Radio telescope scanning observation method and system

Abstract

The application relates to a radio telescope scanning observation method and system, which comprises the following steps: determining a scanning center point of a radio telescope; determining an optimal value of a scanning parameter of the radio telescope for realizing a preset scanning track through two-dimensional periodic motion around the scanning center point; sending the optimal value of the scanning parameter to a telescope pointing and control system, so that the telescope pointing and control system controls the radio telescope to perform two-dimensional periodic motion around the scanning center point according to the optimal value of the scanning parameter; and controlling a data acquisition system of the radio telescope to start synchronously with the two-dimensional periodic motion, and synchronously acquiring observation data collected by the data acquisition system in real time and real-time pointing data of the telescope pointing and control system.

Description

Technical Field

[0001] This invention relates to the field of radio astronomy observation technology, and more specifically to a radio telescope scanning observation method and system, which is applicable to two-dimensional scanning observation of large fully steerable radio telescopes, especially suitable for deep space imaging and molecular spectral line surveys at high frequencies (such as K-band and Q-band) of the Shanghai Tianma 65-meter radio telescope, so as to improve imaging quality and observation efficiency. Background Technology

[0002] Radio astronomy observations are rapidly developing towards higher frequencies (millimeter waves) and greater depth sensitivity. Systematic errors have gradually replaced thermal noise as the core factor limiting the dynamic range and imaging accuracy of astronomical imaging. Large, fully steerable radio telescopes, such as the Tianma Telescope, are susceptible to significant errors in observational data and imaging results when conducting scientific observations in the K-band (approximately 22 GHz), Q-band (approximately 40 GHz), and higher frequency bands, including molecular spectral line imaging and fine structure of active galactic nuclei. These errors are caused by multiple factors, such as complex atmospheric conditions at the site, antenna pointing accuracy and structural stability, and receiver system noise.

[0003] To suppress the aforementioned errors, existing radio telescopes generally employ specific scanning strategies to achieve sky coverage and data calibration. Traditional raster scans or ongoings scans achieve observations by moving the antenna at a constant speed along the rows and columns of the sky. While these methods are simple to implement and easy to operate, they are highly sensitive to time-varying systematic errors such as atmospheric fluctuations and antenna drift, easily introducing stripe artifacts into the final image. Furthermore, they require frequent insertion of calibration observations, reducing overall observation efficiency.

[0004] To improve image quality, existing technologies have proposed strategies such as box scan, cross scan, circular scan, and spiral scan. These methods increase the frequency of access to the central calibration source to some extent and help suppress some systematic errors, but they still have limitations in terms of sky coverage uniformity, scanning efficiency, or trajectory controllability, making it difficult to meet the requirements of high dynamic range and high-precision imaging. Therefore, there is an urgent need for a scanning observation method that can be deeply integrated with the hardware performance of a specific telescope and combines scientific observation with system self-calibration. Summary of the Invention

[0005] The purpose of this invention is to provide a radio telescope scanning observation method and system that can improve the uniformity of sky coverage, scanning efficiency and trajectory controllability while suppressing systematic errors, thereby meeting the requirements of high dynamic range and high precision imaging.

[0006] To achieve the above objectives, the present invention provides a radio telescope scanning observation method, comprising:

[0007] Determine the scanning center point of the radio telescope;

[0008] The optimal values ​​of the scanning parameters are determined for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve the preset scanning trajectory.

[0009] The optimal value of the scanning parameters is sent to the telescope pointing and control system, so that the telescope pointing and control system controls the radio telescope to perform a two-dimensional periodic motion around the scanning center point according to the optimal value of the scanning parameters;

[0010] The data acquisition system of the radio telescope is started synchronously with the two-dimensional periodic motion, and the observation data collected in real time by the data acquisition system and the real-time pointing data of the telescope pointing and control system are acquired simultaneously.

