As expected, IGS 1B manoeuvred; it was about 1.5 min early. IGS 1A may also have manoeuvred. 27698 03 009A 2701 G 20030425024201430 17 25 1839689+630849 28 S 27698 03 009A 2701 G 20030425024253360 17 25 2123439+650140 37 S 27699 03 009B 2701 G 20030425033913900 17 25 0414778+482867 28 S Site 2701: 43.68764 N, 79.39243 W, 230 m I derived the following from observations by Bjoern Gimle, Mike Waterman and myself, received to this moment: Arc 2003 Apr 23 - 25 UTC: IGS 1A 0.0 0.0 0.0 5.6 v 1 27698U 03009A 03115.10353359 .00008866 00000-0 35165-3 0 07 2 27698 97.4064 187.1418 0008435 152.9921 207.1758 15.25381256 01 WRMS residuals = 0.2 deg Arc 2003 Apr 25 - 25 UTC: IGS 1B 0.0 0.0 0.0 3.1 v 1 70000U 03115.15224421 .00010000 00000-0 39700-3 0 04 2 70000 97.4104 187.1102 0003000 119.3753 294.0848 15.25380000 05 WRMS residuals = 0.015 deg I am reasonably confident of IGS 1A's mean motion, but I cannot exclude the possibility that it made a small downward manoeuvre prior to my observation. The IGS 1B search elements are based on the assumption that its mean motion was the same as that of IGS 1A. I propagated the pre-manoeuvre elements to the time of my observation, then adjusted the mean anomaly for best fit. Regardless of the accuracy of the above mean motions, we can reasonably assume that both objects are destined to have operational values of about 15.26 +/- 0.002 rev/d (required for exact 61:4 resonance); therefore, it would be prudent to expect them to be at least 30 s early tonight. Ted Molczan ----------------------------------------------------------------- To unsubscribe from SeeSat-L, send a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@satobs.org List archived at http://www.satobs.org/seesat/seesatindex.html
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