Gamma-ray Burst 150622A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

BACODINE Notice

TITLE:           GCN/MAXI NOTICE
NOTICE_DATE:     Mon 22 Jun 15 11:35:20 UT
NOTICE_TYPE:     MAXI Unknown Source Position
EVENT_ID_NUM:    195326733
EVENT_RA:        251.74d {+16h 46m 57s} (J2000),
                 252.04d {+16h 48m 10s} (current),
                 250.75d {+16h 42m 59s} (1950)
EVENT_DEC:       -52.94d {-52d 56' 27"} (J2000),
                 -52.97d {-52d 58' 03"} (current),
                 -52.85d {-52d 51' 04"} (1950)
EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX:      735.0 +- 0.0 [mCrab] 
EVENT_DATE:      17195 TJD;   173 DOY;   15/06/22
EVENT_TIME:      37423.00 SOD {10:23:43.00} UT
EVENT_TSCALE:    30s
EVENT_EBAND:     Low, 2-4 keV  
SUN_POSTN:        90.82d {+06h 03m 17s}  +23.43d {+23d 26' 05"}
SUN_DIST:        147.21 [deg]  
MOON_POSTN:      160.06d {+10h 40m 15s}   +6.02d {+06d 01' 01"}
MOON_DIST:        95.99 [deg]  
MOON_ILLUM:      32 [%]
GAL_COORDS:      334.12, -4.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      257.37,-30.30 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.

GCN Circular #17952
Y. Kawakubo (AGU), S. Nakahira, S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, T. Sakamoto, H. Ohtsuki (AGU), H. Tsunemi, R.Imatani (Osaka U.), H. Negoro, M. Nakajima, K. Tanaka, T. Masumitsu (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, S. Kanetou (Chuo U.), M. Yamauchi, D. Itoh (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Morii (ISM)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 10:23:43 UT. Assuming that the source flux was constant over the transit, we obtain the source position at
(R.A., Dec) = (252.028 deg, -52.768 deg) = (16 48 06, -52 46 04) (J2000)
with a statistical 90% C.L. elliptical error region with long and short radii of 0.22 deg and 0.14 deg, respectively. The roll angle of long axis from the north direction is 62.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 342 +- 40 mCrab (4-10keV, 1 sigma error). Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners:
```
(R.A., Dec) = (251.874 deg, -52.244 deg) = (16 47 29, -52 14 38) (J2000)
(R.A., Dec) = (251.283 deg, -52.506 deg) = (16 45 07, -52 30 20) (J2000)
(R.A., Dec) = (252.300 deg, -53.392 deg) = (16 49 11, -53 23 29) (J2000)
(R.A., Dec) = (252.900 deg, -53.128 deg) = (16 51 36, -53 07 39) (J2000)
```
There was no significant excess flux in the previous transit at 8:48 UT.
GCN Circular #17953
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the MAXI GRB 150622A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00046
Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the MAXI event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular #17954
D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 150622A (Kawakubo et al. GCN Circ. 17952) in a series of observations tiled on the sky. The total exposure time is 1.9 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 1.3 ks. The data were collected between T0+14.2 ks and T0+16.2 ks, and are entirely in Photon Counting (PC) mode.
One uncatalogued X-ray source has been detected, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below:
Source 1:
```
  RA (J2000.0):  252.4574  =  16:49:49.79
  Dec (J2000.0): -52.8499  =  -52:50:59.6
  Error: 5.4 arcsec (radius, 90% conf.)
  Count-rate: 0.032 +/- 0.010 ct s^-1
  Flux: (1.29 +/- 0.41)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00046.
This circular is an official product of the Swift-XRT team.
GCN Circular #17987
D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the MAXI-detected burst GRB 150622A (Kawakubo et al. GCN Circ. 17952). The observations now extend from T0+14.7 ks to T0+843.1 ks. The source previously reported by Burrows et al. (GCN Circ. 17954), "Source 1", is fading with 3-sigma significance, and is therefore likely the GRB afterglow. Using 483 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 252.45633, -52.85017 which is equivalent to:
```
RA (J2000): 16h 49m 49.52s
Dec(J2000): -52d 51' 00.6"
```
with an uncertainty of 4.1 arcsec (radius, 90% confidence). This position is 16.3 arcmin from the MAXI position. The source is fading with alpha >0.4.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020534. The results of the full analysis of the tiled XRT observations are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00046.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 02-Jul-2015 [Disclaimer]