[0011] Optionally, the scanning trajectory is a daisy-shaped trajectory, which is defined in a local offset coordinate system relative to the scanning center point by the following equation:

[0012]

[0013] Where δAz(t) is the azimuth deviation relative to the scan center point, δEl(t) is the pitch deviation relative to the scan center point, t is time, r0 is the maximum radial offset amplitude of the scan trajectory, ω is the angular frequency of radial oscillation, Ω is the angular frequency of the overall trajectory precession, φ1 is the initial phase of Ω, φ2 is the initial phase of ω, and El src The elevation angle of the scan center point.

[0014] Optionally, the scanning parameters include r0, ω, and Ω, where ω / Ω is π or a real number greater than 2;

[0015] Determining the optimal values ​​of scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve a preset scanning trajectory specifically includes:

[0016] The constraints on the scanning parameters are determined based on the performance of the radio telescope;

[0017] The value space of the scanning parameters is determined based on the constraints.

[0018] An iterative operation is performed within the value space. In each iteration, a scanning parameter value is selected from the value space, and a scanning trajectory is obtained through simulation using the selected scanning parameter value. The performance index of the scanning trajectory is evaluated, and the overall cost is determined based on the performance index of the scanning trajectory. With the goal of minimizing the overall cost, the scanning parameter value is updated and iterated to obtain the optimal value of the scanning parameter.

[0019] Optionally, the constraints include velocity constraints, acceleration constraints, sampling constraints, frequency constraints, and calibration frequency constraints. The velocity constraint requires that the instantaneous velocity r0×ω of the scanning motion be less than the maximum safe tracking velocity of the radio telescope at the observation elevation angle. The acceleration constraint requires that the maximum instantaneous acceleration of the scanning motion be less than the maximum safe acceleration of the radio telescope's drive system, with the maximum instantaneous acceleration being r0×(ω). 2 +Ω 2 The sampling constraint is that the speed of the scanning motion satisfies the Nyquist sampling theorem; the frequency constraint is that ω and Ω must avoid the known major mechanical resonance frequencies of the radio telescope structure; and the calibration frequency constraint is that the half-period π / ω of the radial oscillation is between 10 seconds and 60 seconds.

[0020] Optionally, the performance metrics of the scanning trajectory include center revisit period, coverage area, and sampling uniformity coefficient, and the overall cost satisfies the following relationship:

[0021] F=w1×U / U ref +w2×t cyc / t ref -w3×S / S ref

[0022] Where F is the overall cost, w1, w2, and w3 are weights, and the sum of the three is 1, and U is the sampling uniformity coefficient. ref t is the reference value for the sampling uniformity coefficient. cyc For the center revisit period, t ref Here is the reference value for the center revisit cycle, and S is the coverage area. ref This is a reference value for the coverage area.

[0023] Another aspect of the present invention provides a radio telescope scanning observation system, comprising:

[0024] The first determining module is used to determine the scanning center point of the radio telescope;

[0025] The second determining module is used to determine the optimal value of the scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve the preset scanning trajectory.

[0026] The transmitting module is used to send the optimal value of the scanning parameters to the telescope pointing and control system, so that the telescope pointing and control system controls the radio telescope to perform a two-dimensional periodic motion around the scanning center point according to the optimal value of the scanning parameters;

[0027] The data acquisition module is used to control the data acquisition system of the radio telescope to start synchronously with the two-dimensional periodic motion, and to synchronously acquire the observation data collected in real time by the data acquisition system and the real-time pointing data of the telescope pointing and control system.

[0028] Optionally, the scanning trajectory is a daisy-shaped trajectory, which is defined in a local offset coordinate system relative to the scanning center point by the following equation:

[0029]

[0030] Where δAz(t) is the azimuth deviation relative to the scan center point, δEl(t) is the pitch deviation relative to the scan center point, t is time, r0 is the maximum radial offset amplitude of the scan trajectory, ω is the angular frequency of radial oscillation, Ω is the angular frequency of the overall trajectory precession, φ1 is the initial phase of Ω, φ2 is the initial phase of ω, and El src The elevation angle of the scan center point.

