SAR (ERS) Cal/Val

ERS-1 SAR Cal/Val

Cal/Val Plan: Download Derivation of the Backscattering Coefficient Sigma0 in ESA ERS SAR PRI Products

Calibration Activities: The calibration plan is described in a paper on the performance of the ERS-1 SAR. This was presented at the CEOS SAR Calibration Workshop held in Tokyo, Japan from 2 to 5 April 2001.
Download the paper "The ERS-1 SAR Performance: A Final Update" its contents include:

  • Image Quality Assessment
  • Radiometric Calibration (Internal Calibration, ADC Power Loss Correction, Stability, Noise Equivalent Radar Cross-Section, Nominal Replica Pulse Products)
  • Distributed Target Radar Cross-Section Derivation
  • Point Target Radar Cross-Section Derivation
  • ERS-2 Attitude and Doppler Variations

ERS-2 SAR Cal/Val

Cal/Val Plan: Download the technical note Derivation of the Backscattering Coefficient Sigma0 in ESA ERS SAR PRI Products

Calibration Activities: Activities performed based on the ERS-2 calibration plan are illustrated in a paper on the performance of the ERS-2 SAR. This was presented at the ESA Living Planet Symposium in 2010 held in Bergen, Norway.

Download the paper "The Performance of the ERS-2 SAR after 15 Years", its contents include:

  • Elevation Antenna Pattern
  • Quality Assessment
  • Radiometric Calibration (Internal Calibration, Raw Data Quality, Stability, Noise Equivalent Radar Cross-Section, ADC Power Loss Correction, Nominal Replica Pulse Products)
  • Distributed Target Radar Cross-Section Derivation
  • Point Target Radar Cross-Section Derivation
  • Attitude and Doppler Variations
  • Image Localisation
  • Processor Evolution
  • Sampling Window Start Time Anomaly

Attitude Control Modes and Orbit Dead-band control

Proba-1

The piloting of the ERS-1 and ERS-2 satellites was initially performed using three gyroscopes (out of six available), with the number of functioning gyroscopes reducing during the mission lifetime due to failures. SAR products were used to monitor the Doppler centroid frequency of imagery acquired by the ERS missions as shown in the figure below.

There were several occasions, during the early years of the ERS missions, when there was a larger than expected change in Doppler centroid frequency. This was due, primarily, to imagery acquired during orbit manoeuvres (imagery acquired during a manoeuvre can still be processed but it may be unsuitable for interferometry). The negative Doppler Centroid frequencies are from ascending pass imagery while positive values are from descending pass imagery. Each product header contains the Doppler information for the product.

Due to the continuing gyroscope failures, a mono-gyro (1GP) piloting mode began operation on 11 February 2000. A consequence of this change was a loss of attitude stability but the impact on SAR product quality was small. For the 1GP mode the Doppler Centroid frequency increased for localised areas and time intervals but values were mostly limited to the first ambiguity number (-1600Hz to 1600Hz). During this IGP period, new on-board software to pilot the satellite without using any gyroscopes by exploiting the capabilities of the Digital Earth Sensor and Digital Sun Sensor was developed and tested.

ERS-2

A first coarse version of this software, the Extra Backup mode (EBM), was uploaded to ERS-2 in December 2000 as a first step for gyro-less operations and was operationally used since mid-January 2001 due to further problems with the remaining gyroscopes. Significant degradation of the ERS-2 attitude (particularly for yaw) occurred during the EBM. Very large Doppler Centroid frequencies are difficult to estimate in SAR processor – particularly for values outside ±4500Hz with the ESA SAR processors.

Improvements in attitude control took place in June 2001 with the introduction of the Zero Gyro Mode (ZGM) and again in March 2002 with ZGM-Yaw Control Monitoring (ZGM-YCM) – 90% of the Doppler Centroid frequencies remained within ±4500Hz. A further refinement involved deriving yaw values in real-time from wave-mode data to automatically correct the instrument attitude during the next orbit pass if necessary. Some changes to the strategy were required after the failure of the on-board tape recorder in June 2003, since wave mode acquisitions all around the orbit could not be used any more. Using a network of receiving ground stations, it was possible to continue receiving wave-mode data although coverage was reduced to the northern hemisphere. This strategy was called Regional YCM (R-YCM).

