RDV20 (Astrometric/Geodetic VLBA-19) 2000 March 13 Notes prepared by Nancy Vandenberg, NVI/GSFC Schedule name: rdv20.skd Pointing files: rdv20crd.br, rdv20crd.fd, rdv20crd.hn, rdv20crd.kp, rdv20crd.la, rdv20crd.mk, rdv20crd.nl, rdv20crd.ov, rdv20crd.pt, rdv20crd.sc ftp://aspen.nrao.edu/home/aspen6/astronomy/mar00/rdv20 PCFS file: vlbigeo@cddisa.gsfc.nasa.gov/vlbigeo/mar00/rdv20.skd http://lupus.gsfc.nasa.gov/sess/1999/sesshtml/rdv20.html Nominal Start: 14:00 U.T. on March 13 (day 073) first observation at 13:30 U.T. on 1803+784 for Br-Fd-Gc-Hn- Kp-La-Nl-Ov-Pt-Sc-Wf first observation at 14:00 U.T. on 0454-234 for Hh-Ts first observation at 14:00 U.T. on 1739+522 for Kk-Ma-Mc-Mk- Ny-On-Wz Duration: 24 hours + 1 hour extra for Gc-Wf-Br-Fd-Hn-Kp-La-Nl-Ov-Pt-Sc Nominal Stop: 14:00 U.T. on March 14 (day 074) last observation at 13:51 U.T. on 1611_343 for Ts last observation at 13:53 U.T. on 1451-375 for Kk-Mk last observation at 13:53 U.T. on 0235+164 for Hh-Ma-Mc-Ny-On-Wz last observation at 14:21 U.T. on NRAO512 for Br-Fd-Gc-Hn-Kp-La Nl-Ov-Pt-Sc-Wf Correlator: VLBA at Socorro Summary file for correlator: rdv20.sksum on aspen Stations: 20 # of tapes : 2.3 2.3 2.2 2.1 2.3 2.2 2.3 2.3 2.1 2.1 2.2 2.3 2.1 2.1 2.3 2.3 2.3 2.1 2.2 1.9 total # scans: 309 328 274 140 288 304 323 332 213 223 301 315 234 200 304 329 281 265 284 203 272 Station Codes # of tapes # of obs Occupation Code Brewster B Br 2.3 (TT) 309 76149901 Fort Davis D Fd 2.3 (TT) 328 76139801 Gilcreek A Al 2.2 (TT) 274 40476601 HartRAO J Hh 2.1 (TT) 140 72326201 Hancock H Hn 2.3 (TT) 288 76185001 Kokee K Kk 2.2 (TT) 304 72983001 Kitt Peak L Kp 2.3 (TT) 323 76109401 Los Alamos M La 2.3 (TT) 332 76119601 Medicina C Mc 2.1 (TT) 213 72308801 Matera I Ma 2.1 (TT) 223 72435701 Mauna Kea N Mk 2.2 (TT) 301 76175501 North Liberty O Nl 2.3 (TT) 315 76129701 Ny Alesund Q Ny 2.1 (TT) 234 73313301 Onsala T On 2.1 (TT) 200 72137701 Owens Valley R Ov 2.3 (TT) 304 76165401 Pie Town S Pt 2.3 (TT) 329 72348601 St. Croix E Sc 2.3 (TT) 281 76159001 Tsukuba U Ts 2.1 (TT) 265 73452301 Westford F Wf 2.2 (TT) 284 72097301 Wettzell V Wz 1.9 (TT) 203 72247801 Special notes for this session: - The VLBA stations will use automatic tape allocation and automatic tape reversal. - Most VLBA stations record two initial fringe finding scans along with geodetic stations Fairbanks and Westford. These stations also record two final long (5-10 minutes) scans. - Green Bank and GGAO will not participate in this session. - Wettzell will record four passes and then stop to do the intensive schedule i00073. They rejoin the schedule at about 19:15 after completion of the Intensive session. - Slewing models for Tsukuba, and Matera were updated to add a few seconds constant to each slew. These changes were made based on an analysis by the stations of the timing in their log files. The slewing model for Ny Alesund will be updated for the next schedule (RDV21). Purpose ======= This is the next of six bi-monthly coordinated astrometric/geodetic experiments in 2000 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 will perform repeated 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 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 small numbers of sources. While the quality of these results will be high, the observing and data reduction overhead required will be minimal because 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 out of the pool of ~400 Northern Hemisphere ICRF 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. Schedule ======== This is a new schedule generated by Nancy Vandenberg using sked. "Requested" Sources in RDV20 : none Yearly (Y), ROTATING & NEW (N) SOURCES FOR RD-V20 0138-097 0159+723 0259+121 0405-385 0507+179 N 0511-220 0615-365 0648-165 0754+100 0859-140 Y 0953+254 1021-006 1127-145 1215+303 1308+328 Y 1351-018 1409+218 1555+001 1655+077 1758+388 1936-155 2021+317 2233-148 N 2245-328 With this session we continue rotating through the large list of candidate ICRF sources. The method