Session Notes for rd1608 Prepared by K. Baver, NVI, Inc./GSFC =========================================================== Purpose and general notes: IVS-INT01 schedules currently use all geodetic sources that are visible to the Kokee-Wettzell baseline. But tests have indicated that the use of a restricted set of sources is likely to reduce the sessions' UT1 formal errors. The geodetic sources that are mutually visible at Kokee and Wettzell are well-distributed in the sky but include weaker sources that, if scheduled, can reduce the number of observations and increase the UT1 formal error. The use of Sked's bestsource command to select a smaller number of well-distributed, but, on average, stronger sources is expected to address the problem of weak sources and to lower the UT1 formal error. Tests using the metric of the UT1 formal error, as well as secondary metrics, such as robustness against source loss, indicate that selecting 50 sources through the bestsource command is a promising strategy. We divide the eight stations in this session into two subnets which are scheduled independently: 1.) The first subnet is Fortaleza, Hartrao, Kashim34, Nyales20, Onsala60 and Seshan25. This runs from 17:30 on September 7 to 17:30 on September 8. This network will observe independently of the second subnet and will serve as an independent external check on EOP obtained from the second subnet. 2.) The second subnet is the intensive network of Kokee-Wettzell. This will start at 17:50:57 on September 7 and end with a final observation at 17:39:10 on September 8. These observing times are offset from the standard RD1608 observing times of 17:30 September 7 through 17:30 September 8 by special arrangement. These times are necessary to observe specific areas of the sky as explained below. Unlike 24 hour sessions, which can observe the whole sky, intensives can observe only a small slice of the sky, and this slice varies depending on the day of the year and the time of day when the intensive starts. The slice of sky observed is likely to have different distributions of sources at different times, in extreme cases offering sparse coverage or exceptionally good coverage, as well as variations in the strengths of the observable sources. Because of this, the results from intensive sessions will depend partly on what part of the sky is observed, and any tested strategy should be compared to the use of a control strategy that observed the same part of the sky. The GST at which an intensive session starts identifies the area of the sky observed. The goal of RD1608 and a companion R&D session, RD1610, is to observe 24 areas of the sky with both the standard IVS-INT01 list of sources and a test list. In each R&D session, the Kokee-Wettzell network will be scheduled as a series of 24 consecutive, independent pseudo-intensives using the alternating strategies of a) using the full geodetic source list, which is the standard IVS-INT01 strategy and serves here as the control strategy and b) selecting 50 sources from the geodetic source list using the Sked program's bestsource command (the test strategy). In RD1608, the intensives that start at even hours of GST (GST 00:00, 02:00, ..., 22:00) are scheduled using the full geodetic source list and are the control intensives. The intensives that start at odd hours of GST (e.g., 01:00, 03:00, ..., 23:00) are scheduled using the restricted source list that contains 50 sources and are the test intensives. This source list was selected using a flux catalog developed on August 25, 2016. In the companion R&D, RD1610, the strategies will be switched, so that pseudo-intensives that start at even hours of GST will be scheduled as test intensives and ones that start at odd hours of GST will be scheduled as control intensives. This will allow the direct comparison of the two techniques at 24 starting GST times (00:00, 01:00, ..., 23:00). The GSFC analysis center will analyze the 24 pseudo intensive sessions with a view towards determining if one of the scheduling strategies is better in terms of things such as lower formal errors, better