Photometric calibration of the Swift ultraviolet/optical telescope

Poole T. S., Breeveld A. A., Page M. J., Landsman W., Holland S. T., Roming P., ...More

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.383, no.2, pp.627-645, 2008 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 383 Issue: 2
  • Publication Date: 2008
  • Doi Number: 10.1111/j.1365-2966.2007.12563.x
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.627-645
  • Keywords: instrumentation : photometers, techniques : photometric, ultraviolet : general, STANDARD STARS, UBV
  • Istanbul University Affiliated: Yes


We present the photometric calibration of the Swift Ultraviolet/Optical Telescope (UVOT) which includes: optimum photometric and background apertures, effective area curves, colour transformations, conversion factors for count rates to flux and the photometric zero-points (which are accurate to better than 4 per cent) for each of the seven UVOT broad-band filters. The calibration was performed with observations of standard stars and standard star fields that represent a wide range of spectral star types. The calibration results include the position-dependent uniformity, and instrument response over the 1600-8000 angstrom operational range. Because the UVOT is a photon-counting instrument, we also discuss the effect of coincidence loss on the calibration results. We provide practical guidelines for using the calibration in UVOT data analysis. The results presented here supersede previous calibration results.