[0031] Optionally, the scanning parameters include r0, ω, and Ω, where ω / Ω is π or a real number greater than 2;

[0032] Determining the optimal values ​​of scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve a preset scanning trajectory specifically includes:

[0033] The constraints on the scanning parameters are determined based on the performance of the radio telescope;

[0034] The value space of the scanning parameters is determined based on the constraints.

[0035] An iterative operation is performed within the value space. In each iteration, a scanning parameter value is selected from the value space, and a scanning trajectory is obtained through simulation using the selected scanning parameter value. The performance index of the scanning trajectory is evaluated, and the overall cost is determined based on the performance index of the scanning trajectory. With the goal of minimizing the overall cost, the scanning parameter value is updated and iterated to obtain the optimal value of the scanning parameter.

[0036] Optionally, the constraints include velocity constraints, acceleration constraints, sampling constraints, frequency constraints, and calibration frequency constraints, wherein the velocity constraint requires that the instantaneous velocity r0×ω of the scanning motion be less than the maximum safe tracking velocity of the radio telescope at the observation elevation angle, and the acceleration constraint requires that the maximum instantaneous acceleration r0×(ω) of the scanning motion be less than the maximum safe tracking velocity of the radio telescope at the observation elevation angle. 2 +Ω 2The sampling constraint is that the speed of the scanning motion satisfies the Nyquist sampling theorem, the frequency constraint is that ω and Ω must avoid the known major mechanical resonance frequencies of the radio telescope structure, and the calibration frequency constraint is that the half-period π / ω of the radial oscillation is between 10 seconds and 60 seconds.

[0037] Optionally, the performance metrics of the scanning trajectory include center revisit period, coverage area, and sampling uniformity coefficient, and the overall cost satisfies the following relationship:

[0038] F=w1×U / U ref +w2×t cyc / t ref -w3×S / S ref

[0039] Where F is the overall cost, w1, w2, and w3 are weights, and the sum of the three is 1, and U is the sampling uniformity coefficient. ref t is the reference value for the sampling uniformity coefficient. cyc For the center revisit period, t ref Here is the reference value for the center revisit cycle, and S is the coverage area. ref This is a reference value for the coverage area. Attached Figure Description

[0040] Figure 1 This is a flowchart of a radio telescope scanning observation method according to an embodiment of the present invention;

[0041] Figure 2A , Figure 2B , Figure 2C and Figure 2D The diagrams show the chrysanthemum trajectories at different time lengths, illustrating the complex but regular covering characteristics resulting from the synthesis of radial oscillations and overall precession.

[0042] Figure 3 To reconstruct the 1σ noise sensitivity distribution map of the sky region after Q-band observation using the radio telescope scanning observation method of this embodiment;

[0043] Figure 4 for Figure 3 Histogram of pixel noise levels in the sensitivity distribution map;

[0044] Figure 5 This is a structural block diagram of a radio telescope scanning observation system according to an embodiment of the present invention. Detailed Implementation

[0045] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0046] like Figure 1 As shown, this embodiment of the invention provides a radio telescope scanning observation method, which includes the following steps:

[0047] S100: Determine the scanning center point of the radio telescope.

[0048] The scanning center point can be determined based on the observation target and adapted to the observation frequency band of the radio telescope. The observation target is the scientific target, which can be molecular spectral line imaging (obtaining interstellar molecular spectral line information through millimeter-wave observations to study the physicochemical properties of the interstellar medium, star formation processes, etc.), active galactic nucleus research (observing the radio emission characteristics of active galactic nuclei to explore their structure, energy source, and evolutionary laws, etc.), or any other suitable target. The scientific target directly determines the scanning area and resolution requirements, thus determining the coordinates of the scanning center point. The scanning center point is usually a strong calibration source or the center of the target sky region.

[0049] S200: Determine the optimal values ​​of the scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve the preset scanning trajectory.

