PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 OBJECT = TEXT PUBLICATION_DATE = 2001-01-02 NOTE = "Description of GEODYN SPK Files" END_OBJECT = TEXT END GEODYN SPK files (data type GDN) are QUICK LOOK orbits produced by the MOLA POD (Precise Orbit Determination) team. They are used for preliminary analysis of the MOLA data, and have been made available to other MGS project participants. They are produced on a best efforts basis, as time and resources permit. Each file is in SPK format, compatible with readers in the SPICE toolkit (see companion files TK_FTP.TXT, TK_DESCR.TXT, and TK_INSTL.TXT in this DOCUMENT directory for more information on the SPICE toolkit and files). The data were originally written out by GEODYN (the orbit processor) at five or ten second intervals. They were converted from the original true of date (IAU of date) coordinates to J2000, and then were written in an SPK-format (type 8, discrete states, evenly spaced, Lagrange Interpolation). A TOPEX-like/POE (ASCII) format is available upon request from the MOLA POD Team. File names have the format gdn_qlnn_ymmddhhmm_ymmddhhmm.tsp where the components refer to: gdn derived from analysis using the GEODYN orbit processor; ql quick-look; nn version number; yymmddhhmm start and stop times tsp suffix designating an SPK transfer file Files can also be obtained via anonymous ftp from geodesy.gsfc.nasa.gov (node number 128.183.201.91). Change directories (Unix command "cd") to directory /dist/MGS/quick-look-orbits/ and retrieve the data of interest. Version 02 Orbits ================= Version 02 orbits are produced from a preliminary analysis of the Doppler and range data supplied by the DSN. They are preliminary, because certain ancillary information may be missing at the time these orbits are reconstructed, for instance the dates and times of momentum dumps, weather data (used for Earth troposphere refraction corrections), finalized Earth orientation (polar motion) values. The a priori modelling includes the GMM-1 gravity field, the 1991 IAU model, the Stewart (1987) drag model, and the DE403 ephemeris. Each arc adjusts the state vector, a drag coefficient, pass-by-pass range biases, and empirical parameters at regular intervals to absorb orbit error and other mismodeling. Version 04 Orbits ================= Version 04 orbits are derived from a reanalysis of the tracking data using an improved gravity model to 70x70 (MGM0827E) that includes the MGS tracking data from SPO-1, orbit insertion, and the hiatus (October, November 1997). Other than the improvement in the gravity model, the parameterization remains the same as the Version 02 orbits. The orbits will be refined on a schedule yet to be determined. Greg Neumann of the MOLA team has evaluated the orbits using the MOLA altimetry. For the MGM0827E orbits, the standard deviation of the crossovers in SPO-1 is 60 m; Using the square-root of two rule of thumb, the radial orbit error for the SPO-1 orbits would then be about 42 to 43 meters. For SPO-2, the crossover standard deviation is higher (168 m or a radial orbit error of 119 m via the square-root of two rule of thumb), reflecting the fact that the apriori gravity model (mgm0827e) does not yet include SPO-2 tracking. Hiatus vs SPO-1 crossovers are 60 m in the standard deviation. Version 06 orbits are released beginning on November 2, 1998. ============================================================= These orbits are based on an updated preliminary gravity model, mgm0883, a 70x70 model that includes the historical tracking (mariner 9, viking orbiter), and the tracking of MGS for both SPO-1 and SPO-2. No other changes to the processing were made, other than updating the gravity model. Version 09 orbits are released beginning on February 4, 1999 ============================================================ These orbits are based on an updated gravity model, mgm0890,a 70x70 model. The changes from the previous model, mgm0883, are the following: (1) The remaining SPO-2 tracking data from Sept. 1, to Sept. 17 1998 were included; (2) All the one-way Doppler data in SPO-1 and SPO-2 were rigorously reanalyzed and scrutinized on a pass-by-pass basis, and the Low Gain Antenna (LGA) measurement offset correction was systematically applied (in conjunction with the spacecraft quaternions which orient the spacecraft as a function of time) in the reduction of these data. Previously, in the mgm0827e and mgm0883 solutions the one-way Doppler data had not included the measurement offset correction; (3) The one-way Doppler data were upweighted in the OD solutions from 1 Hz (3.57 mm/s), to 0.2 Hz (0.71 mm/s). Greg Neumann has evaluated the SPO-1 and SPO-2 altimeter crossovers using the gdn_ql06* orbits, and the new gdn_ql09* orbits by computing the L2 and L2 norms. Remember, so far the altimeter data are an independent data type. The new mgm0890 orbits show a major improvement, especially for SPO-2. His report follows: ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Wed, 3 Feb 1999 19:05:19 -0500 (EST) From: Greg Neumann To: flemoine@ares.gsfc.nasa.gov The crossovers for SPO-1/SPO-1 and SPO2/SPO-2 show slight improvement in SPO-1 and major improvement in SPO-2. In both cases, attitude kernels were set to Dave's preferred values. Observation timing bias was set to 115.2 ms. I see a small component of drift in both groups, this bias could be upped to 116 or 117 but it is not a major factor. orbits: gdn_ql06 (0885) gdn_ql09 (0890) -------- -------- SPO-1/SPO-1 L2 63.94 61.57 L1 10.14 9.50 N 1188 1189 SPO-2/SPO-2 L2 141.86 70.87 L1 38.83 13.86 N 5879 5875 (slight difference due to in-plane changes) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Version 10 orbits released beginning March, 18, 1999 ===================================================== These orbits are based on the mgm0890i gravity model, a 70x70, solution that includes MGS data through February 23, 1999 (thus this solution includes 19 days of GCO data, in addition to the MGS data acquired during Hiatus and SPO). Note that the tracking in March 1999 was quite sparse, with at most only four hours of tracking per day (the remainder of the time the spacecraft was nadir rather than Earth pointing). Consequently, the start and stop times for the March 1999 arcs correspond closely to the start and stop of tracking on the starting and ending days of the arc. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Version 11+12 orbits released beginning June 14, 1999. ========================================================== These orbits are based on the mgm0964c5a gravity model, a 70x70 solution that includes MGS data through March 27, 1999. More MGS data is included from the near-circular orbit than in mgm0890i (see above), and further the modelling was improved to allow the solar array panels to articulate in the orbit modelling. The Kaula constraint was relaxed, effectively applying a Kaula constraint of 13.0*sqrt(2)e-5/L**2 where L is the spherical harmonic degree (compared to the "standard" Kaula rule for Mars of 13.0e-5/L**2). Overlap overlaps for arcs in April and May 1999 show an improvement with this new model, compared to mgm0890i (see below). Orbit Overlap Summary for MGS Altimeter Orbits (Mapping) ======================================================== Npts in OVL: Number of points in the overlap Delta-t: Time step in trajectory files in seconds. Gravity: Gravity field used in Data reductions. Arcs: Designations of arcs used in the comparisons. Rad, Crs, Along, Total: RMS Radial, Cross-track, Along-track and Total orbit