************************************************************************ *** Non-VLBA stations must use the drudg in FS9.3.13 or later. **** *** Non-VLBA stations please read and use the checklist. **** ************************************************************************ RDV07 (Astrometric/geodetic VLBA-06) 1998 February 9 Notes prepared by Nancy Vandenberg, NVI/GSFC Schedule name: rdv07.skd Pointing files: rdv07crd.br, rdv07crd.fd, rdv07crd.hn, rdv07crd.kp, rdv07crd.la, rdv07crd.mk, rdv07crd.nl, rdv07crd.ov, rdv07crd.pt, rdv07crd.sc on aspen in directory dec97 PCFS files: rdv07.skd on cddisa in directory feb98 Nominal Start: 14:00 U.T. on February 9 (day 40) first observation at 13:30 U.T. on NRAO512 for Gg-Gc-Wf-Hn first observation at 14:00 U.T. on NRAO512 for Br-La-Nl-On-Sc first observation at 14:00 U.T. on 1739+522 for Fd-Kk- Kp-Mc-Mk-Ny-Ov-Pt first observation at 17:04 U.T. on 1741-038 for Gn Duration: 24 hours + 1 hour for Gc-Gg-Wf Nominal Stop: 14:00 U.T. on February 10 (day 41) last observation at 14:00 U.T. on 4C39.25 for Br-Fd-Kk- Kp-La-Mk-Nl-Ny-On-Ov-Pt last observation at 13:55 U.T. on 1300+580 for Mc-Sc last observation at 14:13 U.T. on 1739+522 for Gc-Wf-Gg-Hn Correlator: VLBA at Socorro Summary file for correlator: rdv07.sksum on aspen Stations: 18 Station Codes # of tapes # of obs Occupation Code Brewster B Br 2.6 (TT) 280 76149901 Fort Davis D Fd 2.7 (TT) 289 76139801 Gilcreek A Al 2.2 (TT) 259 40476601 Hancock H Hn 2.8 (TT) 269 76185001 Kokee K Kk 2.1 (TT) 256 72983001 Kitt Peak L Kp 2.7 (TT) 286 76109401 Los Alamos M La 2.7 (TT) 294 76119601 Medicina C Mc 2.1 (TT) 205 72308801 Mauna Kea N Mk 2.6 (TT) 257 76175501 North Liberty O Nl 2.6 (TT) 290 76129701 Green Bank 20m P Gn 1.9 (TT) 234 72484701 Ny Alesund Q Ny 2.2 (TT) 237 73313301 Onsala T On 2.2 (TT) 218 72137701 GGAO (MV3) Z Gg 3.1 (TT) 252 71085301 Owens Valley R Ov 2.7 (TT) 279 76165401 Pie Town S Pt 2.7 (TT) 294 72348601 St. Croix E Sc 2.8 (TT) 245 76159001 Westford F Wf 2.3 (TT) 270 72097301 Special Notes on tape usage: This experiment uses THIN TAPES ONLY at all stations. VLBA stations begin on pass 7 or 9 and then have a tape change during normal site working hours. Hancock records the MV3 fringe finding scans on passes 1 and 2, then starts the main experiment on pass 9. For Green Bank, there is a tape change around 11 p.m. local time and the schedule start is delayed until 17:00 UT after the Intensive session finishes. Purpose ======= This is the first of six bi-monthly coordinated astrometric/geodetic experiments in 1998 that use the full 10-station VLBA plus the 8 geodetic stations currently capable of recording in VLBA format. This year's series is a continuation of the highly successful series 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 Marshall Eubanks using the 9706 version of the NASA sked program which handles continuous tape motion. This will be the second session to have thin tapes at all the stations. With this session we start rotating through the large list of candidate ICRF sources. For this session, the method was as follows: 1) Remove 12 sources from the core list of 80 sources used last year. 2) Add 12 sources from the list of candidates that already have some NEOS or VLBA data available. 3) Add 2 sources from the list of candidates that have never been observed with the VLBA. It is hoped that up to 20 sources can be rotated into the schedule with each new session. 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 following sources were scheduled by request of NRAO users. assumed X-band Source #scans #obs flux (Jy) Comments 0942+358 2 121 .19 Request from H. van Langevelde (NfRA). 1330+476 3 310 .25 Request from L. Greenhill. 1628+216 1 15 .10 Request from H. van Langevelde (NfRA). 