************************************************************************ ******* Non-VLBA stations must use the drudg in FS9.3.13 ******** ************************************************************************ RDV05 (Astrometric/geodetic VLBA-04) 1997 September 8 Notes prepared by Nancy Vandenberg, NVI/GSFC Schedule name: rdv05.skd Pointing files: rdv05crd.br, rdv05crd.fd, rdv05crd.hn, rdv05crd.kp, rdv05crd.la, rdv05crd.mk, rdv05crd.nl, rdv05crd.ov, rdv05crd.pt, rdv05crd.sc on aspen in directory sep97 PCFS files: rdv05.skd on cddisa in directory sep97 Nominal Start: 14:00 U.T. on September 8 (day 251) first observation at 13:30 U.T. on 0552+528 for Gg-Gc-Wf first observation at 14:00 U.T. on NRAO512 for Br-Hn-Mc Gn-On-La-Nl-Sc first observation at 14:00 U.T. on 0552+528 for Kk-Kp- Mk-Ov-Pt-Fd Duration: 24 hours + 1 hour for Gc-Gg-Wf Nominal Stop: 14:00 U.T. on September 8 (day 252) last observation at 13:46 U.T. on 0133+476 for Gn last observation at 13:49 U.T. on 1741-038 for Mc-On last observation at 13:58 U.T. on CTA26 for Br-Fd-Hn- La-Mk-Nl-Ov-Pt-Sc-Kp-Kk last observation at 14:16 U.T. on 4C39.25 for Gg-Gc-Wf Correlator: VLBA Summary file for correlator: RDV05.sksum on aspen Stations: 17 Station Codes # of tapes # of obs Occupation Code Brewster B Br 2.6 (TT) 322 76149901 Fort Davis D Fd 2.6 (TT) 328 76139801 Gilcreek A Al 2.3 (TT) 292 40476601 Hancock H Hn 2.8 (TT) 208 76185001 Kokee K Kk 2.2 (TT) 288 72983001 Kitt Peak L Kp 2.6 (TT) 326 76109401 Los Alamos M La 2.6 (TT) 330 76119601 Medicina C Mc 2.1 (TT) 256 72308801 Mauna Kea N Mk 2.6 (TT) 293 76175501 North Liberty O Nl 2.6 (TT) 329 76129701 Green Bank 20m P Gn 2.1 (TT) 291 72484701 Onsala T On 2.2 (TT) 273 72137701 GGAO (MV3) Z Gg 2.2 (TT) 285 71085301 Owens Valley Q Ov 2.6 (TT) 312 76165401 Pie Town R Pt 2.6 (TT) 330 72348601 St. Croix E Sc 2.8 (TT) 288 76159001 Westford F Wf 2.3 (TT) 318 72097301 Note: This experiment uses THIN TAPES ONLY at all stations. The tape change at the VLBA stations occurs during normal site working hours. There is a gap in the Green Bank schedule for the Intensive session and a tape change before 11 p.m. local time. Purpose ======= This is the fifth of six bi-monthly coordinated astrometric/geodetic experiments in 1997 that use the full VLBA plus geodetic stations capable of recording in VLBA format. 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 VLBA stations demonstrate high peculiar transverse velocities, i.e., residual motion after accounting for gross plate tectonic models. All of the VLBA stations also exhibit anomalous vertical motions. Analysis of a long-term data set will enable us to tell whether these motions are measurement artifacts, are of geophysical significance, or represent localized subsidence problems at the VLBA sites. The data will incorporate the VLBA stations into the VLBI reference frame through the inclusion of other geodetic stations in the network. 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 experiment were selected from a list of 106 sources with repeated observations by the geodetic networks in the last two years. It was decided that sources observed in these experiments should meet the standards imposed by Alan Fey in his imaging survey using the VLBA, of at least three scans and 135 total observations. It was also decided that this requirement would be relaxed for sources South of -25 degrees declination. After much discussion, it was also decided that a small number of sources with definite structure would be included, to better test the ability to apply image corrections. The same source list has been used during the all 1997 sessions. 