differences in the overlap interval. NB: (1) once/rev accels along-track were adjusted daily with constraints to tie together multiple along-track OPR parameters that might occur in a single day; Momentum dumps are also modeled. (2) The orbits in March 1999 have sparse tracking, and only four hours of tracking are available per day. The arcs are constructed to begin and end with a period of tracking - hence the orbit overlaps span slightly more than one day in March 1999. Arcs Gravity Rad Crs Along Total Npts Delta-t ==== ======== (RMS Orbit Overlaps, m) in OVL secs ==== ======== ======================================== mgs990428.990505. mgm0890i 25.47 122.68 129.67 180.38 4321 20 + mgs990504.990507. mgs990428.990505. mgm0964c5a 17.68 12.84 53.99 58.24 4321 20 + mgs990504.990507. mgs990507.990511. mgm0890i 8.39 116.68 164.01 201.45 4321 20 + mgs990510.990517. mgs990507.990511. mgm0964c5a 5.33 23.90 34.16 42.03 4321 20 + mgs990510.990517. mgs990510.990517. mgm0890i 5.06 42.67 67.41 79.94 4321 20 + mgs990516.990522. mgs990510.990517. mgm0964c5a 3.30 6.22 11.57 13.35 4321 20 + mgs990516.990522. mgs990516.990522. mgm0890i 11.02 113.76 171.46 206.06 4321 20 + mgs990521.990527. mgs990516.990522. mgm0964c5a 3.59 65.82 116.80 134.11 4321 20 + mgs990521.990527. mgs990521.990527. mgm0890i 3.96 72.81 136.19 154.15 4321 20 + mgs990526.990601. mgs990521.990527. mgm0964c5a 1.86 21.44 40.48 45.84 4321 20 + mgs990526.990601. Version 13 Orbits released starting July 28, 1999. ================================================== These orbits are based on the mgm0964c20 (70x70) gravity model. This model is a substantial improvement over earlier models. The new model's improvements result from (1) a reiteration (reanalysis) and upweighting of the February+March 99 MGS data; (2) use of improved quaternions in the data analyses for the February & March MGS data; The numerous gaps in the spacecraft and solar array quaternions were carefully filled in to properly model the spacecraft orientation. Note, that in contrast to earlier gravity models, the mgm0964c20 model is based solely on the MGS tracking (hiatus, SPO, GCO and early mapping). None of the historical Mariner 9 and Viking Orbiter data was used; Nevertheless, the fits to the tracking data with this model are as good as if these data had been included - with an exception for some orbit geometries: Viking-1 1500 km. The orbit overlaps of the march orbits with antecedent models and the current gravity model (mgm0964c20) is detailed below. Eventually, all the orbital arcs will be released with this new gravity model. RMS (radial, cross-tr, along-track, meters) MGS orbit overlaps in march 1999 with mgm0890i (used with gdn_ql10* orbits) mgs990303.990308..mgs990306.990311.: RMS 4.2600586 25.806708 33.212556 mgs990306.990311..mgs990309.990315.: RMS 14.413881 1.9237137 31.689564 mgs990309.990315..mgs990314.990319.: RMS 1.6639737 12.195420 6.2318459 mgs990314.990319..mgs990318.990323.: RMS 2.3638347 46.494512 10.021852 mgs990318.990323..mgs990322.990327.: RMS 19.790675 66.075233 49.026836 RMS (radial, cross-tr, along-track, meters) MGS orbit overlaps in march 1999 with mgm0964c5a (mgm0964c5a used with gdn_ql11,gdn_ql12* orbits) mgs990303.990308..mgs990306.990311.: RMS 3.8660801 19.087365 9.9782882 mgs990306.990311..mgs990309.990315.: RMS 2.1219543 22.057942 6.7096560 mgs990309.990315..mgs990314.990319.: RMS .17322404 15.437319 2.1629255 mgs990314.990319..mgs990318.990323.: RMS .73962809 7.1244121 4.5743318 mgs990318.990323..mgs990322.990327.: RMS 4.7325677 2.6287782 9.5587080 RMS (radial, cross-tr, along-track, meters) MGS orbit overlaps in march 1999 with mgm0964c20 (used with gdn_ql13* orbits) mgs990303.990308..mgs990306.990311.: RMS .16016257 2.5957884 2.0032081 mgs990306.990311..mgs990309.990315.: