CHAMP Orbit Format CHORB ------------------------ Issue 1.3 2000/04/05 Orbit Products -------------- Naming: +type-sss_YYYY_DOY_HH | | | | | |___ hour of beginning of arc | | | | |______ day of year of beginning of arc | | | |__________ year of beginning of arc | | |_______________ GPS ... GPS satellites, CHA ... CHAMP | |____________________ reference frame TDS or CTS, or ephemeris | type (BRC, TLE, IRV) |_________________________ product name, f.i. CH-OG-3-RSO List of orbit products: Rapid science orbits: CH-OG-3-RSO+CTS-GPS_YYYY_DOY_HH CH-OG-3-RSO+CTS-CHA_YYYY_DOY_HH iCH-OG-3-RSO+TDS-GPS_YYYY_DOY_HH iCH-OG-3-RSO+TDS-CHA_YYYY_DOY_HH Predicted science orbits re. ephemeris: CH-OG-3-PDO+CTS-GPS_YYYY_DOY_HH CH-OG-3-PDO+CTS-CHA_YYYY_DOY_HH iCH-OG-3-PDO+TDS-GPS_YYYY_DOY_HH iCH-OG-3-PDO+TDS-CHA_YYYY_DOY_HH CH-OG-3-PDO+BRC-GPS_YYYY_DOY_HH CH-OG-3-PDO+BRC-CHA_YYYY_DOY_HH ... tbc iCH-OG-3-PDO+TLE-GPS_YYYY_DOY_HH CH-OG-3-PDO+TLE-CHA_YYYY_DOY_HH CH-OG-3-PDO+IRV-CHA_YYYY_DOY_HH Post-processed science orbits: CH-OG-4-PSO+CTS-GPS_YYYY_DOY_HH CH-OG-4-PSO+CTS-CHA_YYYY_DOY_HH iCH-OG-4-PSO+TDS-GPS_YYYY_DOY_HH iCH-OG-4-PSO+TDS-CHA_YYYY_DOY_HH - CHAMP twoline elements (CH-OG-3-PDO+TLE-CHA_YYYY_DOY_HH) and IRVs (CH-OG-3-PDO+IRV-CHA_YYYY_DOY_HH) for the SLR community will be generated twice per day - Standard format of the GPS orbits and clocks is sp3 - Standard format of the LEO orbits is the CHORB format as given here. Because of the wide spectrum of informations needed, sp3 will not be used. AP Requirements on the RSO -------------------------- General - Delivery at 0, 3, 6, ... , 21 h UTC; independent of data dumps - Period covered: 18 h up to delivery time - 15 h overlap - State vector density: 30 s, tbc for geomagnetic storms Informations Provided in Header Records - Observation types and periods used: "GPS SST" ... GPS onboard data "GPS GS " ... GPS ground station data "SLR " ... Satellite Laser Ranging data "ACC " ... Onboard accelerometer data "ASC " ... Onboard star compass data - Model identifier: gravity field model: e.g. "GRIM5-Pre-CHAMP" atmospheric model: e.g. "DTM94" - Processing identifier: solved for parameters: f.i. "EX ", "EY ", "EZ ", "EXP", ..." - Quality parameters: - Standard deviation of 1st state - Cycle slip occurence number (AP recommended) or quality flag - Difference TT-UTC (s) - Reference frame: CTS: ITRF-xx, migrated due to availability - GPS modes (AP recommended): - SA off/on - AS off/on Trajectory Record Contents - Time tags: TT - Position: 10**-3 m - Velocity: 10**-7 m/s - Attitude (roll, pitch, yaw) - Manoeuvre flag - Land/water flag - Ascending/descending arc flag - Eclipse flag - Revolution numbering - Neutral gas density Example CHORB Format for CHAMP: ------------------------------- DSIDP CH-OG-3-RSO+CTS-CHA_YYYY_DOY_HH COMENT The DSIDP line shall always come first COMENT The COMENT line can appear anywhere in the header COMENT Inline comments are initiated by a # COSPAR 2000-009A PERIOD 13295 1834184000 13255 64184000 INIREV 17998 OBSINF GPS SST LEV 1 n = 22456 OBSINF GPS GS LEV 1 n = 78901 OBSINF SLR LEV 1 n = 789 HKDATA ACC LEV 2 n = 5820 HKDATA ASC LEV 2 n = 5820 PARAMS EX EY EZ EXD EYD EZD MNA MNC MTR FS1 FSY SX SY SZ QUALCO Sta_Dev_Initial_Elements = 381 275 2606 mm; 123 123 123 mm/s QUALCO Sigma_Unit_Weight = 1.15 QUALCO Sta_Dev_Obs_GPScode = 572 mm; n = 22000, elim = 456 QUALCO Mean_Obs_GPScode = 19 mm QUALCO Sta_Dev_Obs_GPSphase = 19 mm; n = 22000, elim = 456 QUALCO Mean_Obs_GPSphase = 1 mm QUALCO Sta_Dev_Obs_Laser = 72 mm; n = 700, elim = 89 QUALCO Mean_Obs_Laser = 19 mm QUALCO Overlaps #tbd RFRAME CTS: ITRF-96 TFRAME TT MATMOS CIRA86 MGRAVI GRIM5-PRE-CHAMP GPS-SA on GPS-AS on TT-UTC 64184 ms LEAPS from -3285 64184000 inclusive and subsequent #leap second COMENT The ORBIT line marks end of the header and COMENT start of the trajectory records. COMENT The trajectory records end at the end of file ORBIT 13295 1834184000 987409424 394374694 7074498049 29395733720-68591970200 -281953750 0050 0001 -0015 1111 LDE 13295 1864184000 1075100983 188439990 7070195196 29060556380-68686678470 -2586384280 0050 0012 -0137 1111 LDE 13295 1894184000 1161744432 -17678417 7058982246 28697049540-68714428510 -4888312390 0050 0022 -0260 1111 LDE 13295 1924184000 1247255301 -223779592 7040870060 28305564380-68675191880 -7185503050 0050 0033 -0382 1111 WDE ... 13295 6334184000 -2857266631 6568878853 -187673563 9417205980 6111112160 73746269720 -0001 0009 3906 1111 WA 13295 6364184000 -2827625073 6584003145 33620971 10342242020 3970889690 73771387310 0000 -0002 3907 1111 WA # 1st state in rev no. 17999 ... 1329566574184000 1491440145 -1712214004 6784721264-68685631580 23105874820 20882624300 0048 -0091 1109 1111 LA 1329566604184000 1284846568 -1641625359 6844042657-69031663030 23949664240 18661768180 0048 -0082 0992 1111MLA 1329566634184000 1077320810 -1568537923 6896673736-69307053770 24771549920 16422776090 0049 -0073 0873 1111MLA ------ Ruler: ------ 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890 1 2 3 4 5 6 7 8 9 0 1 2 ------ Trajectory Record Description: ------------------------------ 1 - 6 I6 Time tag (*10 = days since J2000.0) 7 - 17 I11 Time tag (*10**6 = seconds since 0 hours) 18 - 29 I12 X coordinate of position (10**-3 m) 30 - 41 I12 Y coordinate of position (10**-3 m) 42 - 53 I12 Z coordinate of position (10**-3 m) 54 - 65 I12 X coordinate of velocity (10**-7 m/s) 66 - 77 I12 Y coordinate of velocity (10**-7 m/s) 78 - 89 I12 Z coordinate of velocity (10**-7 m/s) 90 - 96 I7 Roll angle (10**-3 deg) 97 - 103 I7 Pitch angle (10**-3 deg) 104 - 110 I7 Yaw angle (10**-3 deg) 111 - 115 I5 Neutral gas density (10**-16 g/cm**3) 116 A1 Manoeuvre flag (M = yes, else blank) 117 A1 Land/water flag (L = Land, W = Water) 118 A1 Ascending/descending arc flag (A = ascending, D = descending) 119 A1 Eclipse flag (E = satellite in Earth's shadow, else blank)