IRIS-S142 (International Radio Interferometric Surveying - South) 1999 Sep, 20 Notes prepared by Arno Mueskens Geodetic Institute of the University of Bonn, Germany Nominal Start: 14:00 U.T. on Sep.20 (day 263) name yyddd-hhmmss Ft Gc Hh Wf Wz Nominal Stop : 14:00 U.T. on Sep.21 (day 264) name yyddd-hhmmss Ft Gc Hh Wf Wz Duration: 24 hours Correlator: BONN Purpose ======= The purpose of the IRIS-S sessions is to continue the series of measurements for the determination of earth rotation parameters. IRIS-S experiments are set up to provide all earth orientation parameters (UT1, polar motion, and nutation), baseline components and positions of extragalactic radio sources. SInce a long period this network produced excellent EOP results and with the long north-south and east-west baselines as well as the wideband capability provides a good EOP determination. Network ======= The standard configuration of the monthly observed IRIS-S (South) experiments consists of four stations. One station in the United States(Westford,Ma), one station in South Africa (Hartebeesthoek), one radio telescope in Europe (Wettzell,Germany) and one radio telescope in South America (Fortaleza,Brasil). Since January 1997 the network is augmented by station Fairbanks(Alaska). During the O'Higgins occupations two more stations of the southern hemispere are added to this network. With O'Higgins (Antartika) and Hobart (Tasmania) we will have seven participate station in this network. Schedule ======== This schedule was generated by (auto)-SKED using the NEOS-WB frequency setup, using variable scan lengths with a minimum of : 70 seconds. The most recent source flux models are included. SNR goals are 20 at X-band and 15 at S-band for all baselines. On all baselines with Fortaleza the SNR goal for the X-band is 23. The predicted SNRs used include a 30 ps noise contribution added in quadrature, which is a typical magnitude for the reweight constants applied in SOLVE solutions. The schedule is generated for the estimation of all five (seven) earth orientation parameters, clock offsets and clock rates for all participating stations except the reference station and atmo- sphere parameters for all participating stations. It was optimized for three earth orientation parameters (polar motion, UT1). Other optimization features enabled for this experiment : - the covariance analysis during schedule generation considers the previous 24 hours of observations, - minor SKED optimization parameters . maximum number of observations, . minimum time, . sky coverage, were optimized over the best ( in a covariance sense ) 75% of the possible observations, this produces a somewhat more even sky distribution, - observations were weighted by their expected SNRs, - 30 ps noise contribution added, - mimimum time between observations of the same radio source was set to 20 min - using 59 source for improving the sky covorage Simulation Results ================== Simulation results of this schedule was used in a global solution estimate the formel errors for Earth orientation parameters. X Wobble <40 microasec Y Wobble <20 microasec UT1-TAI < 2 microsec Nutation offset in longitude (Psi) <50 microasec Nutation offset in obliquity (Eps) <20 microasec Procedures ========== NO PREPASS TIME: There is no time allowed in the schedule for prepassing tapes. Therefore all tapes needed for this experiment must