Pre-Discovery Optical Detections of the Apparent Nova (2014-07a?) in M31Reported in ATel #6305

ATel #6324; G. S. Stringfellow, B. Bell, N. Bremer, S. Grandone, & J. Witbrod (University of Colorado)
on 18 Jul 2014; 01:22 UT
Credential Certification: Guy S. Stringfellow (Guy.Stringfellow@Colorado.edu)

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We present pre-discovery observations confirming the presence of the object reported as an apparent nova candidate in M31 by Henze et al. (2014) in ATel #6305 based on the discovery observation made on 2014 July 08.05 UT. Our observations were conducted with the 0.5m Astrophysical Research Consortium Small Aperture Telescope (ARCSAT) located at Apache Point Observatory using the SurveyCam imaging camera. SurveyCam utilizes an Apogee U16M-HC CCD camera with 0.83" pixels for 2x2 binning and provides a ~31'x31' field-of-view.

Repeated observations of this field in M31 were obtained between 2014 July 01-05 UT. The images analyzed result from the median stack of three consecutive 200s exposures in each filter, except for 2014 July 01.409 UT for which a single 200s image was evaluated. We detect the object on multiple dates. Photometry measurements were made using the AAVSO photometry analysis package VPhot. Photometric consistency was achieved using multiple comparison and check stars, producing comparative photometry for numerous stars in the field for which photometric measurements have been previously reported, including those given in Massey et al. (2006, AJ, 131, 2478). On 2014 July 01.409 UT only an upper limit with V fainter than 18.7 is estimated from an image obtained under unfavorable weather conditions, while on 2014 July 03.393 UT the object is clearly detected at V=18.66 +/- 0.14. The object did not change markedly on subsequent dates: 2014 July 04.448 UT V=18.54 +/- 0.12, R=18.22 +/- 0.22; 2014 July 05.451 UT V=18.81 +/- 0.10, R=18.30 +/- 0.11. The object appears to display low-level variability so far as indicated by the slight fading on our final date and the subsequent observations reported in ATel #6305 that show a slight brightening at R.

Spectroscopic observations are needed to confirm this brightening event as a nova. Additional pre-discovery imaging preceding those reported herein would also help constrain the timing of this event and the nature of the object. Continued photometric monitoring is encouraged.

We thank D. Bizyaev, S. Hawley, J. Huehnerhoff, W. Ketzeback, R. McMillan, R. Owen, and C. Sayres (APO affiliations) for their efforts in developing and supporting user observing with ARCSAT.