was as follows: - Remove sources from the core list of 80 sources used last year. - Add up to 20 sources from the list of candidates that already have some NEOS or VLBA data available (rotating sources). - Add 2 sources from the list of candidates that have never been observed with the VLBA (new sources). The same criteria were used for generating this schedule as were used during the first year of these sessions. The criteria for sources to be mapped are a minimum of 3 scans and 135 observations. These criteria are relaxed for sources below -25 degrees declination. Most of the sources in this schedule meet the mapping criteria. The schedule was made using a combination of automatic selection plus manual scheduling to improve the coverage of the sources. Automatically scheduled scans were selected first on their improvement of sky coverage in the previous 1 hour, and then the best 60% were evaluated for the minor options: minimize idle time, minimize slewing time, and maximize the number of observations. An individual source was not observed more often than every 90 minutes. An early start of 30 seconds was used for the first scan on a tape pass. The minimum scan length was 40 seconds. Recording Mode and Frequencies: same as previous experiment RDV19 ================================================================= The data will be recorded using the following setup: 8 channels 1:4 fan-out 16 MHz sample rate 1-bit sampling This recording mode is designated 128-8-1. The correlator speed-up factor is 2. The frequency sequence covers 490 MHz in 8 channels. 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 are available when observing with the VLBA stations, a wider spanned bandwidth is not advisable. With the 1:4 fanout at 16 MHz sample rate, all 32 tracks are recorded in one pass, so there will be 14 passes on a tape. These tables list the setup for the VLBA stations, the geodetic stations with VLBA back ends, and the geodetic stations with Mark IV back ends. These are the SAME frequencies used in all the standard RDV sessions. Geodetic stations: please read the special procedures in the next section! VLBA | Fairbanks | Kokee, NRAO20 Chan Sky Tracks LO IF BBC | LO IF BBC #| LO IF BBC # 1 X 8405.99 2, 4, 6, 8 7900 B 505.99| 7600.1 A 805.89 3| 7600 A 805.99 3 2 X 8475.99 10,12,14,16 7900 B 575.99| 7600.1 A 875.89 4| 7600 A 875.99 4 3 X 8790.99 18,20,22,24 7900 B 890.99| 8080.0 C 710.99 5| 8100 C 690.99 5 4 X 8895.99 26,28,30,32 7900 B 995.99| 8080.0 C 815.99 6| 8100 C 795.99 6 5 S 2220.99 3, 5, 7, 9 2900 A 679.01| 1540.1 B 680.89 9| 1500 B 720.99 9 6 S 2240.99 11,13,15,17 2900 A 659.01| 1540.1 B 700.89 10| 1500 B 740.99 10 7 S 2330.99 19,21,23,25 2900 A 569.01| 1540.1 B 790.89 13| 1500 B 830.99 13 8 S 2360.99 27,29,31,33 2900 A 539.01| 1540.1 B 820.89 14| 1500 B 860.99 14 VLBA | Tsukuba Chan Sky Tracks LO IF BBC | LO IF BBC # 1 X 8405.99 2, 4, 6, 8 7900 B 505.99| 7680 A 725.99 3 2 X 8475.99 10,12,14,16 7900 B 575.99| 7680 A 795.99 4 3 X 8790.99 18,20,22,24 7900 B 890.99| 8080 A 710.99 5 4 X 8895.99 26,28,30,32 7900 B 995.99| 8080 A 815.99 6 5 S 2220.99 3, 5, 7, 9 2900 A 679.01| 1600 B 620.99 9 6 S 2240.99 11,13,15,17 2900 A 659.01| 1600 B 640.99 10 7 S 2330.99 19,21,23,25 2900 A 569.01| 1600 B 730.99 13 8 S 2360.99 27,29,31,33 2900 A 539.01| 1600 B 760.99 14 Onsala, Medicina, Wettzell, Matera VLBA | Westford, Ny Alesund, HartRAO 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 L 4 X 8895.99 26,28,30,32 7900 B 995.99| 8580.1 3 315.89 6 H 5 S 2220.99 3, 5, 7, 9 2900 A 679.01| 2020.0 2 200.99 9 L 6 S 2240.99 11,13,15,17 2900 A 659.01| 2020.0 2 220.99 10 L 7 S 2330.99 19,21,23,25 2900 A 569.01| 2020.0 2 310.99 13 H 8 S 2360.99 27,29,31,33 2900 A 539.01| 2020.0 2 340.99 14 H Procedures ========== With continuous tape motion, the tape starts moving and recording at the beginning of the first scan of a pass. The tape runs and records continuously thereafter to the end of the tape (EOT or BOT). A parity check is done after the tape