is No), the process returns to S615, and the CPU 211 rotates the polar axis adjusting screw 111 again by a certain amount so that the deviation is canceled.
Then, when the deviation is within the predetermined value (S617 is Yes), the polar alignment is completed.
In the second embodiment, the rotation of the polar axis adjusting screw 111 based on the amount of deviation is controlled by the adjusting unit 315 by the CPU 211, so that the live view does not have to be displayed on the display unit 317.

100 Equatorial mount 101 Polar axis (Right ascension axis)
102 Declination axis 103 Altitude axis 104 Direction axis 111 Polar axis adjustment screw 111a Polar axis altitude adjustment screw 111b Polar axis orientation adjustment screw 121 Polar axis telescope 122 Balance weight 123 Tripod 130 Telescope 200 Control unit 211 CPU
212 Memory 213 Motor I / F
214 Memory I / F
215 Camera I / F
216 Operation unit I / F
217 Display I / F
221 Motor 222 External memory 223 Camera 224 Operation unit 225 Display unit 500 User interface 510 Screen 511 Origin 512 Cross 513 Numerical value 514 Yen

Claims (7)

By instructing the telescope to rotate around the right ascension axis of the equatorial mount with the declination axis of the equatorial mount connected to the telescope fixed, the position of the telescope is different on the celestial sphere. At the stage of acquiring at least three images,
By matching each of the at least three images with a database of the positions of a plurality of stars on the celestial sphere, the position on the celestial sphere pointed to by the telescope when each of the at least three images is taken. At the stage of identifying the coordinates of at least three different points,
By identifying the deviation between the true RA axis of the celestial sphere and the RA axis of the equatorial mount from the coordinates of at least three points, the direction of the RA axis of the equatorial mount is reduced so as to reduce the deviation. At the stage of outputting the adjustment amount of
A program that causes a computer to run. The stage of outputting the adjustment amount is
A step of converting the adjustment amount into an adjustment amount of an adjustment mechanism for adjusting the direction of the RA axis and outputting the adjustment amount.
The program according to claim 1, further comprising. The stage of outputting the adjustment amount is
And three points coordinates even without least the, stars from the state of the telescope when the even without least three points coordinates are specified, the imaging range of the telescope when the deviation has to be zero The declination axis and the RA axis are operated so as to introduce the star into the imaging range in the virtual position within the imaging range to which the is introduced and the actual state of the telescope. At the stage of outputting the captured image
The program according to claim 1 or 2, further comprising. The step of identifying the coordinates of at least three points is
The stage of applying the correction for the influence of the atmosphere to the coordinates of the above three points,
The program according to any one of claims 1 to 3, further comprising. The stage of outputting the adjustment amount is
A step of identifying the deviation by a plane normal vector containing the coordinates of at least three points.
The program according to any one of claims 1 to 4, further comprising. The stage of outputting the adjustment amount is
A step of correcting the adjustment amount using the time when each of the at least three images is captured and the time when the adjustment amount is calculated.
The program according to any one of claims 1 to 5, further comprising. A step of giving the adjustment amount to the adjusting unit that adjusts the direction of the RA axis so that the direction of the RA axis is adjusted.
The program according to any one of claims 1 to 6, further comprising.

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