RMS 1.6255024 1.0102231 4.0857209 mgs990309.990315..mgs990314.990319.: RMS .061041669 .47109997 .38480918 mgs990314.990319..mgs990318.990323.: RMS .074601268 .94963889 1.0223646 mgs990318.990323..mgs990322.990327.: RMS .92144684 2.1161828 1.9734381 Version 14 (gdn_ql14*) orbits ============================= These orbits were released starting in October 1999. The Version 14 orbits still use the mgm0964c20 gravity model, but change the solution technique. By loosening the a priori constraint on the empirical accelerations that are estimated at the times of momentum dumps, smaller discontinuties and disturbances are observed in the altimeter data following these desaturation maneuvers. Version 15(gdn_ql15*) orbits ============================ These orbits are released starting February 8, 2000. Eventually, all orbits will be redone with this model. These orbits use a new gravity model (mgm0989a). The mgm0989a model is still complete to 70x70, but includes more MGS mapping orbit tracking data from May-June, Sept-Oct, and Nov-December 1999. Orbit fits on five to six day arcs are now typically 0.15 mm/s, compared to 0.35 mm/s with mgm0964c20. The new data definitely strengthen the gravity sollution, and improve the orbit modelling. more information on version 15 (gdn_ql15* orbits) 2/29/2000 The new gdn_ql15* orbits will all be available on the geodesy.gsfc.nasa.gov anonymous ftp web site, (cd to dist/MGS/quick-look-orbits) and include the following changes over the previous generations of orbits (gdn_ql13* and gdn_ql14) (1) New gravity model (mgm0989a) to 70x70 that includes five months of tracking data after HGA deployment, specifically, May-June 1999; Sept-Dec 1999. The gdn_ql13 and gdn_ql14 used the mgm0964c20 gravity model (70x70) that only included MGS low altitude data from Feb and March 1999. (2) Proper application of the Earth troposphere correction for arcs from August 99 to October 1999. A format change on the DSN weather data files meant that DSN station meteorological data was not being used and rather mean climatological data was used to compute the Earth tropo corrections in the tracking data. This error has been corrected for the reprocessing and the new gdn_ql15* orbits. (3) Here and there, some other miscellaneous anomalies were detected for instance momentum dump information was missing on some arcs; some tracking data on some days went missing or was never downloaded. (4) In particular for the arcs in July-August 1999, the start and stop times were scrutinized to ensure that the arcs always started and ended with a few hours of tracking. This avoids "extrapolation" which hurts some of the orbit overlaps for the gdn_ql13* series. (5) A change was made in the method used to estimate empirical accelerations to accommodate momentum desaturations. In the OD solutions for the gdn_ql13* series, these empirical accels. were too tightly constrained- loosening up on the sigmas for these accels has improved the orbit solutions (confirmed by Greg Neumann who looked at this by comparing the gdn_ql13* and gdn_ql14* orbits). (6) For completeness orbits are also made available for the period of the HGA anomaly. Some anomalies persist: (a) The orbits in mid-October 1999 do not seem well behaved - for no apparent reason the residual fits are higher and the overlaps are slightly worse. (b) We cannot fix periods where there was simply sparse tracking for example- between the 990729-990805 and the 990803-990809 arcs. The use of crossvers in the OD later on might improve these. (c) No knowledge of the time of momentum desat maneuvers is available from 990414 0615 to the start of the HGA anomaly on 990416 04:30. This information was probably lost when the spacecraft went into safe mode. The orbits will be degraded over this two day