[vsnet-alert 8856] XTE J1817-330

[Daisaku NOGAMI]

Dear colleagues,

XTE J1817-330 is a recently discovered X-ray transient currently
in an active phase, and is a good black hole candidate (ATEL 714).
The following report (Torres et al., ATEL 733) tells that a bright
optical counterpart (g' = 14.93 +/- 0.05) was discovered!

The infrared counterpart position was reported to be
RA = 18h17m43.54s, Dec = -33o01'06.7" (J2000; +/- 0.5 arcsec; ATEL
724).  The location is bad so that we can observe this source only
in a short time before the dawn from the ground.  But any methods
of observations are strongly encouraged!

Best regards,
Daisaku Nogami
VSNET Collaboration Team

Begin forwarded message:

Date: Sat, 11 Feb 2006 15:37:03 +0900
From: atel at astronomerstelegram.org
Subject: ATel  731, 733


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Posted: Fri Feb 10 01:30:01 EST 2006 -- Sat Feb 11 01:30:01 EST 2006
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ATEL #731							     ATEL #731

Title:		INTEGRAL detects hard X-ray emission from XTE J1817-330
Author:	S.E. Shaw (Southampton, UK/ ISDC, Geneva); J. Zurita (ISDC,
		Geneva); E. Kuulkers (ESA/ESAC, Spain); S. Brandt, J. Chenevez (DNSC,
		Denmark); T.J.-L. Courvoisier (ISDC, Geneva); K. Ebisawa (NASA/GSFC,
		USA); P. Kretschmar (ESA/ESAC, Spain); C. Markwardt (NASA/GSFC, USA);
		N. Mowlavi (ISDC, Geneva); T. Oosterbroek (ESA/ESTEC, Netherlands);
		A. Orr (ESA/ESTEC, Netherlands); A. Paizis (IASF, Milano); C. Sanchez-Fernandez
		(ESA/ESAC, Spain); R. Wijnands (UvA, Netherlands) 
Queries:	simon.shaw at obs.unige.ch
Posted:	10 Feb 2006;  10:38  UT
Subjects:	X-ray, Gamma Ray, Black Holes, Transients

During the start of the third period of the INTEGRAL Galactic Bulge monitoring
observations (Kuulkers et al 2005, ATel #438), the X-ray transient and
black-hole candidate XTE J1817-330 (ATel #714) has been detected in the
20 - 150 keV range.  The observations comprised ~7 ksec taken on 9 Feb
2006 between 09:02 and 11:43 UTC.      

The estimated flux seen by ISGRI in the 20-60 keV range was ~33 mCrab,
which compares with an earlier measurement, on 27 Jan 2006, of 22 mCrab
in the 10-30 keV band (ATel #714).  There is also evidence of emission
at higher energies, with an average flux in the 60-150 keV band of 1.9
ア 0.4 cps (~ 44 mCrab).  Spectral analysis indicates a hard spectrum with
a power-law photon index of 1.6 +/- 0.3.      

Unfortunately, the source was outside of the field of view of the JEM-X
instrument and so no comment can be made on the sources's behaviour below
15 keV.      

Images and light curves from the observations are available at     

http://isdc.unige.ch/Science/BULGE      

The source will again be observed by INTEGRAL in the next Galactic Bulge
pointing on 11-12 Feb 2006.  A longer (195 ksec) INTEGRAL TOO observation
is foreseen on 15-18 Feb, 2006.         

Simultaneous observations are encouraged. 

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Password Certification:  Nami Mowlavi (Nami.Mowlavi at obs.unige.ch)
http://www.astronomerstelegram.org/?read=731
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ATEL #733							     ATEL #733

Title:		The Optical Counterpart to XTE J1817-330.
Author:	M. A. P. Torres (CfA), D. Steeghs (CfA), P. G. Jonker (SRON/CfA),
		K. Luhman (Pennsylvania State Univ.), J. E. McClintock (CfA), M. R.
		Garcia (CfA)
Queries:	MTORRES at CFA.HARVARD.EDU
Posted:	11 Feb 2006;  1:57  UT
Subjects:	Request for Observations, Binaries, Black Holes, Transients

We report the counterpart to the X-ray transient and black hole   candidate
XTE J1817-330 (ATEL #714).      

Our observations consist of a series of 5s and 10s g'-band images   obtained
with the 6.5m Magellan Clay telescope during 2006 Feb 10   09:23-09:42
UT using the multi-object imaging spectrograph LDSS-3. The   frames were
acquired with an image quality of 1.2 arcsec and a   projected pixel scale
of 0.188 arcsec/pixel. The images were   calibrated using the Landolt and
u'g'i'r' standard star G 162-62 that   was observed at similar airmass
as XTE J1817-330.       

Comparison of our images with the Digitized Sky Survey and 2MASS shows
a new single point-like source consistent with the position reported
for the radio and near-infrared counterparts (ATEL #721, #724). We  
measure a mean magnitude for the optical counterpart of g'= 14.93 +/- 
0.05 from preliminary photometry.      

The optical apparent magnitude is comparable to the K-band   magnitude
reported in ATEL #724 and supports a low reddening towards   the source.
The large outburst amplitude in the optical band (the   source is not detected
in POSS plates) suggests a short orbital period   system (see e.g. Shahbaz
& Kuulkers,1998,MNRAS,295,L1).      

Follow-up observations at all wavelengths, in particular UV, are   encouraged.
A finding chart for the candidate may be found at:   http:/hea-www.cfa.harvard.edu/~mtorres/XTEJ1817m330/

Finding chart.: http://hea-www.harvard.edu/~mtorres/XTEJ1817m330/
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Password Certification:  Manuel Torres (mtorres at cfa.harvard.edu)
http://www.astronomerstelegram.org/?read=733
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Your keywords: Radio, Millimeter, Sub-Millimeter, Far-Infra-Red, Infra-Red,
Optical, Ultra-Violet, X-ray, Gamma Ray, >GeV, Request for Observations,
A Comment, AGN, Binaries, Black Holes, Cosmic Rays, Cataclysmic Variables,
Globular Clusters, Gamma-Ray Bursts, Microlensing Events, Neutron Stars,
Novae, Pulsars, Quasars, Soft Gamma-ray Repeaters, Solar System Objects,
The Sun, Supernovae, Supernova Remnants, Transients, Variables, Stars

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