RDV81 (Astrometric/Geodetic VLBA-81) 2010 Sep. 14 17:30 Day 257 Notes prepared by David Gordon, John Gipson, and Ed Himwich, NVI/GSFC Special notes for this experiment ================================= This session will use 2-bit sampling again, as in the last few RDV's. Frequencies and channel bandwidths (8 MHz) are the same as in previous RDV's. The bit rate will be 256 Mbits/sec. The 8 MHz, 2-bit sampling is preferable to 16 MHz, 1-bit sampling because the 16 MHz filters are not very good at the non-VLBA stations. The data will be correlated at the VLBA using the DiFX software correlator. The 4 non-VLBA stations (HARTRAO, Kashima, Ny Alesund, and Westford) should see the "Special operations notes for non-VLBA stations" section below for special instructions. Ny Alesund will drop out of the RDV81 session at ~18:15 UT to observe the daily UT1 Intensive and will resume RDV81 at ~19:45 UT. With HARTRAO in this schedule, there can be no full network scans. However, the schedule begins and ends with nearly full network scans without HARTRAO and large scans with HARTRAO that can be used for fringe finding. There are also several nearly full network scans scattered throughout the schedule. These scans are: Source Start DURATIONS name yyddd-hhmmss Br Fd Hh Hn Kb Kp La Mk Nl Ny Ov Pt Sc Wf 1053+815 10257-173000| 300 300 300 300 300 300 300 300 300 300 300 300 300| 1510-089 10257-173648| 300 300 300 300 300 300 300 300| 1428+370 10257-232415| 186 170 173 319 186 169 262 164 250 186 169 190 319| 1053+815 10258-021432| 100 100 100 100 100 100 100 100 100 100 100 100 100| 0059+581 10258-095444| 100 100 100 100 100 100 100 100 100 100 100 100 100| 1053+815 10258-115910| 100 100 100 100 100 100 100 100 100 100 100 100 100| 1651+391 10258-172032| 200 200 200 200 200 200 200 200 200 200 200| 1053+815 10258-172533| 260 260 260 260 260 260 260 260 260 260 260 260 260| Additional Notes: - Two-bit sampling is used. - In this RDV, all stations will record on Mark5A, except Kashima and Westford. Westford will record on a Mark5B. Kashima will record on K5 and the data will be later transferred to Mark5A. - The synch time for the VLBA correlator using Mark5 is ~25 seconds. Because of this, stations will start taking data 30 seconds prior to the normal scan time. They will continue to take data between scans if there is a gap of less than 30 seconds. - The fluxes use our most recent models. Purpose ======= This is the third of six coordinated astrometric/geodetic experiments in 2010 that use the full 10-station VLBA plus up to 10 geodetic stations capable of recording VLBA modes. This year's series is a continuation of the highly successful RDV series begun in 1997. These experiments are being coordinated by the geodetic VLBI programs of three agencies: USNO, NASA, and NRAO. The experiments have been designed so that the same data set may be used by each agency for its particular goals. USNO and Bordeaux Observatory will perform imaging and correction for source structure. These sources will establish a set of core reference sources with known structure and precisely known positions. These data will provide the basis for evaluating the long term stability of the radio reference frame and the ultimate accuracy of wide angle astrometric measurements of extragalactic radio sources using VLBI. NASA will analyze this data to determine a high accuracy terrestrial reference frame. The data will incorporate the VLBA stations into the VLBI reference frame through the inclusion of other geodetic stations for which we have long histories. The data will also produce the most accurate Earth rotation results ever produced. We will use these data to make accurate absolute measurements of UT1. NRAO will use these sessions to provide a service to users who require high quality positions for a small number of sources. While the quality of these results will be high, the observing and data reduction overhead required will be minimal because a small number of such sources can be incorporated into a session of the regular geodetic observations, instead of requiring special observations. Sources for this series of experiments will be selected using the proposed approach. For each experiment we will select a set of 70-80 sources from the pool of geodetic, astrometric, and monitoring sources. About 40-50 of these will remain the same from experiment to experiment and will be chosen to optimize the goals of the three groups. A small number of poorly observed and/or new requested sources may also be included to obtain or improve their positions. Schedule information ==================== This is a new schedule generated by David Gordon at GSFC using sked. Schedule file name: rdv81.skd On ftp.aoc.nrao.edu (aspen): VLBA