RV129 (Astrometric/Geodetic VLBA-129) 2018 APR 04 17:30 DOY 094 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. 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 being shifted up by 8 MHz from the last few RV's to try to avoid RFI in the third S-band channel (2352.75-2360.75 MHZ) at five VLBA stations. The S-band frquencies for this session will be: 2240.75, 2270.75, 2360.75 and 2380.75 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 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. SC-VLBA has been down since September due to hurricanes but is included in the schedule in case thay are able to observe. 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 1803+784 18094-173000| 308 342 328 300 342 320 336 300 305 300 341 340 321| 0544+273 18094-173656| 353 318 300 347 328 349 388 377 325 300 388| 0133+476 18095-171146| 300 300 300 300 300 323 300 350 350 304 300 348 304| 0544+273 18095-171845| 300 300 300 396 300 399 397 370 300 393 399| We are again using the new '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 increased from 48% to 61%, and the average idle time decreased from 23% 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 2018 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 experiments are being coordinated by the geodetic/astrometric VLBI programs of USNO, NASA, and the LBO. 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 and USNO will analyze this data to determine and maintain high accuracy terrestrial reference frame 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 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 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. Schedule file name: rv129.skd At the IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2018/rv129): Sked file: rv129.skd Text file: rv129.txt At the LBO/VLBA: VLBA Pointing files: rv129crd.br rv129crd.fd rv129crd.hn rv129crd.kp rv129crd.la rv129crd.mk rv129crd.nl rv129crd.ov rv129crd.pt rv129crd.sc Summary file: rv129.sksum Sked file: rv129.skd Text file: rv129.txt Vex file: rv129.vex This experiment uses the 10 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: 64 65 57 66 65 66 56 65 64 65 65 66 64 71 64 % cal. time: 5 5 3 4 5 5 4 5 3 3 5 5 4 3 4 % slew time: 23 22 31 21 23 22 20 23 13 13 21 23 20 8 21 % idle time: 7 6 8 8 6 5 19 6 19 18 8 5 11 17 11 total # scans: 420 424 218 376 450 428 358 415 289 263 430 440 350 285 367 # scans/hour : 18 18 9 16 19 18 15 17 12 11 18 18 15 12 15 Avg scan (sec): 131 133 225 152 125 134 135 136 190 212 130 130 159 216 157 # 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): 1.76 1.81 1.57 1.83 1.80 1.83 1.55 1.81 1.76 1.78 1.78 1.82 1.78 1.97 1.77 # OF OBSERVATIONS BY BASELINE | Br Fd Hh Hn Kp La Mk Nl Ny On Ov Pt Sc Wz Total -------------------------------------------------------------------------------- Br| 305 20 242 336 316 296 306 122 50 346 330 192 46 2907 Fd| 37 268 376 396 252 349 83 44 322 402 255 57 3146 Hh| 70 21 35 0 43 120 183 10 31 84 201 855 Hn| 240 282 161 309 131 84 221 270 290 108 2676 Kp| 371 309 321 81 43 392 395 225 42 3152 La| 246 370 86 47 332 413 261 57 3212 Mk| 217 65 17 325 267 142 18 2315 Nl| 109 66 297 357 271 73 3088 Ny| 154 80 87 92 178 1388 On| 34 42 83 209 1056 Ov| 348 198 32 2937 Pt| 250 53 3245 Sc| 110 2453 Wz| 1184 Number of 2-station scans: 1 Number of 3-station scans: 223 Number of 4-station scans: 130 Number of 5-station scans: 53 Number of 6-station scans: 63 Number of 7-station scans: 61 Number of 8-station scans: 72 Number of 9-station scans: 58 Number of 10-station scans: 121 Number of 11-station scans: 28 Number of 12-station scans: 17 Number of 13-station scans: 5 Number of 14-station scans: 0 Total number of scans: 832 Total number of obs: 16807 INTENSIVE BREAKS ================ There is an IVS INT01 Intensive session scheduled during RV129. Wettzell will drop out from ~18:15 - 19:45 on DOY 094 for this Intensive. There will also be a USNO/LBO UT1 Intensive session, scheduled to start at ~06:30 UTC (+/- 4 hrs) on DOY 095, using Pietown and MK-VLBA, so these stations will drop out for about 100 minutes. 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 82 sources scheduled in this session. Among them, 60 are from the geodetic monitoring list, and 22 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 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 2240.75 3, 5, 7, 9 3100 A 859.25| 2020.0 C1 220.75 9 6 S 2270.75 11,13,15,17 3100 A 829.25| 2020.0 C1 250.75 10 7 S 2360.75 19,21,23,25 3100 A 739.25| 2020.0 C1 340.75 13 8 S 2380.75 27,29,31,33 3100 A 719.25| 2020.0 C1 360.75 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 2240.75 3, 5, 7, 9 3100 A 859.25| 2020.0 2N 220.75 9 6 S 2270.75 11,13,15,17 3100 A 829.25| 2020.0 2N 250.75 10 7 S 2360.75 19,21,23,25 3100 A 739.25| 2020.0 2N 340.75 13 8 S 2380.75 27,29,31,33 3100 A 719.25| 2020.0 2N 360.75 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 2240.75 3, 5, 7, 9 3100 A 859.25| 2020.0 C1 220.75 9 6 S 2270.75 11,13,15,17 3100 A 829.25| 2020.0 C1 250.75 10 7 S 2360.75 19,21,23,25 3100 A 739.25| 2020.0 D1 340.75 13 8 S 2380.75 27,29,31,33 3100 A 719.25| 2020.0 D1 360.75 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 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.