[vsnet-alert 11058] re Nova LMC 2009 = possible recurrent nova in the LMC - astrometry needed

[varposts at Safe-mail.net]

Kato Taichi notified :-

"Possible recurrent nova in the LMC

   According to CBAT's Unconfirmed Observations page and AVSON information, W. Liller has discovered a possible nova (mag 10.6) in the LMC.  The object is located close to the recorded position of Nova LMC 1971b = LMCV3958 according to Mati Morel."

W. Liller's quoted position is as yet not all that precise by the look of the cbat unconfirmed page

http://www.cfa.harvard.edu/iau/unconf/cbat_unconf.html

which is why sometimes the first call for novae should be some tight astrometry: in tandem with any instrumental confirmation should come some astrometry.

There's a plethora of datasets for the LMC, including a large amount of epoch photometry usable down to about 20th red and blue magnitude from MACHO in this area, some of it surrounding LMCV3958 close enough to be connected/related to said (MACHO astrometry doesn't appear to be quite as good as one arcsec which makes things tricky too), given several candidate progenitors.  Epoch photometry of a progenitor, wouldn't that be nice?  Even if not, it gives a lower limit to said.

There's SAGE data too, and many other surveys in the LMC, including in some LMC areas the 2MASS deeper 6x survey.  These surveys come in useful for showing, or removing from being a concern, any bright object being either very red or very extincted not noticed normally in the optical.  Around LMCV3958
there are no MIR sources for quite a few arcsecs, but there are some, and until the reference is checked we don't know how accurate LMCV3958's position is either (SIMBAD gives no reference earlier than 1988 for this 1971 object, GCVS gives IAUC 2353 as the reference, of which no electronic online copy seems to exist).  If the same holds for the precise position of the new object then several classes of object can be precluded.

We do know that the lower limit given is 14, which leaves many options open as to type and candidacy.

There are plenty of catalogues around here, photometric ones, ones with epoch photometry, and although we're off the main region of the galaxy, a fair old density of faint stars, as well as relativey deep satellite survey stuff.

So one of the first things needed with things like this is some usable astrometry.  Well, for all Novae and candidate Novae really.  Seeing as people are likely going to be observing it with instrumentation anyway.

Cheers

John