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: http://star.arm.ac.uk/~aac/tips.htm
Дата изменения: Wed Aug 29 15:49:28 2001 Дата индексирования: Mon Oct 1 20:19:13 2012 Кодировка: Поисковые слова: aurora |
If you're an observer willing to attempt and observe the occultation, here's some tips which can help you make the most of what you have:
There are basically two areas of research which can benefit from your observations:
Both of these do not require particularly large apertures. Even a pair of 50mm binoculars away from city lights should be sufficient to show the star and its vanishing behind Titania. Bear in mind that you will lose as much as a magnitude's worth of brightness because of Uranus' low altitude at the time (10-11 deg). Titania will be about 19 arcseconds away from Uranus at the time of occultation.
Timing is perhaps the most important aspect of this type of observation. As a rule of thumb, one second of timing accuracy corresponds to about a milliarcsec at the distance of Uranus. For the astrometry part, getting the time of occultation (vanishing and reappearance of the star) to within a second is the minimum acceptable. This is achievable by synchronizing a stopwatch with some standard time reference several minutes before and after the occultation.
However, in order to detect an atmosphere on Titania, the eye is just not a good enough light detector. You are going to need some kind of specialized equipment such as a photoelectric or CCD photometer or a video camera. It is also necessary to time-stamp your data with sub-second (0.1-0.5 sec) accuracy. Here it pays to have as large an aperture as possible as this will maximize your signal-to-noise ratio.
On the subject of observing site, try to observe from as far south as possible. There is a significantly higher probability that the event could be observed from the south coast of Ireland but not from the North. On the other hand, well-equipped observers should be geographically dispersed to cover more area. It's really not a good idea to have two or more individuals or groups with state-of-the-art equipment observing from the same place especially as we're also trying to beat the weather at the same time. Rather, each group should be observing at least several hundred km apart from each other.
Finally, if you can observe the star throughout the night, do it! As it passes through Uranus' satellite system there is always a chance that an unknown satellite will give itself away by briefly cutting out its light. It may sound far-fetched, but that was what happened during an occultation by Neptune in 1981.