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[vsnet-alert 7470] a strong radio transient = MCQC_J162847-4152
- Date: Fri, 13 Sep 2002 11:23:06 +0900 (JST)
- To: vsnet-campaign@kusastro.kyoto-u.ac.jp, vsnet-campaign-xray@kusastro.kyoto-u.ac.jp, vsnet-alert@kusastro.kyoto-u.ac.jp
- From: Hitoshi YAMAOKA <yamaoka@rc.kyushu-u.ac.jp>
- Subject: [vsnet-alert 7470] a strong radio transient = MCQC_J162847-4152
- Delivered-To: vsnet-alert@kusastro.kyoto-u.ac.jp
- Sender: owner-vsnet-alert@ooruri.kusastro.kyoto-u.ac.jp
Dear colleagues,
In IAUC 7968, Rupen et al. (NRAO) reported that a strong (about
3-mJy) radio transient was detected by VLA on Sept. 9. The nominal
position of this transient is R.A. = 16h28m47s.3, Decl. = -41o52'35"
(2000.0, accuracy ~ a few arcsec), which agrees closely with the
position of a probable microquaser 1RXS J162848.1-415241 = GSC
7861.1088. Urgent observations in any wavelength are highly
urged.
Recent optical observation reports of this object ;
MCQC_J162847-4152 recent (cont'd)
YYYYMMDD(UT) mag observer
20020606.741 136 (Berto Monard)
20020608.794 135 (Berto Monard)
20020614.710 135 (Berto Monard)
20020628.766 135 (Berto Monard)
20020629.746 135 (Berto Monard)
20020711.733 135 (Berto Monard)
20020713.737 135 (Berto Monard)
20020727.722 135 (Berto Monard)
20020805.801 135 (Berto Monard)
20020901.757 134 (Berto Monard)
The discovery of this object by Tsarevsky et al. is described in
[vsnet-campaign 1058] = [vsnet-campaign-xray 78] (2001 Aug. 3) and in
[vsnet-campaign-xray 100, 101] (2001 Dec. 12) as follows:
---
>Date: Sat, 4 Aug 2001 08:47:44 +0900 (JST)
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
Subject: [vsnet-campaign 1058] (fwd) Microquasar candidate J1628-41: Call for observations
(fwd) Microquasar candidate J1628-41: Call for observations
(Comment by T. Kato): The object has the following identifications:
GSC7861.1088 162847.30 -415239.0 (2000.0) 13.14 6
USNO0450.24415462 162847.294 -415238.76 (2000.0) 10.9 15.6
162848.0 -415240 (2000.0) 1RXS_J162848.1-415241 0.119 1.00 0.60
Date: Sat, 4 Aug 2001 01:24:54 +0400 (EEST)
From: "Gregory S. Tsarevsky" <tsar@gamma.asc.rssi.ru>
Subject: [vsnet-alert 6183] Microquasar candidate J1628-41: Call for observations
Dear colleagues,
As you know microquasars are a very rare class of the X-ray binaries (XRB)
showing relativistic radio jets closely resembling misterius jets from
the extragalactic quasars/AGNs. Only a half of a dozen microquasars have
been discovered up-to-date from the ~300 XRBs known (see comprehensive
review by Mirabel and Rodriguez in Annual Review of Astronomy and
Astrophysics, vol. 37, p. 409, 1999).
In the course of systematic search for new microquasars in the whole
Galactic Plane, we have found a few tens of promising objects.
One of them is a relatively bright microquasar candidate J1628-41a
as follows:
-1) It is a bright ROSAT source in the Galactic Plane with a hard spectrum
characteristic for the X-ray binaries (XRB).
-2) It was detected by the Australia Telescope Compact Array (ATCA) as
a 7 mJy flat spectrum radio source with an unresolved core and some
evidence of the jet.
-3) With precision radio coordinates, it was identified with a star-like
object, which has the following USNO data:
===========================================================
Name RA_2000 DEC_2000 r-o" Bmag Rmag
-----------------------------------------------------------
J1628-41a 16 28 47.267 -41 52 38.6 0.4 15.5 11.4
===========================================================
(r-o" - the difference in the radio and optical positions)
Note:
Apparent color-index B-R=4.1 may suggest a possible strong source
variability or/and large absorption in the source direction.
-4) Preliminary low resolution spectroscopy with the Anglo-Australian
4-m Telescope showed J1628-41a as a K5 spectrum object with a strong
and variable H-alpha emission, i.e. possible low mass XRB (LMXRB).
We very much need help of the Southern VSNET community to start a
multicolor photometry of our best microquasar candidate J1628-41a,
to reveal its possible
- disc driven flare activity,
and
- eclipsing behavior with orbital period in a wide range say 0.1-20 d.
I would be happy to send a detailed description of the project to those
VSNET colleagues who would like to participate in the observations
requested.
Dr Elena Pavlenko from the Crimean Astroph. Observatory will report this
in The Physics of Cataclismic Variables and Related Objects Conference
to be held in Goetingen just next week, see
http://vsnet.uni-sw.gwdg.de/CVConference/
A finding chart will be send by request.
