VHS Proposal Preparations Zone

VISTA material

Quite an old page with many broken links
  • VISTA Home Page
  • VISTA Science Committee Home Page
  • IOA VISTA Science Committee Resources

    Site Characteristic and Sky Brightness Resources

    High redshift quasars and VISTA

    Survey Power comparison

    IR survey modes

    Standare Dither and Stare

    2MASS scanning

    During survey data-taking the telescope moves continuously in declination at approximately 57/second, while tracking in hour angle at the sidereal rate. The articulated secondary executes a sawtooth pattern of motion which freezes the image of the sky on the focal plane during the frame exposures. The shift between consecutive images is 1/6 of the array width. The arrays are aligned to that subpixel steeping is obtained via this geometric tilt. Each region of sky is observed for 1.3 secsonds with an elaped time of 1.445 secs. This the total exposure is 7.8 seconds. The reported observing efficiency is 85% including all overheads.

    DENIS scanning

    The survey is carried out by observing strips of 30 degrees in declination and 12 arcminutes in Right Ascension with an overlap of 2 arcminutes between consecutive strips. Dithering is via a microscanning mirror. Each expsoures is 1 sec and there are 9 dithers with a shift of 1/3 pixel in RA and 7/3 pixels in Dec. Thus the total travel is 3 pixels by 21pixels or 9arcsecs by 63arcsecs.

    Drift Scanning

    Cambridge Astronomy Homepage | Richard McMahon' Homepage

    Richard McMahon, rgm@ast.cam.ac.uk
    Last modified: Sun Mar 12 10:59:40 2006