[AZ-Observing] Summer Twilight
- From: Paul Lind <pulind@xxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Wed, 18 Jun 2014 13:18:14 -0400 (EDT)
While observing at Ash Fork during the last DOTM we noticed that the evening
twilight crept slowly northward, reaching a point almost below Polaris. This
was long after the end of astronomical twilight, which was listed as about 9:20
pm. The phenomenon is logical since the sun was only about 30 degrees below
the horizon in the north at its very lowest. I'd never noticed this before in
my hundreds of years of observing. (Well maybe not hundreds). It's definitely
interesting and worth looking for this time of year, requiring only a dark site
and no light domes in the NW.
As a side effect of the "not very low sun", I had satellite trails in one-sixth
of my 5-min sub-exposures in the Coma area. This area was only about 100
degrees from the sun. Apparently, the lesson is to image close to the
anti-solar point in the summer.
Paul Lind
--
See message header for info on list archives or unsubscribing, and please
send personal replies to the author, not the list.
Other related posts:
