[ATMoB-discuss] Suburban light pollution / last night's seeing

[Bert Halstead]

Bruce,

Generally I wouldn't expect the "seeing" conditions to have much effect 
on your experience when observing through 10x50 binoculars.  Of course, 
the effect of the seeing conditions becomes major as you move up to 100x 
magnification or beyond, and especially if you're looking for fine 
detail, as in the case of planetary observing or splitting close double 
stars.

Of course the sky transparency and the sky darkness do have a big effect 
on your experience with binoculars as well as with larger instruments.  
I did a few minutes of casual naked-eye stargazing last night from my 
back yard in Belmont, and I would say the transparency was only so-so, 
as has been reported by many others.  FWIW, only on an exceptionally 
dark night can I see the stars in the handle of the Little Dipper 
naked-eye from my back yard, though it is always easy to find them in my 
10x50 binoculars unless I am actually clouded in!  So if you could see 
most of the stars of the Little Dipper naked-eye, then I would say your 
conditions were better than the typical conditions in my back yard.

I think that possibly a lot of the objects you were looking for are not 
as impressive in binoculars (when the sky is not totally dark) as you 
expect, so you could actually have had them in the field of view and 
missed them!  Also, star-hopping your way to some objects can be harder 
than it looks.

I would say the showiest binocular object on the sky map you were using 
would be M13, and it's also pretty easy to find.  I'd concentrate on 
looking for that first.  It will help set your expectations when you 
realize that most of the objects you are looking for will not be as 
bright and distinctive as that.  I do think you should have been able to 
see M3, even in imperfect viewing conditions; maybe after you find M13 
you'll have an easier time visualizing what you're looking for.  A lot 
of the galaxies shown on that map are, in my opinion, tough binocular 
objects unless you find much darker skies, as are many of the fainter 
and smaller globulars.  Among the galaxies, maybe M51 is your best bet, 
if memory serves.  I think you should be able to see a small, even 
point-like, core with some diffuse glow around it, but you won't see a 
"Sky and Telescope" type picture.  A lot of open clusters like M44 also 
make great binocular objects (too BIG for most telescopes!) so that's 
another thing to look for, though I found M44 a bit challenging to 
locate in a less-than-ideal sky the first time I ever looked for it.

Another tip is that generally the sky is most transparent when you're 
looking fairly straight up.  (Too bad it often seems like you have to be 
a contortionist to look straight up while using tripod-mounted 
binoculars!)  Closer to the horizon the sky glow is much brighter, and 
there is also more chance that you're actually looking through a thin 
cloud that you haven't noticed.  It also helps to get into a position 
where there are no lights shining directly on you.  If such lights are 
around, try to get to a place where they're blocked by trees or some such.

I'm sure you can see a number of fun objects from your Weston site on a 
decent night, so I wouldn't give up on it yet.  Good luck!

-Bert


Bruce Wilson wrote:

> I'm relatively new to astronomy and was wondering if some of you more
> experienced folks could offer some advice. I went out to the Weston
> reservoir last night, hoping to see a few binocular objects (10 x 50 on a
> tripod). I could see most, but not all, of the stars in the Little 
> Dipper. I
> could identify most of the constellations in my planisphere and, of 
> course,
> Venus and Saturn. I was disappointed, however, that I could not see 
> any of
> the binocular objects such as M3 and others listed in
> http://www.skymaps.com/skymaps/tesmn0705.pdf
>
> So here's my question: was the problem suburban light pollution, poor
> seeing, or both? Or was it my technique? Do I need to travel the 55 
> minutes
> to the clubhouse to get darker skies, or was last night just poor seeing
> (despite the lack of clouds and moon) and on another night I'll be 
> able to
> see plenty from Weston?
>
> Suggestions? Thanks!
>