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XTE J1901+014
R. A. Remillard, Massachusetts Institute of Technology (MIT);
and D. A. Smith, University of Michigan, for the RXTE ASM Team at
MIT and NASA Goddard Space Flight Center, report the discovery of
a fast x-ray transient. The detection was initially thought to be
a gamma-ray burst (cf. http://gcn.gsfc.nasa.gov/gcn/gcn3/1332.gcn3),
with a peak flux of 0.9 Crab (2-12 keV). The event began on Apr.
6.76268 UT, lasting > 2 min and < 3.15 hr (see
http://xte.mit.edu/xtej1901+104). The ASM data show rapid
evolution to a very hard spectrum during this outburst, but the IPN
instruments failed to detect the source above 15 keV (K. Hurley,
private communication). Furthermore, archival ASM data show a
previous outburst at the same position on 1997 June 21.215, which
was longer than 6 min and < 8 hr, with a peak flux of 0.4 Crab.
The combined ASM observations yield a best position R.A. =
19h01m36s, Decl. = +1 26'.4 (equinox J2000.0; estimated uncertainty
3' in R.A. and 2' in Decl.). The error box contains one very faint,
2E 1859.1+0122 (R.A. = 19h01m40s.2, Decl. = +1 27'13", equinox
J2000.0; error radius 48"; Hertz and Grindlay 1988, A.J. 96, 233).
The time scales for these eruptions are reminiscent of the
microquasar and blackhole binary V4641 Sgr, so optical and radio
observations of XTE J1901+014 are strongly encouraged.
(C) Copyright 2002 CBAT
2002 April 18 (7880) Daniel W. E. Green
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***Instant Email Notice***: Transients

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ATEL #88 ATEL #88

Title: XTE J1901+014: a new, fast X-ray transient
Author: Ron Remillard (M.I.T.) and Don Smith (U. Michigan)
Queries: rr@space.mit.edu
Posted: 17 Apr 2002; 18:50 UT
Subjects: X-ray, Transients

The RXTE All-Sky Monitor has discovered a fast X-ray transient that was
initially thought to be a gamma ray burst, reported on the GCN network
as GRB020406. The event began on 2002 April 6.76268, lasting more than
2 min and less than 3.15 hr, with a peak flux of 0.9 Crab (2-12 keV).
(see http://xte.mit.edu/xtej1901+104). The ASM data show rapid evolution
to a very hard spectrum during this outburst, but the IPN instruments
failed to detect the source above 15 keV (K. Hurley, private communication).
Furthermore, archival ASM data show a previous outburst at the same position
on 1997 June 21.215, which was longer than 6 min and less than 8 hr, with
a peak flux of 0.4 Crab. The combined ASM observations yield a best position:
R.A. = 19h01m36s, Decl. = +1 26'.4 (equinox J2000.0; estimated 3' uncertainty
in R.A. and 2' uncertainty in Decl.). The error box contains one very
faint, unidentified X-ray source from the Einstein Galactic Plane Survey:
2E1859.1+0122 (J2000 R.A. = 19h01m40.2s, Decl. = +1 27' 13''; error radius
eruptions are reminiscent of the microquasar and black hole binary V4641
Sgr, so we strongly encourage optical and radio observations of XTE J1901+014.

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Posted: Wed Apr 17 03:30:00 PDT 2002 -- Thu Apr 18 03:30:00 PDT 2002
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ATEL #89 ATEL #89

Title: XTE J1901+014 is 1RXS J190141.0+012618 ?
Author: Rudy Wijnands (MIT)
Queries: rudy@space.mit.edu
Posted: 17 Apr 2002; 21:52 UT
Subjects: X-ray, Request for Observations, Binaries, Black Holes,
Transients

Using the ROSAT All-Sky Survey Source Catalogue, it was found that the
ROSAT source 1RXS J190141.0+012618 is located in the RXTE/ASM error box
of XTE J1901+014 (ATEL 88) and at the edge of the Einstein error circle.
The PSPC position listed in the Catalogue is 19h01m41.0s, +1 26' 18" (1
sigma error radius of 12") and the PSPC count rate of the source was 0.17+/-0.02
counts/s (0.1-2.4 keV). During a pointed ROSAT/HRI observation performed
on 1994 October 3 the source was also detected. However, examining the
raw data, the position of the source appears to be slightly offset from
the PSPC position (the tentative HRI position is 19h01m40.1s, +1 26' 30"
with an error radius of 10"). The ROSAT source 1 RXS J190141.0+012618
could be the quiescent (non-flaring) X-ray counterpart of XTE J1901+014.
Observations at all wavelengths are encouraged to confirm the association
of 1RXS J190141.0+012618 with XTE J1901+014 and to determine the nature
of this object.
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 1338
SUBJECT: GRB020406(?), optical observations
DATE: 02/04/07 22:25:26 GMT
FROM: Arne A. Henden at USNO/USRA

