[vsnet-chat 3980] (fwd) Suggestions (re: QX Pup)

[Taichi Kato <tkato>]

(fwd) Suggestions (re: QX Pup)

From: "Thomas M. Bisque" <thomas@bisque.com>
Subject: Suggestions
Date: Tue, 16 Jan 2001 10:32:24 -0700

If you wish to come to a better conclusion as to what the object on the CCD
image is it is always best to have several images (at least two) of the
object since one image is rarely conclusive.  Also, just moving the
telescope slightly and then re-imaging can often times either make the
object disappear or move it to another part of the image indicating an
internal reflection or problem with the system.  If the object is not on the
second image you also know it was an artifact, i.e. cosmic ray hit, etc.

Another option is to take out the focal reducer and re-image the same field
again on a second night you will have your answer as to whether or not the
object is real or simply an artifact.  Note that it is very common to find
objects on your images that are not cataloged and or objects that are
cataloged incorrectly.  The nebula in the middle of M46 is an example.  The
coordinates for the planetary nebula are quite far off from its' actual
position and the GSC star in the middle is actually the nebula itself
interpreted incorrectly and cataloged as GSC 5422:587 at 6.2 magnitude!
Using TheSky you can actually create your own entry for an object after
linking in the CCD image by using our catalog creating tool.  The tool
allows you to place a moveable and sizeable circle that can be scaled and
rotated to match the object more precisely.  When finished you have a new
catalog entry for the object that more closely resembles the real data.  The
18 CD-ROMS of RealSky compressed Palomar data from the Astronomical Society
of the Pacific can also be used for this and for identifying objects on your
own CCD images,
	http://vsnet.bisque.com/thesky/tom/  

Another thing.  You need to be careful when comparing CCD images to the
Palomar plates.  The CCD camera is very sensitive in the Red and this will
often bias the magnitude of stars making them appear much brighter since the
plates were taken using film.  I have seen many images where people assumed
the bright star had to be a new variable since it was several magnitudes
brighter on their image when compared to the Palomar data.  In this case
several images using different wavelength filters would have answered the
question but taking images using photometric filters is always a lot more
work.

We were able to create a catalog of 3,000 galaxies which we could not find
on any other source when using TheSky linked to the 102 CD-ROM's of the
Palomar Sky Survey.  Attached is your CCD image embedded within TheSky
astronomy software identifying the objects on the image based on the stellar
and non-stellar catalogs present.  You will see the NGC catalog says the
nebula is versus the real position on the CCD image.
 <<m46.jpg>> 
Additional information on this type of catalog issue was covered in article
in Sky & Telescope magazine and a reprint can be read on-line here,
	http://vsnet.bisque.com/thesky/tom/catalogs.htm
If you are interested in an evaluation copy of TheSky which includes
complete telescope control for the LX-200 let me know and I can send you
one.  Also, when you find out what the object is I would like to know what
it turns out to be (or not to be)!

(image omitted)

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