Pointing files: rdv81crd.br rdv81crd.fd rdv81crd.hn rdv81crd.kp rdv81crd.la rdv81crd.mk rdv81crd.nl rdv81crd.ov rdv81crd.pt rdv81crd.sc Summary file for correlator: rdv81.sksum Sked file: rdv81.skd Text file: rdv81.txt Vex file: rdv81.vex At IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2010/rdv81) Sked file: rdv81.skd Text file: rdv81.txt This experiment uses the 10 VLBA stations and 4 IVS stations. The IVS stations are: HARTRAO, KASHIM34, NYALES20, and WESTFORD. Below is the sked summary: Total time: 1440 minutes ( 24.0 hours). Key: Br=BR-VLBA Fd=FD-VLBA Hh=HARTRAO Hn=HN-VLBA Kb=KASHIM34 Kp=KP-VLBA La=LA-VLBA Mk=MK-VLBA Nl=NL-VLBA Ny=NYALES20 Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Wf=WESTFORD Br Fd Hh Hn Kb Kp La Mk Nl Ny Ov Pt Sc Wf Avg % obs. time: 45 46 41 43 29 45 46 40 45 36 42 46 41 43 42 % cal. time: 4 4 3 4 4 4 4 4 4 3 4 4 4 3 4 % slew time: 26 24 48 22 35 27 24 29 24 14 29 24 23 16 27 % idle time: 24 25 8 30 31 23 24 26 27 45 24 24 31 37 28 total # scans: 346 341 265 311 330 365 341 384 322 286 381 343 303 285 328 # scans/hour : 14 14 11 13 14 15 14 16 13 12 16 14 13 12 14 Avg scan (sec): 113 117 132 120 76 106 117 90 120 110 94 116 117 130 110 # data tracks: 16 16 16 16 16 16 16 16 16 16 16 16 16 16 # Mk5 tracks: 16 16 16 16 16 16 16 16 16 16 16 16 16 16 Total GBytes: 1779 1800 1550 1676 1265 1790 1808 1664 1738 1437 1702 1809 1600 1639 1661 Total GB(M5): 1581 1600 1377 1490 1124 1591 1607 1479 1545 1277 1513 1608 1422 1457 1477 # OF OBSERVATIONS BY BASELINE | Br Fd Hh Hn Kb Kp La Mk Nl Ny Ov Pt Sc Wf StnTotal -------------------------------------------------------------------------------- Br| 256 45 193 98 270 262 209 236 116 277 267 152 145 2526 Fd| 66 216 51 314 324 177 269 84 263 327 190 178 2715 Hh| 113 75 46 67 0 86 163 22 62 147 139 1031 Hn| 42 198 222 102 254 142 164 216 232 231 2325 Kb| 81 50 210 49 100 125 56 25 31 993 Kp| 310 221 256 81 311 320 168 157 2733 La| 173 282 93 267 333 191 183 2757 Mk| 139 54 275 181 89 63 1893 Nl| 115 221 275 210 207 2599 Ny| 78 88 115 153 1382 Ov| 274 137 126 2540 Pt| 185 177 2761 Sc| 199 2040 Wf| 1989 Number of 2-station scans: 237 Number of 3-station scans: 125 Number of 4-station scans: 65 Number of 5-station scans: 44 Number of 6-station scans: 54 Number of 7-station scans: 52 Number of 8-station scans: 45 Number of 9-station scans: 54 Number of 10-station scans: 73 Number of 11-station scans: 53 Number of 12-station scans: 28 Number of 13-station scans: 7 Number of 14-station scans: 0 Total # of scans, observations: 837 15142 SOURCE SELECTION ================ There are a total of 90 sources scheduled in this session. Among them, 30 sources are from the astrometric monitoring list and 44 are from the geodetic monitoring list. There are also 8 previously observed sources that have only a few observations and 8 new sources requested by L. Petrov. The requested sources are observed in two scans each at the VLBA sites, with the goal of accurately determining their coordinates. They are not optimized for imaging. The requested sources are: 0106+130 01 08 52.868 +13 20 14.218 J0108+1318 0421+023 04 24 02.5782 +02 26 42.646 J0424+0226 1754+292 17 56 05.2515 +29 14 16.057 J1756+2914 1817+512 18 18 30.5195 +51 17 19.740 J1818+5117 0038+319 00 41 15.9357 +32 11 07.579 J0041+3211 1455+348 14 57 57.3043 +34 39 50.396 J1457+3439 2146+019 21 48 39.8762 +02 11 26.830 J2148+0211 2329+068 23 31 55.5244 +07 05 42.072 J2331+0705 SCHEDULING ALGORITHMS ===================== This schedule uses the "SRCEVN SQRT" mode of Sked. In the absence of any constraints, Sked will preferentially observe strong sources that have high visibility. This mode attempts to smooth out the number of observations per source. RECORDING MODE and FREQUENCIES ============================== NOTE: THERE ARE SOME CHANGES FROM PREVIOUS EXPERIMENTS FOR 2-BIT SAMPLING. The data will be recorded using the following setup: 8 channels 1:2 fan-out 16 MHz sample rate 2-bit sampling This recording mode is designated 256-8(RDV). There is no correlator speed-up factor. The frequency sequence covers 490 MHz at X-band and 140 MHz at S-band using 4 channels in each band. This span fits in one VLBA receiver passband but it uses both the high and low parts of the geodetic receivers. Because only 8 channels total are available when observing with the VLBA stations, a wider spanned bandwidth is not advisable. These tables list the setup for the VLBA stations, the geodetic stations with K5 back ends, and the geodetic stations with Mark IV back ends. These are the SAME frequencies used in all the standard RDV sessions. M#: Main recording channel number for Kashima34 B#: Backup recording channel number at Kashima34 VLBA | Kashima34 M B Chan Sky Tracks LO IF