D. Durig (ddurig@sewanee.edu) and A. McDermott
report on behalf of the International AAVSO
GRB Network:

We observed the RXTE/ASM error box for the short X-ray
transient 020406 (Smith et al. GCN 1332), that may be related
to a GRB, with the Cordell-Lorenz Observatory 0.3m telescope
and ST-9E/AO-7 CCD system. The western
half of the error box was mosaiced with limiting
magnitude approximately 20. Near the center of
the error box an object was found that does
not appear on either the blue or red POSS-II plate.
At coordinates:
19:00:42.10 +01:27:22.4 J2000
+/- 0.2s +/- 0.4"
this object had an estimated unfiltered magnitude
of 18.9 (USNO-A2.0 red) on a 10-minute exposure with midpoint
UTD 020407.394 (13hrs after the ASM detection);
two subsequent exposures showed fading behavior (19.2 and 19.3mag),
but a constant brightness also fits within the photometric
asteroid is near this position. As this is a
crowded field with no obvious galaxies on the POSS
plates, this object may just be an unrelated galactic
variable of large amplitude.

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 1332
SUBJECT: Short RXTE/ASM transient 020406; may be a GRB
DATE: 02/04/06 22:47:03 GMT
FROM: Don Smith at U michigan

D. A. Smith (U of Michigan) and A. M. Levine (MIT) report on behalf of the
RXTE/ASM teams at MIT and NASA/GSFC:

The ASM has detected a hard, brief (>~30 s), bright (peak 5-12 flux ~2 Crab)
X-ray flare from a location inconsistent with any known source in the ASM
catalog. The event appears to have be a single flare (the ASM scanned off the
source before the flux went to zero), beginning at around 2002/04/06 18:18:15
(UTC). The flare was detected in two of the ASM scanning shadow cameras,
although the source location was barely 30 arcminutes from the edge of SSC 1,
rendering localization difficult in this camera. Nevertheless, we believe the
source to be localized to within a parallelogram (with 90% confidence) centered
on the coordinates (J2000.0):

19h 00m 24s.29, 01d 24' 49".1

With corners at the following locations:
R.A.: 18 59 54.01 19 04 11.18 19 03 45.70 18 59 28.52
Dec.: 01 23 9.06 01 24 55.62 01 27 34.74 01 25 47.48

The characteristics of these observations are similar to other detections of
GRBs with the ASM, and so we tentatively designate it as GRB 020406.
We await confirmations with higher energy / IPN instruments.

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Posted: Wed May 1 03:30:00 PDT 2002 -- Sat May 11 03:30:01 PDT 2002
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ATEL #93 ATEL #93

Title: Identification of the optical counterpart of 1RXS J190141.0+012618
and a search for the optical counterpart of XTE J1901+014
Author: C.R.Powell, A.J. Norton, C.A. Haswell, S.D.Wolters, S.F.
Green (Open University), L. Morales-Rueda, P.A. Charles (Southampton
University), H. Worters (ING)
Queries: c.r.powell@open.ac.uk
Posted: 10 May 2002; 12:43 UT
Subjects: Infra-Red, Optical, X-ray, A Comment, Binaries, Transients,
Variables, Stars

The RXTE error circle of X-ray transient XTE J1901+014, reported
in IAUC #7880, includes the much smaller error circle of ROSAT source
1RXS J190141.0+012618, HRI position 19h01m40.1s, +1 26' 30" (J2000)
uncertainty 10" (ATEL #89). We obtained Jacobus Kaptyn Telescope
B, V, R, I images of the field on 2002 April 18 04:15 - 04:30, the
same filters at the IAC80 Telescope (Instituto de AstrofМsica de Canarias,
Tenerife) on the same night 04:30 - 04:50, and R on the JKT on 2002
April 28 04:45. We find a source at 19h01m39.90s, +01 26' 39.2", coincident
with the HRI position, with V=18.72, B-V=2.44, V-R=-0.93, R-I=1.64.
The V magnitude is calibrated against the Guide Star Catalog owing
to lack of standard observations. Plots of B-V vs. R and B-R vs. I
show this to be the only significantly blue object in the field. No
variability was detected, so we cannot confirm identification with
the RXTE object, nor find an alternative candidate, and no objects
were visibly different from the Digitised Sky Survey. Photometry of
JKT20020418 for 354 objects is tabulated at
http://physics.open.ac.uk/~crpowell/J1901_014/JKT20020418BVRI.html.
The candidate is star #346, ordered by I magnitude, and is indicated
by the purple cross on the image at
http://physics.open.ac.uk/~crpowell/J1901_014/JKT20020418.html.

Combined filter image of the X-ray position of J1901+014: http://physics.open.ac.uk/~crpowell/J1901_014/JKT20020418.html
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Password Certification: Craig Powell (c.r.powell@open.ac.uk)
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Your keywords: X-ray, Binaries, Black Holes, Gamma-Ray Bursts, Neutron
Stars

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