ING Banner
Home > Astronomy > ACAM > ACAM known problems

ACAM known problems / features

This is an occasionally-updated summary list of common problems / features which may be encountered when observing with ACAM. The links guide the reader to more detailed information in the main ACAM web pages.

Imaging - filters and adaptors

Imaging - PSFs

Imaging - background light

Imaging - other



  • Target not visible - possible causes are bad telescope pointing (ask the operator to point the WHT to a star of known position) or something blocking the light path (see below).
  • Not enough photons - possible causes are clouds / dust, dome not aligned with telescope, mirror petals not fully open, A&G flat mirror not correctly positioned, use of a filter with poor throughput (or ND filters left in light path of calibration lamp), incorrect assumed object magnitude (or calibration lamp off, or failed), CCD gain (detected photons per count) not taken into account. Try imaging a photometric standard, using SIGNAL to calculate how many counts are expected.
  • CCD not responding correctly - try dasreset acam . You'll need to reset the readout window (and speed and binning) afterwards.

Top | Back

Contact:  (ACAM Instrument Specialist)
Last modified: 21 January 2011