arXiv subjects
Publications and source records attributed to Jeremy Shears.
During 2006 November an outburst of the dwarf nova AW Sge was observed using CCD photometry. This revealed 0.25 magnitude superhumps confirming it to be a superoutburst, possibly only the second confirmed such outburst of this star. The superhumps were observed for 4 days and had a stable period Psh = 0.0745(2)d, a value which is consistent with Psh measured during the 2000 superoutburst.
During 2006 March the first confirmed superoutburst of the dwarf nova SDSS J080434.20+510349.2 was observed using unfiltered CCD photometry. Time-series photometry revealed superhumps with a period of 0.0597 +/- 0.0011 d and an amplitude of 0.2 magnitude, thereby independently establishing its UGSU classification. Following the decline from a peak magnitude of 13.1, at least two rebrightening events were observed. Evidence is presented which is consistent with the star being a member of the UGWZ sub-class.
During 2006 May the first confirmed superoutburst of the dwarf nova V337 Cygni was observed using unfiltered CCD photometry. The outburst reached a peak magnitude of 15.2 on May 22 and lasted 13 days before the object returned to quiescence at around magnitude 20. Time-series photometry revealed superhumps with a period of 0.07012 +/- 0.00033d and amplitude 0.1 magnitude, thereby establishing for the first time its UGSU classification. Astrometry of V337 Cyg in outburst determined an accurate position and enabled the identity of the star in quiescence to be confirmed.
Nova Lyrae was discovered at the Harvard College Observatory on 1919 December 6 at magnitude 6.5. We present a lightcurve for this nova based on published and archival observations. This was a classical fast nova, probably of type B. Decline times were t2 = 31 or 47d, depending on the method used, and t3 = 97d. The amplitude was at least 9.5 magnitudes. Based on our t2 values, we estimate that the absolute magnitude at maximum was -6.9 or -7.2 (+ or -1.1) and at minimum is +2.3 or +2.6 (+ or - 1.1). The star shows an active quiescence with brightness variations on a variety of timescales. Visual observations over a period of ten years also reveal long periods when the star was around 15.4v and others when it was close to 15.7v. Finally, we point out that some characteristics of the star are similar to those of recurrent novae and propose further monitoring of future activity.
The dwarf nova CG Dra was intensively monitored during 2005 as part of the Variable Star Sections Recurrent Objects Programme and seven outbursts were detected. These observations were combined with others from the BAA and AAVSO databases which confirmed that the star shows frequent outbursts with a period of around 11 days. Two types of outburst have been detected. Short outbursts lasting about 4 days and long outbursts lasting about 8 days.
We report new measurements of the superhump period of the UGSU-type dwarf nova V701 Tau during the 2005 December superoutburst. Using unfiltered time series CCD observations on 3 nights, we determine a probable superhump period Psh = 0.0690, plus or minus 0.0002d, but note that our data also permit a possible shorter period of 0.0663, plus or minus 0.0002d. The longer period agrees with the value measured during the first recorded superoutburst in 1995.
1RXS J053234.9+624755 is a recently discovered dwarf nova. We present CCD and visual photometry during March 2005 of the first ever observed superoutburst in this system
Several brief outbursts were detected in the dwarf nova V1316 Cyg during 2005. These events have an average amplitude of 1.4 magnitude and a duration of <1 to 2 days. Whilst no outburst period could be confirmed, the shortest period between detected events is 10 days. These curious brief outbursts appear to be the normal pattern of behaviour for this system. They are of smaller amplitude and shorter duration than normal outbursts previously reported in this star. V1316 Cyg appears to be a very unusual system and we suggest that further observations by both amateur and professional astronomers could yield important information about the underlying mechanism.