RV141 (Astrometric/Geodetic VLBA-141) 2020 JUL 07 17:30 UTC DOY 189 Notes prepared by David Gordon NVI/GSFC Special notes for this session: =============================== This session will use the RDBE/DDC/Mark5C system at the VLBA sites, as in previous RV sessions. The X-band frequencies are: 8365.75, 8445.75, 8805.75 and 8925.75 MHz, and spans 560 MHz. The S-band frequencies are: 2232.75, 2262.75, 2372.75 and 2392.75 MHz, and spans 160 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. RV141 will record 8 16-MHz bandwidth channels using 2-bit sampling. The bit rate will be 512 Mbits/sec. The data will be correlated at the VLBA using the VLBA DiFX software correlator. There are 4 non-VLBA stations scheduled - HARTRAO, NYALES20, ONSALA60 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 some long scans on fairly strong sources with most antennas 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 Mk Nl Ny On Ov Pt Sc Wz 0133+476 20189-173000| 414 313 300 316 414 364 302 300 307 403 414 300 329| 0925-203 20189-173733| 405 300 381 405 393 389 | 1803+784 20190-171048| 304 300 310 300 300 300 302 304 301 303 300 310 310| 0925-203 20190-171842| 342 300 389 338 344 359 342 389 | We are again using the 'Fill' scheduling option. 'Fill' is run after a schedule is finished in the normal manner. It increases the scan times at 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 increases from 48% to 60%, and the average idle time decreases from 22% to 10%. The observing time increases most at the faster antennas and least at the slower antennas. Purpose ======= This is the third of six coordinated astrometric/geodetic sessions in 2020 that use the full 10-station VLBA plus several geodetic stations capable of recording VLBA modes. This year's series is a continuation of the highly successful RDV series begun in 1997. These are now being run under the USNO's VLBA time allocation. These sessions are being coordinated by the geodetic/astrometric VLBI programs of USNO, NASA and NRAO. They have been designed so that the same data set may be used by each agency for its particular goals. USNO, NASA and Bordeaux Observatory will perform imaging and study possible corrections for source structure. These sources will establish a set of core reference sources with known structure and precisely known positions. These data will help 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 and USNO will analyze this data to determine and maintain high accuracy terrestrial reference and celestial reference frames. 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. This data will also produce highly accurate Earth orientation results and possibly the best nutation results ever produced. NASA and NRAO will use these sessions to provide a service to users who request 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. For each RV session we will select a set of ~60 sources from the pool of geodetic and monitoring sources. A number of poorly observed and/or 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: rv141.skd At the IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2020/rv141): Sked file: rv141.skd Text file: rv141.txt At the VLBA/NRAO: VLBA Pointing files: rv141crd.br rv141crd.fd rv141crd.hn rv141crd.kp rv141crd.la rv141crd.mk rv141crd.nl rv141crd.ov rv141crd.pt rv141crd.sc Summary file: rv141.sksum Sked file: rv141.skd Text file: rv141.txt Vex file: rv141.vex This session uses the VLBA stations and 4 IVS stations. The IVS stations are: HARTRAO, NYALES20, ONSALA60 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 On=ONSALA60 Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Wz=WETTZELL Br Fd Hh Hn Kp La Mk Nl Ny On Ov Pt Sc Wz Avg % obs. time: 54 59 59 62 58 59 48 59 65 71 56 59 61 70 60 % cal. time: 6 6 3 5 6 6 5 6 3 3 6 6 5 3 5 % slew time: 31 27 33 24 28 28 25 27 13 13 29 28 25 7 25 % idle time: 8 7 4 8 6 6 21 7 17 13 7 6 9 18 10 total # scans: 542 540 232 446 547 544 449 512 301 263 549 548 424 298 