2251+158 3 311 7.00 The second priority Lebach request. (3C454.3) With the indicated fluxes, and with good a priori source positions, there should be no problem obtaining fringes on these sources. 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. Due to its low sensitivity, MV3 was not included directly into the schedule because the necessarily longer scan lengths would have compromised the experiment results. Instead, after the schedule was made, MV3 was tagged along to the schedule. In the tagalong mode, MV3 observes with the longest scan duration of all the stations participating in each scan, to maximize SNR. MV3 will make fringes on about 2/3 of the observations in which it participates. This amount of data will allow a good determination of MV3's position in the reference frame. Extra Part of Schedule ====================== Fairbanks, Westford, Hancock and MV3 will observe an extra 30 minutes at the start and end of the experiment. The purpose is to make long scans with MV3 to help the VLBA correlator find fringes very efficiently. There are two 500 or 600-sec scans at each end of the experiment, one on NRAO512 and one on 1739+522. Recording Mode and Frequencies: same as previous experiments ============================================================ The data will be recorded using 8 channels in VLBA format, 1:4 fan-out, 16 MHz sample rate, 1-bit sampling. This mode is designated 128-8-1. The correlator gets a speed-up factor of 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 the first two RDV0x sessions. Geodetic stations: please read the special procedures in the next section! VLBA | Fairbanks | Kokee, GB 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 B 805.89| 7600 B 805.99 2 X 8475.99 10,12,14,16 7900 B 575.99| 7600.1 B 875.89| 7600 B 875.99 3 X 8790.99 18,20,22,24 7900 B 890.99| 8080.0 C 710.99| 8100 C 690.99 4 X 8895.99 26,28,30,32 7900 B 995.99| 8080.0 C 815.99| 8100 C 795.99 5 S 2220.99 3, 5, 7, 9 2900 A 679.01| 1540.1 A 680.89| 1500 A 720.99 6 S 2240.99 11,13,15,17 2900 A 659.01| 1540.1 A 700.89| 1500 A 740.99 7 S 2330.99 19,21,23,25 2900 A 569.01| 1540.1 A 790.89| 1500 A 830.99 8 S 2360.99 27,29,31,33 2900 A 539.01| 1540.1 A 820.89| 1500 A 860.99 Onsala, Medicina, VLBA | Westford, MV3, Ny Alesund 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 will be different from normal start&stop schedules. Please read this section carefully so that you know what to expect. At the time the antenna gets on source, you should see the "Data start" comment from the SNAP schedule. This is the signal that the VLBA correlator will use to determine when to start correlating this scan. Please make notes in the log if your antenna is consistently late or early for the "Data start". We may need to adjust some antenna slewing parameters to correct the models in sked for the next schedule. At the time the antenna begins slewing to the next source, you will see the "Data stop" comment 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 an extra 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. At the end of each pass a parity check is done. You will need procedures named "check2m1, check2m2" or "check2v1, check2v2". If you have not already done so for the first two sessions, please create these procedures as a copy of "check2c1, check2c2" and change the tracks to be "v0,v1,v2,v3". Check and adjust the timing of this procedure and then make sure it can complete in the 70 seconds that the schedule allows. If it cannot be completed, you could check the odd tracks in one direction and the even tracks in the other. If you have any questions or problems with these parity procedures, please contact Nancy Vandenberg as soon as possible. There could be some times when the tape reaches the end of a pass and you should still be observing. This should not happen, but since this is the first time we are trying continuous recording, it might. Please note in the