Notes for: rd0204 Prepared by C. Thomas, NVI, Inc./GSFC =========================================================== Parameter values for experiment RD0204 Experiment description: R&D Scheduler: NASA Correlator: HAYSTACK Nominal start: 2002-093-18:00:00 Nominal end: 2002-094-18:00:00 Current yyyyddd: 2002093 (2002.25) ( 12368 MJD, WED. 3APR.) Greenwich sidereal time: 6:47:34.68 (18: 0: 0 UT) Sun's RA and DEC: 0h 50.8m 5d 26.9 =========================================================== First observations Source Start DURATIONS name yyddd-hhmmss Ap Gc Kk Ma Ny Wf Wz 1044+719 02093-180000| 229 214 468 468 | 0552+398 02093-180000| 120 120 43| =========================================================== Last observations Source Start DURATIONS name yyddd-hhmmss Ap Gc Kk Ma Ny Wf Wz 1741-038 02094-173451| 30 30 | 0235+164 02094-173808| 48 222 294 221 294 233| =========================================================== Notes by Dan MacMillan, March 27, 2002 Purpose of Experiment The goal of this experiment is to investigate instrumental errors by scheduling observations with very high SNR. The high SNR is necessary in order to allow phase delay ambiguities to be resolved. With the much more precise phase delay observables one can then investigate possible systematic variations. For instance, we have seen subdaily cycles in the time variation of solution residuals. If these systematic variations can be identified, it may be possible to introduce corrections for them. Additionally, we will investigate intra-scan variations of residual fringe phase. Usually VLBI experiments are scheduled with target minimum SNRs of 20 at X-band and 15 at S-band. To resolve phase delays, we chose a much higher minimum of 80 at X-band and 60 at S-band. Once this experiment is analyzed, we will assess whether such high limits are necessary since this significantly reduces the number of observations/hour that can be observed at each site. For this R&D experiment in contrast to the last one, we scheduled a quasi-continuous observation of the source 4C39.25 for about one hour. To do this, three sequential 22 minute scans were scheduled at about 4 hours from the beginning of the experiment. The purpose is to investigate variations of fringe phase and amplitude at time scales from 5 seconds to 1 hour. Type of Experiment This experiment uses a 7-station northern hemisphere geodetic network. We had to compromise between the parameters of a standard geodetic schedule made with smooth sky coverage and the high SNR requirement that significantly reduces the possible number of station observations/hour. The antenna at Harteboestoek was available, but we decided not to include it because schedule simulations showed that HartRAO was not connected well enough to observe more than 2-3 observations/hour. Simulations showed that EOP formal uncertainties were not significantly improved by including HartRAO at this level. The high SNR requirement reduced the number of observations for this network significantly from an average of about 12-15 observations/hour for other routine schedules to 7-8 observations/hour (for non-HartRAO sites). Another consideration in making the schedule was that we decided to reduce the possible number of sources observed to increase the average number of observations made on each source. The standard list of 70 sources was reduced to 36 sources by taking out infrequently observed sources or sources that were redundant in the sense of being close to other more frequently observed sources. We tried to maintain good low elevation coverage for atmosphere parameter estimation. =========================================================== SKED Summary from file ./rd0204.skd for experiment RD0204 (all scans with at least one subnet station) Average number of obs. per baseline per source (normalized by up-time) = 5.3 Min = .0 Max = 105.4 (Baseline Ny-Wz on 1741-038) RMS = 8.3 Total time: 1419 minutes ( 23.7 hours). Key: Ap=ALGOPARK Gc=GILCREEK Kk=KOKEE Ma=MATERA Ny=NYALES20 Wf=WESTFORD Wz=WETTZELL Ap Gc Kk Ma Ny Wf Wz Avg % obs. time: 16 30 38 40 33 38 40 34 % cal. time: 2 2 1 2 2 2 2 2 % slew time: 54 16 10 14 11 10 8 17 % idle time: 27 50 48 42 52 49 49 45 # of tapes : .9 1.6 2.1 2.3 1.9 2.1 2.2 total # scans: 194 187 161 183 172 177 209 183 # scans/hour : 8 7 6 7 7 7 8 7.6 Avg scan (sec): 72 138 204 189 167 183 164 159 tape change times (hhmm): 0000 0826 0449 0503 0729 0548 0503 0000 0000 1555 1455 0000 1702 1601 # OF OBSERVATIONS BY BASELINE | Ap Gc Kk Ma Ny Wf Wz StnTotal ------------------------------------------ Ap|194 112 98 70 99 165 89 633 Gc| 187 143 55 112 95 76 593 Kk| 161 22 73 78 37 451 Ma| 183 111 82 182 522 Ny| 172 100 135 630 Wf| 177 98 618 Wz| 209 617 Number of 2-station scans: 145 Number of 3-station scans: 78 Number of 4-station scans: 46 Number of 5-station scans: 48 Number of 6-station scans: 36 Number of 7-station scans: 17 Total # of scans, observations: 370 2032 =========================================================== Recording mode Name Code GEOSX4F 4F Recording mode setup for: ALGOPARK MATERA 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) 32 160.00 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) 32 160.00 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) 32 160.00 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 =========================================================== Tape types ID Station Tape length Density Ap ALGOPARK 17400feet (Thin ) 56250. (High) Gc GILCREEK 17400feet (Thin ) 56700. (High) Kk KOKEE 17400feet (Thin ) 56700. (High) Ma MATERA 17400feet (Thin ) 56250. (High) Ny NYALES20 17400feet (Thin ) 56250. (High) Wf WESTFORD 17400feet (Thin ) 56250. (High) Wz WETTZELL 17400feet (Thin ) 56250. (High) =========================================================== SNR Targets Minimum SNR by baseline for multi-baseline scans X-band (margin 5) S-band (margin 5) Ap Gc Kk Ma Ny Wf Ap Gc Kk Ma Ny Wf Gc 80 Gc 60 Kk 80 80 Kk 60 60 Ma 80 80 80 Ma 60 60 60 Ny 80 80 80 80 Ny 60 60 60 60 Wf 80 80 80 80 80 Wf 60 60 60 60 60 Wz 80 80 80 80 80 80 Wz 60 60 60 60 60 60