TY - JOUR
T1 - Difference image analysis of defocused observations with CSTAR
AU - Oelkers, Ryan J.
AU - Macri, Lucas M.
AU - Wang, Lifan
AU - Ashley, Michael C.B.
AU - Cui, Xiangqun
AU - Feng, Long Long
AU - Gong, Xuefei
AU - Lawrence, Jon S.
AU - Qiang, Liu
AU - Luong-Van, Daniel
AU - Pennypacker, Carl R.
AU - Yang, Huigen
AU - Yuan, Xiangyan
AU - York, Donald G.
AU - Zhou, X. U.
AU - Zhu, Zhenxi
PY - 2015/2/1
Y1 - 2015/2/1
N2 - 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.
AB - 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.
KW - Methods: data analysis
KW - Stars: variables: general
UR - http://www.scopus.com/inward/record.url?scp=84922496124&partnerID=8YFLogxK
U2 - 10.1088/0004-6256/149/2/50
DO - 10.1088/0004-6256/149/2/50
M3 - Article
AN - SCOPUS:84922496124
VL - 149
SP - 1
EP - 13
JO - Astronomical Journal
JF - Astronomical Journal
SN - 0004-6256
IS - 2
M1 - 50
ER -