Session Notes for rd1706 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 June 27 to 17:30 on June 28. 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 17:35:49 on June 27 and end with a final observation at 17:29:55 on June 28. These observing times are offset from the standard RD1706 observing times of 17:30 June 27 through 17:30 June 28 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 RD1706 and a companion R&D session, RD1707, 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 RD1706, 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 June 16, 2017. The schedule was developed on June 21, 2017. In the companion R&D, RD1707, 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: RD1706 Description NEOSA Scheduler: NASA Correlator: HAYS Start: 2017-178-17:30:00 End: 2017-179-17:35:49 Current yyyyddd: 2017178 (2017.49) ( 17932 MJD, TUES 27JUN.) Greenwich sidereal time: 11:54:03 (17:30:00 UT) Sun's RA and DEC: 6h 27.2m 23d 17.3 =========================================================== First observations Observation listing from file ./rd1706.skd for experiment RD1706 Source Start DURATIONS name yyddd-hhmmss Ft Hh Ho Kb Kk Ma Ny Wz 1749+096 17178-173000| 60 60 60 60 60 | 2208-137 17178-173329| 60 60 | OJ287 17178-173329| 60 60 60 | 0059+581 17178-173549| 46 46| 1156+295 17178-173610| 66 60 63 66 | 1929+226 17178-173740| 200 200| 0529+483 17178-173953| 277 79 241 277 | 1424-418 17178-174124| 60 60 | 0804+499 17178-174227| 200 200| 1519-273 17178-174405| 60 60 | End of listing. =========================================================== Last observations Observation listing from file ./rd1706.skd for experiment RD1706 Source Start DURATIONS name yyddd-hhmmss Ft Hh Ho Kb Kk Ma Ny Wz 1057-797 17179-170626| 118 118 85 | 0059+581 17179-170733| 60 60 60 | 0537-441 17179-170946| 400 400 | 0345+460 17179-171010| 200 200| 1308+554 17179-171025| 259 400 400 | 0641+392 17179-171418| 200 200| 0347-211 17179-171806| 386 386 | 0529+483 17179-171817| 78 78| 1555+001 17179-171858| 152 60 152 120 | 0738+491 17179-172017| 200 200| 1749+096 17179-172341| 60 60 60 60 | 1929+226 17179-172506| 200 200| 1617+229 17179-172641| 89 60 89 87 | 0345+460 17179-172955| 200 200| End of listing. =========================================================== SKED Summary from file ./rd1706.skd for experiment RD1706 (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 = 80.0 (Baseline Kb-Ma on 1920-211) RMS = 6.6 Total time: 1443 minutes ( 24.0 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: 46 40 33 33 67 55 53 67 49 % cal. time: 2 3 3 4 5 3 4 5 4 % slew time: 25 40 37 33 18 24 17 10 26 % idle time: 26 16 26 29 9 16 26 17 21 total # scans: 205 229 282 358 466 286 320 466 326 # scans/hour : 9 10 12 15 19 12 13 19 14 Avg scan (sec): 193 151 100 81 124 168 142 124 134 # data tracks: 16 16 16 16 16 16 16 16 # Mk5 tracks: 16 16 16 16 16 16 16 16 Total TB(M5): 1.3 1.1 0.9 0.9 1.8 1.5 1.5 1.8 1.4 # OF OBSERVATIONS BY BASELINE | Ft Hh Ho Kb Kk Ma Ny Wz Total -------------------------------------------------- Ft| 112 40 24 0 132 109 0 417 Hh| 76 60 0 159 107 0 514 Ho| 202 0 36 62 0 416 Kb| 0 138 211 0 635 Kk| 0 0 466 466 Ma| 225 0 690 Ny| 0 714 Wz| 466 Number of 2-station scans: 775 Number of 3-station scans: 166 Number of 4-station scans: 121 Number of 5-station scans: 16 Number of 6-station scans: 0 Number of 7-station scans: 0 Number of 8-station scans: 0 Total number of scans: 1078 Total number of obs: 2159 Total integrated obs-time: 282673 Average obs-time: 130.9 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: | 48| 1088| 121| 100| 121| 87| 44| 182| 54| 24| 31| 18| 34| 10| 3| 9| 21| 164Average X-band SNRs by baseline | Ft Hh Ho Kb Kk Ma Ny Wz AVG ------------------------------------------------- Ft| 32 18 38 - 33 38 - 33 Hh| 32 45 - 50 48 - 42 Ho| 61 - 33 36 - 45 Kb| - 66 98 - 72 Kk| - - 35 35 Ma| 78 - 58 Ny| - 70 Wz| 35 Average S-band SNRs by baseline | Ft Hh Ho Kb Kk Ma Ny Wz AVG ------------------------------------------------- Ft| 21 24 20 - 16 17 - 18 Hh| 39 29 - 25 23 - 26 Ho| 48 - 21 23 - 38 Kb| - 31 44 - 40 Kk| - - 27 27 Ma| 27 - 25 Ny| - 29 Wz| 27 ===========================================================