GRV01T (Preliminary experiment for measurements of speed of propagation of gravity) 2002 March 20 Notes prepared by Leonid Petrov, NVI/GSFC ( pet@leo.gsfc.nasa.gov ) Station CODE Code # tapes # of obs Start Time End Time Algonquin G Ap 2 89 March 20, 21:25 March 21, 08:36 UT Fairbanks A Gc 3 147 March 20, 23:02 March 21, 14:35 UT HartRAO J Hh 2 68 March 20, 18:00 March 21, 18:01 UT Kokee K Kk 2 111 March 20, 23:02 March 21, 18:01 UT Medicina B Mc 2 108 March 20, 18:00 March 21, 18:01 UT Ny Alesund Q Ny 4 209 March 20, 18:00 March 21, 18:01 UT Westford E WF 2 90 March 20, 21:25 March 21, 07:55 UT Wettzell V Wz 3 119 March 20, 18:00 March 21, 18:01 UT Long gaps: HartRAO does not observe between March 21, 00:00 and March 21, 15:13 Medicina does not observe between March 21, 03:03 and March 21, 13:28 Wettzell does not observe between March 21, 03:13 and March 21, 13:06 Purpose ======= The primary purpose of this session is to find the best strategy of observations for the future gravity experiment on 2002.09.08. Results of analysis this experiment will help first, to work out recommendations for optimization of the schedule of the experiments grv01c and grv01 on 2002.08.07 and 2002.09.08, second, to evaluate the accuracy of future measurements of speed of propagation of gravity. The schedule is designed for precise measurement of the change of the angular distance between the target quasar and two calibrators within a session. It is expected that this change should be zero in the grav01t experiment. During the event of 2002.09.09 when Jupiter will pass 3.7 arcmin from the target quasar 0839+187, the theory based on general relativity predicts ( Kopeikin, S.M. "Testing the relativistic effect of the propagation of gravity by very long baseline interferometry", ApJ Lett., vol. 556, p. L1-L5, 2001 ) a special term for the differences in phases between the target and two calibrators. This phase difference changes in the range of 3-15 degrees during 3-10 hours before and after passing Jupiter due to the fact that according to general relativity gravity propagates with the same speed as light in vacuum. Measurements of this term would allow confirmation of the validity of general relativity for a NON-STATIONARY gravitation field. Up to now, no direct tests of such kind have been done. Since Jupiter will be far away from the target quasar on 2002.03.20, variations in phase differences between the target and quasar should be due only to noise and unmodeled effect. The level of these variations sets the accuracy limit. Refer to http://gemini.gsfc.nasa.gov/pet/discussion/grav/grav.html for more details. Schedule ======== THIS IS NOT A GEODETIC SCHEDULE! It was generated to observe only the targer sources and calibrators. Station observes only when these sources are up. This experiment is done on "nodding mode". The primary observable is the phase difference between the target quasar 0839+187 and two calibrators, OJ287 and 0836+182. Several scans for atmosphere path delay calibration are added after 2-3 hours of nodding observations. Three sources are the most frequently observed: 1) the target, 0839+187 ( flux 0.30 Jy, Jupiter will pas in 3.7 arcmin from this quasar on 2002.09.08 ) 2) the calibrator 1, 0836+182 ( flux 0.17 Jy, 49 armin away from 0839+187 ) 3) the calibrator 2, OJ287 ( flux 2.0 Jy, 3d15 armin away from 0839+187 ) The sequences (target, cal-1, target, cal-2, target) is observed at 85% of time. Two another sequences (target, cal-2, target, cal-2, target) and (target, cal-1, cal-2, target) are observed as well. Every 2-3 hours the burst of 2-4 other strong sources are observed