IRIS-S154
(International Radio Interferometric Surveying - South)
2000 Sept. 14
Notes prepared by Arno Mueskens
Geodetic Institute of the University of Bonn, Germany
Nominal Start: 14:00 U.T. on Sept.14 day 258)
name yyddd-hhmmss Ft Gc Hh Wf Wz
0552+398 00258-140000| 90 90 90 90|
1749+096 00258-140353| 90 90|
Nominal Stop : 14:00 U.T. on Sept.15 (day 259)
name yyddd-hhmmss Ft Gc Hh Wf Wz
1749+096 00259-134009| 90 90|
0823+033 00259-134111| 90 90 |
0727-115 00259-134403| 140 140 |
Duration: 24 hours
Correlator: BONN MK4
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 25 at X-band and 25 at S-band for all baselines.
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 NONE!! 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 is154.skd for experiment IS154
(all scans with at least one subnet station)
SOURCE |0 6 12 18 | #SCANS #OBS #Obs/bl
0003-066I xx xxx I 5 15 3.5
0048-097I xxx I 3 3 .6
0104-408Ixxxx xx x xx xxxI 12 12 3.5
0106+013Ix x xx xxxx xx x xxxx I 15 21 4.6
0119+041I x I 1 1 .2
0229+131I x x x x xx x x I 8 12 2.2
CTA26 Ixxxxx x x x xxx xx I 13 13 2.9
0402-362I x xx I 3 3 .9
0454-234I x x xx x I 5 7 2.1
0458-020I x x xI 3 3 .7
0528+134I xx xxxx xxxxxx x xx x I 16 28 5.0
0537-441I xx xxx xx xx x I 11 11 3.8
0552+398Ix xxx xxxx xx xxx xxx xxxx xxxxxxxxxxx xxx xxxxI 38 151 27.2
0637-752I x x x x I 4 4 1.4
0718+793I x I 1 1 .1
0727-115I x xx x xx xxx x x xxxxx I 16 45 9.6
0749+540Ix xxxx xxxx xx x x x xxx x xxx xxxxxxxxx xxxxI 34 129 21.8
0804+499I x x x x xx x x xx I 10 22 2.9
0805+410I x I 1 1 .1
0823+033I xx x x xxxxx xxxxx I 14 16 3.4
OJ287 I xxxx x xx x xxxx xxx xxxxx I 21 61 11.6
0920-397I I 0 0 .0
4C39.25 Ix xxxxxx xx xx xxxxxxxxxxxxxxxxxxxx xI 32 112 19.0
OK290 I x x x x x x I 6 6 .8
0955+476I xx xx xx xx xx x xx xI 14 26 3.5
1044+719I x x x x x x I 6 18 2.3
1057-797I x x x I 3 3 1.1
1124-186I xx xx x x xx x I 9 20 6.0
1144-379I x x I 2 2 .6
1334-127I x xxxx I 5 5 1.3
1351-018Ix xx x xxI 6 6 1.5
1357+769I x x x I 3 9 1.1
1424-418I x x xx x x I 7 7 2.1
1606+106Ixx x x xx xx xxxxx I 14 20 3.8
1610-771I x x x x I 4 4 1.4
1622-253I x x x I 3 3 .9
NRAO512 I xxx xxxx x x xxxx xx xx xxxxxx xxx xxxxxI 31 55 6.2
1726+455I x xx I 3 3 .4
1739+522Ixxx x x xx xx x x x x x x x x x xI 19 51 6.5
1741-038I xxx x x x xx xxx xx I 13 19 4.3
1749+096Ixx x xxxx x x xxxx x xx xx x xx x I 23 64 13.4
1815-553I I 0 0 .0
1921-293Ixx xxx x xxx x xxxI 14 14 4.1
1954-388I x x I 2 2 .6
1958-179I x xxx x x I 6 6 1.7
2121+053I x I 1 1 .2
2128-123I x x I 2 2 .4
2145+067I x x xx x xxxx x xx xx xx x xx I 20 26 5.3
2234+282I x x xx x x x xx x I 10 18 2.5
2255-282I x I 1 1 .3
Total scans, obs: 493 1062
Average number of obs. per baseline per source (normalized by up-time) = 3.7
Min = .0 Max = 36.3 (Baseline Hh-Wz on 0552+398) RMS = 7.4
Total time: 1426 minutes ( 23.8 hours).
Key: Ft=FORTLEZA Gc=GILCREEK Hh=HARTRAO Wf=WESTFORD Wz=WETTZELL
Ft Gc Hh Wf Wz Avg
% obs. time: 40 51 38 62 56 49
% cal. time: 1 3 1 3 3 2
% slew time: 25 17 30 14 10 19
% idle time: 32 27 29 18 29 27
# of tapes : 2.3 .8 .6 .8 .8
total # scans: 165 304 141 338 284 246
# scans/hour : 6 12 5 14 11 10.3
Avg scan (sec): 207 143 234 158 170 182
# OF OBSERVATIONS BY BASELINE
| Ft Gc Hh Wf Wz StnTotal
----------------------------------
Ft|165 53 83 107 73 316
Gc| 304 12 260 181 506
Hh| 141 27 87 209
Wf| 338 179 573
Wz| 284 520
Number of 2-station scans: 316
Number of 3-station scans: 116
Number of 4-station scans: 53
Number of 5-station scans: 8
Total # of scans, observations: 493 1062
Average baseline components for all observations
Average XY = 5407.
Average XZ = 5101.
Average YZ = 5019.
Average length = 6593.