Session Notes for rd1707 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. The eight stations in this session are divided into two subnets which are scheduled independently: 1.) The first subnet is Fortaleza, Hartrao, Hobart26, Matera, Nyales20, and Seshan25. This runs from 18:00 on July 12 to 18:00 on July 13. 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 observing at 17:36:40 on July 12 and end with a final observation at 17:28:53 on July 13. These observing times are offset from the standard RD1707 observing times of 18:00 July 12 through 18:00 July 13 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 RD1707 and a companion R&D session, RD1706, is to observe 24 areas of the sky with both the standard IVS-INT01 list of sources and a test list. Two additional pairs of R&D sessions have observed the 24 areas with both the standard IVS-INT01 source list and a test list. The first pair, RD1608 and RD1610, was observed in 2016, and the second pair, RD1701 and RD1702, was observed in early 2017. Both pairs followed the same plan as RD1706 and RD1707. 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). This command will select 50 strong and well-distributed sources based on a flux catalog that has been developed shortly before scheduling using the recent performance of sources in 24-hour sessions. In RD1707, the intensives that start at odd hours of GST (GST 01:00, 03:00, ..., 23:00) are scheduled using the full geodetic source list and are the control intensives. The intensives that start at even hours of GST (e.g., 00:00, 02:00, ..., 22:00) 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 July 5, 2017. The schedule was developed on July 7, 2017. In the companion R&D, RD1706, the strategies were switched, so that pseudo-intensives that started at odd hours of GST were scheduled as test intensives and ones that started at even hours of GST were 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: RD1707 Description NEOSA Scheduler: NASA Correlator: HAYS Start: 2017-193-17:36:40 End: 2017-194-18:00:00 Current yyyyddd: 2017193 (2017.53) ( 17947 MJD, WED. 12JUL.) Greenwich sidereal time: 12:59:53 (17:36:40 UT) Sun's RA and DEC: 7h 28.9m 21d 51.8 =========================================================== First observations Observation listing from file ./rd1707.skd for experiment RD1707 Source Start DURATIONS name yyddd-hhmmss Ft Hh Ho Kk Ma Ny Sh Wz 0059+581 17193-173640| 48 48| 0805+410 17193-173834| 132 132| 1803+784 17193-174149| 45 45| 0716+714 17193-174321| 51 51| 0529+483 17193-174455| 75 75| 0345+460 17193-174650| 200 200| 0552+398 17193-175055| 60 60| 2229+695 17193-175305| 105 105| 2113+293 17193-175544| 200 200| 1617+229 17193-180000| 400 400 400 326 221 | 1823+689 17193-180000| 200 200| 2214+350 17193-180414| 200 200| 0008-264 17193-180639| 70 70 | 0749+540 17193-180857| 200 200| 0529+483 17193-181009| 81 60 81 | 1920-211 17193-181022| 60 60 | OJ287 17193-181248| 60 60 60 | 0552+398 17193-181259| 52 52| 2318+049 17193-181339| 60 60 | OJ287 17193-181443| 115 115| 2215+150 17193-181555| 60 60 60 | 1657-261 17193-181646| 60 60 | 0738+491 17193-181723| 195 195| 2319+317 17193-181836| 229 237 237 | 1424-418 17193-182024| 60 60 60 | End of listing. =========================================================== Last observations Observation listing from file ./rd1707.skd for experiment RD1707 Source Start DURATIONS name yyddd-hhmmss Ft Hh Ho Kk Ma Ny Sh Wz 0749+540 17194-172047| 200 200| 1657-261 17194-172134| 60 60 60 60 | 1144-379 17194-172401| 60 60 | 1759-396 17194-172413| 304 225 304 | 0641+392 17194-172447| 200 200| 1424-418 17194-172649| 60 60 | 0345+460 17194-172853| 200 200| 2113+293 17194-172946| 133 133 | 2208-137 17194-173051| 136 136 | 0008-264 17194-173441| 70 70 | 1156+295 17194-173443| 64 60 64 64 | 2318+049 17194-173734| 60 60 | OJ287 17194-173745| 60 60 60 | 2215+150 17194-174022| 60 60 60 | 1406-076 17194-174204| 400 238 400 | 2319+317 17194-174244| 229 238 238 | 0055-059 17194-174825| 157 157 | 3C274 17194-175012| 400 277 400 400 | 0229+131 17194-175236| 60 60 | End of listing. =========================================================== SKED Summary from file ./rd1707.skd for experiment RD1707 (all scans with at least one subnet station) Average number of obs. per baseline per source(normalized by up-time) = 2.5 Min = 0.0 Max = 58.8 (Baseline Ft-Sh on 2318+049) RMS = 6.7 Total time: 1457 minutes ( 24.3 hours). Key: Ft=FORTLEZA Hh=HARTRAO Ho=HOBART26 Kk=KOKEE Ma=MATERA Ny=NYALES20 Sh=SESHAN25 Wz=WETTZELL Ft Hh Ho Kk Ma Ny Sh Wz Avg % obs. time: 44 39 37 67 53 52 44 67 50 % cal. time: 2 3 3 5 3 3 4 5 4 % slew time: 25 39 34 17 24 15 33 9 25 % idle time: 28 18 25 10 18 29 19 18 21 total # scans: 191 220 254 451 293 298 335 451 311 # scans/hour : 8 9 10 19 12 12 14 19 13 Avg scan (sec): 201 155 128 129 158 151 115 129 145 # data tracks: 16 16 16 16 16 16 16 16 # Mk5 tracks: 16 16 16 16 16 16 16 16 Total TB(M5): 1.2 1.1 1.0 1.9 1.5 1.4 1.2 1.9 1.4 # OF OBSERVATIONS BY BASELINE | Ft Hh Ho Kk Ma Ny Sh Wz Total -------------------------------------------------- Ft| 101 43 0 114 92 17 0 367 Hh| 83 0 144 95 89 0 512 Ho| 0 47 63 186 0 422 Kk| 0 0 0 451 451 Ma| 230 166 0 701 Ny| 201 0 681 Sh| 0 659 Wz| 451 Number of 2-station scans: 702 Number of 3-station scans: 184 Number of 4-station scans: 103 Number of 5-station scans: 25 Number of 6-station scans: 0 Number of 7-station scans: 0 Number of 8-station scans: 0 Total number of scans: 1014 Total number of obs: 2122 Total integrated obs-time: 306060 Average obs-time: 144.2 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: | 69| 885| 125| 104| 124| 107| 43| 216| 44| 57| 21| 36| 40| 29| 18| 18| 12| 174Average X-band SNRs by baseline | Ft Hh Ho Kk Ma Ny Sh Wz AVG ------------------------------------------------- Ft| 34 22 - 36 39 36 - 35 Hh| 34 - 49 43 43 - 41 Ho| - 40 37 57 - 44 Kk| - - - 37 37 Ma| 74 63 - 58 Ny| 82 - 64 Sh| - 64 Wz| 37 Average S-band SNRs by baseline | Ft Hh Ho Kk Ma Ny Sh Wz AVG ------------------------------------------------- Ft| 23 22 - 17 18 15 - 19 Hh| 32 - 26 22 22 - 25 Ho| - 19 23 33 - 29 Kk| - - - 26 26 Ma| 26 21 - 23 Ny| 27 - 24 Sh| - 26 Wz| 26 ===========================================================