[0050] The preset scanning trajectory can be a chrysanthemum trajectory, which resembles a chrysanthemum shape, such as... Figure 2A , Figure 2B , Figure 2C and Figure 2D As shown. The chrysanthemum trajectory, in a local offset coordinate system (e.g., horizontal coordinate system Az-El or celestial coordinate system RA-Dec) relative to the scan center point, is defined by the following parametric equations:

[0051] In the horizontal coordinate system:

[0052]

[0053] Or equivalently in the celestial coordinate system:

[0054]

[0055] Where: δAz(t) is the azimuth deviation relative to the scan center point, δEl(t) is the pitch deviation relative to the scan center point, δRA(t) is the right ascension deviation relative to the scan center point, δDec(t) is the declination deviation relative to the scan center point, t is time, r0 is the maximum radial offset amplitude (angular distance) of the scan trajectory, ω is the angular frequency of radial oscillation, Ω is the angular frequency of the overall trajectory precession, φ1 is the initial phase of Ω, φ2 is the initial phase of ω, used to adjust the starting azimuth and oscillation phase of the trajectory, El src dec0 is the elevation angle of the scan center point (used for the conversion from horizontal coordinates to the tangent plane), and dec0 is the declination of the scan center point.

[0056] The formation of the scan trajectory is determined by the ratio of ω to Ω. By setting ω / Ω to an irrational number (such as approximately π) or a real number greater than 2, it can be ensured that the trajectory does not repeat over multiple periods, thereby achieving uniform coverage of local sky areas.

[0057] The scan parameters include r0, ω, and Ω. The optimal values ​​of the scan parameters are determined as follows:

[0058] Constraints for determining scanning parameters based on the performance of the radio telescope;

[0059] The value space of the scanning parameters is determined based on the constraints of the scanning parameters;

[0060] An iterative operation is performed within the value space of the scanning parameters. In each iteration, a scanning parameter value is selected from the value space of the scanning parameters, and the scanning trajectory is obtained by simulation using the selected scanning parameter value. The performance index of the scanning trajectory is evaluated, and the overall cost is determined based on the performance index of the scanning trajectory. With the goal of minimizing the overall cost, the scanning parameter value is updated and iterated to obtain the optimal value of the scanning parameters.

[0061] The constraints on the scan parameters include:

[0062] Velocity constraint: Instantaneous velocity v of the scanning motion max ≈r0×ω must be less than the maximum safe tracking speed of the radio telescope at the observation elevation angle. For example, taking the Tianma Telescope as an example, it must be much lower than the software speed limits for azimuth / elevation, which are 30 arcminutes / second and 15 arcminutes / second, respectively.

[0063] Acceleration constraint: The maximum instantaneous acceleration a of the scanning motion. max ≈r0×(ω 2 +Ω 2 (This expression is an upper limit estimate of the acceleration amplitude, which needs to be verified by numerical simulation during actual trajectory optimization.) It must be less than the maximum safe acceleration of the drive system of the radio telescope (e.g., the Tianma Telescope).

[0064] Sampling constraints: The scanning speed must satisfy the Nyquist sampling theorem for the back-end sampling rate and the observation wavelength. For example, when performing beam measurements in the Q-band, the scanning speed needs to be slow enough to ensure sufficient spatial sampling of the radio telescope's main beamwidth.

[0065] Frequency constraints: ω and Ω must avoid the known major mechanical resonant frequencies of the radio telescope (e.g., the inherent vibration frequencies of its base or panel) to prevent resonance that could damage the equipment or affect pointing accuracy.

[0066] Calibration frequency constraint: Half-period t of radial oscillation cyc=π / ω reflects the frequency at which the radio telescope returns to near the center of the scan. Taking the Tianma Telescope as an example, based on the requirements of high-frequency observations for error correction speed (such as rapid atmospheric changes in the Q-band), t cyc The interval is typically set between 10 and 60 seconds, preferably between 10 and 30 seconds, to enable frequent sampling of the system status.

