[vsnet-alert 9715] (fwd) XMMSL1 J070542.7-381442 is a nova

[Taichi Kato]

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The Astronomer's Telegram                   http://www.astronomerstelegram.org 
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Posted: Sat Nov 17 01:30:02 EST 2007 -- Sun Nov 18 01:30:01 EST 2007
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ATEL #1285                                                           ATEL #1285

Title:          XMMSL1 J070542.7-381442 is a nova 
Author: M.A.P. Torres (CfA), P. G. Jonker (SRON/CfA), P. Challis (CfA),
                M. Modjaz (Berkeley), R. Kirshner, A.M. Read (U. Leicester), E. Kuulkers
                (ESA/ESAC), R.D. Saxton (ESAC)
Queries:        mtorres at cfa.harvard.edu
Posted: 17 Nov 2007;  20:39  UT
Subjects:       Optical, Binaries, Cataclysmic Variables, Transients

We report on optical observations of XMMSL1 J070542.7-381442. This 
X-ray source has recently been discovered during XMM-Newton Slew   Survey
observations (Read, Saxton & Esquej 2007, ATel #1282).          

In order to identify its optical counterpart we observed the field of
XMMSL1 J070542.7-381442 on 2007 Nov 16 08:15 - 08:28 UT with the   Magellan
Clay 6.5m telescope equipped with the LDSS-3 spectrograph. In   a 20 second
exposure image we find a bright, saturated star within   the 8'' error
circle for the X-ray location reported in ATel   #1282. The position of
the optical counterpart is consistent with that   of USNO A2.0 0450-03360039
(ATel #1282).         

A total of 8 spectra with exposure times ranging 1 to 60s were   acquired.
The LDSS-3 setup (VPH ALL grism + 1'' slit) provided a   3700-10000 AA
wavelength coverage with a dispersion of 2 AA/pix and   resolution better
than 10 AA. The strongest lines in the spectra are   [0III] 5007 (blended
with [OIII] 4959) followed by Halpha (FWHM ~ 2100   km/s), [OIII] 4363
(blended with Hgamma; FWHM ~ 1600 km/s) and [NII]   5755 (FWHM ~ 1800 km/s).
Note that Halpha may be blended with   unresolved [NII]. NIII 4640, HeII
4686,  NII 5679, HeI 5876, [FeVII]   6087, [OI] (6300,6364) and [0II] 7325
emission lines are identified in   spectra. Hbeta is stronger than HeII
4686.         

>From the above properties, the object is likely a nova in the auroral
phase (see e.g. Williams et al,1991,ApJ,376,721). The USNO object   is
the possible progenitor of the nova.       

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Password Certification:  Manuel Torres (mtorres at cfa.harvard.edu)
http://www.astronomerstelegram.org/?read=1285
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