reaches this point. The tape starts moving in the opposite direction at the early start time (30 seconds) before the next scan. There will be a variable length of time between tape passes. For the VLBA stations, there will normally be a long enough time gap between passes for playback. Special procedures for non-VLBA stations ======================================== The tape motion in this experiment is different from normal start&stop schedules. At the time the antenna gets on source, you should see the command "data_valid=on" from the SNAP schedule. This is the signal that the VLBA correlator will use to determine when to start correlating this scan. At the time the antenna begins slewing to the next source, you will see the command "data_valid=off" from the schedule. This is the signal the correlator will use to stop correlating that scan. There will be no "et" command at the end of a scan. The DRUDG listing has a column that lists the time that the tape will stop. Note the "Start Tape" and "Stop Tape" columns list times only when the tape will start or stop, otherwise the time is blanked out because the tape is moving. For each scan, the "Start Data" column will be the time when the antenna is expected to be on source. The "Stop Data" column is the time when the antenna starts slewing to the next source. After the setup procedure, the tape is started at the beginning of each pass and will continue to move, at record speed, until it reaches the end of the pass. There are no fast tape motions in this schedule. The tape is continuously recording from the initial "st" command at the start of the pass. There are no other "st" commands during a pass and there are no other setup procedures called. If you have to re-start the schedule for a problem or emergency, you will be able to do it either 1) at the beginning of a pass or 2) in the middle of a pass by entering the setup and start tape commands manually. The problem is that the heads cannot be positioned reliably when the tape is moving if there is recorded data on the tape. If the tape is moving the reproduce power level can cause cross-talk with the head positioner and give false indications of position. Another problem is that the data disappears on tape while the formatter resets itself, thus largely eiliminating the benefits of continuous motion. At the end of each pass a parity check is done. You will need procedures named "checkf80" and "checkr80". Check and adjust the timing of this procedure and then make sure it can complete in the 100 seconds that the schedule allows. Special procedures for Onsala, Medicina, Westford, Ny Alesund, Wettzell, HartRAO, Tsukuba, Matera ================================================================== These stations have Mark IV formatters. Use the procedures generated by DRUDG. These should be the same as the ones used in previous RDV sessions, starting with RDV13. This is a non-standard setup. There are 8 video converters used: 3, 4, 5, 6, 9, 10, 13, and 14. These were selected so that you will NOT have to change the standard geodetic IF patching. The 6 unused VCs 1, 2, 7, 8, 11, and 12 should be set to frequencies which do not occur in any of the passbands. Any value in the 100-200 MHz range is OK. The Mark IV formatters currently have no barrel roll capability, so please verify that your FORM command has no specification for barrel roll. The IF3 command in the procedure IFDSX assumes that VC3 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. If you have questions about the wiring, please contact Brian Corey at Haystack. Special procedures for Fairbanks, Kokee ======================================= These stations have VLBA back ends. Use the procedures generated by DRUDG. BBCs 3,4,5,6 are used at X-band with IFs A and C. BBCs 9,10,13,14 are used at S-band with IF B. The unused BBCs 1,2,7,8,11,12 should be set to frequencies which do not occur in any of the passbands. Any value in the range 500-600 MHz is OK. The formatter should be set up to use barrel roll. Please verify that you are using the same barrel roll as you used in previous sessions correlated at the VLBA. 