IVS-R1006 (International VLBI Services-Rapid Turnaround 1006) 2002 February 11 Notes prepared by Cynthia Thomas and Nancy Vandenberg,NVI/GSFC Session code: r1006 Schedule file: feb02/r1006.skd on CDDISA Nominal Start: 17:00 U.T. on February 11 (day 042) first observation at 17:00 U.T. on 1044+719 Nominal Stop: 17:00 U.T. on February 12 (day 043) last observation at 16:49 U.T. on 1300+580 Correlator: Haystack 1 letter 2 letter Station Code Code # of tapes # of obs Fairbanks A GC 2 (TT) 467 Matera I MA 2 (TT) 480 Ny Alesund N NY 2 (TT) 531 Westford E WF 2 (TT) 457 Wettzell V WZ 2 (TT) 570 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 IVS-R1 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 49 seconds Median SNR 40.0 at X-band 25.0 at S-band Number of observations 3515 observations Average scans per station 501 scans 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 ./r1006.skd for experiment R1006 (all scans with at least one subnet station) Average number of obs. per baseline per source (normalized by up-time) = 11.5 Min = .0 Max = 76.4 (Baseline Ny-Wz on CTA26 ) RMS = 9.8 Total time: 1430 minutes ( 23.8 hours). Key: Gc=GILCREEK Ma=MATERA Ny=NYALES20 Wf=WESTFORD Wz=WETTZELL Gc Ma Ny Wf Wz Avg % obs. time: 28 27 28 29 30 28 % cal. time: 5 5 6 5 6 5 % slew time: 29 33 28 22 19 26 % idle time: 36 33 36 42 43 38 # of tapes : 1.6 1.6 1.6 1.7 1.8 total # scans: 467 480 531 457 570 501 # scans/hour : 19 20 22 19 23 20.9 Avg scan (sec): 51 49 45 55 45 49 # OF OBSERVATIONS BY BASELINE | Gc Ma Ny Wf Wz StnTotal ---------------------------------- Gc|467 226 395 364 310 1295 Ma| 480 348 277 474 1325 Ny| 531 348 440 1531 Wf| 457 333 1322 Wz| 570 1557 Number of 2-station scans: 213 Number of 3-station scans: 186 Number of 4-station scans: 149 Number of 5-station scans: 185 Total # of scans, observations: 733 3515 Average baseline components for all observations Average XY = 4400. Average XZ = 3450. Average YZ = 3006. Average length = 4615.