agreement with independent measures of UT1, and robustness of the schedule. =========================================================== ----- Parameter listing -------------------------------------- Experiment: RD1608 Description NEOSA Scheduler: NASA Correlator: HAYS Start: 2016-251-17:30:00 End: 2016-252-17:30:00 Current yyyyddd: 2016251 (2016.69) ( 17639 MJD, WED. 7SEP.) Greenwich sidereal time: 16:38:53 (17:30:00 UT) Sun's RA and DEC: 11h 6.7m 5d 42.6 =========================================================== First observations Observation listing from file ./rd1608.skd for experiment RD1608 Source Start DURATIONS name yyddd-hhmmss Ft Hh Kb Kk Ny On Sh Wz 2013+163 16251-173000| 400 145 400 400 370 | 1418+546 16251-173822| 67 60 67 | 0332-403 16251-173831| 60 60 | OJ287 16251-174131| 60 60 | 3C446 16251-174135| 60 60 60 60 | 0059+581 16251-174501| 60 60 60 60 | 0642+449 16251-174805| 60 60 60 60 | 1424-418 16251-174839| 60 60 | 0716+714 16251-175008| 60 94 97 97 | 0716+714 16251-175057| 70 70| 1354-152 16251-175152| 400 400 | 2229+695 16251-175254| 60 62 126 126 | 1144+402 16251-175303| 94 94| 0059+581 16251-175554| 40 40| End of listing. =========================================================== Last observations Observation listing from file ./rd1608.skd for experiment RD1608 Source Start DURATIONS name yyddd-hhmmss Ft Hh Kb Kk Ny On Sh Wz 0613+570 16252-173910| 200 200| End of listing. Observation listing from file ./rd1608.skd for experiment RD1608 Source Start DURATIONS name yyddd-hhmmss Ft Hh Kb Kk Ny On Sh Wz 3C418 16252-172145| 60 60 60 60 | 0613+570 16252-172235| 200 200| 1846+322 16252-172350| 100 100 | 1741-038 16252-172400| 60 60 60 | 0016+731 16252-172643| 42 42| 0716+714 16252-172709| 60 60 | 1418+546 16252-172731| 67 60 67 | 0718+793 16252-172808| 200 200| 2229+695 16252-173211| 114 114| 0345+460 16252-173457| 200 200| 0613+570 16252-173910| 200 200| End of listing. =========================================================== SKED Summary from file ./rd1608.skd for experiment RD1608 (all scans with at least one subnet station) Average number of obs. per baseline per source(normalized by up-time) = 2.3 Min = 0.0 Max = 56.8 (Baseline Ft-Ny on 1741-038) RMS = 6.7 Total time: 1453 minutes ( 24.2 hours). Key: Ft=FORTLEZA Hh=HARTRAO Kb=KASHIM34 Kk=KOKEE Ny=NYALES20 On=ONSALA60 Sh=SESHAN25 Wz=WETTZELL Ft Hh Kb Kk Ny On Sh Wz Avg % obs. time: 39 37 33 67 52 53 45 67 49 % cal. time: 2 2 4 5 4 4 4 5 4 % slew time: 29 41 37 20 20 22 32 9 27 % idle time: 29 19 25 7 23 20 18 17 20 total # scans: 208 213 378 452 342 317 381 452 342 # scans/hour : 9 9 16 19 14 13 16 19 14 Avg scan (sec): 163 151 76 129 132 147 102 129 127 # data tracks: 16 16 16 16 16 16 16 16 # Mk5 tracks: 16 16 16 16 16 16 16 16 Total TB(M5): 1.1 1.0 0.9 1.9 1.4 1.5 1.2 1.9 1.4 # OF OBSERVATIONS BY BASELINE | Ft Hh Kb Kk Ny On Sh Wz Total -------------------------------------------------- Ft| 134 36 0 99 114 37 0 420 Hh| 53 0 72 94 81 0 434 Kb| 0 232 182 346 0 849 Kk| 0 0 0 452 452 Ny| 278 217 0 898 On| 182 0 850 Sh| 0 863 Wz| 452 Number of 2-station scans: 743 Number of 3-station scans: 114 Number of 4-station scans: 159 Number of 5-station scans: 51 Number of 6-station scans: 4 Number of 7-station scans: 0 Number of 8-station scans: 0 Total number of scans: 1071 Total number of obs: 2609 Total integrated obs-time: 312359 Average obs-time: 119.7 Histogram of observation durations Dur: 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400#Obs: | 75| 1459| 189| 109| 67| 66| 63| 228| 28| 16| 60| 27| 3| 16| 10| 11| 19| 163Average X-band SNRs by baseline | Ft Hh Kb Kk Ny On Sh Wz AVG ------------------------------------------------- Ft| 31 44 - 40 32 40 - 35 Hh| 46 - 53 41 52 - 43 Kb| - 101 66 138 - 103 Kk| - - - 35 35 Ny| 76 96 - 81 On| 67 - 62 Sh| - 101 Wz| 35 Average S-band SNRs by baseline | Ft Hh Kb Kk Ny On Sh Wz AVG ------------------------------------------------- Ft| 19 26 - 17 15 17 - 18 Hh| 32 - 24 21 24 - 23 Kb| - 45 33 62 - 48 Kk| - - - 26 26 Ny| 26 30 - 31 On| 23 - 25 Sh| - 40 Wz| 26 ===========================================================