Optical spectroscopy of X-ray source 1RXS J194211.9+255552
ATel #4209; N. Masetti, R. Landi (INAF/IASF, Bologna), P. Parisi, A. Bazzano (INAF/IAPS, Rome) and A. J. Bird (Univ. Southampton)
on 25 Jun 2012; 16:16 UT
Credential Certification: Nicola Masetti (masetti@iasfbo.inaf.it)
Subjects: Optical, X-ray, Binary, Transient
Using the 1.5m "Cassini" telescope of the Astronomical Observatory
of Bologna in Loiano (Italy) equipped with the BFOSC instrument,
we spectroscopically observed the putative optical counterpart
(ATel #3818) of the transient X-ray source 1RXS J194211.9+255552
detected with INTEGRAL/JEM-X (ATel #3816).
Observations were acquired starting at 22:47 UT of 16 June 2012, for a
total exposure time of 5400 s.
The spectrum, in the 3800-8500 Angstroms range, shows a highly reddened
(but otherwise intrinsically blue) continuum with superimposed several
absorption lines of Galactic interstellar origin and a single narrow
emission of equivalent width 14.8 +- 1.2 Angstroms, which we identify
as Halpha at a redshift consistent with 0.
The optical spectral appearance of the counterpart is thus typical of
an absorbed Galactic high mass X-ray binary (HMXB), similar to those
identified with this method by Masetti et al. (2012, A&A, 538, A123
and references therein). This confirms the HMXB nature for this source
suggested in ATel #3818.
We thank S. Galleti and R. Gualandi for the observations performed in
service mode.
