rdv56 (Astrometric/Geodetic VLBA-55) 2006 April 25 Notes prepared by John Gipson, NVI/GSFC Schedule name: rdv56.skd Pointing files: rdv56crd.br, rdv56crd.fd, rdv56crd.hn, rdv56crd.kp, rdv56crd.la, rdv56crd.mk, rdv56crd.nl, rdv56crd.ov, rdv56crd.pt, rdv56crd.sc ftp://vlbiobs@aspen.nrao.edu/home/aspen6/astronomy/apr06/rdv56 Summary file for correlator: rdv56.sksum on aspen PCFS file: ftp://vlbigeo@cddisa.gsfc.nasa.gov/vlbigeo/apr06/rdv56.skd http://lupus.gsfc.nasa.gov/sess/2006/sesshtml/rdv56.html The following stations participate in this session. Key: Br=BR-VLBA Fd=FD-VLBA Hh=HARTRAO Hn=HN-VLBA Kb=KASHIM34 Kp=KP-VLBA La=LA-VLBA Ma=MATERA Mk=MK-VLBA Nl=NL-VLBA On=ONSALA60 Gg=ORION_5M Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Tc=TIGO Wf=WESTFORD Wz=WETTZELL Zc=ZELENCHK First observations: name yyddd-hhmmss Br Fd Hh Hn Kb Kp La Ma Mk Nl 0642+449 06115-173000| 300 300 300 300 300 300 300 300 1749+096 06115-173000| 300 300 0135-247 06115-173708| 300 300 300 300 300 300 300 3C274 06115-173904| 300 name yyddd-hhmmss On Gg Ov Pt Sc Tc Wf Wz Zc 0642+449 06115-173000| 300 300 300 300 300 300 300| 1749+096 06115-173000| | 0135-247 06115-173708| 300 300 300 300 300 300 | 3C274 06115-173904| 300 300 300| ----------------------------------------------------------------------- Last Observations: name yyddd-hhmmss Br Fd Hh Hn Kb Kp La Ma Mk Nl 0420-014 06116-171442| 300 300 300 300 300 300 0059+581 06116-171903| 300 300 CTA26 06116-172017| 509 280 315 316 347 OJ287 06116-172654| 300 300 300 0805+410 06116-172717| 300 300 300 name yyddd-hhmmss On Gg Ov Pt Sc Tc Wf Wz Zc 0420-014 06116-171442| 300 300 300 300 300 | 0059+581 06116-171903| 300 300| CTA26 06116-172017| 386 318 509 | OJ287 06116-172654| 300 300 300 300 300 300| 0805+410 06116-172717| 300 | ----------------------------------------------------------------- SUMMARY OF OBSERVATIONS Key: Br=BR-VLBA Fd=FD-VLBA Hh=HARTRAO Hn=HN-VLBA Ho=HOBART26 Kk=KOKEE Kp=KP-VLBA La=LA-VLBA Ma=MATERA Mc=MEDICINA Mk=MK-VLBA Nl=NL-VLBA Gg=ORION_5M Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Tc=TIGO Wf=WESTFORD Wz=WETTZELL Br Fd Hh Hn Kb Kp La Ma Mk Nl % obs. time: 71 70 58 72 51 71 72 80 63 72 % cal. time: 3 4 2 3 2 4 4 2 3 3 % slew time: 21 20 25 19 24 21 20 15 16 20 % idle time: 3 5 15 5 22 3 3 3 17 4 total # scans: 293 303 133 275 212 313 306 183 246 292 # scans/hour : 12.2 12.6 5.5 11.4 8.8 13.0 12.7 7.6 10.2 12.2 Avg scan (sec): 210 201 378 225 210 197 205 376 223 213 Total GBytes: 1110 1097 920 1117 802 1108 1130 1240 988 1122 Total GB(M5): 987 975 818 993 713 985 1004 1102 878 997 # of tapes : 2.4 2.4 2.1 2.4 .1 2.4 2.4 .1 2.4 2.4 tape change times (hhmm): 0346 0346 0443 0355 0000 0346 0346 0000 0346 0346 1355 1355 1611 1355 0000 1355 1355 0000 1357 1355 On Gg Ov Pt Sc Tc Wf Wz Zc Avg % obs. time: 85 67 68 72 74 54 87 78 57 70 % cal. time: 2 3 4 4 3 1 2 2 3 3 % slew time: 11 6 21 21 16 3 9 6 33 18 % idle time: 1 23 6 3 6 40 1 12 6 10 total # scans: 172 225 316 315 236 94 209 195 224 239 # scans/hour : 7.2 9.4 13.1 13.1 9.8 3.9 8.7 8.1 9.3 9.9 Avg scan (sec): 429 258 186 197 270 501 359 347 221 273 Total GBytes: 1328 1062 1058 1118 1149 863 1352 1217 891 1088 Total GB(M5): 1180 944 940 994 1022 767 1202 1082 792 967 # of tapes : .1 2.1 2.4 2.4 2.4 2.0 .1 .1 .1 tape change time 0000 0457 0346 0346 0346 0558 0000 0000 0000 0000 1630 1355 1355 1355 0000 0000 0000 0000 Special Notes for this session: - IMPORTANT. In this RDV 6 non-VLBA stations will record on Mark5. These stations are: Kashima, Matera, Onsala, Westford, Wettzell, Zelenchk For these stations we will make the snap files at GSFC. These will be placed on cddisa and should be picked up the stations. This