Method and system for automatically extracting very long baseline interference outline and generating track file

Abstract

The invention discloses a method and a system for automatically extracting a very long baseline interference outline and generating a track file. The method comprises the following steps: extracting information of a specific station from an observation outline file issued in very long baseline interference observation, wherein the information comprises coordinates of a source and starting and ending time corresponding to each scan; calculating the right ascension and declination of the telescope between every two scans under the speed and acceleration limiting conditions of the telescope; in combination with the right ascension and declination of the observation source in each scan, generating an azimuth pitching direction of 0.1 second precision of the specified station; and detecting the data and generating an observation track file. According to the method, one-key generation from the very long baseline observation outline to the observation track file can be realized, so that on one hand, errors caused by human factors are reduced; and on the other hand, the telescope is not limited by an observation mode when participating in very long baseline observation.

Description

Technical Field

[0001] The present invention relates to the technical field of information extraction and conversion, and in particular to a method and system for automatically extracting very long baseline interferometry observation outline information and generating observation trajectory files. Background Art

[0002] Before the Very Long Baseline Interferometry (VLBI) observation, the organizer will issue an observation outline to each station. The observation outline includes the equipment configuration information of each station, the coordinate information of the observation source, and the time information of each scan. Generally, the station can control the pointing, tracking and back-end configuration of the telescope according to the requirements of the observation outline.

[0003] The Five-hundred-meter Aperture Spherical radioTelescope (FAST) is a major national scientific and technological infrastructure and the most sensitive single-aperture radio telescope in the world. For the safe operation of the telescope, the antenna control and back-end equipment operation of FAST are carried out independently. The operation and control software (Field System, FS) used by general stations can only control the operation and data recording of VLBI back-end equipment, but cannot control the pointing and tracking of FAST.

[0004] Currently, FAST has developed a variety of observation modes to control the pointing and tracking of the telescope, of which only the tracking mode and phase reference mode are applicable to simple VLBI observations. The tracking mode is applicable to observations with only one observation source, while the phase reference mode is applicable to periodic switching observations with only two sources. At present, many VLBI observations usually include one target source and multiple calibration sources, and the switching between the sources is not periodic.

[0005] FAST also has a user defined observation mode, which requires the user to directly provide azimuth and elevation with a step length of 0.1 seconds. The telescope will control the antenna according to the provided azimuth and elevation files. If the coordinates, time and other information can be extracted from the VLBI outline to generate azimuth and elevation observation files with a step length of 0.1 seconds, FAST can get rid of the restrictions on the number of sources and switching cycles when participating in VLBI observations, and participate in various VLBI observation projects more flexibly.

[0006] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a method and system for automatically extracting a very long baseline interferometer outline and generating a trajectory file, so as to solve the above problems existing in the prior art. The method can realize one-key generation from a very long baseline observation outline to an observation trajectory file, which reduces the errors caused by human factors on the one hand; on the other hand, the telescope is not restricted by the observation mode when participating in very long baseline observation.

[0008] To achieve the above object, the present invention provides a method for automatically extracting a very long baseline interferometer outline and generating a trajectory file, the method comprising the following steps: S1. Extracting information of a specific station from a VLIO outline file, the information including the coordinates of the source and the start and end times corresponding to each scan; S2. Generate right ascension and declination with a step length of 0.1 seconds according to the coordinates of the source corresponding to each scan and the start and end time; S3. Generate right ascension and declination with a step length of 0.1 seconds according to the source coordinates and start and end times corresponding to each two scans; S4. Convert the 0.1 second right ascension and declination into azimuth and elevation using the station location and time information; S5. Test data, including time length, duplication and omission checking, acceleration and speed; S6. Save the azimuth and elevation with a step length of 0.1 as an observation trajectory file.

[0009] Further, step S1 comprises: S1.1 reads the outline file and extracts the coordinates of the source in the form of a string; S1.2 reads the information of each scan, determines the source corresponding to the scan in which the specified station participates, and records the start and end time of the current scan.

[0010] Furthermore, in step S2, the start and end times of the scan are linearly interpolated in combination with the source coordinates to generate a list of 0.1 second step times and source coordinates during the scan.

[0011] Further, in step S3, according to the coordinates of the sources of the two previous and subsequent scans, the telescope pointing corresponding to the source switching period is interpolated using the cosine function, and combined with the linear interpolation of the start and end time of the source switching, a list of 0.1 second step time and telescope pointing during the source switching period is generated.

