Re: Celestron Plate Solving Demo

Lew Cook
 

The following file types are supported:
  • JPEG, GIF, PNG, or FITS image
  • FITS binary table, containing a BINTABLE of detected objects, with X and Y pixel positions in "D" (double) or "E" (float) columns, with one object per row
  • text list, containing two columns of digits separated by commas or white space, listing the X,Y positions of sources, sorted with the brightest sources first
  • tarball (.tar, .gz), containing files of any of the above types
Advantages:
1) It is free (run by the Canadian gov't and the US NSF)
2) you can download a WCS solved image
3) it's fast - they advertise return of the solution within 10 minutes, but I find it to be much faster - like 45 seconds
4) you don't have to tell it where in the sky you are looking (if you do, it is ignored)
5) You get the plate scale (arc sec per pixel) and dimensions of the image (x arc min wide, y arc min height
6) Raw images are just fine (no need to dark subtract or flat field)

BUT:

1) There are limits on the size of input: the image must be larger than 0.1 degree and smaller than 180 degrees.
2) The service isn't always available - only about 95% - 98% up time.

Here's a small section of the output for an image I sent in:
Center (RA, hms):11h 43m 50.188s
Center (Dec, dms):+71° 45' 27.483"
Size:25.9 x 25.9 arcmin
Radius:0.305 deg
Pixel scale:1.52 arcsec/pixel
Orientation:Up is 179 degrees E of N
You get your image displayed with the HD and Tycho stars identified - and the identification of NGC objects. You also get a .kmz image for displaying in Google Sky.

Lewis M. Cook (Lew)

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