AAVSO Special Notice #81: Possible Nova/X-ray Transient [V598 Pup]

November 18, 2007: Read et al. (ATEL #1282) report the discovery by XMM-Newton of a very bright new transient, XMMSL1 J070542.7-381442 [Nova Pup 2007 = V598 Pup], located at

07:05:42.7 -38:14:42 J2000

with an error radius of 8 arcsec. It was detected in a slew that took place on October 8, showing an extremely soft spectrum. Since it is in the galactic plane where there is large column density (extinction), they suggest that it is Galactic in origin and perhaps very close. They proposed an optical counterpart of USNO-A2.0 0450-03360039 (which has a Bmag=15.7 and Rmag=15.9, indicating a blue object).

Torres et al. (ATEL 1285) observed the object on Nov. 16 with the Magellan 6.5m telescope, finding a bright saturated star with typical nova lines, but most likely in the auroral phase - that is, long past the peak of the nova outburst.

Images from Shawn Dvorak and Bill Allen indicate that the USNO-A2.0 star has brightened to about V=10.5 currently; the peak brightness is unknown at this time.

VizieR is still not back up, and we cannot give precise coordinates at this time. A further notice will be issued with more details when they are available. In the meantime, we suggest observing visually using nearby ASAS comparison stars, or using a V filter and time series with a CCD camera. Do not observe unfiltered since the spectrum is full of emission lines.

Arne Henden



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