[0012] Further, step S4 includes: S4.1 merge the lists of steps S2 and S3 to obtain a list of 0.1 second step times and telescope pointing times for the entire observation period; S4.2 converts the 0.1 second step right ascension and declination in S4.1 into a 0.1 second step azimuth and elevation list in combination with the station coordinates.

[0013] Further, step S5 includes: S5.1 Check the length of the list to see if there are any omissions and check if there are any duplications in the list; S5.2 uses the time pointing list of S4.2 to calculate the pointing speed and acceleration, and determines whether the pointing speed and acceleration meet the requirements; S5.3 If the pointing speed and acceleration do not meet the requirements, adjust the source change time in the outline, repeat steps S1.1 to S5.2, and generate a new azimuth and pitch list with a step time of 0.1 seconds; until the pointing speed and acceleration meet the requirements.

[0014] Further, step S6 includes: saving the time azimuth elevation list and submitting it to the telescope controller.

[0015] Furthermore, the method is applied to the FAST custom observation mode.

[0016] On the other hand, the present invention also provides a system for automatically extracting a very long baseline interferometry outline and generating a trajectory file, the system comprising an observation outline information extraction module, a 0.1 second step right ascension and declination generation module, a 0.1 second step azimuth and pitch conversion module, and a data detection module.

[0017] Furthermore, the observation outline information extraction module is used to extract the time and source coordinate information corresponding to the station from the outline file information; the 0.1 second step right ascension and declination generation module is used to generate the 0.1 second right ascension and declination corresponding to each scan according to the source coordinates and start and end time corresponding to each scan, and to generate the 0.1 second right ascension and declination corresponding to the intermediate process of every two scans according to the source coordinates and start and end time corresponding to each two scans; the 0.1 second azimuth and pitch conversion module is used to convert the 0.1 second step right ascension and declination into the 0.1 second step azimuth and pitch corresponding to the station; the data detection module is used to detect whether the total length of time is consistent with the observation outline, whether the generated 0.1 second step data has duplication or omission, and whether the velocity and acceleration corresponding to each data point meet the requirements.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects: According to the method and system of the present invention, the time and source coordinate information corresponding to the station can be completely extracted, and according to the scanning start and end time and the station coordinates, the telescope's 0.1 second azimuth and elevation control file is automatically generated under the constraints of the telescope on speed and acceleration, and the duplicate and omission checks on the generated data are completed. When FAST participates in VLBI observations, it is free from the restrictions on the number of sources and switching cycles, and can participate in various VLBI observation projects more flexibly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flowchart of the overall system architecture of the method and system for extracting summary information of very long baseline interferometry observation and automatically generating observation trajectory files according to the present invention; Figure 2 The combined list of the present invention is shown; Figure 3 An azimuth-pitch table showing the converted Julian time, azimuth, and elevation. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] The following combination Figure 1-Figure 3 The specific embodiments of the present invention are described in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] The present invention provides a method for automatically extracting a very long baseline interferometer outline and generating a trajectory file. This method can realize one-click generation from a very long baseline observation outline to an observation trajectory file. On the one hand, it reduces errors caused by human factors; on the other hand, it allows the telescope to participate in very long baseline observations without being restricted by the observation mode. The observation modes of FAST include tracking mode, OnOff mode, and phase reference mode. The tracking mode can only focus on one target for observation; the OnOff mode can only switch periodically between two sources, and the observation time of the two sources must be kept consistent; the phase reference mode also switches periodically between the two sources, but compared to the OnOff mode, the observation time of the two sources does not need to be kept consistent. Figure 1 As shown, the method comprises the following steps: S1. Extract the information of a specific station from the VLIO outline file, the information including the coordinates of the source and the start and end times corresponding to each scan.

[0025] The outline document includes user information, backend settings, station information, source information and file format, which respectively describe the detailed parameters of users, equipment, stations and equipment, while the observation scan part describes the start and end time, participating stations and equipment used.

[0026] Read the vex file through python, and perform string matching on each line in the corresponding part. In the source information part, extract the source name and corresponding coordinates; in the observation scan part, extract the corresponding start and end time and source name. Step S1 is used to break through the limitation of the observation mode, and there is no requirement for the number of sources, observation time, and cycle switching.

[0027] S2. Generate right ascension and declination with a step length of 0.1 seconds according to the source coordinates and start and end time corresponding to each scan.

