The Dual CCD ST-9XE and Single CCD ST-9XEI

The Model ST-9XE is a dual sensor, self-guiding CCD camera made for users with longer focal lengths who may want a larger CCD but don't need a megapixel for their application. The ST-9XE is perfect for such things as astrometry and supernova searches with larger telescopes. It uses a Class 1  CCD with high QE and no column defects. It includes the built-in TC-237H tracking CCD, Remote Guiding Head Port, custom carrying case, water cooling heat exchanger, relay adapter plug, relay cables for self-guiding, and extra software.

The ST-9XEI is the single sensor version with no internal guiding CCD, however it does include the Remote Guiding Head Port for attachment of an optional external guiding head at any time. The imaging CCD is also a Class 1 KAF-0261E with no column defects. Like the ST-7XEI, this single CCD version is an ideal way to get started with a professional quality camera at a reasonable price or for anyone who may already have a guiding solution such as the STV or another CCD camera. It is also an excellent TDI imager. For more details see Alan Holme's recent PDF application note on the subject of TDI imaging with the ST-7XMEI or ST-9XEI cameras. A TC-237H tracking CCD, water cooling and custom case may also be added at any time.

The ST-9XE has been a successful camera in its own right among those seeking a large field of view and high sensitivity at a relatively low cost for minor planet and supernova searches with long focal length telescopes. The ST-9XE and ST-9XEI cameras use the KAF-0261E CCD from Kodak with 512 x 512 pixels at 20 microns. The area of the array is about 80% the size of the more expensive ST-8XE and 330% the size of the array used in the ST-7XME.

When the ST-9E camera was introduced, the first images received were from two amateurs, Gary Hug and Graham Bell, who discovered a ~19th magnitude comet: Comet P/1999 X1 Hug-Bell. At that time, with a single exception, we are informed that this is the faintest comet ever discovered by an amateur astronomer. Gary and Graham were using a SCT at f/6.3. The discovery was made while blinking 6 minute exposures taken in search of an asteroid. Subsequent 10 minute and 20 minute exposures revealed the comet's tail. Recently we were informed that UK amateur, Mark Armstrong, has discovered no less than 40 supernova using three ST-9E cameras!

TDI (Time Delay Integration, or Drift Scan imaging) is particularly interesting because one can image large areas of the sky without guiding so any telescope will do. Basically, one points the camera at an area of sky and turns off the telescope drive to let the stars drift across the field of view. The CCD is clocked in sync with the rate of drift and the resulting image has an exposure time equal to the amount of time it takes the stars to drift across the CCD. Depending on the focal length of the scope this can be many minutes. But there is no periodic error and no guiding error! Furthermore the image can just scroll as the sky moves past so the image file can be 512 x 1000 or 512 x 2000 etc. One gets a deeper image with a more sensitive CCD. In the case of the ST-9XEI the large pixels make it quite sensitive to extended objects and very good wide field astro images can be created with no tracking at all.