Re: [APML] Measuring Sky Background With an ST-4

["Rick Kellogg" <rkellog1@twcny.rr.com>]

If you want a method to measure the night sky brightness with absolute
accuracy, check out:

http://debora.pd.astro.it/cinzano/en/sbeam2.html

This method is rather involved, and is likely to be more trouble than most
are willing to do.

Rick Kellogg


----- Original Message -----
From: <Aplanatic@aol.com>
To: <astro-photo@seds.org>
Sent: Wednesday, February 25, 2004 6:34 PM
Subject: Re: [APML] Measuring Sky Background With an ST-4


> Hello Jim, Chuck and Geoff.
>
> Geoff found the link (thanks), see below.
>
> Chuck writes:
>
> >Yes I remember it but I don't remember the procedure. It's in the
> >archives somewhere but I know things can sometimes be hard to find.
> >Dave Rowe was the author but I remember him stating at some later date
> >that he didn't think it was as good of a method as he originally
> >thought. Where is Dave these days?
>
> The method works fine, I think, and I still use it from time to time to
> evaluate the darkness of a site.  As long as the same camera is used to
make the
> evaluation, relative results can be compared to each other with reasonable
> accuracy.
>
> The problem occurs when different cameras are used, or absolute accuracy
is
> desired.  Over the years I've had the opportunity to measure a few ST-4's
> side-by-side with my own and have found that they differ by as much as
0.75
> magnitude.  Unfortunately, this limits the usefulness of the test to
"pretty rough,"
> unless a calibration is performed with each individual camera.
>
> I made such a calibration with my own ST-4 under several different sky
> conditions, at several different locations.  This allowed me to calibrate
the ST-4
> to within about 0.25 magnitudes, which I consider to be quite good for
such a
> simple method.  To make the calibration, the local sky background must be
> measured by stellar photometry, a science that is both interesting and
involved in
> its own right.
>
> Dave Rowe
>
> > Jim writes:
> >  > Could not find this in the archives so I thought I would see if some
of
> > the
> >  > long time members remember this.  A thread was done some time ago
> > regarding
> >  > measuring sky background with an ST-4.  Does anyone remember this and
> does
> >  > the information still exist somewhere?
> >
> >   Hey Jim...
> >
> >       Try this link:
> >           http://astro.umsystem.edu/apml/ARCHIVES/JAN01/msg01405.html
> >
> >   Best...
> >
> >  --
> >   Geoff Powers
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