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One SBIG upgrade from the ST-4 is the ST-6. The ST-6
utilizes a Texas Instrument TC241 chip. This is an array of 375
by 242 pixels each 23
m by 27
m. The components of the
ST-6 system are similar to the ST-4. There is a CPU box, camera
head, and the same relay box. This system also uses a motorized
filter wheel made by Compuscope. The filter wheel contains BVRI
Bessel filters and a clear filter. (See Appendix III for the
response curves of the filters.) The TEC for this camera head is
similar in operation to that of the Lynxx, however the ST-6
allows the temperature to be set. The ST-6 is usually set at
-35
Celsius at Mt. Stony Brook Observatory.
The ST-6 is capable of simultaneous data acquisition and guiding. Used together with the ST-4, longer uninterrupted exposures are possible. The uninterrupted exposures will reduce read out noise since only one read-down occurs. This makes simultaneous use the preferred method of operation; however it is too cumbersome for regular use. A function in the software allows the operator to combine several short exposures to create a composite image. The basic idea of the track and accumulate function is to take a short image, and then chose a star for the telescope to track on. The software will take short exposures and move the telescope to keep the star in the same region of the chip. Another image is taken, and the two images are aligned. This is the main data collection method. The track and accumulate function allows very deep exposures to be made. A 60-second exposure of a star forming region in Aurigae contained a 18th magnitude object in the infrared. The maximum magnitude detected by the Lynxx was 16th magnitude in 600 seconds. The ST-6 does not have a physical shutter. Instead of a physical shutter, an electronic shutter is used in conjunction with a vane. This can lead to short images not being exposed uniformly.