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 third geodetic experiment to use continuous tape recording and the first to have thin tapes at all the stations. The benefits of continuous recording are 1) greatly increased SNR because most of the on-source time will be correlated, and 2) anticipated higher data quality from the correlator because the tapes need to be synchronized only once per pass instead of on every scan. The disadvantage of continuous recording is increased tape usage: 3 thin tapes at each station. The previous experiment, RDV04, was processed in under three weeks, an indication of the ease of processing continuous recording. The increased SNR results from increased observing time. Much of the former "idle" time is converted directly into observing time, as shown in the comparison of RDV02 with RDV05 below. (The average and median SNRs in the table do not include the GGAO scans.) Session #obs #scans %obs %idle %slew AvgSNR MedianSNR RDV02 33042 582 33 39 23 99 70 RDV03 27318 464 52 21 23 128 85 RDV04 30268 511 51 22 22 110 70 RDV05 The same criteria were used for generating this schedule as were used for the first two of these sessions. The schedule has a total of 85 sources, 65 of which meet the 3 scans / 135 observation criteria. All but 4 of the remaining sources are below -25 degrees declination where the criteria were relaxed. From the list of 7 sources provided by NRAO last time, three of the remaining four were included in this schedule. The sources are: --- Source Name ---- #scans #obs assumed flux (Jy) 2120+099 3 228 0.4 2147+077 1 105 0.4 1919+086 1 66 0.15 This will complete the observations of the Dhawan list and will mean the observation of all but one of the Wrobel list. 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 2200 of the 3700 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, 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 10-minute scans at each end of the experiment, one on 0552+398 and one on 4C39.25. 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 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 ====================================================== Onsala, Medicina, Westford, and MV3 have Mark IV formatters. You can use the same procedures as for the previous RDV0x sessions. 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. 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 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 this 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! Thank you for remembering last time. on cddisa: rdv05xx.log in directory "sep97" on aspen: rdv05log.xx in directory "sep97" 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 ./rdv05.skd for experiment RDV05 (all scans with at least one subnet station) SOURCE |0 6 12 18 | #SCANS #OBS #Obs/bl 0003-066I x x x x x x x x I 8 382 6.8 0014+813I x x x x x x x x x x x xI 12 1616 11.9 0048-097I x x x x x I 5 239 4.4 0059+581I x x x x x x x x x x I 10 1009 8.5 0104-408I x x x x x I 5 76 4.3 0111+021I x x I 2 160 2.5 0119+115I xx x x x x x I 7 400 5.7 0119+041I x x x x x x I 6 231 3.6 0133+476I x xx x x x x x x x xI 11 981 9.5 0201+113I x x x x I 4 263 3.8 0202+149I x x x x x I 5 239 3.3 0208-512I x x I 2 2 .2 0229+131I x x x x I 4 252 3.6 0234+285I x x x x x x x x I 8 635 7.7 NGC1052 Ix x x x x I 5 253 5.4 CTA26 I x x x x I 4 313 5.2 0402-362I x x x x x x I 6 90 3.2 3C120 Ix x x x x I 5 340 5.2 0454-234I x x x x x x I 6 226 5.6 0458-020I x x x x I 4 288 4.8 0528+134I x x x x x x x I 7 508 7.2 0537-441I x x x I 3 37 2.4 0552+398I x x x x x xx x x x I 12 736 7.9 0556+238I x x x x x x xI 7 467 6.0 0642+449I x x x x x x x x I 8 823 8.3 0727-115I x x x x xx x I 7 308 5.6 0742+103I x x x x x I 5 406 5.9 0804+499I x x x x x x x I 7 639 6.0 0823+033I x x x xx x I 6 341 5.3 OJ287 I x x x xx x x x x I 9 615 8.1 0919-260Ix x x x x I 5 124 3.4 0920-397I x x x I 4 51 2.7 4C39.25 Ix x x x xx x x x x I 10 684 7.4 OK290 I x x x x x x I 6 236 3.0 0955+476I x x x x x x x x I 8 469 4.5 1004+141Ix x x x x I 5 311 4.4 1034-293Ix x x x I 4 125 3.9 1044+719I x x x x x x xx x x x x x x x I 15 1350 10.3 1101+384I x x x I 3 144 1.6 1124-186I x x x x x xI 6 244 5.4 1128+385I x x xx x x