Re: Can't Find An Object.

nicolaslefau2 Dec 10, 2006

hi Mike.

it would be really good if you could tell us were this is.
many strange things can happen while imaging.

as you use a refractor, a ghost reflection (two internal reflections
on the optical surfaces) could be the source of the "nebula".

these ghost images generally require a "bright" star nearby (a
bright star can be a mv10 star if you have a very deep image). is
there such a star in the area?

does the "nebula" show features inside? a ghost reflection is
generally featureless. if there is a "bright" star close it could
also be caused by diffractive structure in your setup. theses
diffractions sometime show radial structures.
it would very interesting that you check that using for example
another optical setup or shifting your field of view to see if
the "nebula" has the same motion that the background sky. ghost
reflections often move the opposite way that the star whereas
diffraction artifacts move with the backgroung sky.

if it moves the same way as the background stars and if you can
image it with a different setup, then you might have found something

good luck

nicolas lefaudeux

--- In guide-user@yahoogroups.com, "Mike Holloway"
<HollowayCometObs@...> wrote:
>
> Thanks. No sir no filters were used. 22x60 sec exposures showed
an
> area which covers my aprox 1' image and would have been much
larger. I
> will post this as soon as I figure out or someone points out what
this
> is. It may be part of something larger which I do not find in the
area
> and is very faint but big. Thanks for your time
> Mike
>
> --- In guide-user@yahoogroups.com, "H.Luethen" <h.luethen@> wrote:
> >
> >
> >
> > Did you use an IR-block filter with your CCD? If not a very red
star
> (eg
> > Mira type) may look like a nebula or faint comet on a CCD image.
> >
> >
> > Hartwig
> >
>