On behalf of the international team of the project
A Search for New Microquasars in X-ray, Radio and Optics,
Dr Gregory S. Tsarevsky
_____________________________________________________
Australia Telescope National Facility, Sydney ,
and Astro Space Centre, Moscow ,--_|\
/ \
Tel: +612 9372 4260 Fax: +612 9372 4176 \_,--._#
http://vsnet.atnf.csiro.au/people/gtsarevs/ v
-----------------------------------------------------
---
>Date: Wed, 12 Dec 2001 10:36:18 +0900 (JST)
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
Subject: [vsnet-campaign-xray 100] (fwd) MCQC J162847-4152 - a Possible Brightest Microquasar found
(fwd) MCQC J162847-4152 - a Possible Brightest Microquasar found
This message is from ATEL #80:
[Please use MCQC_J162847-4152 instead of the former designation J1628-41a
in future observation reports to vsnet-obs].
Title: MCQC J162847-4152 - a Possible Brightest Microquasar found
Author: G.S. Tsarevsky (ATNF, Sydney, & ASC, Moscow), N.S. Kardashev
(ASC), R.A. Stathakis (AAO, Sydney), O.B. Slee (ATNF), R. Ojha (ATNF)
Queries: Gregory.Tsarevsky@atnf.csiro.au
Posted: 11 Dec 2001; 10:19 UT
Subjects: Radio, Millimeter, Infra-Red, Optical, X-ray, Request for
Observations, Binaries, Black Holes, Neutron Stars, Transients, Variables,
Stars
MCQC J162847-4152 is one of 40 objects found in the course of our systematic
and complete survey for new microquasars in the whole Galactic plane (see
project description in <a href="http://arXiv.org/abs/astro-ph/0110511";>astro-ph/0110511</a>).
It is optically brightest and mostly definite microquasar candidate in
the list, which we describe as follows: 1) It is a bright ROSAT source,
1RXS J162848.1-415241, in the Galactic plane (b=4.7deg), with a hard X-ray
spectrum (HR1 = 1.00+/-0.04), which is characteristic of X-ray binaries
(Motch et al., AAS 132, 341, 1998). 2) It was detected at 4.8 and 8.6
GHz by the Australia Telescope Compact Array (ATCA) in October 2000 as
a ~7 mJy flat spectrum radio source with an unresolved core, but with
no conclusive evidence for the presence of a jet on an arcsec scale.
3) Using precision radio coordinates, MCQC J1628-4152 was identified
with a relatively bright star-like object as follows:
_________________________________________________________________
Source of data RA J2000 DEC J2000 r-o B V R
-----------------------------------------------------------------
USNO (PMM) 16h28m47s.267 -41o52'38".63 0".5 15.5 13.4 11.4
-----------------------------------------------------------------
V-magnitude is an averaged visual estimation by B. Monard (<a href="http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/etc/searchobs.html";>VSNET</a>).
Apparently large color-indices measured in different epochs may suggest
a possible strong source variability. 4) Low resolution spectroscopy
with 4-m (AAO) and 2.3-m (MSSSO) telescopes, showed MCQC J162847-4152
as a K5 spectrum star with a <a href="http://vsnet.atnf.csiro.au/people/gtsarevs/J1628-41_Halpha.ps";>strong
and rapidly variable H-alpha emission</a>, i.e. consistent with a low
mass XRB (LMXB). 5) Our three observing sessions with the ATCA revealed
the following variability in flux density (RMS ~0.1 mJy, 4-sigma limit
of detection):
_____________________________________
Epoch of ATCA F_4.8 F_8.6 Spectral
observations [mJy] [mJy] Index
-------------------------------------
29.10.2000 7.2 6.6 -0.1
05.09.2001 8.8 12.3 +0.5
02.12.2001 <0.5 <0.4 -
-------------------------------------
It is evident from the table that the source shows a violent transient-
like radio activity. Significant variability on time scales of several
hours is also present. The above X-ray, optical and radio characteristics
are suggestive of microquasar behavior (which still is not well established
as there are only a few microquasars known, cf Mirabel and Rodriguez,
ARAA 37, 409, 1999). For all that, we cannot exclude the possibility that
the object is an active K-star. So we call for observations of MCQC
J162847-4152 in radio (flux monitoring and structure variability, preferably
by VLBI), optical spectroscopy (to find evidence for the object's binarity),
optical photometry (to monitor disc driven flare activity and evidence
for possible eclipse), and in X-rays (high spatial, spectral and time-resolved
observations by Chandra, XMM and RXTE may reveal the characteristic structure,
spectral features and flux variations found in the few established microquasars).
We have already sent out a call to <a href="http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/";>VSNET</a>
for photometric observations of this object.
---
>Date: Wed, 12 Dec 2001 11:08:13 +0900 (JST)
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
Subject: [vsnet-campaign-xray 101] (fwd) Re: MCQC J162847-4152 - a Possible Brightest Microquasar found
Date: Tue, 11 Dec 2001 19:06:37 -0700 (MST)
From: Brian Skiff <bas@lowell.edu>
The best current position for this object is probably from UCAC1,
which shows: 16 28 47.285 -41 52 39.00 (2000). Uncertainty is 8mas in RA
and 11mas in Dec. The reported "orange" magnitude is 12.5. Note also that
UCAC1 shows a proper motion of about 0".024/year, but the errors are
of the same order, so the motion is not significant.
\Brian
---
Sincerely,
Hitoshi Yamaoka
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