 

 

Download 'Review of the Impact of ERS-2 Piloting Modes on the SAR Doppler Stability' (FRINGE 2003 Workshop) paper describing the gyro operational status and impact. This paper also provides more detail of the changes in the interferometric dead-band indicated below due to the impact of gyroscope failures.

ERS-2

 

Instrument Calibration - Replica pulse power correction factor

A small number of products generated within the ESA ground segment (< 1%) are processed with a nominal replica pulse rather than a replica generated at the time of imaging (an extracted replica). This occurs when the extracted replica pulse is corrupt. Products generated with a nominal replica have significantly higher pixel values than products generated using an extracted replica. These products can be corrected. For ERS-2 SAR products, the correction depends on the extracted replica pulse power at the time of data acquisition. This can be estimated from the quarterly averaged values given in the table below.

For 2003 Q1, two corrections are given, one before 26 February and the other after 28 February due to the gain change between these dates (increase of the Image up-converter level by 2.5dB on 26 February 2003 and increase of the image receiver attenuation gain by 1dB on 28 February 2003). Replica pulse powers between 4 September 10:04:14 and 14 October 2004 14:37:11 UTC were increased by 4dB to correct for the erroneous calibration attenuation gain setting during this period. The correction factor is applied such that the image intensity values need to be reduced. Note that as the correction given in the table has been derived from replica pulses from the start of imaging sequences, no account is made for any variations in replica power between the start and end of imaging sequences.

Download the technical note ERS calibration derivation of the backscattering coefficient sigma nought in ESA ERS SAR PRI products for more information.

Quarterly averaged nominal replica pulse correction for the ERS-2 SAR (dB)

Year Q1 Q2 Q3 Q4
1995     23.57 23.38
1996 23.23 23.15 23.05 22.78
1997 22.61 22.43 22.29 22.11
1998 21.97 21.81 21.57 21.42
1999 21.29 21.15 20.98 20.78
2000 20.60 20.47 20.44 20.21
2001 20.02 19.90 19.67 19.40
2002 19.19 19.21 18.90 18.63
2003 18.44, 21.52 21.49 21.33 21.10
2004 20.90 20.98 20.90 20.66
2005 20.40 20.35 20.21 19.89
2006 19.63 19.52 19.42 19.21
2007 19.02 18.98 18.82 18.64
2008 18.59 18.48 18.36 18.18
2009 18.11 17.96 17.82 17.63
2010 17.50 17.36 17.29 17.13
2011 16.93 16.88    

   

ERS-2 EBM Mode

Height rate Doppler available at ESRIN for EBM (from January to June 2001):

