Difference image analysis of defocused observations with CSTAR

Journal Article · Sun Feb 01 00:00:00 EST 2015 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/149/2/50· OSTI ID:22342131

Oelkers, Ryan J.; Macri, Lucas M.; Wang, Lifan ^[1]; Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel ^[2]; Cui, Xiangqun; Gong, Xuefei; Qiang, Liu; Yang, Huigen; Yuan, Xiangyan; Zhou, Xu ^[3]; Feng, Long-Long; Zhu, Zhenxi ^[4]; Pennypacker, Carl R. ^[5]

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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)

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.

• OSTI ID: 22342131
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 149, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANTARCTIC REGIONS
APERTURES
DATA ANALYSIS
FAILURES
FILTERS
IMAGE PROCESSING
IMAGES
PHOTOMETRY
SEASONS
TELESCOPES
VARIABLE STARS