RDV92 (Astrometric/Geodetic VLBA-92) 2012 APR 18 18:00 DOY 109 Notes prepared by David Gordon, Ed Himwich and John Gipson 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. There are 5 non-VLBA stations scheduled (HARTRAO, NYALES20, TSUKUB32, WESTFORD and WETTZELL). These stations should see the "Special operations notes for non-VLBA stations" section below for special instructions. To facilitate fringe-finding, there are several long scans on fairly strong sources at the beginning of the schedule and near the end. All stations please try to be onsource and recording data for the first of these scans. There are also several nearly full-network scans in the middle of the session. These scans are: Source Start DURATIONS name yyddd-hhmmss Br Fd Hh Hn Kp La Mk Nl Ny Ov Pt Sc Ts Wf Wz 2229+695 12109-180000| 300 300 300 300 300 300 300 300 300 300 300 300 300 300| 0420-014 12109-180709| 300 300 300 300 300 300 300 300 300 300| 0716+714 12109-184916| 45 45 45 45 45 45 45 45 45 45 45 45 45 45| NGC6251 12109-191848| 182 198 119 195 183 206 119 279 189 190 150 110 279 263| 0110+495 12109-195156| 83 85 89 84 84 89 85 274 83 84 100 74 256 274| 0716+714 12110-041328| 200 200 200 200 200 200 200 200 200 200 200 200 200 200| 0420-014 12110-173827| 300 300 300 300 300 300 300 300 300 300 300 300| 2229+695 12110-174541| 300 300 300 300 300 300 300 300 300 300 300 300 300 300| Additional Notes: - Two-bit sampling is used. - In this RDV, all stations will record on Mark5A/B, except Tsukuba. Tsukuba will record on K5 and the data will be later transferred to Mark5A at Haystack Observatory. - The synch time for the VLBA DiFX correlator using Mark5 is only a few seconds. Because of this, the 'early' start has been reduced to 10 seconds. - The fluxes use our most recent models. Purpose ======= This is the second of six coordinated astrometric/geodetic sessions in 2012 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 and maintain 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: rdv92.skd On ftp.aoc.nrao.edu (aspen): VLBA Pointing files: rdv92crd.br rdv92crd.fd rdv92crd.hn rdv92crd.kp rdv92crd.la rdv92crd.mk rdv92crd.nl rdv92crd.ov rdv92crd.pt rdv92crd.sc Summary file: rdv92.sksum Sked file: rdv92.skd Text file: rdv92.txt Vex file: rdv92.vex At IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2012/rdv92) Sked file: rdv92.skd Text file: rdv92.txt This experiment uses the 10 VLBA stations and 5 IVS stations. The IVS stations are: HARTRAO, NYALES20, TSUKUB32, WESTFORD and WETTZELL. Below is the sked summary: Key: Br=BR-VLBA Fd=FD-VLBA Hh=HARTRAO Hn=HN-VLBA Kp=KP-VLBA La=LA-VLBA Mk=MK-VLBA Nl=NL-VLBA Ny=NYALES20 Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Ts=TSUKUB32 Wf=WESTFORD Wz=WETTZELL Br Fd Hh Hn Kp La Mk Nl Ny Ov Pt Sc Ts Wf Wz Avg % obs. time: 47 49 37 44 49 49 46 46 40 47 49 45 33 40 40 44 % cal. time: 4 4 3 4 4 4 4 4 4 4 4 4 4 4 4 4 % slew time: 26 25 52 24 26 25 26 24 19 26 25 24 17 18 10 25 % idle time: 21 21 7 27 20 21 22 25 36 21 21 26 44 37 45 27 total # scans: 355 356 299 342 361 357 359 350 337 358 358 331 373 318 331 345 # scans/hour : 15 15 12 14 15 15 15 15 14 15 15 14 16 13 14 14 Avg scan (sec): 115 118 106 111 117 118 111 114 104 114 119 116 77 110 105 109 Total GBytes: 1599 1640 1253 1489 1656 1648 1567 1558 1379 1604 1657 1505 1163 1369 1367 1497 Total GB(M5): 1422 1458 1114 1323 1472 1465 1393 1385 1225 1426 1473 1338 1034 1217 1215 1331 # OF OBSERVATIONS BY BASELINE | Br Fd Hh Hn Kp La Mk Nl Ny Ov Pt Sc Ts Wf Wz StnTotal ------------------------------------------------------------------------------------- Br| 248 20 212 272 258 221 242 104 280 259 169 120 134 56 2595 Fd| 45 240 322 337 189 284 74 266 340 221 69 173 61 2869 Hh| 82 30 46 0 64 135 10 44 109 80 113 245 1023 Hn| 219 246 126 287 123 190 242 259 69 238 106 2639 Kp| 320 218 271 63 301 327 198 87 148 49 2825 La| 189 299 78 274 351 224 68 177 64 2931 Mk| 152 63 260 194 104 188 65 25 1994 Nl| 102 231 294 