SCENE DATE DOPPLER (near range)
ORBIT=29861-FRAME=2871 05/01/2001 04:37:15 75.2390
ORBIT=30418-FRAME=6939 13/02/2001 03:27:34 -1982.3840
ORBIT=30418-FRAME=6939 13/02/2001 03:27:34 -1982.3840
ORBIT=30418-FRAME=6975 13/02/2001 03:28:04 -1849.3560
ORBIT=30418-FRAME=6975 13/02/2001 03:28:04 -1849.3970
ORBIT=30418-FRAME=6975 13/02/2001 03:28:04 -1849.3560
ORBIT=30418-FRAME=6975 13/02/2001 03:28:04 -1849.3970
ORBIT=30418-FRAME=6993 13/02/2001 03:28:19 -1823.4720
ORBIT=30418-FRAME=6993 13/02/2001 03:28:19 -1823.4720
ORBIT=30418-FRAME=7011 13/02/2001 03:28:34 -1811.5840
ORBIT=30418-FRAME=7011 13/02/2001 03:28:34 -1811.5840
ORBIT=30451-FRAME=2763 15/02/2001 09:48:59 -6709.8850
ORBIT=30451-FRAME=2781 15/02/2001 09:49:14 -6515.0990
ORBIT=30473-FRAME=0801 16/02/2001 22:14:50 314.3640
ORBIT=30473-FRAME=0819 16/02/2001 22:15:05 299.6750
ORBIT=30494-FRAME=2745 18/02/2001 09:54:36 -347.5760
ORBIT=30494-FRAME=2763 18/02/2001 09:54:51 -140.3070
ORBIT=30795-FRAME=2482 11/03/2001 10:31:17 -6413.5850
ORBIT=30827-FRAME=3321 13/03/2001 16:22:12 -1354.5490
ORBIT=30827-FRAME=3339 13/03/2001 16:22:27 -1057.0220
ORBIT=30838-FRAME=2529 14/03/2001 10:37:41 -5954.8940
ORBIT=30838-FRAME=2547 14/03/2001 10:37:56 -5914.6460
ORBIT=30873-FRAME=1053 16/03/2001 20:58:02 -2363.0230
ORBIT=30874-FRAME=0567 16/03/2001 22:31:53 1507.1440
ORBIT=30874-FRAME=0837 16/03/2001 22:35:39 2299.9110
ORBIT=30874-FRAME=1053 16/03/2001 22:38:41 2423.7430
ORBIT=30874-FRAME=1467 16/03/2001 22:44:27 1953.3760
ORBIT=30881-FRAME=2331 17/03/2001 10:40:39 -4713.0450
ORBIT=30881-FRAME=2583 17/03/2001 10:44:11 -3706.1400
ORBIT=30881-FRAME=2979 17/03/2001 10:49:44 -1552.2860
ORBIT=30887-FRAME=0819 17/03/2001 20:23:09 -1396.1890
ORBIT=30887-FRAME=1053 17/03/2001 20:26:25 -1486.8310
ORBIT=30895-FRAME=2295 18/03/2001 10:08:31 -5369.1810
ORBIT=30895-FRAME=2547 18/03/2001 10:12:03 -4385.6900
ORBIT=30895-FRAME=3015 18/03/2001 10:18:37 -1742.9470
ORBIT=30902-FRAME=0567 18/03/2001 21:28:41 7089.6590
ORBIT=30931-FRAME=1539 20/03/2001 22:19:32 -340.5980
ORBIT=30945-FRAME=1611 21/03/2001 21:48:55 -851.7220
ORBIT=30974-FRAME=0621 23/03/2001 22:12:27 3722.8800
ORBIT=30974-FRAME=0801 23/03/2001 22:14:58 4337.4890
ORBIT=30974-FRAME=1053 23/03/2001 22:18:30 4171.7030
ORBIT=30974-FRAME=1521 23/03/2001 22:25:02 3705.6010
ORBIT=30980-FRAME=2547 24/03/2001 08:42:53 -2521.0040
ORBIT=30980-FRAME=2799 24/03/2001 08:46:25 -820.0330
ORBIT=30980-FRAME=3015 24/03/2001 08:49:28 875.4810
ORBIT=30988-FRAME=0567 24/03/2001 21:40:03 2741.7980
