本帖最后由 Archimedes 于 2009-10-8 02:01 编辑
Hi all,
I just finished my Jupiter observation at around 16:30 UT, Oct 05. During the session I encountered a very weird phenomenen which I had never seen before, that Ganymede had been invisible from at least at 14:40 UT, succeeding a negative observation of comet C/2006 W3 due to strong urban artificial lights despite transparent sky, obvously discrepant to the result performed by all of my softwares, however, strangely, other Galilean satellites were good in their respective predicted positions given by the softwares. Initially I was under the impression that something wrong had occurred with my computer, for example, a specialized virus might play a trick to dislocate the norm. The situation didn't change until 15:40 UT when I went indoors to sort out my observation record. The more I thought about the phenomenon, the stranger I felt. So I decided to have a review via my refractor at about 16:20 UT. Miraculously Ganymede appeared (or 'reappeared?)!!! Evidently there shall not be any occultation between Ganymede and the Jovian planet since the distant was somewhat far away from each other and hence it was impossible for Ganymede to move 3R[sub]J[/sub] within an hour. But something odd was detected as the magnitude of Ganymede was only about 7 (without carefully estimation but according to my experience), which was greatly deviated from its normal value. I backed to check the software and then reviewed it again at 16:30 UT or thereabout the object has already back to the normal value (4.6m at the moment).
What had happened???? Awaiting all of your kind assistance! Thanks!
Location: +23deg09m12.24s, +113deg18m53.99s, +18m
Instrumentation: 10.0cm-R f/7 + Plössl 10mm + 2x Barlow
Seeing: 6/10 ~ 8/10 P; Transparency: 4/6 ALPO
Cheers, M.-T. Hui |
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