I 6 571 6.2 1144-379I x x x xI 4 29 1.1 1145-071I x x x x x x I 6 400 7.1 1156+295I x x x I 3 315 3.8 1219+044I x x x x I 4 122 1.9 3C274 I x x x x x x x x I 8 548 7.8 3C279 Ix x x x x x I 6 319 5.5 1255-316I x x I 2 132 4.1 1300+580I x x x I 3 221 1.8 1308+326Ix x x x x x x x I 8 430 5.0 1313-333I x x xI 3 122 4.2 1334-127I x x x x x I 5 274 5.5 1351-018I x x I 2 72 1.2 1357+769I x x x x x x x x x I 9 929 6.9 OQ208 I x x I 2 136 1.7 1418+546I x x x x x x x x x xI 10 933 8.2 1424-418I x x I 2 37 3.0 1451-375I x x x x I 4 57 2.3 1504-166Ix x x x xx I 6 281 6.0 1514-241I x x x I 3 120 3.0 1606+106I x x x x x x x xx x I 10 492 7.1 1611+343I x x x x x xx x I 8 567 6.5 1622-253I x x x x x I 5 114 2.9 NRAO512 I x xx x x x x I 7 642 6.9 1726+455I x x x x xx I 6 313 3.1 1739+522I x x x x x I 5 383 3.4 1741-038I x xx x x x x x x xI 10 310 5.2 1745+624I x x x x x x x x x x x I 11 1149 9.2 1749+096I x x x x x x x I 7 416 6.1 1803+784Ix x x x x x x x x x I 10 1114 8.2 1815-553I x xx I 3 3 .6 1908-201I x x x x x x x x I 9 281 6.4 1919+086I x I 1 66 1.0 1921-293I x x x x I 4 86 2.6 1954-388I x x x x xI 5 86 4.0 2052-474I x x x I 3 22 1.8 2120+099I x x x I 3 228 3.3 2136+141Ix x x x x x I 6 386 5.4 2145+067I x x x x x x x x x x I 10 330 5.0 2147+077I x I 1 105 1.6 VR422201I x x x x x x x x x x x I 11 951 9.9 CTA102 I x x x x x I 5 320 4.6 2234+282I x x I 2 61 .7 2243-123I x x x xx x x x I 8 280 5.1 2255-282I x x x x x I 5 122 3.5 Total scans, obs: 507 31488 Average number of obs. per baseline per source (normalized by up-time) = 5.1 Min = .0 Max = 17.1 (Baseline Nl-Gn on 0104-408) RMS = 3.4 Total time: 1496 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 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 On Gg Ov Pt Sc Wf Avg % obs. time: 54 53 61 54 56 50 50 34 47 50 56 55 68 53 52 47 69 53 % cal. time: 3 3 3 3 3 3 3 2 3 3 3 3 3 3 3 3 3 3 % slew time: 27 27 18 26 16 27 27 30 25 27 16 19 9 25 27 24 15 23 % idle time: 14 15 16 15 23 17 18 32 23 17 23 22 18 17 16 25 11 19 # of tapes : 2.6 2.6 2.3 2.8 2.2 2.6 2.6 2.1 2.6 2.6 2.0 2.2 2.2 2.6 2.6 2.8 2.3 total # scans: 322 328 292 308 288 326 330 256 293 329 290 273 285 312 330 288 318 304 # scans/hour : 12 13 11 12 11 13 13 10 11 13 11 10 11 12 13 11 12 12.7 Avg scan (sec): 152 145 188 158 177 140 137 119 146 138 176 182 215 152 142 146 196 159 # OF OBSERVATIONS BY BASELINE | Br Fd Gc Hn Kk Kp La Mc Mk Nl Gn On Gg Ov Pt Sc Wf StnTotal ---------------------------------------------------------------------------------- Br|322 293 263 274 224 295 300 159 230 298 250 182 230 289 299 240 266 3680 Fd| 328 238 276 220 320 322 153 230 307 264 167 235 294 324 260 277 3825 Gc| 292 234 210 243 245 163 209 246 211 183 205 238 243 191 231 4003 Hn| 308 183 273 279 180 192 294 261 189 245 255 277 263 299 3697 Kk| 288 224 222 95 281 207 176 118 166 232 224 156 179 3559 Kp| 326 322 152 233 306 260 168 231 298 324 254 272 3709 La| 330 157 231 314 266 174 237 298 328 260 278 4124 Mc| 256 92 170 156 241 166 135 155 158 184 3585 Mk| 293 216 183 115 170 241 233 167 188 3785 Nl| 329 275 188 249 284 312 271 290 3556 Gn| 290 167 226 242 264 245 266 3725 On| 273 178 158 172 159 192 3459 Gg| 285 220 235 225 254 3703 Ov| 312 299 232 252 4157 Pt| 330 259 276 2903 Sc| 288 264 3865 Wf| 318 3641 Number of 2-station scans: 90 Number of 3-station scans: 27 Number of 4-station scans: 20 Number of 5-station scans: 13 Number of 6-station scans: 11 Number of 7-station scans: 13 Number of 8-station scans: 15 Number of 9-station scans: 14 Number of 10-station scans: 19 Number of 11-station scans: 22 Number of 12-station scans: 18 Number of 13-station scans: 23 Number of 14-station scans: 62 Number of 15-station scans: 72 Number of 16-station scans: 32 Number of 17-station scans: 56 Total # of scans, observations: 507 31488 Average baseline components for all observations Average XY = 3616. Average XZ = 3192. Average YZ = 2246. Average length = 3859.