ORBIT=30988-FRAME=0873 24/03/2001 21:44:20 3100.8600
ORBIT=30988-FRAME=1035 24/03/2001 21:46:36 2814.3300
ORBIT=30988-FRAME=1593 24/03/2001 21:54:23 1132.6480
ORBIT=30995-FRAME=2547 25/03/2001 09:51:51 -1661.1930
ORBIT=30995-FRAME=2763 25/03/2001 09:54:53 -816.7810
ORBIT=30995-FRAME=3015 25/03/2001 09:58:25 686.3260
ORBIT=31002-FRAME=0567 25/03/2001 21:08:22 -2001.4850
ORBIT=31002-FRAME=0801 25/03/2001 21:11:39 -692.8330
ORBIT=31002-FRAME=1053 25/03/2001 21:15:11 89.5240
ORBIT=31002-FRAME=1629 25/03/2001 21:23:16 2251.4230
ORBIT=31010-FRAME=2007 26/03/2001 10:53:16 -3553.3260
ORBIT=31010-FRAME=2547 26/03/2001 11:00:48 -3450.8290
ORBIT=31010-FRAME=2799 26/03/2001 11:04:20 -2572.1220
ORBIT=31010-FRAME=3015 26/03/2001 11:07:22 -1226.8700
ORBIT=31053-FRAME=2835 29/03/2001 11:10:32 322.0590
ORBIT=31053-FRAME=2853 29/03/2001 11:10:47 412.7730
ORBIT=31067-FRAME=2547 30/03/2001 10:34:50 -3085.2250
ORBIT=31067-FRAME=2673 30/03/2001 10:36:36 -1991.2480
ORBIT=31067-FRAME=2691 30/03/2001 10:36:51 -1780.4310
ORBIT=31074-FRAME=0909 30/03/2001 21:56:09 247.9160
ORBIT=31074-FRAME=0927 30/03/2001 21:56:24 198.0400
ORBIT=31102-FRAME=2277 01/04/2001 21:11:58 2318.6520
ORBIT=31102-FRAME=2295 01/04/2001 21:12:13 2453.1370
ORBIT=31104-FRAME=6777 02/04/2001 01:36:03 4063.9780
ORBIT=31104-FRAME=6795 02/04/2001 01:36:18 4001.9910
ORBIT=31115-FRAME=2615 02/04/2001 19:04:23 -744.8260
ORBIT=31139-FRAME=3051 04/04/2001 11:24:46 1330.8180
ORBIT=31139-FRAME=3069 04/04/2001 11:25:01 1501.1400
ORBIT=31144-FRAME=7155 04/04/2001 20:45:02 -4804.4940
ORBIT=31144-FRAME=7173 04/04/2001 20:45:17 -4658.6600
ORBIT=31154-FRAME=2277 05/04/2001 12:22:52 -1707.5140
ORBIT=31154-FRAME=2295 05/04/2001 12:23:07 -1759.2880
ORBIT=31167-FRAME=2493 06/04/2001 10:13:40 -980.0460
ORBIT=31167-FRAME=2511 06/04/2001 10:13:55 -907.9170
ORBIT=31181-FRAME=2763 07/04/2001 09:45:54 6489.7500
ORBIT=31181-FRAME=2781 07/04/2001 09:46:10 6619.3750
ORBIT=31188-FRAME=1071 07/04/2001 21:06:26 1645.3490
ORBIT=31188-FRAME=1089 07/04/2001 21:06:41 1610.2920
ORBIT=31224-FRAME=2763 10/04/2001 09:51:38 -3912.8910
ORBIT=31238-FRAME=2205 11/04/2001 09:12:17 1893.1670
ORBIT=31238-FRAME=2817 11/04/2001 09:20:52 4353.3490
ORBIT=31253-FRAME=2385 12/04/2001 10:23:47 -655.2570
ORBIT=31253-FRAME=2871 12/04/2001 10:30:37 3273.8610
ORBIT=31254-FRAME=1935 12/04/2001 11:58:03 -6155.2120
ORBIT=31260-FRAME=0729 12/04/2001 21:44:51 303.8980
ORBIT=31260-FRAME=1017 12/04/2001 21:48:53 339.1180
ORBIT=31260-FRAME=1575 12/04/2001 21:56:40 488.4700
ORBIT=31260-FRAME=2529 12/04/2001 22:10:02 3586.1500
