Stellar object interval?
Posted 26 April 2013 - 11:02 AM
I think I know but wanna be sure:)
Posted 26 April 2013 - 12:53 PM
If you actually want to view it near sunset then you need to realize that you need to wait a few months longer to allow it to rise sufficiently above the horizon. If you want to view it sooner, then wait a few months from now and you can catch it in the morning before sunrise.
Posted 26 April 2013 - 01:05 PM
Once an item, say M42 sets in the west at sunset, how long until is rises in the east at sunset?
It depends on the object's declination and on the season. And also, of course, what you mean by "at sunset." No deep-sky object is visible less than 45 minutes after sunset, especially if it's low in the sky.
M42 is a smidge south of the celestial equator, so at northern latitudes it spends almost half of the time above the horizon. That means it will be reappearing at roughly the same time of night in roughly 6 months. As luck would have it, nights will be significantly longer by then, so it will indeed be visible not long after sunset despite the 1.5 to 2 hours lost to twilight.
Far-north objects like M81 and M82 are always above the horizon for observers around latitude 40 north, and therefore observable whenever the sky is reasonably dark.
Far-south objects like M7 just skim above the horizon for a few hours, so their viewing season is quite short.
Posted 26 April 2013 - 05:58 PM
Posted 26 April 2013 - 08:01 PM