[0028] The source coordinates include right ascension and declination. The source coordinates (right ascension and declination) in each scan remain unchanged, and the start time increases in steps of 0.1 seconds until the end time, and the time series of the scan is obtained. In the sequence, the right ascension and declination corresponding to each time point remain unchanged, and the right ascension and declination with a step of 0.1 seconds are obtained.

[0029] Set the start time t1 and the end time t2. The scanning time sequence is [t1, t1+0.1, t1+0.2,…, t2], right ascension RA, declination Dec, then the right ascension and declination with a step length of 0.1 seconds are: [t1, RA, Dec; t1+0.1, RA, Dec; t1+0.2, RA, Dec; … t2, RA, Dec;] S3. Generate right ascension and declination with a step length of 0.1 seconds according to the source coordinates and start and end times corresponding to every two scans.

[0030] Set the start time of the second scan to t3, and the source coordinates to right ascension RA2 and declination Dec2.

[0031] Use a half-period sine function to interpolate the changes in coordinates. The specific formula is as follows: in, is the starting value, is the end value, is the number of interpolations, The speed is simulated from increasing to decreasing by a half-period sine function, which conforms to the law of motion of the feed cabin; the acceleration is simulated from decreasing to increasing, which conforms to the law of force on the cable pulling the feed cabin.

[0032] Take right ascension RA to RA2 as an example: get[ , ],in, For the The time corresponding to the interpolation. Using the same formula, we get [ , ].

[0033] S4. Convert the 0.1 second right ascension and declination into azimuth and pitch using the station position and time information.

[0034] Specific process using Python: from astropy.coordinates import SkyCoord, AltAz, EarthLocation import astropy.units as u Loc=EarthLocation(lon=(1.8650006658875442)*u.rad,lat=(0.44772847428643703)*units.rad,height=(1110.03)*units.m) pos_icrs=SkyCoord(ra= ,dec= ,obstime= ,location=loc,relative_humidity=0.7,pressure=90500*u.Pa,temperature=20*u.deg_C,obswl=21*u.cm) pos_altaz=pos_icrs.transform_to('altaz') Among them, loc uses the station coordinates of FAST, pos_altaz is the azimuth and elevation coordinates obtained after conversion, the azimuth value is pos_altaz.az.degree, and the elevation value is pos_altaz.alt.degree.

[0035] S5. Test data, including time length, duplication and omission checking, acceleration and speed.

[0036] S6. Save the azimuth and elevation with a step length of 0.1 as an observation trajectory file.

[0037] Step S1 includes: S1.1 Read the outline file and extract the source coordinates in the form of a string; read the outline file in Python using readline. When the '$SOURCE' part is read, the source name, right ascension, declination and epoch are saved in the form of a dictionary.

[0038] [{'source_alias': 'SNPHAC', 'ra': ' 11h11m41.7052000s', 'dec': '29d23\'50.518500"', 'frame': ' J2000'}, {'source_alias': 'J1111+2841', 'ra': ' 11h11m13.1864000s', 'dec': '28d41\'47.011000"', 'frame': ' J2000'}, {'source_alias': 'J1118+2922', 'ra': ' 11h18m57.9212000s', 'dec': '29d22\'13.750000"', 'frame': ' J2000'}] S1.2 reads the information of each scan, determines the source corresponding to the scan in which the specified station participates, and records the start and end time of the current scan.

[0039] In Python, readline reads the outline file. In the "scan" section, read the scan containing 'Fa' and save the scan number, station code, start time, source name and observation time in dictionary form.

[0040] [{'scan': 'No0004', 'station': 'Fa', 'start': '2023:332:20:22:00', 'source': 'SNPHAC', 'timedur': 1020}, {'scan': 'No0005', 'station': 'Fa', 'start': '2023:332:20:40:00', 'source': 'J1111+2841', 'timedur': 60}, {'scan': 'No0006', 'station': 'Fa', 'start': '2023:332:20:42:00', 'source': 'SNPHAC', 'timedur': 1020}, {'scan': 'No0007', 'station': 'Fa', 'start': '2023:332:21:00:00', 'source': 'J1111+2841', 'timedur': 60}] Step S2 includes: Combined with the source coordinates, the start and end times of the scan are linearly interpolated to generate a list of 0.1 second step times and source coordinates during the scan; The right ascension and declination of the source coordinates in each scan remain unchanged, and the start time increases in steps of 0.1 seconds until the end time, and the time series of the scan is obtained. In the sequence, the right ascension and declination corresponding to each time point remain unchanged, and the right ascension and declination with a step of 0.1 seconds are obtained.