[0067] The performance metrics of the scan trajectory include the center revisit period (i.e., the half-cycle of the radial oscillation) t. cyc The coverage area S and the sampling uniformity coefficient U, where the coverage area S = π × , where R eff The effective coverage radius of the scan trajectory is related to the maximum radial offset amplitude r0. Considering the sparse sampling at the trajectory edges, Reff is usually taken as αr0, with the coefficient α between 0.8 and 1.0. The sampling uniformity coefficient U (defined as a measure of the uniformity of the scan trajectory's sampling of the target sky area) is calculated as follows:

[0068] Divide the target sky area (e.g., a square area with a side length of 2.2r0 centered at the scan center point) into a grid. The grid size is usually set to grid. size = Beamwidth / 3 (satisfying Nyquist sampling); Simulate the daisy scan trajectory for T seconds, count the number of times each grid is visited, calculate the mean and standard deviation of the number of visits for all grid cells, U is equal to the standard deviation of the number of visits for all grid cells divided by the mean (i.e., the ratio of the two), the smaller the value of U, the smaller the difference in the number of visits for each grid cell, that is, the better the sampling uniformity of the scan trajectory, ideally U=0 indicates completely uniform sampling.

[0069] The total cost F satisfies the following relationship:

[0070] F=w1×U / U ref +w2×t cyc / t ref -w3×S / S ref

[0071] Where w1, w2, and w3 are weights, and the sum of the three is 1, U ref t ref and S ref All are normalized reference values, U ref t can be 0.5 or 1.0 (as a benchmark for uniformity). ref 20 seconds is acceptable (the ideal calibration period desired by the user), S ref It can be taken as π×r 0max 2 (Theoretical maximum coverage area).

[0072] Iterative optimization: Within the value space determined by the constraints, the optimal scanning parameters are found by using iterative algorithms (such as grid search, genetic algorithm, etc.) to minimize the comprehensive cost F.

[0073] S300: Sends the optimal values ​​of the scanning parameters to the Telescope Pointing and Control (TPTC) system, so that the Telescope Pointing and Control system controls the radio telescope to perform two-dimensional periodic motion around the scanning center point according to the optimal values ​​of the scanning parameters.

[0074] The Telescope Pointing and Tracking Control (TPTC) system is used to interpret observation commands and drive the radio telescope's movement. Once the optimal values ​​for the scanning parameters are determined, they are sent to the TPTC system, which then drives the radio telescope according to these optimal values, creating a daisy-shaped trajectory determined by the optimal scanning parameters. The TPTC system is an integral part of the radio telescope and is existing technology; its specific working principle will not be elaborated here.

[0075] The TPTC system employs an "in-flight" mode to initiate scanning, allowing the radio telescope to smoothly transition from a stable tracking state to the scanning trajectory, avoiding shocks and pauses. "In-flight" startup is a scanning initiation mode that enables the radio telescope to smoothly overlay scanning offsets into a preset trajectory while tracking the target source, avoiding pauses at the starting point or complex velocity matching.

[0076] S400: The data acquisition system of the radio telescope (such as the DIBAS (Digital Back-End System) of the Tianma Telescope) is started synchronously with the two-dimensional periodic motion, and simultaneously acquires the observation data collected in real time by the data acquisition system and the real-time telescope pointing data with high-precision timestamps from the telescope pointing and control system.

[0077] During the movement of the radio telescope, the data acquisition system controlling the radio telescope is activated synchronously, enabling the system to collect observational data in real time. This data, along with high-precision timestamped real-time telescope pointing data from the TPTC system, can be used for subsequent processing. The observational data includes total power and spectrum, while the telescope pointing data includes the radio telescope's azimuth and elevation angles (or corresponding right ascension and declination).

[0078] In some embodiments, the radio telescope scanning observation method may further include the following steps:

[0079] S500: Uses observation data and pointing data when the radio telescope passes or approaches the scanning center point to perform gain drift correction, pointing deviation correction, and atmospheric / system baseline correction to obtain corrected observation data and correction parameters (such as gain factor, pointing offset, etc.).

[0080] S600: Using telescope pointing data, the observation data collected in time series is "placed" to its corresponding celestial position. Through regridization algorithms (such as nearest neighbor, bilinear interpolation, etc.), these data are interpolated into a regular celestial coordinate network, and finally the intensity distribution map (continuous spectrum) or data cube (spectral line) of the target sky region is generated.

