NOTES FOR: rd0205 Prepared by C. Thomas, NVI, Inc./GSFC =========================================================== Parameter values for experiment RD0205 Experiment description: R&D Scheduler: NASA Correlator: HAYSTACK Nominal start: 2002-135-18:00:00 Nominal end: 2002-136-18:00:00 Current yyyyddd: 2002135 (2002.37) ( 12410 MJD, WED. 15MAY.) Greenwich sidereal time: 9:33:10.00 (18: 0: 0 UT) Sun's RA and DEC: 3h 29.5m 18d 57.1 =========================================================== First observations Source Start DURATIONS name yyddd-hhmmss Ap Gc Kk Ma Ny Wf Wz 1357+769 02135-180000| 68 238 441 452 332 452 329| =========================================================== Last observations Source Start DURATIONS name yyddd-hhmmss Ap Gc Kk Ma Ny Wf Wz 0003-066 02136-173001| 51 234 450 450 | 0528+134 02136-173833| 33 91 185 177 185 179| =========================================================== 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 ./rd0205.skd for experiment RD0205 (all scans with at least one subnet station) Average number of obs. per baseline per source (normalized by up-time) = 5.2 Min = .0 Max = 54.7 (Baseline Ny-Wz on 1741-038) RMS = 7.3 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: 15 24 29 34 29 29 36 28 % cal. time: 2 2 1 2 1 1 2 2 % slew time: 61 18 10 17 11 10 7 19 % idle time: 20 54 58 46 56 58 53 49 # of tapes : .9 1.4 1.6 1.9 1.6 1.6 2.0 total # scans: 209 193 158 180 170 166 210 183 # scans/hour : 8 8 6 7 7 7 8 7.7 Avg scan (sec): 63 108 156 162 147 152 146 133 tape change times (hhmm): 0000 1120 0714 0645 1056 0938 0615 # OF OBSERVATIONS BY BASELINE | Ap Gc Kk Ma Ny Wf Wz StnTotal ------------------------------------------ Ap|209 119 94 68 91 155 93 620 Gc| 193 138 47 96 85 63 548 Kk| 158 19 63 72 30 416 Ma| 180 110 78 178 500 Ny| 170 89 134 583 Wf| 166 93 572 Wz| 210 591 Number of 2-station scans: 167 Number of 3-station scans: 90 Number of 4-station scans: 46 Number of 5-station scans: 41 Number of 6-station scans: 29 Number of 7-station scans: 17 Total # of scans, observations: 390 1915 =========================================================== 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