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Title: Difference image analysis of defocused observations with CSTAR

The Chinese Small Telescope ARray carried out high-cadence time-series observations of 27 square degrees centered on the South Celestial Pole during the Antarctic winter seasons of 2008–2010. Aperture photometry of the 2008 and 2010 i-band images resulted in the discovery of over 200 variable stars. Yearly servicing left the array defocused for the 2009 winter season, during which the system also suffered from intermittent frosting and power failures. Despite these technical issues, nearly 800,000 useful images were obtained using g, r, and clear filters. We developed a combination of difference imaging and aperture photometry to compensate for the highly crowded, blended, and defocused frames. We present details of this approach, which may be useful for the analysis of time-series data from other small-aperture telescopes regardless of their image quality. Using this approach, we were able to recover 68 previously known variables and detected variability in 37 additional objects. We also have determined the observing statistics for Dome A during the 2009 winter season; we find the extinction due to clouds to be less than 0.1 and 0.4 mag for 40% and 63% of the dark time, respectively.
Authors:
; ;  [1] ; ; ;  [2] ; ; ; ; ; ;  [3] ; ;  [4] ;  [5] ;  [6]
  1. George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy Texas A and M University, College Station, TX 77843 (United States)
  2. School of Physics, University of New South Wales, NSW (Australia)
  3. Chinese Center for Antarctic Astronomy, Nanjing (China)
  4. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing (China)
  5. Institute of Nuclear and Particle Astrophysics, Lawrence Berkeley National Laboratory, Berkely, CA (United States)
  6. Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, Chicago, IL (United States)
Publication Date:
OSTI Identifier:
22342131
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 149; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANTARCTIC REGIONS; APERTURES; DATA ANALYSIS; FAILURES; FILTERS; IMAGE PROCESSING; IMAGES; PHOTOMETRY; SEASONS; TELESCOPES; VARIABLE STARS