[0081] The correction method in step S500 and the regrid imaging method in step S600 are existing technologies, and their specific steps and principles will not be elaborated here.

[0082] To verify the effectiveness of the method of the present invention, simulation observations were conducted, and the results are as follows: Figure 3 and Figure 4 As shown. From Figure 3 It can be seen that, after applying the method of the present invention, the uniformity of the noise sensitivity distribution map of the reconstructed sky area is far superior to the striped noise structure that may be generated by traditional scanning, thus resulting in higher imaging quality; from Figure 4 It can be seen that, Figure 4 The pixel noise levels are concentrated in a narrow range, proving that the method can effectively suppress large-scale systematic errors and obtain uniform data quality.

[0083] In some embodiments, an Archimedean spiral or logarithmic spiral scan with a radius varying over time can also be employed. By finely designing the radius change rate, coverage of the outer region and frequent revisiting of the central region can also be achieved, but different trajectory velocity and acceleration change patterns may require different control optimization strategies.

[0084] In some embodiments, scanning parameters (e.g., r0 or ω) can be dynamically adjusted based on real-time atmospheric coherence time or system noise measurements. For example, r0 can be increased to cover a larger sky area when the atmosphere is very stable, and r0 can be decreased to increase the calibration frequency when the atmosphere is unstable.

[0085] In some embodiments, two or more daisy scans of different amplitudes (r0) or frequencies (ω) can be nested in a single observation. First, a small-amplitude high-frequency scan is used to accurately calibrate the central region and system parameters, and then a large-amplitude low-frequency scan is used to cover the outer sky region.

[0086] In some embodiments, daisy trajectory scanning can be used as the main observation mode, combined with periodic full-antenna pointing calibration (such as the five o'clock method) or noise injection calibration to form a more complex hybrid observation scheme to correct some systematic errors that daisy trajectory scanning itself may not be able to fully capture.

[0087] The radio telescope scanning observation method of this invention, through a specific daisy-shaped scanning trajectory, can achieve high-frequency monitoring and correction of systematic errors such as pointing error and gain drift during a single scan; it integrates scientific sky coverage and system self-calibration into a single continuous scan process, avoiding the time loss of mode switching and improving the telescope's time utilization and data output rate; it ensures that the key scanning parameters (such as amplitude and frequency) of the scanning trajectory are strictly limited by the known driving performance (velocity and acceleration limits) and observation constraints (beamwidth and sampling rate) of the radio telescope (such as the Tianma Telescope), ensuring that the trajectory can be executed safely and smoothly; and it is tightly integrated with the radio telescope's TPTC system and data acquisition system, ensuring the accurate execution of scanning commands and high-quality synchronous recording of observation data.

[0088] like Figure 5 As shown, this embodiment of the invention also provides a radio telescope scanning observation system, which includes a first determining module 10, a second determining module 20, a transmitting module 30, and a data acquisition module 40.

[0089] The first determining module 10 is used to determine the scanning center point of the radio telescope.

[0090] The second determining module 20 is used to determine the optimal value of the scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve the preset scanning trajectory.

[0091] The transmitting module 30 is used to send the optimal value of the scanning parameters to the telescope pointing and control system, so that the telescope pointing and control system controls the radio telescope to perform two-dimensional periodic motion around the scanning center point according to the optimal value of the scanning parameters;

[0092] The data acquisition module 40 is used to control the data acquisition system of the radio telescope to start synchronously with the two-dimensional periodic motion, and to synchronously acquire the observation data collected in real time by the data acquisition system and the real-time pointing data of the telescope pointing and control system.

[0093] The first determining module 10, the second determining module 20, the sending module 30, and the data acquisition module 40 are the functional modules corresponding to steps S100-S400, and their specific implementation methods can be found in the descriptions in steps S100-S400, which will not be repeated here.

[0094] In some embodiments, the system may further include:

[0095] The correction module is used to perform gain drift correction, pointing deviation correction, and atmospheric / system baseline correction using observation data and pointing data when the radio telescope passes through or approaches the scanning center point, so as to obtain the corrected observation data and correction parameters (such as gain factor, pointing offset, etc.).