period prior to the HGA anomaly. Overall, the gdn_ql15* orbits are a substantial improvement over the previous generation of orbits. gdn_ql13*orbit overlaps with mgm0964c20 --------------------------------------- RMS (rad, cross-tr, along-tr) MGS orbit overlaps in apr-jun 1999 with mgm0964c20 for arc set orbit6d.articulate (all units are meters) 990402.990409.990408.990416. RMS 8.5478871 8.5738000 24.361220 990428.990505.990504.990507. RMS 12.794992 5.2559646 37.305254 990507.990511.990510.990517. RMS 4.7353123 3.9718403 12.134107 990510.990517.990516.990522. RMS 2.8457408 1.4603881 6.0618437 990516.990522.990521.990527. RMS 3.2613190 6.2501872 19.900643 990521.990527.990526.990601. RMS 1.0217967 1.7342791 3.9580685 990531.990606.990604.990610. RMS 5.9566392 37.905730 77.826173 990610.990616.990614.990621. RMS 2.7152193 3.5597722 16.562606 990614.990621.990619.990626. RMS 3.6610427 44.202035 113.45547 990619.990626.990624.990701. RMS 13.690489 13.603720 33.505998 990624.990701.990629.990706. RMS 3.3027734 30.224560 78.488887 990629.990706.990704.990711. RMS 4.5630410 7.2827163 36.078289 990704.990711.990709.990716. RMS 5.8833224 19.539573 80.431233 990709.990716.990714.990721. RMS 36.444519 20.672090 1850.7563 990714.990721.990719.990726. RMS 3.5793738 105.70277 294.01707 990719.990726.990724.990731. RMS 8.2439697 29.935881 103.55589 990724.990731.990729.990805. RMS 18.016063 26.836933 1666.8873 990729.990805.990803.990809. RMS 6.5096780 29.347110 82.188620 990811.990819.990817.990824. RMS 7.4809164 56.606029 207.82842 990817.990824.990822.990829. RMS 4.2204799 12.532611 50.083650 990822.990829.990827.990903. RMS 6.4114722 15.986730 67.892548 990827.990903.990901.990908. RMS 8.7635897 31.498692 137.65659 990901.990908.990906.990913. RMS 16.346757 21.794102 123.66222 990906.990913.990911.990918. RMS 9.4722347 33.771217 166.28677 990911.990918.990916.990923. RMS 4.3821741 6.3620710 33.081496 990916.990923.990921.990928. RMS 5.4271513 3.3433700 22.681609 990921.990928.990926.991003. RMS 6.4846701 7.7355377 59.225652 990926.991003.991001.991008. RMS 2.7186806 1.3313987 8.5170878 new gdn_ql15* orbits with mgm0989a ============================== RMS (rad, cross-tr, along-tr) MGS orbit overlaps in apr-jun 1999 with mgm0989a for arc set orbit6e.articulate (all units are meters) 990402.990409.990408.990411. RMS .26602135E-01 2.4404452 1.4042684 990408.990411.990411.990414. RMS .29289153E-01 6.7990012 4.2292421 990411.990414.990411.990416. RMS 24.077367 82.814325 110.72312 (hga anomaly from 990416 to 990428; No altimeter data) *990415.990420.990419.990423. RMS 14.454085 9.3382247 42.541879 *990415.990420.990419.990426. RMS 11.674179 6.3528254 32.141780 *990419.990423.990422.990426. RMS 21.072293 89.873746 131.32076 *990419.990426.990425.990501. RMS 8.0518707 24.730370 29.729717 *990422.990426.990425.990501. RMS 4.6003099 3.6321188 11.814762 *990425.990501.990428.990505. RMS 2.6916475 10.626004 13.769 990428.990505.990504.990507. RMS .84071776 34.533468 18.501459 990507.990511.990510.990517. RMS .24521696E-01 2.0211352 2.8601187 990510.990517.990516.990522. RMS .49648244E-01 .88977530 1.4557974 990516.990522.990521.990527. RMS 2.9528288 .80504988 10.893720 990521.990527.990526.990601. RMS .38449218E-01 .37721692 .72345897 990526.990601.990531.990606. RMS .18497435 .24879138 .50628277 990531.990606.990604.990610. RMS .63623884E-01 .22038774 .44333733 990610.990616.990614.990621. RMS 2.1634424 2.2480613 9.6529723 990614.990621.990619.990626. RMS 6.8218056 1.4469060 23.742182 990619.990626.990624.990701. RMS .54199988 4.0350169 9.7199520 990624.990701.990629.990706. RMS .16052960 9.4176705 24.621438 990629.990706.990704.990711. RMS .30156572 5.3912208 14.077718 990704.990711.990709.990716. RMS .71588654 2.1618235 5.5462150 