be pre-checked before the start of this experiment. Please generate the procedures for this session using drudg. FREQUENCY SEQUENCE: The NEOS-wideband RF band frequency sequence ------------------ is used for this experiment. THIS SCHEDULE HAS A 10 SECOND EARLY TAPE START ---------------------------------------------- Wettzell, Westford, Fairbanks (Gilcreek) and HartRAO record at high (56kbpi) density (thin tape). Appendix ======== SKED Summary from file is142.skd for experiment IS142 (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 I 7 7 1.8 0048-097I x x x x x xx xI 9 36 7.7 0059+581Ix x x xx xx x x x x x x x x xx x xx x x x xI 24 103 19.0 0104-408Ix x xx x x xI 7 7 2.1 0119+041I x x x x I 4 6 1.3 0229+131Ixx x xx x x x I 8 12 2.3 CTA26 Ix x x x I 4 4 .9 0402-362I xx x x I 4 4 1.2 0454-234I x xx x x x x I 7 20 6.1 0528+134Ixxx xxx x x xxxxx x x x I 17 80 16.9 0537-441I x I 1 1 .4 0552+398I xx x x xxxxx xx xxx xx xxxx x x x x x xxI 27 142 26.4 0637-752I x x I 2 2 .7 0718+793I x I 1 3 .4 0727-115I x xx xxxxx xx I 10 43 9.2 0749+540Ixxx x xxx x x x xx x xxx x x xx xx xx x xx I 27 104 17.8 0804+499I x x xx x x x I 7 28 5.2 0805+410I xx x xx x x x x x xI 11 21 2.4 0823+033I x x xxxx I 6 6 1.3 OJ287 I xx x x xx xxx xx x x xxxxx x I 20 76 15.3 0920-397I x I 1 1 .3 4C39.25 I x xx x x xxx xx x x xxxx xxx x x xI 22 111 20.8 OK290 I xx I 2 2 .3 0955+476I x x xx x x x xx xx xx xI 14 33 4.9 1034-293I x I 1 1 .3 1044+719I x x x x x x x x x x x xx x x x xI 17 55 8.5 1057-797I x x I 2 2 .8 1124-186I x xx x I 4 16 5.0 1128+385I x x x x x x x xx I 9 17 2.0 1144-379I x I 1 1 .3 1255-316I x I 1 1 .3 1308+326I x x x x I 4 4 .6 1334-127I x I 1 1 .2 1351-018I xx x xI 4 4 1.0 1357+769I x x x x x x xx x x x x xI 13 51 11.3 1424-418I xx x I 3 3 1.1 1606+106Ixx xx x xx x xxx x xxxI 16 24 4.5 1610-771I x x I 2 2 .7 1622-253I xx x I 3 3 .9 NRAO512 Ixxx xx x x x x x x xxxxxx x x x xxx x I 24 110 20.4 1726+455Ixx xx x xx x x x x x xI 13 33 4.5 1739+522Ixxx xxx xx xx x x xx x xx x x xxx xx xxx I 27 117 21.5 1741-038Ixxx x x xxxx xxxxxxxx x I 19 70 15.2 1749+096Ix x x x x x xx xxxxxx xx x x I 18 65 14.0 1921-293I xx x xx xxx x I 9 13 3.9 1954-388I x xx xxxxx xx xI 11 11 3.3 1958-179I xxx xxx xxx xI 10 38 11.7 2121+053I x xx x I 4 9 1.9 2128-123Ix I 1 1 .3 2145+067I x xx x x x x x x xxxx x x I 15 19 4.0 2234+282I xx xx I 4 8 1.1 2255-282I x xx I 3 7 2.1 Total scans, obs: 481 1538 Average number of obs. per baseline per source (normalized by up-time) = 5.6 Min = .0 Max = 36.6 (Baseline Ft-Wf on 0552+398) RMS = 8.7 Total time: 1443 minutes ( 24.1 hours). Key: Ft=FORTLEZA Gc=GILCREEK Hh=HARTRAO Wf=WESTFORD Wz=WETTZELL Ft Gc Hh Wf Wz Avg % obs. time: 44 48 30 49 44 43 % cal. time: 2 3 1 4 3 3 % slew time: 30 17 31 17 13 22 % idle time: 21 31 36 29 38 31 # of tapes : 2.5 .8 .5 .8 .7 total # scans: 226 309 169 362 339 281 # scans/hour : 9 12 7 15 14 11.7 Avg scan (sec): 170 134 155 117 113 137 # OF OBSERVATIONS BY BASELINE | Ft Gc Hh Wf Wz StnTotal ---------------------------------- Ft|226 105 125 169 155 611 Gc| 309 23 285 226 369 Hh| 169 72 119 698 Wf| 362 259 722 Wz| 339 676 Number of 2-station scans: 193 Number of 3-station scans: 149 Number of 4-station scans: 123 Number of 5-station scans: 16 Total # of scans, observations: 481 1538 Average baseline components for all observations Average XY = 5505. Average XZ = 5291. Average YZ = 5391. Average length = 6856.