246 67 205 86 2830 Ny| 63 75 95 162 155 208 1500 Ov| 279 165 114 119 39 2591 Pt| 221 70 173 61 2930 Sc| 46 213 109 2379 Ts| 56 89 1285 Wf| 141 2110 Wz| 1339 Number of 2-station scans: 285 Number of 3-station scans: 143 Number of 4-station scans: 103 Number of 5-station scans: 50 Number of 6-station scans: 61 Number of 7-station scans: 50 Number of 8-station scans: 47 Number of 9-station scans: 42 Number of 10-station scans: 80 Number of 11-station scans: 65 Number of 12-station scans: 26 Number of 13-station scans: 11 Number of 14-station scans: 6 Number of 15-station scans: 0 Total # of scans, observations: 969 16920 INTENSIVE BREAKS ================ There is no INT01 UT1 session on April 18, so no intensive break is included in the schedule. However, there may be a USNO/NRAO UT1 intensive session using PIETOWN and MK-VLBA. The timing for this is somewhat flexible - sometime between 15:00 and 23:00 UTC. Therefore, PT and MK may be taken out of RDV92 for an ~1.5-2.0 hr period sometime during that window. We will leave the timing of this break to the discretion of the VLBA operators. From our standpoint, there is no particular period that is better or worse than another, and the loss of these two antennas for a short period should have only a minimal effect. SOURCE SELECTION ================ There are a total of 91 sources scheduled in this session. Among them, 30 sources are from the astrometric monitoring list, 35 are from the geodetic monitoring list, 25 are previously observed sources that have only a few observations or were observed in only one session, and 1 is a new source whose position was requested by Y. Kovalev. The requested source is: 2121-199 21 24 44.66 -19 41 42.8 J2124-1941 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. The following 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. VLBA | TSUKUB32 Chan Sky Tracks LO IF BBC | LO IF BBC # 1 X 8405.99 2, 4, 6, 8 7900 B 505.99| 7680 1 725.99 3 2 X 8475.99 10,12,14,16 7900 B 575.99| 7680 1 795.99 4 3 X 8790.99 18,20,22,24 7900 B 890.99| 8080 3 710.99 5 4 X 8895.99 26,28,30,32 7900 B 995.99| 8080 3 815.99 6 5 S 2232.99 3, 5, 7, 9 2900 A 667.01| 1600 2 632.99 9 6 S 2262.99 11,13,15,17 2900 A 637.01| 1600 2 662.99 10 7 S 2352.99 19,21,23,25 2900 A 547.01| 1600 2 752.99 13 8 S 2372.99 27,29,31,33 2900 A 527.01| 1600 2 772.99 14 HARTRAO, NYALES20, VLBA | WESTFORD, WETTZELL 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, NYALES20, WESTFORD and WETTZELL: These stations have Mark IV or Mark 5 racks. Please use the procedures generated by DRUDG. VCs 3 & 4 are used at X-band with IF 1. VCs 5 & 6 are used at X-band with IF 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. TSUKUB32: This station uses K4-2 VCs and a K5 recorder. Please transfer data to Haystack in Mark IV format. 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 the 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: apr12 directory on aspen: /astronomy/apr12/rdv92 or /home/archive/e2e/archive/operations/VLBA/observe/apr12/rdv92 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 (except Tsukuba) to Socorro as soon after the experiment as is practical. The Tsukuba data should be e-transfered to Haystack in Mark IV format as soon after the experiment as is practical. Ny Alusund may also use e-transfer and will need to coordinate this with Haystack if so. Socorro address for media shipping: VLBA Array Operations Center National Radio Astronomy Observatory Attn: Juan Cordova 1003 Lopezville Road Socorro, NM 87801 U.S.A. Phone: 575-835-7000 Shipping and VLBA contact information is also given at: https://science.nrao.edu/facilities/vlba/contact/shipping_information. Please use one of the recommended shipping companies (FedEx, UPS, DHL, TNT). 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. Therefore, please 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 and David.Gordon-1@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.