is necessary because the version of the field system in use at the stations does not do the right thing with RDV schedules. - IMPORTANT: The synch time for the VLBA correlator using Mark5 is 25 seconds. Because of this, stations recording with Mark5 disks will start taking data 25 seconds prior to the normal scan time. They will continue to take data between scans if the there is the gap is less than 25 seconds. - Most stations participate in two initial long (5-min) scans and a final 5-min scans. - GGAO was tagged along in the schedule - Wettzell is absent from 18:20 to 19:40 because of the intensive. - The fluxes use our most recent models. Purpose ======= This is the 2nd of six bi-monthly coordinated astrometric/geodetic experiments in 2006 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 John Gipson using sked. SOURCE SELECTION There are a total of 100 sources in this session. Requested sources: D. Lebach requested 1 source: 2250+194 Lebach. This has been observed regularly in the RDVs since RDV36. This will be observed in a few more RDVS. Monitored sources. 29 sources were selected which had not been recently observed. Other sources. 70 sources were selected from the geodetic catalog to complement the sky distribution. SCHEDULING ALGORITHMS This schedule also uses the "SRCEVN SQRT" mode. In the absense 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. In this schedule observations involving Hobart, Hartrao and Tigo were given preference in scheduling. GGAO was tagged along after the schedule was generated. The VLBA stations routinely use automatic tape allocation and automatic tape reversal. Recording Mode and Frequencies: same as previous experiments ============================================================ 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 500 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 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 2232.99 3, 5, 7, 9 2900 A 667.01| 1540.1 B 692.89 9|1500 B 732.99 9 6 S 2262.99 11,13,15,17 2900 A 637.01| 1540.1 B 722.89 10|1500 B 762.99 10 7 S 2352.99 19,21,23,25 2900 A 547.01| 1540.1 B 812.89 13|1500 B 852.99 13 8 S 2372.99 27,29,31,33 2900 A 527.01| 1540.1 B 832.89 14|1500 B 872.99 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 2232.99 3, 5, 7, 9 2900 A 667.01| 1600 B 632.99 9 6 S 2262.99 11,13,15,17 2900 A 637.01| 1600 B 662.99 10 7 S 2352.99 19,21,23,25 2900 A 547.01| 1600 B 752.99 13 8 S 2372.99 27,29,31,33 2900 A 527.01| 1600 B 772.99 14 Medicina, Wettzell, Matera, GGAO, TIGO VLBA | Westford, NOTO, HartRAO, Onsala 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 2232.99 3, 5, 7, 9 2900 A 667.01| 2020.0 2 212.99 9 H 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 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 ======================================== SEE THE NOTE AT THE START ABOUT MARK5 recording. 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 Medicina, Westford, Onsala, Wettzell, Tsukuba, Matera, GGAO, TIGO ================================================================== These stations have Mark IV formatters. Use the procedures generated by DRUDG. These must be generated for rdv54 because of the new S-band frequency sequence. Note that the patching for VC10 must be changed from L to H for this session. 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 now have barrel roll capability, so please verify that your FORM command has 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 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: apr06 directory on vlbeer: apr06 directory on aspen: /home/aspen6/astronomy/apr06/rdv56 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.