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ATEL # 1286; M.A.P. Torres (CfA), D. Steeghs (Warwick/CfA), P. G. Jonker (SRON/CfA), M. R. Garcia (CfA), P. Challis (CfA), M. Modjaz (Berkeley), R. P. Kirshner (CfA)
on 19 Nov 2007; 9:59 UT
Password Certification: Danny Steeghs (firstname.lastname@example.org)
Subjects: Infra-Red, Optical, X-ray, Binaries, Cataclysmic Variables, Transients, Variables
We report optical spectroscopy of the putative optical counterpart to the Swift source J052522.48+241331.8 (Page, Tueller & Beardmore 2007, ATEL #1279).
We note that the XRT position (ATEL #1279) is consistent with that of the ROSAT source 1RXS J052523.2+241331. Using the X-ray flux and power-law model reported in ATEL #1279, we computed with WebPIMMS a ROSAT PSPC count rate of 0.256 cps for the Swift source. This value is in line with the count rate measured for the ROSAT source (0.127 cps, HR1=0.91, HR2=0.57). Combined with the lack of X-ray flux evolution between the two XRT epochs, suggests that SWIFT J052522.48+241331.8 and 1RXS J052523.2+241331 are the same persistent source and not a new transient.
We acquired a 450s spectrum of the optical counterpart USNO-A2.0 1125-02389994 (ATel #1279) starting on 2007 Nov 15 07:38 UT with the LDSS-3 spectrograph mounted on the Magellan Clay 6.5m telescope. The instrumental setup (VPH ALL grism and 1'' slit) provided a 3700-10000 Angstrom wavelength coverage with a dispersion of 2 A/pix and resolution of ~10 A FWHM. The optical spectrum shows Balmer lines in emission from Halpha (the strongest line in the spectrum; EW = -10.2 +/- 0.3) to Hzeta, HeII 4686,5412 and HeI 5876,6678,7065,7281. The Bowen blend is not detected in our spectrum. The above emission lines have single-peaked narrow profiles dominated by the instrumental profile. The strength of HeII 4686 (EW = -7.4 +/- 0.4 Angstrom) to Hbeta (EW = -4.9 +/- 0.1 Angstrom) is typical of either magnetic Cataclysmic Variables (CVs) or novalike variables. In addition, the spectrum shows absorption features due to the interstellar NaD doublet and diffuse interstellar bands at 5780 and 6280 Angstrom.
The high-excitation emission lines, together with the hard X-ray spectrum support a magnetic or high-Mdot CV nature for the source.