Optical spectroscopy of V404 Cyg during its latest outburst
ATel #8508; Peter Somogyi
on 6 Jan 2016; 02:28 UT
Credential Certification: S. N. Shore (shore@df.unipi.it)
Subjects: Optical, Black Hole, Cataclysmic Variable
Low resolution spectra were obtained during the current outburst (announced in ATel #8453) of the microquasar V404 Cyg. Ten 600 sec exposures were obtained on 2015 Dec. 31 (JD 2457388.202 - 0.27) with a 250 mm Newtonian reflector using an LHires III spectrograph with 150 line/mm grating (R ~ 500) spanning 4500-7500A with the combined S/N ~ 10 (continuum at 6000A; calibration used the standard HD192640). The spectrum showed strong Halpha emission with EW = 104+/-10A and He I 5876 with EW = 21+/-2A. Weak but detectable emission was also present at He I 6678 and 7065. The spectrum was deconvolved using the Richardson-Lucy algorithm and a gaussian lsf. The recovered Halpha FWZI was 2300 km/s, the He l 5876 FWZI was similar. The lower limit for Halpha/Hbeta ratio was about 4, uncorrected for reddening. Using the extinction obtained by Hynes et al. (2009, MNRAS, 399, 2239) of E(B-V)=1.3 a power law fit to the continuum (in wavelength) gives an exponent of -1.6+/-0.1. No statistically significant line variations were detectable among the individual spectra. The data are available through the ARAS Spectral Database and further observations are planned.
A.R.A.S Spectral Data Base