IRIS-S157 (International Radio Interferometric Surveying - South) 2000 Dec.18 Notes prepared by Arno Mueskens Geodetic Institute of the University of Bonn, Germany Nominal Start: 14:00 U.T. on Dec.18 (day 353) name yyddd-hhmmss Ft Gc Hh Wf Wz 1741-038 00353-140000| 100 100 100| 0804+499 00353-140410| 90 90 90| 1958-179 00353-140701| 560 430 560| Nominal Stop : 14:00 U.T. on Dec.18 (day 354) name yyddd-hhmmss Ft Gc Hh Wf Wz 0552+398 00354-134535| 90 90| 2121+053 00354-135556| 540 540| 1622-253 00354-135833| 220 220 | 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 : 90 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 <35 microasec Y Wobble <19 microasec UT1-TAI < 2 microsec Nutation offset in longitude (Psi) <48 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 10 SECOND EARLY TAPE START !! -------------------------------------------- Wettzell, Westford, Fairbanks and HartRAO record at high (56kbpi) density (thin tape). Fortaleza record on thick tapes (33kbpi) Appendix ======== SKED Summary from file is157.skd for experiment IS157 (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 x xx I 10 27 5.9 0048-097I xx x x I 4 9 1.9 0059+581Ix x x I 3 9 1.1 0104-408I xxxxxxxxxxx x I 12 12 3.5 0106+013I x x x xxx xxx x xx xI 13 24 5.2 0119+041I x I 1 1 .2 0229+131I x xxxx x x I 7 7 1.2 CTA26 I x x xx x xxxx x xx I 12 14 3.1 0402-362I x x xx x I 5 5 1.5 0454-234I x x x I 3 5 1.5 0458-020I x x I 2 2 .5 0528+134I xxxxx x xx x I 10 20 3.5 0537-441Ix xx x x x xxxxxI 11 11 3.8 0552+398Ixx xxxxxxxxxxxx xxxxxxx xxxxxxxxx xxxxxxx x xxxI 42 162 27.9 0637-752I x x xI 3 3 1.1 0718+793I x x x I 3 3 .4 0727-115I x x x xx x xxx xI 11 27 5.7 0749+540Ixx xx x x xxxxx xx xx xxxxx x xx xxxxxx xxxxx xI 36 147 26.0 0804+499I x x xxx x x xx x x xx x I 14 38 5.0 0805+410Ixx x x x x x xx x x x x I 13 23 2.6 0823+033I xxxx xx x x xx I 13 15 3.2 OJ287 I x xxx xxxxxx xxxxx x xx xxI 20 69 13.2 0920-397I x x I 2 2 .6 4C39.25 I xx xxx xxxxxxx xxx xxxxx x xx x xx x I 29 145 26.8 OK290 I x xx xxxxx x x x I 11 11 1.5 0955+476I xx x x x xx x xxxxxx x x x x x x x x I 22 80 14.5 1034-293I x x I 2 2 .6 1044+719Ix x x x x x x x x x x x I 12 32 4.0 1057-797I x x x I 3 3 1.1 1124-186I xx x x xxxx x x I 10 17 5.1 1128+385I x x x x x I 5 5 .5 1144-379I x x x I 4 4 1.2 1308+326I x I 1 3 .4 1334-127I x x I 2 2 .5 1351-018I x x x I 4 4 1.0 1357+769Ix x x x x x x x x x x x x I 13 38 5.8 1424-418I xx xx xx xx I 8 8 2.4 1606+106I x x x x x x x xxx xx x I 13 17 3.3 1610-771I x x x I 3 3 1.1 1622-253I xx x x I 4 6 1.8 NRAO512 I x x x xx xx x xx x xxxxI 15 17 1.8 1726+455I x x xx xx x I 7 13 1.7 1739+522Ix xx xx xxx xx x x x xx x xxxxxx xxxxx xxI 29 79 10.0 1741-038I x xx x x xxxx xxx x x x I 15 35 7.7 1749+096I x xx xx x xxx x xxxxxx x x x I 20 80 16.9 1921-293I x xx xxx xx x I 9 9 2.7 1954-388I xx x x I 4 4 1.2 1958-179I xxx x x x I 6 15 4.5 2121+053I x x x x x I 5 5 1.1 2145+067I x x xxx x xx x xx xx x xx xxI 19 23 4.8 2234+282I x x x xxx x x I 8 12 1.6 2255-282I x x x x I 4 4 1.2 Total scans, obs: 537 1311 Average number of obs. per baseline per source (normalized by up-time) = 4.4 Min = .0 Max = 40.4 (Baseline Ft-Wf on 4C39.25 ) RMS = 8.3 Total time: 1442 minutes ( 24.0 hours). Key: Ft=FORTLEZA Gc=GILCREEK Hh=HARTRAO Wf=WESTFORD Wz=WETTZELL Ft Gc Hh Wf Wz Avg % obs. time: 40 51 33 60 54 48 % cal. time: 2 3 1 4 3 3 % slew time: 31 17 32 15 11 21 % idle time: 24 27 32 20 30 26 # of tapes : 2.3 .8 .5 1.0 .8 total # scans: 214 340 155 376 321 281 # scans/hour : 8 14 6 15 13 11.7 Avg scan (sec): 165 130 188 138 147 153 # OF OBSERVATIONS BY BASELINE | Ft Gc Hh Wf Wz StnTotal ---------------------------------- Ft|214 77 104 141 108 430 Gc| 340 19 296 222 614 Hh| 155 34 90 247 Wf| 376 220 691 Wz| 321 640 Number of 2-station scans: 302 Number of 3-station scans: 151 Number of 4-station scans: 71 Number of 5-station scans: 13 Total # of scans, observations: 537 1311 Average baseline components for all observations Average XY = 5475. Average XZ = 5153. Average YZ = 5078. Average length = 6659.