[0041] Step S3 includes: According to the coordinates of the sources of the two previous and next scans, the telescope pointing corresponding to the source change period is interpolated using the cosine function, and combined with the linear interpolation of the start and end time of the source change, a list of 0.1 second step time and telescope pointing during the source change period is generated; Use a half-period sine function to interpolate the changes in coordinates. The specific formula is as follows: in, is the starting value, is the end value, is the number of interpolations, The speed is simulated from increasing to decreasing by a half-period sine function, which conforms to the law of motion of the feed cabin; the acceleration is simulated from decreasing to increasing, which conforms to the law of force on the cable pulling the feed cabin.

[0042] Take RA to RA2 as an example: get[ , ],in, For the The time corresponding to the interpolation. Using the same formula, we get [ , ].

[0043] Step S4 includes: S4.1 merge the lists of steps S2 and S3 to obtain a list of 0.1 second step times and telescope pointing times for the entire observation period; Figure 2 The merged list is shown. The list before line 3000 is generated by S2, and the list after line 3001 is generated by S3.

[0044] S4.2 Combined with the station coordinates, convert the 0.1 second step right ascension and declination in S4.1 into a 0.1 second step azimuth and pitch list; Figure 3 An azimuth-pitch table showing the converted Julian time, azimuth, and elevation.

[0045] Step S5 includes: S5.1 Check the length of the list to see if there are any omissions and check if there are any duplications in the list; Check the length of the list to find out if there are any omissions. Specifically, use shape in Python to check whether the length of the list is equal to the length of the observation time * 10.

[0046] To check for duplicates, use python.unique([time series]) and [time series] to see if they are equal. If they are equal, there is no duplication.

[0047] Check and modify the code if there are duplications or omissions.

[0048] S5.2 uses the time pointing list of S4.2 to calculate the pointing speed and acceleration and check whether the requirements are met; The velocity is the subtraction of two adjacent coordinates, divided by the time step of 0.1 seconds; the acceleration is the subtraction of two adjacent velocities, divided by the time step of 0.1 seconds; The speed and acceleration limits of FAST are as follows: The velocity is less than 30 angular seconds / second and the acceleration is less than 0.0025 degrees / second / second.

[0049] S5.3 If S5.2 does not meet the requirements, adjust the source change time in the outline, repeat S1.1 to S5.2, and generate a new azimuth and pitch list with a step time of 0.1 seconds until the requirements are met.

[0050] Step S6 includes: Save the time-azimuth-elevation list and submit it to the telescope controller.

[0051] The present invention also provides a system for extracting very long baseline interferometry observation outline information and automatically generating observation trajectory files, the system comprising an observation outline information extraction module, a 0.1 second step right ascension and declination generation module, a 0.1 second step azimuth and pitch conversion module, and a data detection module.

[0052] The observation outline information extraction module is used to extract the time and source coordinate information corresponding to the station from the outline file information; The 0.1 second step right ascension and declination generation module is used to generate the 0.1 second right ascension and declination corresponding to each scan according to the source coordinates and start and end times corresponding to each scan, and to generate the 0.1 second right ascension and declination corresponding to the intermediate process of every two scans according to the source coordinates and start and end times corresponding to every two scans; The 0.1 second azimuth pitch conversion module is used to convert the 0.1 second step length right ascension and declination into the 0.1 second step length azimuth pitch corresponding to the station; The data detection module is used to detect whether the total length of time is consistent with the observation, whether the generated 0.1 second step data has duplication or omission, and whether the speed and acceleration corresponding to each data point meet the requirements.

[0053] The technical advantages of the present invention are as follows: The method and system of the present invention can completely extract the time and source coordinate information corresponding to the station, and automatically generate the 0.1 second azimuth and elevation control file of the telescope based on the scanning start and end time and the station coordinates, while satisfying the telescope's constraints on speed and acceleration, and complete the duplication and omission checks on the generated data. This allows FAST to get rid of the restrictions on the number of sources and switching cycles when participating in VLBI observations, and participate in various VLBI observation projects more flexibly.

[0054] Any process or method description in the flowchart of the present invention or described in other ways herein can be understood as a module, segment or part of a code including one or more executable instructions for implementing the steps of a specific logical function or process, which can be implemented in any computer-readable medium for use by an instruction execution system, device or equipment, and the computer-readable medium can be any medium containing storage, communication, propagation or transmission programs for use by execution systems, devices or equipment, including read-only memories, magnetic disks or optical disks, etc.

