[AZ-Observing] Re: Eridanus Goodies
- From: Andrew Cooper <acooper@xxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Wed, 28 Jan 2004 23:51:54 -0700
Ran into the same problem... Big, small, bright, dim.
All very subject to the scope, magnification and conditions. But I am
using an 18" scope, the same as Hershel used for most of his
observations. I know! speculum mirrors only reflect about 60% of the
light on a good day, with degredation as they tarnished. His scope also
had a 20 foot focal length compared to my two meters. My magnification
is comparable, I use 174x for almost all of my descriptions, compared to
WH's 157x. But our real advantage is Arizona skies, I lived in England
for three years!
One has to consider these things when you follow in the footsteps of
discovery...
Andrew
Steve Coe wrote:
>
> Joe;
>
> Over the years I have always tried to use about the same power as the
> original observations in the NGC. William Herschel used a power of 157X for
> his observations so that he would be consistent. My observations have been
> with several telescopes, so I can't be that consistent, but I can say that I
> have always made those observations at something between 100X and 200X. I
> was internally consistent with each scope. So that, with the 13 inch it was
> always at 100X, and with the new Nexstar 11 inch it has been at 125X, same
> as with my old 17.5 inch Dobsonian.
>
> I know it is an opinion, but it seems to be a pretty repeatable opinion and
> I have found it to be helpful as a method of being able to compare my
> observations to previous observers.
>
> Hope that helps;
> Steve Coe
>
> Author "Deep Sky Observing--The Astronomical Tourist"
> Saguaro Astronomy Club website
> www.saguaroastro.org
>
> --
> See message header for info on list archives or unsubscribing, and please
> send personal replies to the author, not the list.
--
Andrew Cooper
Tucson, AZ
mailto:acooper@xxxxxxxxx
http://www.whitethornhouse.com
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