The Celestron Pixcel 237 CCD
This CCD is similar to the StarLight Xpress HX516 CCD which is discussed elsewhere on this web site. The physical architecture is similar to the SBIG ST-5C with the added feature of a built-in fan. This fan can be turned on or off through the software. All in all, not a bad entry level CCD. Most of my astrometry images (see astrometry section), to date, were taken with this CCD coupled to my 8" SCT (an old orange-tube Celestron Schmidt-Cassegrain - vintage 1976). For color work an optional color wheel can be added. I haven't tried this as astrometry takes up most of my observing time.
Some of the later images (April 1st, 2000 onwards) were taken throught the 8" OTA mounted on my new Astro-Physics 600E GOTO mount. Prior to April 1st, 2000, for CCDing, the Astro-Physics non-GOTO mount was used (July 1998 until March 2000) The 8" was used either at F/4.7 or F/3.7 with an SBIG focal reducer, or in a few instances using an old Celestron focal reducer it was used at F/5.0. With all these combinations there is some vignetting, especially with the Pixcel 237 CCD, and poor star images around the edge. (I have used the Celestron F/6.3 focal reducer but the results were even worse.) Attempts to flat-field out this vignetting gave poor results.
Below are a few images taken with the 8" SCT, with a couple taken through my 6" F/10 Maksutov-Cassegrain (ARO Instruments - Signature Series - vintage 1993). For CCD imaging this scope works well at F/5.0 using the older Celestron focal reducer. With this OTA I didn't find any advantage in using the Celestron F/6.3 focal reducer.
To show what a small telescope
can do, with this fine entry level CCD, I've also added a couple of images
taken with my 4" Televue Genesis SDF F/5.4 refractor.
For additional Supernovae images: Click
here