rdv49 (Astrometric/Geodetic VLBA-48) 2005 February 09 Notes prepared by John Gipson, NVI/GSFC Schedule name: rdv49.skd Pointing files: rdv49crd.br, rdv49crd.fd, rdv49crd.hn, rdv49crd.kp, rdv49crd.la, rdv49crd.mk, rdv49crd.nl, rdv49crd.ov, rdv49crd.pt, rdv49crd.sc ftp://vlbiobs@aspen.nrao.edu/home/aspen6/astronomy/feb05/rdv49 Summary file for correlator: rdv49.sksum on aspen PCFS file: ftp://vlbigeo@cddisa.gsfc.nasa.gov/vlbigeo/feb05/rdv49.skd http://lupus.gsfc.nasa.gov/sess/2004/sesshtml/rdv49.html First observations: Source Start Stations name yyddd-hhmmss 0727-115 05040-180000| Hh On 1741-038 05040-180000| Ap Br Fd Gc Hn Kp La Mk Nl Gg Ov Pt Sc Ts Wf 0736+017 05040-195821| Wz Last observations: name yyddd-hhmmss 0454-234 05041-175841| Hh On Wz 1741-038 05041-175850| Sc 1611+343 05041-180616| Ap Br Fd Gc Hn Kp La Mk Nl Gg Ov Pt Ts Wf Correlator: VLBA at Socorro Key: Ap=ALGOPARK BR=BR-VLBA Fd=FD-VLBA Gc=GILCREEK Gg=GGAO Hh=HARTRAO Hn=HN-VLBA Kp=KP-VLBA La=LA-VLBA Mk=MK-VLBA Nl=NL-VLBA On=ONSALA60 Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Ts=TSUKUB32 Wf=WESTFORD Wz=WETTZELL Ap Br Fd Gc Hh Hn Kp La Mk Nl % obs. time: 30 69 68 63 50 69 68 69 60 69 % cal. time: 2 3 3 3 1 3 3 3 3 3 % slew time: 55 22 22 18 34 19 23 22 23 21 % idle time: 10 4 6 14 12 7 4 4 13 5 total # scans: 258 304 293 273 162 282 305 300 287 294 # scans/hour : 10.7 12.6 12.1 11.3 6.7 11.7 12.6 12.4 11.9 12.2 Avg scan (sec): 103 198 202 203 272 216 196 202 183 205 Total GBytes: 496 1084 1068 1015 811 1097 1080 1095 948 1085 Total GB(M5): 441 964 950 903 721 975 960 973 843 964 # of tapes : 2.2 2.4 2.4 2.6 2.2 2.4 2.4 2.4 2.4 2.4 tape change times (hhmm): 0512 0419 0419 0322 0459 0419 0419 0419 0443 0419 1620 1441 1441 1245 1555 1441 1425 1441 1427 1441 On Gg Ov Pt Sc Ts Wf Wz Avg % obs. time: 66 73 67 69 66 52 73 58 63 % cal. time: 2 2 3 3 3 3 2 2 3 % slew time: 14 7 22 23 19 14 11 8 21 % idle time: 17 16 6 3 11 29 12 30 11 total # scans: 197 257 296 315 264 297 228 217 268 # scans/hour : 8.1 10.6 12.2 13.0 10.9 12.3 9.4 9.0 11.1 Avg scan (sec): 291 248 198 191 219 152 281 232 210 Total GBytes: 1052 1168 1060 1087 1041 831 1170 924 1007 Total GB(M5): 935 1038 942 966 925 739 1040 822 895 # of tapes : 2.2 2.2 2.4 2.4 2.4 2.2 2.2 2.1 tape change times 0454 0456 0419 0419 0427 0518 0456 0649 1555 1558 1425 1425 1441 1622 1558 1751 Number of 2-station scans: 261 Number of 3-station scans: 145 Number of 4-station scans: 71 Number of 5-station scans: 45 Number of 6-station scans: 42 Number of 7-station scans: 36 Number of 8-station scans: 23 Number of 9-station scans: 42 Number of 10-station scans: 37 Number of 11-station scans: 33 Number of 12-station scans: 22 Number of 13-station scans: 38 Number of 14-station scans: 29 Number of 15-station scans: 17 Number of 16-station scans: 8 Number of 17-station scans: 1 Number of 18-station scans: 0 Total # of scans, observations: 850 18530 Special Notes for this session: - Most stations participate in two initial long (5-min) scans and two final 5-min scans. - Wettzell is tagged along in this session. It is undergoing maintainence and it is uncertain if this will be completed in time. - NEW in rdv46. We have used a new algorithm for selecting the sources. - NEW in RDV34: The stations with Mk4 formatters, and with updated formatter firmware, will use barrel roll. - The fluxes used our most current models. If we did not have models for the fluxes we used those determined by Alan Fey (USNO). - NEW since RDV31: The phase cal tones detected at VLBA stations will be 10 kHz and 5010 kHz. In previous sessions the higher tone was 7010 kHz. - NEW since RDV35: This session has a NEWER S-BAND FREQUENCY SEQUENCE that avoids the direct broadcast satellite band of 2320-2345 MHz. We use the same frequency sequence as in RDV35, but shifted up 7 MHz to get further away from the satellite broadcast band. Purpose ======= This is the 1st of six bi-monthly coordinated astrometric/geodetic experiments in 2005 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. In addition to the VLBA, the session also uses ALGOPARK, GILCREEK, ONSALA60, GGAO7108, TSUKUB32, WESTFORD and WETTZELL. TIGO and NOT were originally scheduled to participate in this session but could not because of hardware issues. SOURCE SELECTION There are a total of 95 sources in this session. The following 8 sources were included by special request. 2250+194 $ 22 53 07.369160 19 42 34.628907 2000.0 0.0 Lebach new in RDV36 0403-179 J0406-174 04 06 12.244524 -17 49 57.92704 2000.0 0.0 CIMO 1034-293 J1037-293 10 37 16.079728 -29 34 02.81329 2000.0 0.0 CIMO 1144-379 J1147-381 11 47 01.370695 -38 12 11.02341 2000.0 0.0 CIMO 1257-326 J1300-325 13 00 42.425937 -32 53 12.11020 2000.0 0.0 CIMO 1519-273 J1522-273 15 22 37.675984 -27 30 10.78545 2000.0 0.0 CIMO 1622-253 J1625-252 16 25 46.891639 -25 27 38.32685 2000.0 0.0 CIMO 1622-297 J1626-295 16 26 06.020843 -29 51 26.97118 2000.0 0.0 CIMO In addition we looked at a set of 300 sources, and chose 40 from these that had not been scheduled in at least 2 RDVs over the last year. These 40 were chosen to be widely distributed over the sky. The schedule was generated so that the target number of observations on the first 48 sources was between 1% and 1.5% of the total number of observations. This corresponds to about 120-180 observations. We also chose an additional 47 sources from a catalog of "geodetic quality sources" using the BEST-N algorithm. This algorithm looks at the sources already in the schedule, and tries to choose additional strong sources that complement the sky coverage. 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. Because of mutual visibility constraints, Hartrao has fewer observations than the other stations. To maximize the number of observations involving Hartrao, scans involving this station were prefered. 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 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. Special note for sessions starting with RDV36: The S-band frequency sequence was increased by 7 MHz from RDV35. This was done to put the third S-band channel 7 MHz above the DARS band (2220-2245Mz.) 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 ======================================== 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 rdv49 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: feb05 directory on vlbeer: feb05 directory on aspen: /home/aspen6/astronomy/feb05/rdv49 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.