RV124 (Astrometric/Geodetic VLBA-124) 2017 JULY 17 16:30 DOY 198 Notes prepared by David Gordon, Ed Himwich and John Gipson NVI/GSFC Special notes for this experiment ================================= This session will use the RDBE/DDC/Mark5C system at the VLBA sites, as in previous RV sessions. And it will again use the new RDV frequency sequence. The X-band frequencies are: 8365.75, 8445.75, 8805.75, and 8925.75 MHz, and now span 560 MHz. The S-band frequencies are: 2232.75, 2262.75, 2352.75, and 2372.75 MHz. The ending in .75 MHz is necessary at the VLBA stations. Therefore it will not be possible to monitor phase cals using the 10 kHz filters. This session will record 8 8-MHz bandwidth channels using 2-bit sampling, as in previous RDV's. The bit rate will be 256 Mbits/sec. The data will be correlated at the VLBA using the VLBA DiFX software correlator. There are 5 non-VLBA stations scheduled (HARTRAO, NYALES20, WETTZ13N, WETTZELL and YARRA12M). These 5 stations should see the "Special operations notes for non-VLBA stations" section below for special instructions. To facilitate fringe-finding, there are some long scans on fairly strong sources with most antennas at the beginning 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 Mk Nl Ny Ov Pt Sc Wn Wz Yg 3C418 17198-163000| 300 300 300 300 300 300 300 300 300 300 300| 0847-120 17198-163702| 300 300 300 300 300 300 300 300 300 300 300 | Note: We are again using the new 'Fill' scheduling option, which was recently added to sked by Karine Lebail and John Gipson. 'Fill' is run after a schedule is finished in the normal manner. It increases the scan times at selected stations, when possible, based on how much idle time each station has before its next scan. We used a 'FILL_OFF' margin of 5 seconds. Using 'Fill' on the original schedule the average observing time increased from 51% to 64%, and the average idle time decreased from 24% to 11%. The observing time increased most at the faster antennas and least at the slower antennas. Purpose ======= This is the fourth of six coordinated astrometric/geodetic sessions in 2017 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 orientation results ever produced. We will use these data to make the most precise measurements of UT1 and nutation. The LBO 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 20-30 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. It starts on a Monday, which is somewhat unusual for an RV session. WETTZ13N and YARRA12M are included for CONT17 preparations. Schedule file name: rv124.skd At the IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2017/rv124): Sked file: rv124.skd Text file: rv124.txt At the LBO/VLBA: VLBA Pointing files: rv124crd.br rv124crd.fd rv124crd.hn rv124crd.kp rv124crd.la rv124crd.mk rv124crd.nl rv124crd.ov rv124crd.pt rv124crd.sc Summary file: rv124.sksum Sked file: rv124.skd Text file: rv124.txt Vex file: rv124.vex This experiment uses the 10 VLBA stations and 5 IVS stations. The IVS stations are: HARTRAO, NYALES20, WETTZ13N, WETTZELL and YARRA12M. 