990709.990716.990714.990721. RMS .94041900E-01 6.2990846 18.010297 990714.990721.990719.990726. RMS .33386605 3.8534201 5.5626211 990719.990726.990724.990731. RMS .78712504 5.8201727 13.907414 990724.990731.990729.990805. RMS 1.5823004 11.965775 30.310286 990729.990805.990803.990809. RMS 14.131301 5.9630139 212.28963 990811.990819.990817.990824. RMS .90449172E-01 2.3428405 8.8396513 990817.990824.990822.990829. RMS .16992664 1.2400101 5.1104635 990822.990829.990827.990903. RMS .20966876 5.1924582 17.327613 990827.990903.990901.990908. RMS .35475273 1.4930652 6.2033409 990901.990908.990906.990913. RMS 8.0199503 4.9526030 40.132398 990906.990913.990911.990918. RMS .11370534 3.7912814 18.465808 990911.990918.990916.990923. RMS .18685024 3.2714266 15.842628 990916.990923.990921.990928. RMS .10304025 .48309406 2.6081617 990921.990928.990926.991003. RMS .19243874 1.6035864 7.3462898 990926.991003.991001.991008. RMS .10754712 1.0211810 5.0971979 991001.991008.991006.991013. RMS .20792834 1.7547535 10.752814 991006.991013.991011.991018. RMS .54476433 .78449885 4.5002087 991011.991018.991016.991019. RMS 4.4054786 2.2028631 18.451957 991016.991019.991018.991023. RMS 4.0726221 3.0879400 18.165049 991018.991023.991021.991028. RMS .40279883 1.0066467 5.6460455 991021.991028.991026.991102. RMS 4.2030643 1.0935689 11.913583 991026.991102.991031.991107. RMS .13361002 1.2423392 5.8855735 991031.991107.991105.991112. RMS .30888231 1.8341067 8.2318803 991105.991112.991110.991117. RMS .43889269E-01 .89193060E-02 .10903352 991115.991122.991120.991127. RMS .60652997 .33676538 1.0746306 991120.991127.991125.991202. RMS .93427901E-01 .65779294E-01 .16940613 991125.991202.991130.991207. RMS .60820069E-01 .22333015 .66485832 991130.991207.991205.991212. RMS .86599260 2.0757641 5.9896479 991205.991212.991210.991217. RMS .17525641 1.4979084 3.6591614 991210.991217.991215.991222. RMS .60770565 .82068836 4.7495095 991215.991222.991220.991227. RMS .34836829E-01 .30641639 .73703826 Orbits with mgm0989c (gan_ql16* orbits). mgm0989c is a variant of mgm0989a (ie mgm0989c = mgm0989a to 80x80). We started using this model, because it had slightly better performance on the orbits in may 2000. ================================================== Note as of 06-28-2000, 15:05 UTC. We will suspend orbit production in the vicinity of solar conjunction. No GDN SPK file deliveries will be made for orbits from June 19, 2000 to July 26, 2000. The first post-solar conjunction arc we will deliver will be for a five day arc starting on July 26, 2000. Delivery for this arc can be expected in early-mid August. As of this writing, MOLA is off and will resume operations on August 1. =================================================== Note as of 06-29-2000, 16;24 UTC. Note the steady increase in the magnitude of the overlaps between adjacent arcs as we approach solar conjunction in July 2000: (RMS orbit differences, radial, crs-track, alg-track, meters) Arcs in overlap (gdn_ql16* or mgm0989c) 000508.000515..000513.000520.RMS 3.9076 8.0894 44.253 000513.000520..000518.000525.RMS .6201 7.7979 6.971 000518.000525..000523.000530.RMS 3.9662 3.0194 68.141 000523.000530..000528.000604.RMS 6.2711 5.9256 114.157 000528.000604..000602.000609.RMS 40.5438 53.7463 323.387 000602.000609..000606.000614.RMS 19.3812 61.8831 316.851 ===== As of August 10,2000 we have switched to mgm1004d, an 80x80 model containing mapping data through February 29, 2000, and MGS MOLA altimeter crossover data from five arcs between March and December 1999. All orbits done with mgm1004d will carry the dsignation gdn_ql17****** ====================================================================== As of November 2 we release a series of orbits from JUly-September 2000 that are determined from standard two-way Doppler as well as one-way