log when this occurs, if your station is manned at that time. Special procedures for Onsala, Medicina, Westford, MV3, Ny Alesund ================================================================== Onsala, Medicina, Westford, MV3, and Ny Alesund have Mark IV formatters. You can use the same procedures as for the previous RDV0x sessions. You can also have DRUDG generate the procedures. Please verify your procedures against this writeup. Remember 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, Green Bank =================================================== Fairbanks, Kokee, and Green Bank have VLBA back ends. You can use the same procedures generated for the previous sessions. You can also have DRUDG generate them for you. You must swap your IF inputs so that BBCs 1-8 have the inputs shown in the table above. The unused BBCs 9-14 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. Make and check out parity check procedures. 2. Make .snp file and listings using DRUDG options 3 or 31 and 5. 3. Set up your system to monitor the clocks with the "gps-fmout" or "fmout-gps" commands, per Ed Himwich's messages. If you have questions or problems, please contact Ed as soon as possible. 4. Send a "ready" message an hour or so before the experiment to the ops mail list. Copy Peggy Perley at the VLBA (pperley@nrao.edu) on the message. 5. Send a "start" message soon after you have started recording. Copy Peggy Perley on the message. 6. During the experiment, please continue noting any times when the antenna is not on source at the "Data start" times. Also note any times that the tape stops before the "et" command is issued at BOT or EOT. This information will be useful in checking out the antenna slewing models. 7. At the end of the experiment, send a "finish" message summarizing how the experiment was conducted. 8. *IMPORTANT* Transfer your log files BOTH to aspen.nrao.edu and to cddisa. Remember that you have to use different naming conventions! on cddisa: rdv07xx.log in directory "feb98" on aspen: rdv07log.xx in directory "feb98" 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 ./rdv07.skd for experiment RDV07 (all scans with at least one subnet station) SOURCE |0 6 12 18 | #SCANS #OBS #Obs/bl 0003-066I x x x xI 4 291 4.7 0014+813I x x x x x x x x x x xI 11 1338 8.7 0035+413I x x x x x x I 6 683 6.2 0048-097I x x x x I 4 268 4.3 0059+581I x xx x x x x x x x x x I 12 1156 8.5 0104-408I x I 1 45 2.6 0119+115Ix x x x x I 5 457 5.7 0119+041I x x I 2 119 1.6 0133+476I x x x x x x x x I 8 589 5.1 0201+113I x x x I 3 237 3.0 0202+149I x x x x I 4 328 3.9 0208-512I xx I 2 2 .1 0229+131I x x x xI 4 283 3.5 0234+285I x x x x x x I 6 571 6.0 NGC1052 I x x x I 3 170 3.2 0302+625I x x I 2 225 1.6 CTA26 I x x x I 3 161 2.4 0402-362I x x x I 3 17 .4 0405-385I xx I 2 24 .8 0409+229I x x x I 3 224 2.5 3C120 I x x x I 3 130 1.8 NRAO190 I x x x I 3 232 3.3 0444+634I x x x x x x x x x x x I 11 1443 10.1 0454-234I x x x x I 4 176 4.0 0458-020I x x x x I 4 165 2.7 0528+134I x x x x xI 5 409 5.0 0537-441I x x I 2 29 1.6 0552+398I x x x x x x xI 7 665 6.2 0642+449I x x xx xx x x x I 10 756 6.7 0727-115I xx x x x x I 6 208 3.5 0742+103Ix x x x x x x x I 8 514 6.6 0804+499I x x x x x x I 6 455 3.7 0823+033I x x x I 3 136 1.9 OJ287 I x x x x x x x I 7 526 6.0 0919-260I x x x I 3 77 1.9 0920-397I x x I 2 22 .9 4C39.25 I x x x xx x xI 8 691 6.5 0942+358I x x I 2 121 1.2 M81 I x x I 2 133 .9 0955+476I x x x x x x x x x I 9 752 6.3 1034-293I x xx I 3 137 3.8 1044+719I x x x x xx x x x x x x I 13 1359 9.2 1101+384I x x x I 3 175 1.6 1124-186I x x x I 3 248 5.2 1128+385I x x x x x x x I 7 471 4.5 1144-379I x x I 2 76 2.9 1145-071I x x x x I 4 328 5.4 1156+295I x x x I 3 282 3.0 3C274 I x x x x x x I 6 508 6.4 1300+580I x x I 2 141 1.0 1308+326I x x x x x x x I 7 476 4.9 1313-333I x x I 2 79 2.5 1330+476I x x x I 3 310 