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 Wn=WETTZ13N Wz=WETTZELL Yg=YARRA12M Br Fd Hh Hn Kp La Mk Nl Ny Ov Pt Sc Wn Wz Yg Avg % obs. time: 63 65 48 62 66 66 56 63 67 64 66 60 80 72 57 64 % cal. time: 5 5 3 5 5 5 4 5 4 5 5 4 3 4 2 4 % slew time: 24 23 40 25 23 23 22 24 15 23 23 23 2 9 5 21 % idle time: 7 6 8 7 5 5 17 6 14 7 5 12 14 14 35 11 total # scans: 416 424 253 418 423 425 343 430 303 413 429 370 295 311 181 362 # scans/hour : 17 18 11 17 18 18 14 18 13 17 18 15 12 13 8 15 Avg scan (sec): 132 133 165 129 134 134 141 127 191 135 133 140 234 201 271 159 # data tracks: 16 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 16 Total TB(M5): 1.8 1.8 1.3 1.7 1.8 1.8 1.6 1.8 1.9 1.8 1.8 1.7 2.2 2.0 1.6 1.8 # OF OBSERVATIONS BY BASELINE | Br Fd Hh Hn Kp La Mk Nl Ny Ov Pt Sc Wn Wz Yg Total ------------------------------------------------------------------------------------- Br| 286 15 234 317 304 284 276 94 336 304 172 29 43 46 2740 Fd| 29 261 381 388 243 322 60 329 396 235 22 32 24 3008 Hh| 67 21 29 0 42 113 11 25 75 216 206 93 942 Hn| 232 256 127 360 113 208 245 330 51 78 1 2563 Kp| 382 272 291 66 368 398 210 23 34 31 3026 La| 246 318 64 345 410 231 25 39 27 3064 Mk| 172 60 303 258 104 10 18 58 2155 Nl| 95 264 306 298 36 52 14 2846 Ny| 61 61 91 178 180 88 1324 Ov| 355 174 17 28 38 2837 Pt| 223 23 34 29 3067 Sc| 55 80 0 2278 Wn| 270 126 1081 Wz| 112 1206 Yg| 687 Number of 2-station scans: 0 Number of 3-station scans: 216 Number of 4-station scans: 218 Number of 5-station scans: 86 Number of 6-station scans: 58 Number of 7-station scans: 83 Number of 8-station scans: 63 Number of 9-station scans: 74 Number of 10-station scans: 95 Number of 11-station scans: 24 Number of 12-station scans: 11 Number of 13-station scans: 3 Number of 14-station scans: 0 Number of 15-station scans: 0 Total number of scans: 931 Total number of obs: 16412 INTENSIVE BREAKS ================ There is an IVS INT01 Intensive session scheduled during RV124. Wettzell will drop out from ~18:15 - 19:45 on DOY 198 for this Intensive. There will also be a USNO/LBO UT1 Intensive session, scheduled to run at ~06:30 UTC (+/- 4 hrs)on DOY 199, using Pietown and MK-VLBA, so these stations will drop out for about an hour. The exact time is not fixed, so it is not scheduled in, but the loss of these two antennas for a short period should have only a minimal effect. SOURCE SELECTION ================ There are a total of 80 sources scheduled in this session. Among them, 60 are from the geodetic monitoring list, and 20 are weaker sources whose X/S positions we are trying to improve for ICRF3. 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 560 MHz at X-band and 140 MHz at S-band using 4 channels in each band. At the VLBA, the X-band uses two LO's in order to fit in the VLBA 512 MHz passband. At the Mark4 stations, the X-band uses both the high and low parts of the geodetic receivers. Because only 8 channels are available when observing with the VLBA/RDBE/DDC systems, a wider spanned bandwidth is not advisable. The following tables list the setup for the VLBA stations and the geodetic stations with DBBC, Mark IV, Mark 5, and VLBA5 back ends. VLBA | HARTRAO Chan Sky Tracks LO IF BBC | LO IF BBC BBC# 1 X 8365.75 2, 4, 6, 8 7600 B 765.75| 8080.0 A1 285.75 3 2 X 8445.75 10,12,14,16 7600 B 845.75| 8080.0 A1 365.75 4 3 X 8805.75 18,20,22,24 9600 D 794.25| 8080.0 B2 725.75 5 4 X 8925.75 26,28,30,32 9600 D 674.25| 8080.0 B2 845.75 6 5 S 2232.75 3, 5, 7, 9 3100 A 867.25| 2020.0 C1 212.75 9 6 S 2262.75 11,13,15,17 3100 A 837.25| 2020.0 C1 242.75 10 7 S 2352.75 19,21,23,25 3100 A 747.25| 2020.0 C1 332.75 13 8 S 2372.75 27,29,31,33 3100 A 727.25| 2020.0 C1 352.75 14 VLBA | NYALES20 Chan Sky Tracks LO IF BBC | LO IF BBC BBC# 1 X 8365.75 2, 4, 6, 8 7600 B 765.75| 8080.0 A1 285.75 3 2 X 8445.75 10,12,14,16 7600 B 845.75| 8080.0 A1 365.75 4 3 X 8805.75 18,20,22,24 9600 