Changes
SHOC
,/* Introduction */
== Introduction ==
The SHOC systems consist of a filterwheel unit (with one or two filterwheels), a GPS unit for providing accurate timing triggers, an Andor iXon camera, and a control PC. Currently there are 2 full SHOC systems (shocnawe & shocndisbelief), and 1 development system running a different camera (shocnhorror). As of March 2015, the control software is web-based. Users point their browser to the instrument location, and separate tabs appear to allow control of the camera, GPS, and filter wheel. SHOC can be mounted on the 1.9- and , 1-m and Lesedi telescopes. We have tried to make the usage telescope specific, but it is very useful to know which SHOC instrument is mounted on the telescope you are using. Details on instrument operation are below.
The [http://shoc.saao.ac.za SHOC website] may well have more extensive detail about this instrument.
* '''CONSIDER DECREASING DETECTOR TEMPERATURE IF TAKING LONG EXPOSURES''' Reports in 2016 indicated that the dark current is higher than expected (by a factor of ~ 100; more information to follow). This is most noticeable for long (>=10 minute) exposures. The camera is automatically cooled to -50C. It can be cooled down to -70 C; however, if the ambient temperature is high, the cooler will be stressed and cannot reach minimum temperatures. If you do adjust the temperature to -60, -65 or -70, please listen carefully so that if the temperature alarm triggers (a high-pitched, continuous beep) you can stop cooling and prevent hardware failure. March 2017
* '''THE NEW SOFTWARE HAS DIFFERENT FILE NAMES AND HEADER KEYWORDS THAN PREVIOUS DATA.''' If you use this information in your analyses, you will have to update it. The filename format has been standardized to <Instrument>_YYYYMMDD.####.fits, where the instrument is sha (shocnawe), shd (shocndisbelief), or SHH to designate which SHOC box is being used. Please check the header of a new data file or the wiki [http://topswiki.saao.ac.za/index.php/SHOC#FITS_Header_Keywords FITS header keywords] (the "new" keywords are directly from the Andor iXon camera under Linux). March 2015
* '''THE FILE SIZE IS NO LONGER LIMITED TO 2 GB. ''' This means that if you take large data cubes, the file size has ''no limit'' (this is because we are no longer on a Window-based, 32-bit, operating system). If you end up with a very large file, data analysis can be difficult. We are working on an efficient method to automatically split files into smaller sizes, but for now users need to be aware that requesting a large number of images in one file could return a very large file size (and if you mistakenly delete your file, you have lost alot of work!). It is recommended that multiple files be manually taken. ''If you have any questions or problems with the data, feel free to contact carel@ saao.ac.za or amanda@ saao.ac.za.'' March 2015
== Change Log ==