for atmosphere path calibration. =================================================================== SKED Summary from file grv01t.skd for experiment GRV01T (all scans with at least one subnet station) Average number of obs. per baseline per source (normalized by up-time) = 2.0 Min = .0 Max = 92.0 (Baseline Kk-Ny on 0839+187) RMS = 8.6 Total time: 1441 minutes ( 24.0 hours). Key: Ap=ALGOPARK Gc=GILCREEK Hh=HARTRAO Kk=KOKEE Mc=MEDICINA Ny=NYALES20 Wf=WESTFORD Wz=WETTZELL Ap Gc Hh Kk Mc Ny Wf Wz Avg % obs. time: 30 46 24 35 34 70 30 39 39 % cal. time: 0 0 0 0 0 0 0 0 0 % slew time: 4 0 5 0 3 1 1 0 2 % idle time: 65 52 69 63 61 28 68 59 58 # of tapes : 1.7 2.6 1.4 2.0 2.0 4.0 1.6 2.3 total # scans: 89 147 68 111 108 209 90 119 117 # scans/hour : 3 6 2 4 4 8 3 4 4.9 Avg scan (sec): 292 271 317 278 278 291 288 289 288 # OF OBSERVATIONS BY BASELINE | Ap Gc Hh Kk Mc Ny Wf Wz StnTotal ---------------------------------------------- Ap| 89 74 14 53 37 79 84 38 379 Gc| 147 7 105 46 142 75 51 500 Hh| 68 0 60 62 14 66 223 Kk| 111 13 106 54 16 347 Mc| 108 106 40 106 408 Ny| 209 80 113 688 Wf| 90 41 388 Wz| 119 431 Number of 2-station scans: 15 Number of 3-station scans: 72 Number of 4-station scans: 63 Number of 5-station scans: 38 Number of 6-station scans: 21 Number of 7-station scans: 18 Number of 8-station scans: 0 Total # of scans, observations: 228 1682 Average baseline components for all observations Average XY = 4377. Average XZ = 4490. Average YZ = 3699. Average length = 5361. =================================================================== Name Code GEOSX4F 4F Recording mode setup for: ALGOPARK HARTRAO MEDICINA NYALES20 WESTFORD WETTZELL Mode Tot.Rate Tot.BandW #chan #bits Barrel Mk341:2 256.000 Mbits 128.000 MHz 14 1 NONE Chan.BW #Subpasses Tracks(*fan) Tot.tracks Speed 8.00 MHz 1 16(*2) 32 160 X-band spanned bw= 720.0 MHz rms spanned bw= 280.4 MHz S-band spanned bw= 120.0 MHz rms spanned bw= 48.8 MHz Effective number of channels recorded per sub-pass X S Total 10.000 6.000 16.000 Recording mode setup for: GILCREEK Mode Tot.Rate Tot.BandW #chan #bits Barrel VLBA1:2 256.000 Mbits 128.000 MHz 14 1 8:1 Chan.BW #Subpasses Tracks(*fan) Tot.tracks Speed 8.00 MHz 1 16(*2) 32 160 X-band spanned bw= 720.0 MHz rms spanned bw= 280.4 MHz S-band spanned bw= 120.0 MHz rms spanned bw= 48.8 MHz Effective number of channels recorded per sub-pass X S Total 10.000 6.000 16.000 Recording mode setup for: KOKEE Mode Tot.Rate Tot.BandW #chan #bits Barrel VLBA1:2 256.000 Mbits 128.000 MHz 14 1 16:1 Chan.BW #Subpasses Tracks(*fan) Tot.tracks Speed 8.00 MHz 1 16(*2) 32 160 X-band spanned bw= 720.0 MHz rms spanned bw= 280.4 MHz S-band spanned bw= 120.0 MHz rms spanned bw= 48.8 MHz Effective number of channels recorded per sub-pass X S Total 10.000 6.000 16.000 =================================================================== ID Station Tape length Density Ap ALGOPARK 17400feet (Thin ) 56250. (High) Gc GILCREEK 17400feet (Thin ) 56700. (High) Hh HARTRAO 17400feet (Thin ) 56250. (High) Kk KOKEE 17400feet (Thin ) 56700. (High) Mc MEDICINA 17400feet (Thin ) 56250. (High) Ny NYALES20 17400feet (Thin ) 56250. (High) Wf WESTFORD 17400feet (Thin ) 56250. (High) Wz WETTZELL 17400feet (Thin ) 56250. (High) =================================================================== Minimum SNR by baseline for multi-baseline scans X-band (margin 0) S-band (margin 0) Ap Gc Hh Kk Mc Ny Wf Ap Gc Hh Kk Mc Ny Wf Gc 30 Gc 20 Hh 30 30 Hh 20 20 Kk 30 30 30 Kk 20 20 20 Mc 30 30 30 30 Mc 20 20 20 20 Ny 30 30 30 30 30 Ny 20 20 20 20 20 Wf 30 30 30 30 30 30 Wf 20 20 20 20 20 20 Wz 30 30 30 30 30 30 30 Wz 20 20 20 20 20 20 20