CIRPASS test observations - 24th Jan 2002

The telescope was set up in the CIRPASS lab looking out of a window at the region near the north celestial pole. This was done for several reasons:
  • To avoid the time-consuming process of setting up the telescope on the road and returning it all back to lab at the end of night
  • To avoid cyclists who like to cycle over our cables
  • To prevent the celestron from dewing up
  • To avoid being directly illuminated by the security light

  • The security light was still producing a considerable unwanted background so we came to an arrangement with the security company and switched it off. Observing through the lab window severely limits what we can look at but for testing there are plenty of suitable stars in the small region we can get at. We aim to get to 11th magnitude or so but to begin with we started with the brightest star accessible - Polaris

    Observations were done from 11pm to 5am. We mainly used the time to accurately align the field of view of the finder, the guide scope and the IFU. Most of the observations were of Polaris.

    Data obtained

    The IFU image below shows a beam-switch on Polaris. In each position the exposure time was 5 minutes.

    The spectral image is shown below

    and the extracted spectrum:

    Temperature Stability

    Preliminary measurements of the temperature stability of the system were made, using the position of the OH sky lines as a reference. Initial results suggest that the position of an OH sky line on the detector remains fixed to an accuracy of better than 0.04 pixels. This was measured for 2 1/2 hours of data and we intend to extend the result to the entire night next time we observe.

    Andrew J Dean <>
    Ian Parry  <>

    Last modified: Tue Jan 29 11:41:49 2002