ORBIT=31268-FRAME=1971 13/04/2001 11:26:58 -4796.3580
ORBIT=31268-FRAME=2529 13/04/2001 11:34:46 -2273.1420
ORBIT=31268-FRAME=3051 13/04/2001 11:42:07 1694.7610
ORBIT=31274-FRAME=0603 13/04/2001 21:11:29 -888.1690
ORBIT=31274-FRAME=1251 13/04/2001 21:20:32 -689.0890
ORBIT=31282-FRAME=2871 14/04/2001 11:07:56 -3716.0000
ORBIT=31282-FRAME=3447 14/04/2001 11:16:02 978.7290
ORBIT=31288-FRAME=0621 14/04/2001 20:40:06 -3351.0940
ORBIT=31288-FRAME=1323 14/04/2001 20:49:55 -3035.2920
ORBIT=31296-FRAME=2223 15/04/2001 10:27:16 -5875.9930
ORBIT=31296-FRAME=2871 15/04/2001 10:36:20 -3358.5480
ORBIT=31302-FRAME=0495 15/04/2001 20:06:43 -5744.2310
ORBIT=31302-FRAME=1395 15/04/2001 20:19:18 -4871.9430
ORBIT=31306-FRAME=6057 16/04/2001 04:06:55 3358.1710
ORBIT=31310-FRAME=1953 16/04/2001 09:51:53 -5838.0520
ORBIT=31310-FRAME=2853 16/04/2001 10:04:30 -1184.9780
ORBIT=31325-FRAME=2853 17/04/2001 11:13:28 -4420.3150
ORBIT=31325-FRAME=3411 17/04/2001 11:21:18 -56.1900
ORBIT=31330-FRAME=1629 17/04/2001 19:19:21 -7121.8210
ORBIT=31332-FRAME=0693 17/04/2001 22:27:30 -1873.0380
ORBIT=31339-FRAME=2547 18/04/2001 10:37:36 -2246.6310
ORBIT=31339-FRAME=2889 18/04/2001 10:42:24 -6.1070
ORBIT=31346-FRAME=0729 18/04/2001 21:56:25 488.3080
ORBIT=31346-FRAME=1557 18/04/2001 22:08:00 1308.5760
ORBIT=31353-FRAME=2169 19/04/2001 10:00:41 -5809.4250
ORBIT=31353-FRAME=2781 19/04/2001 10:09:16 -2996.8150
ORBIT=31360-FRAME=0639 19/04/2001 21:23:32 -2622.4910
ORBIT=31360-FRAME=1215 19/04/2001 21:31:35 -2038.8130
ORBIT=31362-FRAME=6687 20/04/2001 02:09:15 -946.5780
ORBIT=31368-FRAME=2835 20/04/2001 11:19:00 -3933.3350
ORBIT=31368-FRAME=3375 20/04/2001 11:26:35 488.5540
ORBIT=31374-FRAME=0657 20/04/2001 20:52:10 -3494.2320
ORBIT=31374-FRAME=1287 20/04/2001 21:00:58 -3679.1640
ORBIT=31382-FRAME=2853 21/04/2001 10:47:39 -3376.0050
ORBIT=31388-FRAME=0621 21/04/2001 20:20:04 -1173.8540
ORBIT=31388-FRAME=1377 21/04/2001 20:30:38 -1245.3940
ORBIT=31396-FRAME=2727 22/04/2001 10:14:17 -1814.5710
ORBIT=31397-FRAME=1989 22/04/2001 11:44:33 -4587.7240
ORBIT=31410-FRAME=2169 23/04/2001 09:34:51 -4226.0660
ORBIT=31410-FRAME=2871 23/04/2001 09:44:42 90.5640
ORBIT=31418-FRAME=0711 23/04/2001 22:39:19 746.7220
ORBIT=31418-FRAME=1323 23/04/2001 22:47:53 1851.7340
ORBIT=31425-FRAME=3483 24/04/2001 11:02:16 2496.5960
ORBIT=31427-FRAME=3645 24/04/2001 14:25:43 1710.0480
ORBIT=31427-FRAME=3645 24/04/2001 14:25:43 1710.0480
ORBIT=31427-FRAME=3663 24/04/2001 14:25:58 1886.6010
ORBIT=31427-FRAME=3663 24/04/2001 14:25:58 1886.6010
