J/A+A/636/A45       CEGM03 model and related gravity anomaly data   (Yan+, 2020)

A degree-100 lunar gravity model from the Chang'e 5T1 mission. Yan J.G., Liu S.H., Xiao C., Ye M., Cao J.F., Harada Y., Li F., Li X., Barriot J. <Astron. Astrophys. 636, A45 (2020)> =2020A&A...636A..45Y 2020A&A...636A..45Y (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Models ; Planets ; Magnetic fields Keywords: Moon - gravitation - planets and satellites: detection - methods: data analysis Abstract: Chinese lunar missions have grown in number over the last ten years, with an increasing focus on radio science investigations. In previous work, we estimated two lunar gravity field models, CEGM01 and CEGM02. The recently lunar mission, Chang'e 5T1, which had an orbital inclination between 18 and 68 degree, and collected orbital tracking data continually for two years, made an improved gravity field model possible. We aimed to estimate a new lunar gravity field model up to degree and order 100, CEGM03, and a new tidal Love number based on the Chang'e 5T1 tracking data combined with the historical tracking data ever used in the solution of CEGM02. The new model makes use of tracking data with this particular inclination, which has not been used in previous gravity field modeling. The solution for this new model was based on our in-house software, LUGREAS. The gravity spectrum power, postfit residuals after precision orbit determination (POD), lunar surface gravity anomalies, correlations between parameters, admittance/coherence with topography model, and accuracy of POD were analyzed to validate the new CEGM03 model. We analyzed the tracking data of the Chang'e 5T1 mission and estimated the CEGM03 lunar gravity field model. We found that the two-way Doppler measurement accuracy reached the 0.2 mm/s with 10 s integration time. The error spectrum shows that the formal error for CEGM03 was at least reduced by about 2 times below the harmonic degree of 20, when compared to the CEGM02 model. The gravity and topography admittance/correlation was also improved when compared to the correlations for the CEGM02 model. The lunar potential Love number k2 was estimated to be 0.02430±0.0001 (ten times the formal error). From the model analysis and comparison of the various models, we identified improvements in the CEGM03 model after introducing Chang'e 5T1 tracking data. Moreover, this study illustrates how the low and middle inclination orbits could contribute better accuracy for a low degree of lunar gravity field. Description: The CEGM03 model was determined from velocity perturbations of the Chang'e 5T1 spacecraft and the historical spacecraft (Chang'e 1, SELENE, LO-I to LO-V, Apollo 15 and 16, Clementine, LP, and SMART-1), as measured from the Doppler shift of the S/X-band radio tracking. Besides, related free-air anomalies, gravity anomaly, and solenoid error data are contained. The coordinate system for the gravity data, and the coefficients in the CEGM03 gravity field, is selenocentric, center of mass, longitude positive east. The location of the pole and the prime meridian are defined by the principal axes as given by the integrated lunar librations of DE421 (Williams et al. 2008). The spherical harmonics coefficients provide both the coefficient values and uncertainties. Others Parameters: 4.90281910072908D+12 : Moon's GM value (unit: m3/s2) 0.1738000D+07 : Moon's reference radius (unit: m) cegm03nc.dat is the Free-air anomalies data based on the CEGM03 model. gaano30.dat and sele30.dat are transfered to ASCII for scientists who are interested. You also can calculate these anomalies by yourself based on the CEGM03 model. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file cegm03.dat 70 10197 Spherical harmonics coefficients of CEGM03 cegm03nc.dat 29 81608 Free-air anomalies data of CEGM03 gaano30.dat 13 65341 Gravity anomaly cut off at 30 degrees sele30.dat 13 65341 Selenoid error cut off at 30 degrees -------------------------------------------------------------------------------- Byte-by-byte Description of file: cegm03.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 6 A6 --- Coeff COEFC or COEFS Coefficients mark 13- 15 I3 --- Degree Degree of C or S coefficient 16- 18 I3 --- Order Order of C or S coefficient 23- 42 E20.14 --- Value Value of C or S coefficient. 60- 70 E11.6 --- e_Value Uncertainty of C or S coefficient -------------------------------------------------------------------------------- Byte-by-byte Description of file: cegm03nc.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 2- 9 F8.3 deg Lat Latitude of Moon 13- 19 F7.3 deg Long Longitude of Moon 22- 29 F8.3 --- Anomaly Free-air anomalies value, in mGal unit -------------------------------------------------------------------------------- Byte-by-byte Description of file: gaano30.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 deg Lat Latitude of Moon 5- 7 I3 deg Long Longitude of Moon 9- 13 F5.3 --- Anomaly Gravity anomaly value, in mGal unit -------------------------------------------------------------------------------- Byte-by-byte Description of file: sele30.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 deg Lat Latitude of Moon 5- 7 I3 deg Long Longitude of Moon 9- 13 F5.3 m Selenoid-error Selenoid error value -------------------------------------------------------------------------------- Acknowledgements: Yan Jianguo, jgyan(at)whu.edu.cn
(End) Yan Jianguo [WHU, China], Patricia Vannier [CDS] 07-Mar-2020
The document above follows the rules of the Standard Description for Astronomical Catalogues; from this documentation it is possible to generate f77 program to load files into arrays or line by line