[0096] The regrid imaging module is used to "place" the time-series collected observation data into its corresponding celestial position using telescope pointing data. Through regrid algorithms (such as nearest neighbor, bilinear interpolation, etc.), these data are interpolated into a regular celestial coordinate network, and finally the intensity distribution map (continuous spectrum) or data cube (spectral line) of the target sky region is generated.

[0097] The radio telescope scanning observation system of this invention, through a specific daisy-shaped scanning trajectory, can achieve high-frequency monitoring and correction of systematic errors such as pointing error and gain drift during a single scan; it integrates scientific sky coverage and system self-calibration into a single continuous scan process, avoiding the time loss of mode switching and improving the telescope's time utilization and data output rate; it ensures that the key scanning parameters (such as amplitude and frequency) of the scanning trajectory are strictly limited by the known driving performance (velocity and acceleration limits) and observation constraints (beamwidth and sampling rate) of the radio telescope (such as the Tianma Telescope), ensuring that the trajectory can be executed safely and smoothly; and it is tightly integrated with the radio telescope's TPTC system and data acquisition system, ensuring the accurate execution of scanning commands and high-quality synchronous recording of observation data.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A radio telescope scanning observation method, characterized in that, include: Determine the scanning center point of the radio telescope; The optimal values ​​of the scanning parameters are determined for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve the preset scanning trajectory. The optimal value of the scanning parameters is sent to the telescope pointing and control system, so that the telescope pointing and control system controls the radio telescope to perform a two-dimensional periodic motion around the scanning center point according to the optimal value of the scanning parameters; The data acquisition system of the radio telescope is started synchronously with the two-dimensional periodic motion, and the observation data collected in real time by the data acquisition system and the real-time pointing data of the telescope pointing and control system are acquired simultaneously. The scanning trajectory is a chrysanthemum trajectory, and the chrysanthemum trajectory, in a local offset coordinate system relative to the scanning center point, is defined by the following equation: ， Where δAz(t) is the azimuth deviation relative to the scan center point, δEl(t) is the pitch deviation relative to the scan center point, t is time, r0 is the maximum radial offset amplitude of the scan trajectory, ω is the angular frequency of radial oscillation, Ω is the angular frequency of the overall trajectory precession, φ1 is the initial phase of Ω, φ2 is the initial phase of ω, and El src The elevation angle of the scan center point; The scanning parameters include r0, ω, and Ω, where ω / Ω is π or a real number greater than 2; Determining the optimal values ​​of scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve a preset scanning trajectory specifically includes: The constraints on the scanning parameters are determined based on the performance of the radio telescope; The value space of the scanning parameters is determined based on the constraints. An iterative operation is performed within the value space. In each iteration, a scanning parameter value is selected from the value space, and the selected scanning parameter value is used to simulate and obtain the scanning trajectory. The performance index of the scanning trajectory is evaluated, and the comprehensive cost is determined based on the performance index of the scanning trajectory. With the goal of minimizing the comprehensive cost, the scanning parameter value is updated and iterated to obtain the optimal value of the scanning parameter. The constraints include velocity constraints, acceleration constraints, sampling constraints, frequency constraints, and calibration frequency constraints. The velocity constraint requires that the instantaneous velocity r0×ω of the scanning motion be less than the maximum safe tracking velocity of the radio telescope at the observation elevation angle. The acceleration constraint requires that the maximum instantaneous acceleration of the scanning motion be less than the maximum safe acceleration of the radio telescope's drive system, with the maximum instantaneous acceleration being r0×(ω). 2 +Ω 2 The sampling constraint is that the speed of the scanning motion satisfies the Nyquist sampling theorem; the frequency constraint is that ω and Ω must avoid the known major mechanical resonance frequencies of the radio telescope structure; and the calibration frequency constraint is that the half-period π / ω of the radial oscillation is between 10 seconds and 60 seconds.