Doppler from the USO on board MGS. It appears the orbits where the two-way tracking is supplemented with the one-way data are improved significantly. However, since these are test solutions, and since we must refine the processing to include these data on a systematic basis, we will continue to release the gdn_ql17* version orbits based solely on the two-way tracking. The gdn_ql18* orbits were supplemented with the one-way Doppler. Below are some test statistics for RMS of fit and orbit overlaps for orbits based solely on the two-way tracking -gdn_ql17* orbits - and that add the one-way data from the MGS USO (the gdn_ql18 orbits). Orbit Overlaps from 2/3 way doppler only (gdn_ql17* orbits) =========================================================== RMS (rad, cross-tr, along-tr) MGS orbit overlaps with mgm1004d for arc set orbit6e.articulate (all units are meters) 000725.000801.9912.000730.000805.RMS .1031 11.7052 4.166 000730.000805.9912.000803.000810.RMS .9623 13.4555 15.847 000803.000810.9912.000808.000815.RMS 1.5175 20.2107 19.500 000808.000815.9912.000813.000820.RMS .4135 18.0222 7.219 000818.000825.9912.000823.000830.RMS 2.8376 8.6947 50.075 000823.000830.9912.000828.000904.RMS 1.6435 47.4773 8.654 000828.000904.9912.000902.000909.RMS 13.9440 8.0459 56.005 Orbit Overlaps from 2/3 way Doppler + One-way Doppler (gdn_ql18* orbits) ========================================================================= RMS (rad, cross-tr, along-tr) MGS orbit overlaps with mgm1004d for arc set orbit6f.articulate (all units are meters) 000725.000801.000730.000805.RMS .0869 8.0547 2.8031 000730.000805.000803.000810.RMS .1636 9.2713 4.5967 000803.000810.000808.000815.RMS .8525 14.8993 7.1191 000808.000815.000813.000820.RMS .9549 24.8063 9.6735 000818.000825.000823.000830.RMS .3133 3.6431 2.1243 000823.000830.000828.000904.RMS .0551 17.3204 6.4721 000828.000904.000902.000909.RMS .9303 6.7224 5.4292 ============================================================================ RMS of fit for arcs with 2/3 way AND 1 way Doppler ---------------------------------------------------------------------------- In OD: sigma of two-way data = 0.1 Hz; sigma of one-way data = 0.2 Hz ---------------------------------------------------------------------------- 0.284 RU approx = 1.0 m; range is round trip. Multiply Hz by approx 35.46 to convert to mm/s (round trip). arc start stop 1wyDoppler 2wyDoppler Range RMSPOS Nobs RMS Bobs RMS Nobs (m) Hz Hz RU 000725 18:10 000801 15:10 12138 0.0093 5727 0.0127 0 9.3 000730 15:50 000805 15:20 8604 0.0067 4352 0.0093 0 15.4 000803 12:00 000810 16:50 10364 0.0060 4740 0.0085 0 15.8 000808 01:50 000815 16:30 11023 0.0067 3991 0.0098 0 10.0 000813 13:20 000820 10:30 5485 0.0055 3461 0.0064 0 17.7 000818 18:50 000825 13:50 8517 0.0051 3874 0.0060 0 41.6 000823 16:20 000830 04:50 7173 0.0052 5890 0.0059 0 14.6 000828 14:40 000904 16:30 5507 0.0051 5679 0.0052 0 16.7 RMS of fit for arcs with 2/3 way Doppler only arc start stop 1wyDoppler 2wyDoppler Range RMSPOS Nobs RMS Bobs RMS Nobs (m) Hz Hz RU 000725 18:10 000801 15:10 5727 0.0121 0 195.7 000730 15:50 000805 15:20 4353 0.0090 0 21.9 000803 12:00 000810 16:50 4740 0.0080 0 23.8 000808 01:50 000815 16:30 3991 0.0075 0 149.5 000813 13:20 000820 10:30 3461 0.0064 0 26.1 000818 18:50 000825 13:50 3874 0.0056 0 41.8 000823 16:20 000830 04:50 5890 0.0058 0 21.0 000828 14:40 000904 16:30 5679 0.0050 0 32.9 RMS POS= Initial epoch position uncertainty (dependent on data weighting, data quality and distribution, and orbital geometry over the arc.) ============================================================== Direct questions to F. G. Lemoine (flemoine@ares.gsfc.nasa.gov) ============================================================== This file last modified November 2, 2000: 16:40 UTC