Resources: Van Allen Observatory Webpage Equipment Page

The CCD camera used on the Van Allen Observatory is shown. It is red and black and has a rectangular shape and a number of ports for wiring to attach. Inside, the pixels of the CCD camera can be seen.
The CCD camera on the VAO, a Santa Barbara Instrument Group (SBIG) STXL-6303E

Astronomers rarely look through the eyepiece of a telescope anymore when observing the sky for research. Research telescopes use electronic sensors called CCDs (charged coupled devices) to record the image coming in through a telescope's optics. The CCD in a telescope camera works a lot like photographic film: a shutter in the camera opens to expose the surface of the chip to light from space. The longer the chip is exposed, the more light builds up. If too long an exposure is used on a very bright object, the chip will be overexposed and the resulting image will not be usable.

Bright objects such as individual stars (point sources) and planets need only short exposure times of fractions of a second or seconds at most in broad-band RGB filters. Very dim, extended objects require long exposure times to see. Objects such as nebulae, planetary nebulae, and galaxies require many seconds or a few minutes of exposure time in RGB filters. When needing very long exposures, its often better to take multiple shorter images and average the images together later; very long exposures run the risk of encountering errors with poor telescope tracking of the object as the Earth turns. Finally, consider the filters you've chosen to pick your exposure time and number of images: remember that filters block light, and narrow-band filters block a lot of light (all but a few wavelengths), only letting a little light through the telescope optics. You'll need to adjust your exposure times and number of images accordingly.

Exposure_Times

Exposure Time Examples for RLMT/VAO
 

broadband

 

narrowband

* A longer exposure time will saturate the camera and should not be attempted (the camera will have reached its maximum recording ability and more light collection will not improve the image)