Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-09T09:47:59.319Z Has data issue: false hasContentIssue false
  • English
  • Français

Calibration of Photometry from the Gemini Multi-Object Spectrograph on Gemini North

Published online by Cambridge University Press:  05 March 2013

Inger Jørgensen
Inger Jørgensen*
Affiliation:
Gemini Observatory, 670 N. A'ohoku Pl., Hilo, HI 96720, USA. Email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

All available observations of photometric standard stars obtained with the Gemini Multi-Object Spectrograph at Gemini North in the period from August 2001 to December 2003 have been used to establish the calibrations for photometry obtained with the instrument. The calibrations presented in this paper are based on significantly more photometric standard star observations than usually used by the individual users. Nightly photometric zero points as well as color terms are determined. The color terms are expected to be valid for all observations taken prior to UT 2004 November 21 at which time the Gemini North primary mirror was coated with silver instead of aluminium. While the nightly zero points are accurate to 0.02 mag or better (random errors), the accuracy of the calibrations is limited by systematic errors from so-called ‘sky concentration’, an effect seen in all focal reducer instruments. We conclude that an accuracy of 0.035 to 0.05 mag can be achieved by using calibrations derived in this paper. The color terms are strongest for very red objects, e.g. for objects with (r′ – z′) = 3.0 the resulting z′ magnitudes will be ≈0.35 mag too bright if the color term is ignored. The calibrations are of importance to the large Gemini user community with data obtained prior to UT 2004 November 21, as well as future users of achive data from this period in time.

Keywords

techniques: photometricmethods: data analysis
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 26 , Issue 1 , 2009 , pp. 17 - 30
Copyright
Copyright © Astronomical Society of Australia 2009

References

Adelman-McCarthy, J. K. et al., 2008, ApJS, 175, 297 Google Scholar
Andersen, M. I., Freyhammer, L. & Storm, J., 1995, in ESO Conf. Proc. 53, Calibrating and understanding HST and ESO instruments, Ed. Benvenuti, P. (Garching: ESO), 87 Google Scholar
Evans, D. W., Irwin, M. J. & Helmer, L., 2002, A&A, 395, 347 Google Scholar
Fan, X., 1999, AJ, 117, 2528 Google Scholar
Hook, I., Jørgensen, I., Allington-Smith, J. R., Davies, R. L., Metcalfe, N., Murowinski, R. G. & Crampton, D., 2004, PASP, 116, 425 Google Scholar
Landolt, A. U., 1992, AJ, 104, 340 Google Scholar
Lewis, J. R., Bunclark, P. S., Irwin, M. J., McMahon, R. G. & Walton, N. A., 2000, in ASPCS 216, Astronomical Data Analysis Software and Systems IX, Eds. Manset, N., Viellet, C. & Crabtree, D., 415 Google Scholar
Monet, D. et al., 1996, USNO-A2.0 (U. S. Naval Observatory, Washington, DC)Google Scholar
Murowinski, R. et al., 2003, SPIE, 4841, 1440 Google Scholar
Ryder, S. D., Murrowood, C. E. & Stathakis, R. A., 2006, MNRAS, 369, L32 Google Scholar
Smith, J. A. et al., 2002, AJ, 123, 2121 CrossRefGoogle Scholar
Trujillo, I., Aguerri, J. A. L., Cepa, J. & Gutiérrez, C. M., 2001, MNRAS, 328, 977 Google Scholar