[0055] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, those skilled in the art can combine or combine different embodiments or examples described in this specification and the features therein without causing any contradiction.

[0056] Although the above contents have shown and described the embodiments of the present invention, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. Method for automatically extracting very long baseline interferometry outlines and generating trajectory files, It is characterized in that The method comprises the following steps: S1. Extracting information of a specific station from a VLIO outline file, the information including the coordinates of the source and the start and end times corresponding to each scan; S2. Generate right ascension and declination with a step length of 0.1 seconds according to the coordinates of the source corresponding to each scan and the start and end time; S3. Generate right ascension and declination with a step length of 0.1 seconds according to the source coordinates and start and end times corresponding to each two scans; S4. Convert the 0.1 second right ascension and declination into azimuth and elevation using the station location and time information; S5. Test data, including time length, duplication and omission checking, acceleration and speed; S6. Save the azimuth and elevation with a step length of 0.1 as an observation trajectory file.

2. The method for automatically extracting a very long baseline interferometer outline and generating a trajectory file according to claim 1, It is characterized in that Step S1 includes: S1.1 reads the outline file and extracts the coordinates of the source in the form of a string; S1.2 reads the information of each scan, determines the source corresponding to the scan in which the specified station participates, and records the start and end time of the current scan.

3. The method for automatically extracting a very long baseline interferometer outline and generating a trajectory file according to claim 1, It is characterized in that In step S2, the start and end times of the scan are linearly interpolated in combination with the source coordinates to generate a list of 0.1 second step times and source coordinates during the scan.

4. The method for automatically extracting a very long baseline interferometer outline and generating a trajectory file according to claim 1, It is characterized in that In step S3, according to the coordinates of the two scanned sources, the cosine function is used to interpolate the telescope pointing during the source change period, and combined with the linear interpolation of the start and end time of the source change, a list of 0.1 second step time and telescope pointing during the source change period is generated.

5. The method for automatically extracting a very long baseline interferometry outline and generating a trajectory file according to claim 1, It is characterized in that Step S4 includes: S4.1 merge the lists of steps S2 and S3 to obtain a list of 0.1 second step times and telescope pointing times for the entire observation period; S4.2 converts the 0.1 second step right ascension and declination in S4.1 into a 0.1 second step azimuth and elevation list in combination with the station coordinates.

6. The method of automatically extracting a very long baseline interferometer outline and generating a trajectory file according to claim 1, It is characterized in that Step S5 includes: S5.1 Check the length of the list to see if there are any omissions and check if there are any duplications in the list; S5.2 uses the time pointing list of S4.2 to calculate the pointing speed and acceleration, and determines whether the pointing speed and acceleration meet the requirements; S5.3 If the pointing speed and acceleration do not meet the requirements, adjust the source change time in the outline, repeat steps S1.1 to S5.2, and generate a new azimuth and pitch list with a step time of 0.1 seconds; until the pointing speed and acceleration meet the requirements.

7. The method of automatically extracting a very long baseline interferometer outline and generating a trajectory file according to claim 1, It is characterized in that Step S6 includes: saving the time azimuth elevation list and submitting it to the telescope controller.

8. The method for automatically extracting a very long baseline interferometry outline and generating a trajectory file according to any one of claims 1 to 7, It is characterized in that The method is applied to the FAST custom observation mode.

9. A system that automatically extracts the VLB interferometric outline and generates trajectory files. It is characterized in that The system is used to implement the method described in any one of claims 1-7, and the system comprises an observation outline information extraction module, a 0.1 second step right ascension and declination generation module, a 0.1 second step azimuth and pitch conversion module, and a data detection module.

10. The system for automatically extracting a very long baseline interferometry outline and generating a trajectory file according to claim 9, It is characterized in that The observation outline information extraction module is used to extract the time and source coordinate information corresponding to the station from the outline file information; The 0.1 second step right ascension and declination generation module is used to generate the 0.1 second right ascension and declination corresponding to each scan according to the source coordinates and start and end times corresponding to each scan, and to generate the 0.1 second right ascension and declination corresponding to the intermediate process of every two scans according to the source coordinates and start and end times corresponding to every two scans; The 0.1 second azimuth pitch conversion module is used to convert the 0.1 second step length right ascension and declination into the 0.1 second step length azimuth pitch corresponding to the station; The data detection module is used to detect whether the total length of time is consistent with the observation, whether the generated 0.1 second step data has duplication or omission, and whether the speed and acceleration corresponding to each data point meet the requirements.

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