Session Notes for rd1702 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, Kashim34, Matera, and Nyales20. This runs from 17:30 on January 24 to 17:30 on January 25. 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 17:42:57 on January 24 and end with a final observation at 17:36:47 on January 25. These observing times are offset from the standard RD1702 observing times of 17:30 January 24 through 17:30 January 25 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 RD1702 and a companion R&D session, RD1701, 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 will observe 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 followed the same plan as RD1701 and RD1702. The final pair, RD1706 and RD1707, is planned for mid-2017. 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 RD1702, 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 January 10, 2017. The schedule was developed on January 14, 2017. In the companion R&D, RD1701, the strategies were switched, so that pseudo-intensives that started at even hours of GST were scheduled as control intensives and ones that started at odd hours of GST were scheduled as test 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: RD1702 Description NEOSA Scheduler: NASA Correlator: HAYS Start: 2017-024-17:30:00 End: 2017-025-17:42:57 Current yyyyddd: 2017024 (2017.07) ( 17778 MJD, TUES 24JAN.) Greenwich sidereal time: 01:46:54 (17:30:00 UT) Sun's RA and DEC: 20h 29.1m -19d 1.9 =========================================================== First observations Observation listing from file ./rd1702.skd for experiment RD1702 Source Start DURATIONS name yyddd-hhmmss Ft Hh Ho Kb Kk Ma Ny Wz 0808+019 17024-173000| 354 400 99 400 384 | 0345+460 17024-173339| 330 330 | 0458-020 17024-173856| 60 60 60 | 0016+731 17024-174218| 101 60 101 69 | 0402-362 17024-174229| 60 60 | 3C418 17024-174257| 40 40| 0920+390 17024-174457| 200 200| 3C418 17024-174502| 60 60 60 | 0308-611 17024-174538| 60 60 | 1617+229 17024-174654| 60 60 | 1144+402 17024-174902| 158 158| End of listing. =========================================================== Last observations Observation listing from file ./rd1702.skd for experiment RD1702 Source Start DURATIONS name yyddd-hhmmss Ft Hh Ho Kb Kk Ma Ny Wz 1040+244 17025-171301| 130 60 130 | 3C446 17025-171459| 67 60 67 | 1803+784 17025-171553| 40 40| 0943+105 17025-171626| 275 144 275 | 0920+390 17025-171737| 200 200| 2209+236 17025-171811| 227 227 | 1101+384 17025-172138| 200 200| 1027-186 17025-172241| 98 98 | 0458-020 17025-172408| 60 60 60 | 1300+580 17025-172547| 139 139| 1749+096 17025-172658| 69 69 | 0537-286 17025-172722| 60 60 60 | NGC6251 17025-172852| 172 172| 1636+473 17025-173231| 200 200| 2113+293 17025-173647| 200 200| End of listing. =========================================================== SKED Summary from file ./rd1702.skd for experiment RD1702 (all scans with at least one subnet station) Average number of obs. per baseline per source(normalized by up-time) = 2.9 Min = 0.0 Max = 360.0 (Baseline Ft-Ho on 1936-155) RMS = 9.9 Total time: 1450 minutes ( 24.2 hours). Key: Ft=FORTLEZA Hh=HARTRAO Ho=HOBART26 Kb=KASHIM34 Kk=KOKEE Ma=MATERA Ny=NYALES20 Wz=WETTZELL Ft Hh Ho Kb Kk Ma Ny Wz Avg % obs. time: 42 37 35 34 69 50 50 69 48 % cal. time: 3 3 3 5 5 4 4 5 4 % slew time: 30 46 41 36 19 26 19 9 29 % idle time: 24 14 20 24 7 19 27 17 19 total # scans: 227 246 300 401 434 323 341 434 338 # scans/hour : 9 10 12 17 18 13 14 18 14 Avg scan (sec): 163 130 103 74 138 136 127 138 125 # 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 1.0 1.0 1.0 1.9 1.4 1.4 1.9 1.3 # OF OBSERVATIONS BY BASELINE | Ft Hh Ho Kb Kk Ma Ny Wz Total -------------------------------------------------- Ft| 117 36 38 0 143 123 0 457 Hh| 92 66 0 154 96 0 525 Ho| 215 0 50 59 0 452 Kb| 0 175 232 0 726 Kk| 0 0 434 434 Ma| 247 0 769 Ny| 0 757 Wz| 434 Number of 2-station scans: 754 Number of 3-station scans: 201 Number of 4-station scans: 135 Number of 5-station scans: 11 Number of 6-station scans: 0 Number of 7-station scans: 0 Number of 8-station scans: 0 Total number of scans: 1101 Total number of obs: 2277 Total integrated obs-time: 270645 Average obs-time: 118.9 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: | 77| 1233| 113| 91| 113| 73| 76| 232| 36| 30| 21| 3| 13| 6| 23| 17| 6| 114 Average X-band SNRs by baseline | Ft Hh Ho Kb Kk Ma Ny Wz AVG ------------------------------------------------- Ft| 32 20 38 - 34 32 - 32 Hh| 40 46 - 46 40 - 41 Ho| 54 - 32 30 - 43 Kb| - 60 72 - 60 Kk| - - 34 34 Ma| 61 - 51 Ny| - 55 Wz| 34 Average S-band SNRs by baseline | Ft Hh Ho Kb Kk Ma Ny Wz AVG ------------------------------------------------- Ft| 19 22 27 - 17 17 - 19 Hh| 32 33 - 24 23 - 25 Ho| 40 - 21 20 - 32 Kb| - 36 43 - 39 Kk| - - 25 25 Ma| 26 - 26 Ny| - 29 Wz| 25 ===========================================================