Optical periodicity of microquasar candidate MCQC J162847-4152
ATel #234; Michelle Buxton, Charles Bailyn (Yale U), Leonid Berdnikov (Sternberg Astronomical Institute, Moscow U), Gregory Tsarevsky (ATNF, Sydney, and ASC, Moscow)
on 13 Feb 2004; 18:44 UT
Credential Certification: Michelle Buxton (buxton@astro.yale.edu)
Subjects: Optical, Binary, Black Hole, Transient
Referred to by ATel #: 292
We report on CCD photometry of the possible brightest microquasar
MCQC J162847-4152 (ATEL #80). This object is coincident with the hard
X-ray spectrum ROSAT source 1RXS J162848.1-415241 (ATEL #80), is
a prominent radio transient (IAUC 8008 , 8275 ) and exhibits a K5
spectrum star with a strong and rapidly variable H-alpha
emission (ATEL #80). Seventy five CCD observations made
between 2003 June-October using the 1.3m CTIO telescope with
ANDICAM showed a 4.835 +/- 0.001 d periodicity with amplitude 0.30
mag in V-band. In 2002 April a short set of photoelecric BVIc observations were
obtained with 24" Siding Spring Observatory telescope. When folded
on 2P = 9.870 d, the combined lightcurve exhibits an ellipsoidal-like shape with a slight
asymmetry: the time taken from maximum to minimum is longer than
from minimum to maximum. We urge observers to obtain radial velocity
measurements to discern whether this object is a pulsating star or a
binary system. If the latter, the radial velocity curve, combined
with the photometric lightcurve, will allow us to estimate the mass of
the unseen companion and resolve the question of whether or not this
object is a microquasar.
V-band lightcurve of MCQC J162847-4152
