//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21788 SUBJECT: GRB 170902A: Swift detection of a burst or possible Galactic transient DATE: 17/09/02 20:41:05 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (NASA/GSFC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 20:00:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170902A (trigger=770431). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 233.895, -57.213, which is RA(J2000) = 15h 35m 35s Dec(J2000) = -57d 12' 44" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, there is nothing significant in the real-time data. The XRT began observing the field at 20:07:20.4 UT, 404.1 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 233.8330, -57.2313 which is equivalent to: RA(J2000) = +15h 35m 19.92s Dec(J2000) = -57d 13' 52.7" with an uncertainty of 5.8 arcseconds (radius, 90% containment). This location is 137 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 128 seconds with the White filter starting 413 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain extinction expected. Because this is a long event (336 second image trigger) that is close to the Galactic Plane (lat=-1.13 deg) there is a possibility that this is a Galactic transient rather than a cosmic GRB. Determination of the nature of this object will require the full downlinked dataset and further observations. Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// ATEL #10699 ATEL #10699 Title: MAXI/GSC discovery of a new hard X-ray transient MAXI J1535-571 Author: H. Negoro (Nihon U.), M. Ishikawa, S. Ueno, H. Tomida, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA), T. Mihara, M. Sugizaki, M. Serino, S. Nakahira W. Iwakiri, M. Shidatsu, M. Matsuoka (RIKEN), N. Kawai, S. Sugita, T. Yoshii, Y. Tachibana, S. Harita, Y. Muraki, K. Morita (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), H. Tsunemi, T. Yoneyama (Osaka U.), M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.), Y. Ueda, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki, H. Kawai (Chuo U.), M. Yamauchi, C. Hanyu, K, Hidaka (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.) Queries: negoro@phys.cst.nihon-u.ac.jp Posted: 3 Sep 2017; 01:08 UT Subjects:X-ray, Black Hole, Neutron Star, Transient The MAXI/GSC nova alert system triggered a bright uncatalogued hard X-ray transient source at 23:55 UT on 2017 September 02. Assuming that the source flux was constant over the transits from UT 10:03 to 23:56 on 2017 September 2, we obtain the source position at (R.A., Dec) = (233.794 deg, -57.179 deg) = (15 35 10, -57 10 43) (J2000) with a 90% C.L. statistical error of 0.34 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan transits was 34 +- 6 mCrab (4.0-10.0keV, 1 sigma error). The X-ray flux has been increased since the beginning of September 2. We encourage followup observations of this source. MAXI Home Page: http://maxi.riken.jp //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21790 SUBJECT: GRB 170902A: Enhanced Swift-XRT position DATE: 17/09/03 03:46:40 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 3279 s of XRT Photon Counting mode data and 5 UVOT images for GRB 170902A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 233.83222, -57.23004 which is equivalent to: RA (J2000): 15h 35m 19.73s Dec (J2000): -57d 13' 48.1" with an uncertainty of 1.5 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// ATEL #10700 ATEL #10700 Title: MAXI J1535-571: Swift detection and localization Author: J. A. Kennea (PSU), P. A. Evans, A. P. Beardmore (U Leicester), H. A. Krimm (NSF/USRA), P. Romano (INAF-IASFPA), K. Yamaoka (Nagoya U.), M. Serino (RIKEN) and H. Negoro (Nihon U.) Queries: kennea@swift.psu.edu Posted: 3 Sep 2017; 04:10 UT Subjects: X-ray, Transient As reported in GCN #21788, at 20:00:36UT Swift/BAT triggered on an outburst from a possible GRB (GRB 170902A) or, based upon its localization near the plane and the nature of the BAT trigger (long image trigger), a possible Galactic Transient. Negoro et al (ATEL #10699) reported a new transient, MAXI J1535-571 was detected by MAXI at 23:55UT on September 2nd, 2017, at a position coincident with the localization of the BAT detected transient (BAT and MAXI localizations lie 3.9 arc-minutes apart). We therefore conclude that the BAT detected transient is not a GRB, but a new Galactic Transient source, co-detected by Swift and MAXI: MAXI J1535-571. Swift observed this new transient using both its normal automated burst response in Windowed Timing (WT) mode between 20:00UT and 21:51UT on September 2nd, 2017, and as a Target of Opportunity upload in Photon Counting (PC) mode between 22:13UT on September 2nd, 2017 and 01:15UT on September 3rd, 2017. Using 3279 s of PC mode data and 5 UVOT images for MAXI J1535-571, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 233.83222, -57.23004 which is equivalent to: RA (J2000): 15h 35m 19.73s Dec (J2000): -57d 13' 48.1" with an uncertainty of 1.5 arcsec (radius, 90% confidence). Based on 1.6ks of WT mode data, we find the spectrum is well fit by an absorbed power-law model, with NH = 3.6 +/- 0.2 x 1022 cm-2 and a photon index of 1.53 +/- 0.07. The average flux, corrected for absorption, is 1.25 +/- 0.05 x 10-9 erg/s/cm2. In data taken from 20:07UT to 01:15UT there was no strong evidence of brightening or fading in the X-ray light-curve. Examination of the Swift/UVOT data reveals no detection of any new optical transient at the above localization. However, given the location on the Galactic Plane and the high measured absorption, this is not surprising. Further observations are encouraged in order to determine the nature of this transient. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21791 SUBJECT: Swift Trigger 770431 (GRB 170902A) is a not a GRB DATE: 17/09/03 04:23:55 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. A. Kennea (PSU) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift team: Swift trigger 770431 (AKA GRB 170902A) is not a GRB, but a Galactic Transient. The source was detected almost 4 hours after BAT triggered by MAXI (Negoro et al. ATEL #10699) and the Swift X-ray light-curve measured after the BAT trigger shows no evidence of fading (Kennea et al., ATEL #10700). Therefore we conclude that this trigger is in fact from a new Galactic Transient named MAXI J1535-571. //////////////////////////////////////////////////////////////////////// ATEL #10734 ATEL #10734 Title: Detection of the low-frequency QPOs in MAXI J1535-571 Author: I. A. Mereminskiy, S. A.Grebenev (Space Research Institute, Moscow) Queries: sergei@hea.iki.rssi.ru Posted: 11 Sep 2017; 17:48 UT Subjects:X-ray, Black Hole During current (on September 11, 2007) Swift-XRT observations of the new black hole transient MAXI J1535-571 (ATel #10699) we detected a strong peak of QPOs at 1.9 Hz. Last days the source demonstrated spectral softening (ATel #10729, #10731), indicating the beginning of a transition between the hard and soft states. The observations were performed in WT-mode, giving time resolution of 1.7 ms. The first and second harmonics of the QPOs were observed at 1.87 and 3.87 Hz (barycenter corrected), with the Lorentzian widths of 0.19 and 0.49 Hz. Since the source is extremely bright (about 800 counts/s) we checked for possible pile-up effects by excluding 5 brightest rows of CCD and using only events with energies above 1 keV. This had a little effect on the detected features, therefore we concluded that the pile-up is not responsible for this QPOs and they are intrinsic features of the source. The extracted power spectrum with the overplotted best-fit (powerlaw plus two Lorentzians) can be found here: https://drive.google.com/open?id=0B_vv997IdS4xamcza0tzMi1GSzA MAXI J1535-571: http://drive.google.com/open?id=0B_vv997IdS4xamcza0tzMi1GSzA