BBC | LO IF BBC # # 1 X 8405.99 2, 4, 6, 8 7900 B 505.99| 7580 1 825.99 3 7 2 X 8475.99 10,12,14,16 7900 B 575.99| 7580 1 895.99 4 8 3 X 8790.99 18,20,22,24 7900 B 890.99| 8080 3 710.99 5 1 4 X 8895.99 26,28,30,32 7900 B 995.99| 8080 3 815.99 6 2 5 S 2232.99 3, 5, 7, 9 2900 A 667.01| 1520 2 712.99 9 15 6 S 2262.99 11,13,15,17 2900 A 637.01| 1520 2 742.99 10 16 7 S 2352.99 19,21,23,25 2900 A 547.01| 1520 2 832.99 13 11 8 S 2372.99 27,29,31,33 2900 A 527.01| 1520 2 852.99 14 12 HartRAO Westford VLBA | Ny Alesund Chan Sky Tracks LO IF BBC | LO IF VC VC# Patch 1 X 8405.99 2, 4, 6, 8 7900 B 505.99| 8080.0 1 325.99 3 H 2 X 8475.99 10,12,14,16 7900 B 575.99| 8080.0 1 395.99 4 H 3 X 8790.99 18,20,22,24 7900 B 890.99| 8580.1 3 210.89 5 3(H) 4 X 8895.99 26,28,30,32 7900 B 995.99| 8580.1 3 315.89 6 3(H) 5 S 2232.99 3, 5, 7, 9 2900 A 667.01| 2020.0 2 212.99 9 L 6 S 2262.99 11,13,15,17 2900 A 637.01| 2020.0 2 242.99 10 H 7 S 2352.99 19,21,23,25 2900 A 547.01| 2020.0 2 332.99 13 H 8 S 2372.99 27,29,31,33 2900 A 527.01| 2020.0 2 352.99 14 H Special operations for non-VLBA stations: ========================================= HartRAO, Ny Alesund, Westford: These stations have Mark IV racks. Please use the procedures generated by DRUDG. VCs 3, 4, 5, & 6 are used at X-band with IFs 1 and 3. VCs 9, 10, 13, & 14 are used at S-band with IF B. The IF3 command in the procedure IFDSX assumes that VC3 and VC10 will be patched to High. Please verify that the switches for your IF3 module are wired this way, and if they are not please edit the IF3 command to change the switches. The standard wiring is described in "help=if3". If you have questions about the wiring, please contact Brian Corey at Haystack. Kashima34: This station uses K4-2 VCs and a K5 recorder. Use the procedures generated by DRUDG. Be sure to set your rack type to K4-2, not K4-2/M4, if that change has not already been made. Please note you will need to comment out the incorrect VC commands in the VCSX8 procedure after the comment about these converters being present, but not used. This will be corrected in a future DRUDG release. Please also set the attenuation and detector appropriately in the va=.. and vb=... commands. The tpicd commands in SX8M12A should be benign and do not need to be commented out unless they cause a problem. If you wish to record back-up channels, please add appropriate valo=..., va=... vblo=... and vb=... commands in the VCSX8 procedure. CHECKLIST for non-VLBA stations =============================== Please follow the checklist below to ensure you have done all the necessary steps for this experiment: 1. Make .prc file with DRUDG and check them out, or use the procedures from last session. Check out parity check procedures. 2. Make the .snp file with DRUDG. 3. Set up your system to monitor the clocks with the "gps-fmout" or "fmout-gps" commands. If you have questions about this, please contact Ed Himwich as soon as possible. 4. Send a "ready" message an hour or so before the experiment to the ivs-ops mail list. Copy analysts@nrao.edu on your ready message. 5. Send a "start" message soon after you have started recording. Copy analysts@nrao.edu on the message. 6. At the end of the experiment, send a "finish" message summarizing how the experiment was conducted. Copy analysts@nrao.edu on your message. 7. Transfer your log files to your normal log file data center. The directories for three possible servers are listed below: ftp cddisin.gsfc.nasa.gov/ivsincoming directory on vlbeer: sep10 directory on aspen: /astronomy/sep10/rdv81 or /home/archive/e2e/archive/operations/VLBA/observe/sep10/rdv81 NOTE: If you don't normally use aspen, you should not put your log file on that server. The VLBA correlator knows where to find your log files. Correlation =========== This experiment will be correlated at the VLBA on the VLBA-DiFX software correlator. Disks should be shipped (or for Kashima34 the data e-transfered to Haystack) to Socorro as soon after the experiment as practical. The VLBA needs to process the session at their correlator as soon as possible, because of limited media. They prefer to have the data within one week of the observation, but in no case later than two weeks after the observation. So, we are asking all stations, participating in the RDV sessions, to ship your media to the VLBA the same day the session ends or the next business day (just like the R1/R4 media is shipped). If you know that there is going to be a problem sending your media to the VLBA the same day the session ends or the next business day, please let us (ivscc@ivscc.gsfc.nasa.gov) know as soon as possible so that we, along with the VLBA, can determine the best course of action. If you have any questions or comments, please let us know.