A radio galaxy as possible counterpart of IGR J21247+5058
ATel #235; M. Ribo (CEA Saclay, France), J. A. Combi (IAR, Argentina), I. F. Mirabel (CEA Saclay, France and IAFE-CONICET, Argentina)
on 15 Feb 2004; 20:50 UT
Credential Certification: Marc Ribo (mribo@discovery.saclay.cea.fr)
Subjects: Radio, Infra-Red, Optical, X-ray, Gamma Ray, AGN, Binary, Black Hole, Quasar
Within the 2 arcmin-radius position error circle of the recently
discovered INTEGRAL source IGR J21247+5058 (ATEL #229) is located the core
of the bright radio source 4C 50.55 (also known as GPSR 93.319+0.394, KR2,
NRAO 659 or BG 2122+50, among other names). The core has a flat radio
spectrum with a peak flux density of 237 mJy/beam at 1.4 GHz. It is at the
center of an elongated structure of 10 x 3 arcmin that ends in two large
radio lobes that have peak flux densities of 288 mJy/beam (NW) and 92
mJy/beam (SE), and spectral indexes alpha~-0.6 (where S_nu is proportional
to nu^+alpha), compatible with optically thin synchrotron radiation (see
NVSS
contour plot). The morphology of 4C 50.55 is typical of a radio
galaxy, and the comparison among published radio data shows no significant
changes in flux and morphology during the last 30 years. These properties
are consistent with an extragalactic source, although, to our knowledge,
no conclusive optical counterpart of a galaxy host has ever been reported,
probably due to its location close to the Galactic plane (l=+93.32,
b=+0.39).
The estimated J2000.0 ICRS position of the radio core from the NVSS map
and data in the literature is RA=21h24m39.3s (+/-0.1s), DEC=+50d58'26"
(+/-1"). Coincident with this position there is the IR source 2MASS
21243932+5058259 (see K-band
2MASS plot), with coordinates RA=21h24m39.32784s, DEC=+50d58'25.9284",
and magnitudes J=13.27, H=12.38, K=11.37. The optical counterpart of this
IR source has average magnitudes B=16.9 and R=15.1 in the USNO B1.0
catalog. The photometry of the IR/optical counterpart is not compatible
with a stellar spectrum. There is no catalogued ROSAT or EGRET source
coincident with IGR J21247+5058. Optical and X-ray observations are
planned to confirm the extragalactic nature of the source and to study its
spectrum in softer X-rays.