D 794.25| 8080.0 B1 725.75 5 4 X 8925.75 26,28,30,32 9600 D 674.25| 8080.0 B1 845.75 6 5 S 2232.75 3, 5, 7, 9 3100 A 867.25| 2020.0 C1 212.75 9 6 S 2262.75 11,13,15,17 3100 A 837.25| 2020.0 C1 242.75 10 7 S 2352.75 19,21,23,25 3100 A 747.25| 2020.0 C1 332.75 13 8 S 2372.75 27,29,31,33 3100 A 727.25| 2020.0 C1 352.75 14 VLBA | WETTZELL, WETTZ13N Chan Sky Tracks LO IF BBC | LO IF BBC BBC# 1 X 8365.75 2, 4, 6, 8 7600 B 765.75| 8080.0 A1 285.75 3 2 X 8445.75 10,12,14,16 7600 B 845.75| 8080.0 A1 365.75 4 3 X 8805.75 18,20,22,24 9600 D 794.25| 8080.0 B1 725.75 5 4 X 8925.75 26,28,30,32 9600 D 674.25| 8080.0 B1 845.75 6 5 S 2232.75 3, 5, 7, 9 3100 A 867.25| 2020.0 C1 212.75 9 6 S 2262.75 11,13,15,17 3100 A 837.25| 2020.0 C1 242.75 10 7 S 2352.75 19,21,23,25 3100 A 747.25| 2020.0 D1 332.75 13 8 S 2372.75 27,29,31,33 3100 A 727.25| 2020.0 D1 352.75 14 VLBA | YARRA12M Chan Sky Tracks LO IF BBC | LO IF BBC BBC# 1 X 8365.75 2, 4, 6, 8 7600 B 765.75| 7600.0 A1 765.75 3 2 X 8445.75 10,12,14,16 7600 B 845.75| 7600.0 A1 845.75 4 3 X 8805.75 18,20,22,24 9600 D 794.25| 7600.0 B4 1205.75 5 4 X 8925.75 26,28,30,32 9600 D 674.25| 7600.0 B4 1325.75 6 5 S 2232.75 3, 5, 7, 9 3100 A 867.25| 1900.0 C2 332.75 9 6 S 2262.75 11,13,15,17 3100 A 837.25| 1900.0 C2 362.75 10 7 S 2352.75 19,21,23,25 3100 A 747.25| 1900.0 D2 452.75 13 8 S 2372.75 27,29,31,33 3100 A 727.25| 1900.0 D2 472.75 14 Special operations for non-VLBA stations: ========================================= All non-VLBA stations: Please note that due to the frequency sequence, phase-cal will not be visible with a 10 kHz viewing filter in the USB channels. If you have another means to verify phase-cal, please use it. If you have a Mark IV Decoder, please contact Ed.Himwich@nasa.gov if you would like advice on how to set it up to check phase-cal for this frequency sequence. HARTRAO: This station uses a DBBC rack. Please use the procedures generated by DRUDG. BBCs 3 & 4 are used at X-band with IF A, input 1. BBCs 5 & 6 are used at X-band with IF B, input 2. BBCs 9, 10, 13 & 14 are used for S-band with IF C, input 1. NYALES20 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 2. 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. 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 RV 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 file to your normal IVS data center. The directories for the IVS servers are listed below: ftp cddisin.gsfc.nasa.gov/ivsincoming ftp ivsopar.obspm.fr/ivsincoming ftp ivs.bkg.bund.de/ivsincoming Correlation =========== This experiment will be correlated at the LBO/VLBA on the LBO DiFX software correlator. Most of the Mark4 stations are now E-transfering their data to Haystack, where it will be copied and shipped to the VLBA in Socorro, New Mexico. These stations will need to coordinate this with Haystack Observatory (contact: Jason SooHoo at jsoohoo@haystack.mit.edu). The VLBA needs to process the session at their correlator as soon as possible because of limited media. So please try to set up the E-transfer as soon as possible after the session ends. If you need to ship the media instead, please ship it to Socorro as soon after the experiment as is practical. It should be shipped to the following address: Socorro address for media shipping: VLBA Array Operations Center Long Baseline 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). 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 (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.