[AZ-Observing] Re: MM date limits (again)
- From: "Jones, Jack (AZ75)" <jack.jones@xxxxxxxxxxxxx>
- To: "'az-observing@xxxxxxxxxxxxx'" <az-observing@xxxxxxxxxxxxx>
- Date: Thu, 18 Mar 2004 16:05:17 -0700
High mags and a tiny field of view make for a very dark background fov, and
is something you should try in the gathering twilight (esp. w/a 72-inch
wow). Also a hood over the head is going to be good for preventing back
reflections - anything to increase contrast. There is supposedly an optimal
detection mag (and exit pupil) but most scopes are way too low. Search on
Mel Bartels or goto:
http://members.efn.org/~mbartels/aa/visual.html
Which may have been posted here before.
Jack
>
> Except for seeing the very faintest things, astronomical twilight
> is more-or-less irrelevant. It is nearly as dark as it's going to get
> within 10 minutes of the time of nautical twilight, and for things
> such as picking up M30 next Sunday morning, I wouldn't be worried
> observing well into the interval between the end of nautical and the
> beginning of civil twilight---something like that not-quite-arbitrary
> 10-deg figure Tom P used. For ordinary deep-sky observing I'd
> certainly start work shortly after nautical in the evening.
> /Brian
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