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XMMSL1 J070542.7-381442 is a nova

ATEL # 1285; 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)
on 17 Nov 2007; 20:39 UT
Password Certification: Manuel Torres (

Subjects: Optical, Binaries, Cataclysmic Variables, Transients
Referred to by ATEL #: 1301

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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R. E. Rutledge , Editor
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