CSS 212625+201948: when is the next superoutburst?

Jeremy Shears

I have begun the analysis of the CSS photometry data from the campaign, so I thought a quick update might be helpful. We have 6552 data points from the BAA VSS, AAVSO and CRTS databases, covering the 2013 and the 2014 observing seasons. You can view the 100-day plots for the recent season (data up to 2015 Jan 2) here: http://www.britastro.org/vss/CSS%20plots%202014.pdf

The red dashes are “fainter than” measurements. The blue data are CV or V.

You can see that coverage got better as the campaign took off. The light curve is typical of an SU Uma system (not an ER UMa as once postulated) with frequent outbursts and in my mind is quite beautiful. There are 4 superoutbursts visible, plus many normal outbursts. Analysing the superoutburst times gives a fairly consistent ephemeris, with a period of 66.4 days, taking into account the 4 supers in 2014 and an additional 2 in 2013; or 68.7 days if I only include the 2014 supers. Of course, superoutbursts are only quasi-periodic and it is a mug’s game to try and predict the next. But for a bit of New Year fun I’ll have a go anyway: sometime between Jan 18 and Jan 25, depending on several assumptions – most likely around Jan 23 if I were a betting man. You heard it here first, as they say….

However, given the field is slipping into the west, it will be a challenge to spot the next superoutburst, but it would be fun to try – and would help to update the ephemeris before the seasonal gap. So single shot imaging of the field would be helpful (as would short photometry to look for confirmatory superhumps). The supers last about 13 days.

Of course, this analysis makes use of the hard-won data submitted by many observers – hats off to them! I have used data kindly contributed by: David Boyd, James Boardman, Juan-Luis Gonzalez Carballo, Ian Miller, Ken Menzies, Roger Pickard, Gary Poyner, Richard Sabo, Pavol Dubovsky, Richard Sargent and Denis Buczynski. If you have observed this star and your name is not listed, please contact me as it probably means I have not seen your data.

Good luck and go well! Jeremy