RV100 (Astrometric/Geodetic VLBA-100) 2013 JULY 24 18:00 DOY 205 Notes prepared by David Gordon, Ed Himwich and John Gipson NVI/GSFC Important Note: =============== Beginning with number 100, the 'RDV' sessions are now called the 'RV' sessions. This was necessary because the VLBA schedules only allow for 5-character project codes, so rdv100 had to be changed to rv100. 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 4 non-VLBA stations scheduled (HARTRAO, MATERA, NYALES20 and WESTFORD). 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 with as many antennas as possible at the beginning and near the end of the schedule. All stations please try to be onsource and recording data for these scans. These scans are: Source Start DURATIONS name yyddd-hhmmss Br Fd Hh Hn Kp La Ma Mk Nl Ny Ov Pt Sc Wf 4C39.25 13205-180000| 300 300 300 300 300 300 300 300 300 300 300 300 300| 3C274 13205-180653| 300 300 300 300 300 300 300 300 300 300| 1803+784 13206-174541| 300 300 300 300 300 300 300 300 300 300 300 300| 3C274 13206-175225| 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. - The fluxes use our most recent models. Purpose ======= This is the fourth of six coordinated astrometric/geodetic sessions in 2013 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/astrometric VLBI programs of 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 60-70 sources from the pool of geodetic, astrometric, and monitoring sources. About 30-40 of these will remain the same from experiment to experiment and will be chosen to optimize the goals of the three groups. A number of poorly observed and/or new requested sources will 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: rv100.skd On ftp.aoc.nrao.edu (aspen): VLBA Pointing files: rv100crd.br rv100crd.fd rv100crd.hn rv100crd.kp rv100crd.la rv100crd.mk rv100crd.nl rv100crd.ov rv100crd.pt rv100crd.sc Summary file: rv100.sksum Sked file: rv100.skd Text file: rv100.txt Vex file: rv100.vex At IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2013/rv100) Sked file: rv100.skd Text file: rv100.txt Vex file: rv100.vex This experiment uses the 10 VLBA stations and 4 IVS stations. The IVS stations are: HARTRAO, MATERA, NYALES20 and WESTFORD. Below is the sked summary: Key: Br=BR-VLBA Fd=FD-VLBA Hh=HARTRAO Hn=HN-VLBA Kp=KP-VLBA La=LA-VLBA Ma=MATERA Mk=MK-VLBA Nl=NL-VLBA Ny=NYALES20 Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Wf=WESTFORD Br Fd Hh Hn Kp La Ma Mk Nl Ny Ov Pt Sc Wf Avg % obs. time: 56 58 34 51 58 58 39 45 55 35 54 58 50 42 50 % cal. time: 4 3 2 3 3 4 3 3 3 3 3 3 3 3 3 % slew time: 23 22 40 21 22 22 27 18 21 17 22 22 21 16 23 % idle time: 16 15 22 24 15 15 29 33 19 43 19 15 25 38 24 total # scans: 305 299 206 290 296 303 275 232 295 278 294 302 262 275 279 # scans/hour : 13 12 9 12 12 13 11 10 12 12 12 13 11 11 12 Avg scan (sec): 158 168 143 152 171 165 124 168 162 110 160 167 165 131 152 # 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 TBytes: 1.7 1.8 1.1 1.6 1.8 1.8 1.2 1.4 1.7 1.1 1.7 1.8 1.6 1.3 1.5 Total TB(M5): 1.5 1.6 0.9 1.4 1.6 1.6 1.1 1.2 1.5 1.0 1.5 1.6 1.4 1.2 1.4 # OF OBSERVATIONS BY BASELINE | Br Fd Hh Hn Kp La Ma Mk Nl Ny Ov Pt Sc Wf Total -------------------------------------------------------------------------------- Br| 234 16 201 237 247 46 185 234 83 250 243 170 115 2261 Fd| 34 209 276 282 40 172 247 51 243 289 195 126 2398 Hh| 67 20 32 189 0 44 150 9 31 73 106 771 Hn| 193 209 80 114 244 87 176 208 223 176 2187 Kp| 276 31 190 235 45 261 282 178 110 2334 La| 41 175 252 59 249 295 195 131 2443 Ma| 31 57 229 31 38 81 164 1058 Mk| 145 59 206 177 103 59 1616 Nl| 72 219 250 214 151 2364 Ny| 54 54 61 150 1154 Ov| 253 158 93 2202 Pt| 191 126 2437 Sc| 146 1988 Wf| 1653 Number of 2-station scans: 3 Number of 3-station scans: 182 Number of 4-station scans: 82 Number of 5-station scans: 31 Number of 6-station scans: 35 Number of 7-station scans: 48 Number of 8-station scans: 43 Number of 9-station scans: 39 Number of 10-station scans: 98 Number of 11-station scans: 27 Number of 12-station scans: 18 Number of 13-station scans: 11 Number of 14-station scans: 0 Total # of scans, observations: 617 13433 INTENSIVE BREAKS ================ The USNO/NRAO UT1 Intensive sessions are now scheduled to run at ~06:30 UTC (+/- 4 hrs). Therefore we expect to lose Pietown and MK for about an hour sometime during this period. 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, 25 sources are from the astrometric monitoring list, 35 are from the geodetic monitoring list, and 31 are previously observed sources that have only a few observations or were observed in only one session. 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 ============================== 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. HARTRAO, MATERA, VLBA | NYALES20, WESTFORD 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, MATERA, NYALES20 and WESTFORD: 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. 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: jul13 directory on aspen: /astronomy/jul13/rv100 or /home/archive/e2e/archive/operations/VLBA/observe/jul13/rv100 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 to Socorro as soon after the experiment as is practical. Ny Alesund may use e-transfer and will need to coordinate this with Haystack Observatory. 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.