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 ----- ***Instant Email Notice***: Transients ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ The Astronomer's Telegram http://atel.caltech.edu/ ============================================================================== 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. ------------------------------------------------------------------------------ Password Certification: Ron Remillard (rr@space.mit.edu) http://atel.caltech.edu/?read=88 ------------------------------------------------------------------------------ The Astronomer's Telegram http://atel.caltech.edu/ ------------------------------------------------------------------------------ Posted: Wed Apr 17 03:30:00 PDT 2002 -- Thu Apr 18 03:30:00 PDT 2002 ============================================================================== 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. ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ The Astronomer's Telegram http://atel.caltech.edu/ ------------------------------------------------------------------------------ Posted: Wed May 1 03:30:00 PDT 2002 -- Sat May 11 03:30:01 PDT 2002 ============================================================================== 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 Astrofísica 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 ------------------------------------------------------------------------------ Password Certification: Craig Powell (c.r.powell@open.ac.uk) http://atel.caltech.edu/?read=93 ============================================================================== Your keywords: X-ray, Binaries, Black Holes, Gamma-Ray Bursts, Neutron Stars ==============================================================================