2. The radio telescope scanning observation method according to claim 1, characterized in that, The performance metrics of the scanning trajectory include center revisit period, coverage area, and sampling uniformity coefficient, and the overall cost satisfies the following relationship: F=w1×U / U ref +w2×t cyc / t ref -w3×S / S ref Where F is the overall cost, w1, w2, and w3 are weights, and the sum of the three is 1, and U is the sampling uniformity coefficient. ref t is the reference value for the sampling uniformity coefficient. cyc For the center revisit period, t ref Here is the reference value for the center revisit cycle, and S is the coverage area. ref This is a reference value for the coverage area.

3. A radio telescope scanning observation system, characterized in that, include: The first determining module is used to determine the scanning center point of the radio telescope; The second determining module is used to determine the optimal value of the scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve the preset scanning trajectory. The transmitting module is used to send the optimal value of the scanning parameters to the telescope pointing and control system, so that the telescope pointing and control system controls the radio telescope to perform a two-dimensional periodic motion around the scanning center point according to the optimal value of the scanning parameters; The data acquisition module is used to control the data acquisition system of the radio telescope to start synchronously with the two-dimensional periodic motion, and to synchronously acquire the observation data collected in real time by the data acquisition system and the real-time pointing data of the telescope pointing and control system. The scanning trajectory is a chrysanthemum trajectory, and the chrysanthemum trajectory, in a local offset coordinate system relative to the scanning center point, is defined by the following equation: ， Where δAz(t) is the azimuth deviation relative to the scan center point, δEl(t) is the pitch deviation relative to the scan center point, t is time, r0 is the maximum radial offset amplitude of the scan trajectory, ω is the angular frequency of radial oscillation, Ω is the angular frequency of the overall trajectory precession, φ1 is the initial phase of Ω, φ2 is the initial phase of ω, and El src The elevation angle of the scan center point; The scanning parameters include r0, ω, and Ω, where ω / Ω is π or a real number greater than 2; Determining the optimal values ​​of scanning parameters for the radio telescope to perform two-dimensional periodic motion around the scanning center point and achieve a preset scanning trajectory specifically includes: The constraints on the scanning parameters are determined based on the performance of the radio telescope; The value space of the scanning parameters is determined based on the constraints. An iterative operation is performed within the value space. In each iteration, a scanning parameter value is selected from the value space, and the selected scanning parameter value is used to simulate and obtain the scanning trajectory. The performance index of the scanning trajectory is evaluated, and the comprehensive cost is determined based on the performance index of the scanning trajectory. With the goal of minimizing the comprehensive cost, the scanning parameter value is updated and iterated to obtain the optimal value of the scanning parameter. The constraints include velocity constraints, acceleration constraints, sampling constraints, frequency constraints, and calibration frequency constraints. The velocity constraint requires that the instantaneous velocity r0×ω of the scanning motion be less than the maximum safe tracking velocity of the radio telescope at the observation elevation angle. The acceleration constraint requires that the maximum instantaneous acceleration r0×(ω) of the scanning motion be less than the maximum safe tracking velocity of the radio telescope at the observation elevation angle. 2 +Ω 2 The sampling constraint is that the speed of the scanning motion satisfies the Nyquist sampling theorem. The frequency constraint is that ω and Ω must avoid the known major mechanical resonance frequencies of the radio telescope structure. The calibration frequency constraint is that the half-period π / ω of the radial oscillation is between 10 seconds and 60 seconds.

4. The radio telescope scanning observation system according to claim 3, characterized in that, The performance metrics of the scanning trajectory include center revisit period, coverage area, and sampling uniformity coefficient, and the overall cost satisfies the following relationship: F=w1×U / U ref +w2×t cyc / t ref -w3×S / S ref Where F is the overall cost, w1, w2, and w3 are weights, and the sum of the three is 1, and U is the sampling uniformity coefficient. ref t is the reference value for the sampling uniformity coefficient. cyc For the center revisit period, t ref Here is the reference value for the center revisit cycle, and S is the coverage area. ref This is a reference value for the coverage area.

Images