ORBIT=31432-FRAME=0819 24/04/2001 22:09:12 -164.4580
ORBIT=31432-FRAME=1539 24/04/2001 22:19:16 293.9920
ORBIT=31439-FRAME=2727 25/04/2001 10:20:02 -2627.4350
ORBIT=31446-FRAME=0567 25/04/2001 21:34:03 -2221.8480
ORBIT=31446-FRAME=0819 25/04/2001 21:37:35 -1413.8030
ORBIT=31446-FRAME=1053 25/04/2001 21:40:51 -1245.0770
ORBIT=31446-FRAME=1611 25/04/2001 21:48:39 -442.3350
ORBIT=31454-FRAME=2007 26/04/2001 11:18:56 -5274.3690
ORBIT=31454-FRAME=3303 26/04/2001 11:37:05 -1195.5360
ORBIT=31460-FRAME=0783 26/04/2001 21:05:29 620.9670
ORBIT=31460-FRAME=1629 26/04/2001 21:17:18 132.9660
ORBIT=31467-FRAME=2205 27/04/2001 09:09:31 -1878.7390
ORBIT=31467-FRAME=2835 27/04/2001 09:18:21 1216.2120
ORBIT=31474-FRAME=0621 27/04/2001 20:31:33 -5190.7860
ORBIT=31474-FRAME=1341 27/04/2001 20:41:37 -4427.7110
ORBIT=31474-FRAME=6489 27/04/2001 21:53:34 -858.0060
ORBIT=31474-FRAME=6489 27/04/2001 21:53:34 -858.0060
ORBIT=31474-FRAME=6489 27/04/2001 21:53:34 -857.0730
ORBIT=31474-FRAME=6507 27/04/2001 21:53:49 -874.3080
ORBIT=31481-FRAME=2547 28/04/2001 08:42:41 -911.2890
ORBIT=31481-FRAME=2781 28/04/2001 08:45:58 1076.2600
ORBIT=31488-FRAME=1215 28/04/2001 20:08:16 -1151.0310
ORBIT=31496-FRAME=2547 29/04/2001 09:51:40 -989.5800
ORBIT=31496-FRAME=2763 29/04/2001 09:54:41 118.8210
ORBIT=31504-FRAME=0747 29/04/2001 22:51:18 -281.2010
ORBIT=31504-FRAME=1323 29/04/2001 22:59:22 214.1780
ORBIT=31511-FRAME=2007 30/04/2001 10:53:04 -4525.2630
ORBIT=31511-FRAME=2547 30/04/2001 11:00:37 -2680.7830
ORBIT=31511-FRAME=3447 30/04/2001 11:13:15 3389.8310
ORBIT=31514-FRAME=3292 30/04/2001 16:12:50 -753.9390
ORBIT=31514-FRAME=3292 30/04/2001 16:12:51 -753.9550
ORBIT=31518-FRAME=0801 30/04/2001 22:20:27 1375.6210
ORBIT=31518-FRAME=1143 30/04/2001 22:25:14 1783.6300
ORBIT=31525-FRAME=2205 01/05/2001 10:24:12 -5703.9430
ORBIT=31525-FRAME=2817 01/05/2001 10:32:47 -2209.4170
ORBIT=31532-FRAME=0855 01/05/2001 21:49:33 -1628.4710
ORBIT=31532-FRAME=1431 01/05/2001 21:57:36 -1799.4670
ORBIT=31539-FRAME=2169 02/05/2001 09:52:05 -4024.1290
ORBIT=31539-FRAME=2745 02/05/2001 10:00:09 -733.7990
ORBIT=31546-FRAME=0819 02/05/2001 21:17:25 -3881.0680
ORBIT=31546-FRAME=1251 02/05/2001 21:23:27 -3573.3660
ORBIT=31554-FRAME=2835 03/05/2001 11:10:22 -2394.2880
ORBIT=31554-FRAME=2853 03/05/2001 11:10:38 -2249.6140
ORBIT=31568-FRAME=2547 04/05/2001 10:34:43 -2940.2500
ORBIT=31568-FRAME=2673 04/05/200110:36:29 -2267.7970
ORBIT=31568-FRAME=2691 04/05/2001 10:36:44 -2143.5480
ORBIT=31582-FRAME=2385 04/05/2001 10:00:49 -4186.7350