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 last session. Check out parity check procedures. 2. Make .snp file and listings using DRUDG options 3 and 5. 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. 8. Transfer your log files to your normal log file data center. The directories for three possible servers are listed below: directory on cddisa: mar00 directory on vlbeer: mar00 directory on aspen: /home/aspen6/astronomy/mar00/rdv20 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 Correlator. Tapes should be shipped to Socorro as soon after the experiment as practical. Summary ======= The following listing is a summary of the observations in this schedule. SKED Summary from file ../schedules/rdv20.skd for experiment RDV20 (all scans with at least one subnet station) Average number of obs. per baseline per source (normalized by up-time) = 3.4 Min = .0 Max = 36.0 (Baseline Gc-Kk on 0859-140) RMS = 3.6 Total time: 1486 minutes ( 24.8 hours). Key: Br=BR-VLBA Fd=FD-VLBA Gc=GILCREEK Hh=HARTRAO Hn=HN-VLBA Kk=KOKEE Kp=KP-VLBA La=LA-VLBA Ma=MATERA Mc=MEDICINA Mk=MK-VLBA Nl=NL-VLBA Ny=NYALES20 On=ONSALA60 Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Ts=TSUKUB32 Wf=WESTFORD Wz=WETTZELL Br Fd Gc Hh Hn Kk Kp La Ma Mc Mk Nl Ny On Ov Pt Sc Ts Wf Wz Avg % obs. time: 55 53 58 23 56 55 52 51 53 40 48 51 53 53 55 54 51 43 62 55 51 % cal. time: 3 3 3 1 3 3 3 3 2 2 3 3 2 2 3 3 3 2 3 2 3 % slew time: 26 27 18 32 25 14 26 28 14 30 23 26 13 16 24 27 24 11 14 7 21 % idle time: 14 16 19 42 14 26 16 16 30 26 24 18 30 28 16 14 20 41 19 34 23 # of tapes : 2.3 2.3 2.2 2.1 2.3 2.2 2.3 2.3 2.1 2.1 2.2 2.3 2.1 2.1 2.3 2.3 2.3 2.1 2.2 1.9 total # scans: 309 328 274 140 288 304 323 332 213 223 301 315 234 200 304 329 281 265 284 203 272 # scans/hour : 12 13 11 5 11 12 13 13 8 9 12 12 9 8 12 13 11 10 11 8 11.4 Avg scan (sec): 161 144 189 148 175 162 145 138 221 160 143 146 204 237 161 148 163 147 197 245 171 # OF OBSERVATIONS BY BASELINE | Br Fd Gc Hh Hn Kk Kp La Ma Mc Mk Nl Ny On Ov Pt Sc Ts Wf Wz StnTotal ---------------------------------------------------------------------------------------------- Br|309 295 253 22 255 231 296 305 131 152 239 289 198 155 293 301 227 162 247 145 4196 Fd| 328 241 34 270 227 311 321 132 153 236 306 190 153 293 321 252 150 263 144 4292 Gc| 274 17 215 205 243 250 132 152 209 240 207 155 240 247 184 177 208 142 3717 Hh| 140 46 0 23 34 94 77 0 37 39 59 13 33 60 38 50 66 742 Hn| 288 178 258 275 145 168 186 277 197 166 246 269 255 119 273 157 3955 Kk| 304 239 232 75 89 287 213 149 103 235 233 154 205 175 93 3323 Kp| 323 315 122 143 248 295 185 147 301 317 236 156 252 137 4224 La| 332 138 160 240 312 200 162 300 326 251 158 268 153 4400 Ma| 213 196 74 140 156 167 116 134 136 78 148 172 2486 Mc| 223 93 162 171 177 137 155 154 93 160 190 2782 Mk| 301 221 146 102 243 242 162 195 177 92 3392 Nl| 315 199 162 282 306 253 145 270 152 4261 Ny| 234 178 182 195 167 135 196 166 3256 On| 200 141 157 147 96 168 175 2770 Ov| 304 299 220 159 238 132 4070 Pt| 329 247 155 263 148 4348 Sc| 281 88 249 143 3585 Ts| 265 115 88 2512 Wf| 284 155 3875 Wz| 203 2650 Number of 2-station scans: 77 Number of 3-station scans: 51 Number of 4-station scans: 17 Number of 5-station scans: 18 Number of 6-station scans: 15 Number of 7-station scans: 8 Number of 8-station scans: 9 Number of 9-station scans: 24 Number of 10-station scans: 22 Number of 11-station scans: 23 Number of 12-station scans: 36 Number of 13-station scans: 33 Number of 14-station scans: 29 Number of 15-station scans: 29 Number of 16-station scans: 46 Number of 17-station scans: 29 Number of 18-station scans: 31 Number of 19-station scans: 31 Number of 20-station scans: 0 Total # of scans, observations: 528 34418 Average baseline components for all observations Average XY = 4537. Average XZ = 3660. Average YZ = 3289. Average length = 4876.