2.7 1334-127I x x x x x I 5 229 3.9 1357+769I x x x x x x I 6 698 4.6 OQ208 I x x x x I 4 265 2.9 1424-418I x x I 2 2 .1 1428+422I x x I 2 169 1.6 1451-375I x x x x x I 5 60 3.3 1459+480I x x x x xx x I 7 662 5.6 1502+106I x x x I 3 181 2.3 1514-241I x x x x I 4 192 4.4 1606+106I x x x x x x x x I 8 590 7.6 1611+343I x x x x I 4 301 3.0 1622-253I x x x x x x I 6 185 4.4 1628+216I x I 1 15 .2 NGC6251 I x x x x I 4 612 4.0 NRAO512 I x x x xx x x x x I 10 374 3.5 1739+522Ix x x xxx x x x x I 11 822 6.6 1741-038I xx x x x I 5 267 4.0 1745+624I x x x I 3 193 1.4 1749+096I x x x x x x I 6 497 6.4 1803+784I x x x x x x I 6 659 4.3 1815-553I xx I 3 3 .6 1842+681I x x x x x x x I 7 852 5.9 1908-201I x x x x I 4 210 4.5 1921-293I x x x I 3 100 2.7 1954-388I x x x I 3 67 2.6 2052-474I x x x I 3 17 1.3 2126-158I xx x I 3 149 2.9 2145+067I x x x x x x I 6 466 6.2 2150+173Ix x x x x I 5 496 5.8 2155-152I x x x x I 4 179 3.5 VR422201Ix x x x x x x x x x x I 11 872 7.9 2234+282I x x I 2 94 1.0 2243-123I x x x I 3 248 4.2 3C454.3 I x x x I 3 311 3.7 2255-282I x x x I 3 40 1.1 Total scans, obs: 416 30495 Average number of obs. per baseline per source (normalized by up-time) = 4.0 Min = .0 Max = 24.0 (Baseline Hn-Kp on 1451-375) RMS = 3.0 Total time: 1491 minutes ( 24.9 hours). Key: Br=BR-VLBA Fd=FD-VLBA Gc=GILCREEK Hn=HN-VLBA Kk=KOKEE Kp=KP-VLBA La=LA-VLBA Mc=MEDICINA Mk=MK-VLBA Nl=NL-VLBA Gn=NRAO20 Ny=NYALES20 On=ONSALA60 Gg=ORION_5M Ov=OV-VLBA Pt=PIETOWN Sc=SC-VLBA Wf=WESTFORD Br Fd Gc Hn Kk Kp La Mc Mk Nl Gn Ny On Gg Ov Pt Sc Wf Avg % obs. time: 55 56 62 56 57 53 52 32 49 51 51 59 61 69 55 55 48 70 55 % cal. time: 3 3 2 3 2 3 3 2 2 3 2 2 2 2 3 3 2 3 2 % slew time: 23 24 16 24 13 23 25 21 21 25 14 11 16 9 22 24 21 13 19 % idle time: 17 16 18 15 25 19 19 43 26 19 30 26 19 18 18 16 27 13 21 # of tapes : 2.6 2.7 2.2 2.8 2.1 2.7 2.7 2.1 2.6 2.6 1.9 2.2 2.2 2.1 2.7 2.7 2.8 2.3 total # scans: 280 289 259 269 256 286 294 205 257 290 234 237 218 252 279 294 245 270 261 # scans/hour : 11 11 10 10 10 11 11 8 10 11 9 9 8 10 11 11 9 10 10.9 Avg scan (sec): 176 173 215 189 200 166 160 143 171 159 198 224 253 246 177 168 177 232 190 # OF OBSERVATIONS BY BASELINE | Br Fd Gc Hn Kk Kp La Mc Mk Nl Gn Ny On Gg Ov Pt Sc Wf StnTotal -------------------------------------------------------------------------------------- Br|280 263 230 240 183 262 271 152 189 269 211 188 161 209 256 270 211 227 3514 Fd| 289 214 242 190 278 286 151 197 272 217 180 157 210 266 286 221 230 3370 Gc| 259 211 176 213 222 161 178 227 181 198 169 184 213 221 175 200 3622 Hn| 269 151 232 244 165 157 254 216 189 169 220 222 242 226 254 3616 Kk| 256 197 194 89 248 182 143 133 114 153 200 195 130 155 3585 Kp| 286 281 142 204 264 209 175 151 206 273 282 210 222 3551 La| 294 152 200 277 218 184 162 212 271 291 221 233 3417 Mc| 205 90 163 140 181 180 143 135 152 147 160 3180 Mk| 257 188 149 131 110 152 206 201 136 156 3630 Nl| 290 229 193 170 219 255 275 231 243 3225 Gn| 234 161 139 186 200 217 193 207 3335 Ny| 237 199 168 168 184 158 190 3546 On| 218 153 143 160 144 175 3020 Gg| 252 201 210 196 220 3548 Ov| 279 272 199 213 3164 Pt| 294 220 231 2895 Sc| 245 221 3466 Wf| 270 3306 Number of 2-station scans: 43 Number of 3-station scans: 16 Number of 4-station scans: 24 Number of 5-station scans: 12 Number of 6-station scans: 11 Number of 7-station scans: 14 Number of 8-station scans: 9 Number of 9-station scans: 14 Number of 10-station scans: 12 Number of 11-station scans: 21 Number of 12-station scans: 17 Number of 13-station scans: 19 Number of 14-station scans: 43 Number of 15-station scans: 37 Number of 16-station scans: 49 Number of 17-station scans: 31 Number of 18-station scans: 44 Total # of scans, observations: 416 30495 Average baseline components for all observations Average XY = 3801. Average XZ = 3250. Average YZ = 2521. Average length = 4070.