At 09:01 30/03/03, Ed Davies wrote: >First RA/Dec pair is ICRF/J2000.0 with which I'm quite happy. Second is >"a-apparent". What does this mean and why is it different? I turned off >refraction correction so the difference is not just that. (Refraction >correction seemed a bit pointless with 6000+km of rock in the way. :-) > >Is it due to nutation, etc: i.e., relative to the ITRF (terrestrial >reference frame) rather than celestial? > >I forwarded John Holtz's message to somebody with a decent tele- >scope and a web-cam modded for long exposures a few days ago when it >looked possible that a front might clear the air here in south eastern >England but actually we've gone from high pressure haze to quite >heavy mist so I'm not too hopeful of him getting any piccies. Ed, the apparent positions are corrected for aberration and nutation. I suspect your friend with the webcam will have too much noise in the exposure long enough to get faint enough to image J002E3 Tony Beresford ----------------------------------------------------------------- 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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