ORBIT=31582-FRAME=2403 05/05/2001 10:01:04 -4153.8320
ORBIT=31603-FRAME=2277 06/05/2001 21:11:57 4853.4460
ORBIT=31603-FRAME=2277 06/05/2001 21:11:57 4853.4460
ORBIT=31603-FRAME=2295 06/05/2001 21:12:12 4937.6440
ORBIT=31603-FRAME=2295 06/05/2001 21:12:12 4937.6440
ORBIT=31632-FRAME=0621 08/05/2001 21:26:05 -1643.7000
ORBIT=31632-FRAME=0639 08/05/2001 21:26:20 -1602.5110
ORBIT=31640-FRAME=3069 09/05/2001 11:25:04 -1166.3190
ORBIT=31645-FRAME=7155 09/05/2001 20:45:07 -4042.0160
ORBIT=31645-FRAME=7155 09/05/2001 20:45:07 -4042.0160
ORBIT=31654-FRAME=2439 10/05/2001 10:44:36 -4808.0040
ORBIT=31654-FRAME=2475 10/05/2001 10:45:07 -4618.5780
ORBIT=31654-FRAME=2493 10/05/2001 10:45:22 -4577.4140
ORBIT=31668-FRAME=2493 11/05/2001 10:13:44 -2897.2300
ORBIT=31668-FRAME=2511 11/05/2001 10:14:00 -2824.7500
ORBIT=31671-FRAME=3375 11/05/2001 15:27:52 -797.1620
ORBIT=31671-FRAME=3393 11/05/2001 15:28:07 -535.2640
ORBIT=31671-FRAME=3411 11/05/2001 15:28:23 -353.2060
ORBIT=31682-FRAME=2763 12/05/2001 09:45:53 -2319.0630
ORBIT=31682-FRAME=2781 12/05/2001 09:46:08 -2212.4640
ORBIT=31697-FRAME=2673 13/05/2001 10:53:34 -4666.8690
ORBIT=31697-FRAME=2691 13/05/2001 10:53:49 -4542.6980
ORBIT=31704-FRAME=0909 13/05/2001 22:13:09 511.3030
ORBIT=31704-FRAME=0927 13/05/2001 22:13:24 501.0860
ORBIT=31711-FRAME=2547 14/05/2001 10:20:10 -4322.0620
ORBIT=31711-FRAME=2565 14/05/2001 10:20:26 -4216.0110
ORBIT=31717-FRAME=0297 14/05/2001 19:52:19 -5050.4370
ORBIT=31718-FRAME=1035 14/05/2001 21:43:15 -2440.0830
ORBIT=31718-FRAME=1053 14/05/2001 21:43:30 -2469.3360
ORBIT=31725-FRAME=2745 15/05/2001 09:51:19 -2227.1760
ORBIT=31725-FRAME=2763 15/05/2001 09:51:34 -2163.4760
ORBIT=31732-FRAME=1251 15/05/2001 21:14:37 -2445.2230
ORBIT=31732-FRAME=1269 15/05/2001 21:14:53 -2337.3590
ORBIT=31739-FRAME=2205 16/05/2001 09:12:07 -4619.0110
ORBIT=31739-FRAME=2817 16/05/2001 09:20:41 -2594.3080
ORBIT=31754-FRAME=2385 17/05/2001 10:23:35 -4364.9720
ORBIT=31754-FRAME=2871 17/05/2001 10:30:24 -2310.3890
ORBIT=31761-FRAME=2529 17/05/2001 22:09:51 3072.9970
ORBIT=31761-FRAME=2529 17/05/2001 22:09:51 3072.9970
ORBIT=31769-FRAME=3051 18/05/2001 11:41:53 -2767.3360
ORBIT=31783-FRAME=2871 19/05/2001 11:07:45 -2498.0820
ORBIT=31783-FRAME=3447 19/05/2001 11:15:51 1960.6900
ORBIT=31797-FRAME=2223 20/05/2001 10:27:04 -5565.2070
ORBIT=31797-FRAME=2871 20/05/2001 10:36:09 -2587.2180
ORBIT=31811-FRAME=1953 21/05/2001 09:51:41 -4737.4550
ORBIT=31811-FRAME=2853 21/05/2001 10:04:17 -1658.3420
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