IVS-R1003 (International VLBI Services-Rapid Turnaround 1003) 2002 January 22 Notes prepared by Cynthia Thomas and Nancy Vandenberg,NVI/GSFC Session code: r1003 Schedule file: jan02/r1003.skd on CDDISA Nominal Start: 17:00 U.T. on January 22 (day 022) first observation at 17:00 U.T. on 4C39.25 for GC-TS-Wz first observation at 17:00 U.T. on 2255-282 for HH-WF Nominal Stop: 17:00 U.T. on January 23 (day 023) last observation at 16:45 U.T. on 1749+096 for GC last observation at 16:46 U.T. on 0528+134 for TS-WZ last observation at 16:47 U.T. on 2255-282 for HH-WF Correlator: Bonn 1 letter 2 letter Station Code Code # of tapes # of obs Fairbanks A GC 2 (TT) 424 HartRAO J HH 1 (TT) 187 Tsukuba T TS 2 (TT) 489 Westford E WF 2 (TT) 442 Wettzell V WZ 2 (TT) 539 Purpose ======= This information is located at http://ivscc.gsfc.nasa.gov/program/descrip2002.html#r1. Observing Mode ============== CORE Mode "4F" (four times the standard mode C, fanned out with barrel roll) ----------------------------------------------------------------- Number of frequencies 14 Frequency sequence X-band standard wide-band frequency sequence modified to avoid RFI at Matera S-band NEW sequence to avoid overlapping channels at the high end Number of channels 16 (14 USB + 2 LSB) Channel bandwidth 8.0 MHz Sample rate 16 Mb/s Bits per sample 1 Total data rate 256 Mb/s Data rate on tape 8 Mb/s/track Fan-out 1:2 Tape speed 160 ips Tracks per pass 32 Passes per tape 14 Barrel roll yes for Fairbanks (*) Track frame format Mark4 and VLBA (*) The 16 recorded channels are comprised of a 14-channel USB frequency sequence plus the LSB channels of the first and last frequencies at X-band. The two outer X-band LSB channels give extra sensitivity. They also slightly narrow the peak of the delay resolution function, resulting in better group delay precision. This session uses a NEW S-BAND FREQUENCY SEQUENCE, generated by Dave Shaffer. Because of the 8 MHz channel bandwidth, the standard S-band sequence had some overlapping channels. This sequence avoids the overlap and tries to avoid the direct-broadcast satellite band of 2320-2345 MHz. (*) Fairbanks, which has a VLBA backend, will use barrel roll during this session and record in VLBA (non-data replacement) format. Stations with Mark 4 formatters cannot barrel roll. Schedule ======== This schedule was made by C. Thomas using sked. Schedule setup parameters: Early start 10 sec Minimum scan length 30 sec Maximum scan length 180 sec* Minimum SNR 20 at X-band 15 at S-band * The maximum scan length was reduced to 180 seconds so that more scans would be scheduled using less tapes. The R1001 sessions were planned with the stations utilizing no more than two (2) tapes per session. Automatic scheduling setup: optimize for uniform sky coverage at all stations, maximize the number of observations, minimize slewing time, minimize time between scans, consider the top 50% of ranked scans for selection, consider the last 1 hour of scans for sky coverage calculations, minimum 50 min between scans on the same source. The characteristics of the generated schedule are listed below. These will vary slightly for each schedule that is generated. Schedule characteristics: Average scan length 53 seconds Median SNR 40.0 at X-band 30.0 at S-band Number of observations 2109 observations Average scans per station 441 scans Station Information =================== Matera will not participate in this session because of azimuth encoder problems. Parity ====== This schedule was made with a minimum scan time of less than the 55 seconds required for parity checks. As a result, some parity checks in the schedule may give bad results even though there is nothing wrong. The next release of the FS, 9.5, will correct this problem. In the meantime, please check when a parity check fails to see if the cause is a short scan. If the problem is presistent and occurs frequently at your station for a given schedule type, you may want to disable parity checks for specific experiments of that type. You can do this by creating empty "checkf80" and "checkr80" procedures (or "checkf135" and "checkr135" if you are using thick tape) in the EXPERIMENT procedure library for the effected experiment. If you do this, it is strongly recommend that you verify recorder performance before the experiment by recording some tape in both directions using the experiment set-up and check it with the appropriate parity check procedures. Flux Information ================ The flux catalog, flux.jan02.cat, was used in preparing this schedule file. The flux catalog is located at gemini:/home/ftp/pub/sked/catalogs. SKED Summary from file ./r1003.skd for experiment R1003 (all scans with at least one subnet station) Average number of obs. per baseline per source (normalized by up-time) = 7.3 Min = .0 Max = 39.3 (Baseline Gc-Ts on 1334-127) RMS = 7.8 Total time: 1429 minutes ( 23.8 hours). Key: Gc=GILCREEK Hh=HARTRAO Ts=TSUKUB32 Wf=WESTFORD Wz=WETTZELL Gc Hh Ts Wf Wz Avg % obs. time: 27 14 26 29 33 26 % cal. time: 6 2 5 5 6 5 % slew time: 37 39 24 22 22 29 % idle time: 27 43 43 43 37 38 # of tapes : 1.7 .9 1.6 1.7 1.9 total # scans: 552 187 489 442 539 441 # scans/hour : 23 7 20 18 22 18.4 Avg scan (sec): 43 67 46 56 53 53 # OF OBSERVATIONS BY BASELINE | Gc Hh Ts Wf Wz StnTotal ---------------------------------- Gc|552 9 409 330 299 1047 Hh| 187 57 50 160 276 Ts| 489 204 274 944 Wf| 442 317 901 Wz| 539 1050 Number of 2-station scans: 402 Number of 3-station scans: 267 Number of 4-station scans: 151 Number of 5-station scans: 0 Total # of scans, observations: 820 2109 Average baseline components for all observations Average XY = 6224. Average XZ = 5148. Average YZ = 4840. Average length = 6933.