joe -------- Original Message -------- Subject: (cba:chat) NSV 1436: an interesting target Date: Sat, 7 Jan 2012 23:16:42 +0100 From: Enrique de Miguel <edmiguel63@xxxxxxxxx> Reply-To: cba-chat@xxxxxxxxxxx To: cba-chat@xxxxxxxxxxx Hi all, I would like to call your attention on this target (NSV 1436, at 04:02:39.02 +42:50:46.0). I think we have a good chance now to unveil some of the mysteries hidden by this system. Some background .... A bright outburst was registered (E. Muyllaert) by the end of March 2011. We managed to get some time series, but the target was not particularly well placed and it was dropped from our target list, as it didn't seem to show any interesting feature at the time, appart from low-amplitude oscillations. Tom also reported a single time series on Oct 12, but the light curve was equally dull (maybe we have further data in the CBA archive, but I haven't checked). Further information about this interesting target can be found in the AAVSO Alert Notice 434, reported by Matthew Templeton on March 30, 2011. From that note, one can learn that the only bright outburst of this system was around 1948 (some other less bright outbursts seem to have occurred since). This is a known X-ray source, and a recent paper (Brown et al., 2010, JAAVSO 38, 176) points to the possibility of NSV 1436 being a recurrent nova (further historical details in that paper). Basically, it looks like we don't know what type of DN this is. Tom reported last January 2 through the cba-chat that Mike Linnolt had just registered a new bright outburst (visually, at 12.4V). We started inmediate follow-up of this target (Tom, Shawn, and myself). The first 3 nights were a bit dissapointing: one could guess the presence of high-frequency oscillations, but difficult to tell about their stability. These oscillations were of low amplitude (0.03-0.05 mag) on top of rapidly decay trend of about 0.8-0.9 per day: apparently, as dull as the light curves we registered some months ago. However, the system entered on January 5 into an interesting state, with very large oscillations (full amplitude of ~0.8 mag). Some plots are shown below. From the data we have collected so far (Tom, Shawn, and myself) it seems that we can unveil the orbital period of the system, which is 0.189(3) d. On top of the nightly light curves, one can easily observe high-frequency oscillations. From the limited data we have collected so far, the main oscillations occurs with a periodicity of 0.02305(7) d. Besides this ~33 min oscillations, there seems to be others (tentatively, at 43.7 min, 22.6 min, and 13.9 min). Needless to say that all this is very preliminary and can (surely, it will) change over the next days. For those interested in following this target, I would suggest only long runs (if possible, covering over one cycle), which is feasible for Norther latitudes. The target is at the moment of writing oscillating between 15.8 and 16.5 CV, I'm using GSC 2885-1928 as comp star. Hope someone else can join the action. Enrique
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