442 # scans/hour : 23 23 10 19 23 23 19 21 13 11 23 23 18 12 18 Avg scan (sec): 86 94 221 119 92 93 93 100 187 232 88 92 124 203 129 # 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 TB(M5): 3.00 3.25 3.28 3.41 3.21 3.24 2.67 3.29 3.61 3.90 3.09 3.24 3.36 3.87 3.31 # OF OBSERVATIONS BY BASELINE | Br Fd Hh Hn Kp La Mk Nl Ny On Ov Pt Sc Wz Total -------------------------------------------------------------------------------- Br| 386 14 298 403 414 367 390 115 32 460 408 241 44 3572 Fd| 23 299 502 511 329 414 78 26 431 522 305 37 3863 Hh| 74 14 21 0 36 143 212 6 19 84 209 855 Hn| 273 305 165 378 146 87 248 298 356 99 3026 Kp| 492 371 390 70 17 473 505 278 28 3816 La| 330 427 90 29 441 530 305 42 3937 Mk| 253 61 10 419 337 163 18 2823 Nl| 116 44 365 417 341 56 3627 Ny| 173 78 86 114 193 1463 On| 17 25 82 230 984 Ov| 451 241 26 3656 Pt| 301 40 3939 Sc| 107 2918 Wz| 1129 Number of 2-station scans: 0 Number of 3-station scans: 248 Number of 4-station scans: 154 Number of 5-station scans: 60 Number of 6-station scans: 84 Number of 7-station scans: 96 Number of 8-station scans: 106 Number of 9-station scans: 77 Number of 10-station scans: 133 Number of 11-station scans: 33 Number of 12-station scans: 5 Number of 13-station scans: 5 Number of 14-station scans: 0 Total number of scans: 1001 Total number of obs: 19804 INTENSIVE BREAKS ================ WETTZELL will drop out from ~08:15-09:45 on DOY 189 to observe the one-hour UT1 Intensive session. And there will probably be a USNO/VLBA Intensive on DOY 190, in which case PIETOWN and MK-VLBA will drop out for ~100 minutes. SOURCE SELECTION ================ There are a total of 78 sources in this session; 60 are from the geodetic source list and 18 are sources with few or no previous observations in IVS sessions. 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 32 MHz sample rate 2-bit sampling This recording mode is a modified version of 256-8(RDV). There is no correlator speed-up factor. The frequency sequence covers 560 MHz at X-band and 160 MHz at S-band using 4 channels in each band. At the VLBA, the X-band uses two LO's in order to fit into 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 2372.75 19,21,23,25 3100 A 727.25| 2020.0 C1 352.75 13 8 S 2392.75 27,29,31,33 3100 A 707.25| 2020.0 C1 372.75 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 1N 285.75 3 2 X 8445.75 10,12,14,16 7600 B 845.75| 8080.0 1N 365.75 4 3 X 8805.75 18,20,22,24 9600 D 794.25| 8580.1 3N 225.65 5 4 X 8925.75 26,28,30,32 9600 D 674.25| 8580.1 3N 345.65 6 5 S 2232.75 3, 5, 7, 9 3100 A 867.25| 2020.0 2N 212.75 9 6 S 2262.75 11,13,15,17 3100 A 837.25| 2020.0 2N 242.75 10 7 S 2372.75 19,21,23,25 3100 A 727.25| 2020.0 2N 352.75 13 8 S 2392.75 27,29,31,33 3100 A 707.25| 2020.0 2N 372.75 14 VLBA | ONSALA60, WETTZELL 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 2372.75 19,21,23,25 3100 A 727.25| 2020.0 D1 352.75 13 8 S 2392.75 27,29,31,33 3100 A 707.25| 2020.0 D1 372.75 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. ONSALA60: 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 1. BBCs 9 & 10 are used for S-band with IF C, input 1. BBCs 13 & 14 are used at S-band with IF D, input 1. 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 session: 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 session to the ivs-ops mail list (ivs-ops@lists.nasa.gov). 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 session, send a "finish" message summarizing how the session 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 ivsopar.obspm.fr/ivsincoming ftp ivs.bkg.bund.de/ivsincoming Correlation =========== This session will be correlated at the NRAO/VLBA on the VLBA DiFX software correlator. The VLBA correlator can now only read Mark6 modules. The Mark4 stations will need to E-transfer their data to Haystack, where it will be copied onto a Mark6 module 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 this session 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.