GRB 170105A
GCN Circular 20387
Subject
GRB 170105A: POLAR Observation
Date
2017-01-07T06:44:37Z (8 years ago)
From
Radek Marcinkowski at PSI/POLAR <radoslaw.marcinkowski@psi.ch>
R. Marcinkowski (PSI), H. Xiao (PSI) and W. Hajdas (PSI) report on behalf
of the POLAR collaboration:
At 2017-01-05T06:14:07.0 UT(T0), during a routine on-ground search of
data, POLAR detected the GRB 170105A, which was also observed by SPIACS
at 2017-01-05T06:14:06 and Konus-Wind at 22450.264s UT (06:14:10.264).
The POLAR light curve consists of 1 peak with duration (T90) of
2.0 +/- 0.5 s measured from T0.
The 0.5 s peak flux at T0 + 0.8 s is equal to 2490 +/- 90 counts/sec.
POLAR recorded 3600 +/- 160 events from the burst.
Above measurements are in the energy range of about 80 - 500 keV.
LC_URL: http://polar.psi.ch/triggers/GRB_170105A_raw.png
or http://polar.psi.ch/pub/lc.php?event=GRB+170105A
The analysis results presented above are preliminary. Calibration of the
instrument is ongoing. POLAR is a dedicated Gamma-Ray Burst polarimeter
which was launched on-board the Chinese space laboratory Tiangong-2 (TG-2)
on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV.
More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .
This message is quotable in publications.
GCN Circular 20389
Subject
GRB 170105A: AstroSat CZTI detection
Date
2017-01-07T13:28:52Z (8 years ago)
From
Vidushi Sharma at IUCAA <vidushi@iucaa.in>
V. Sharma, V. Bhalerao and D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed clear detection of GRB170105A (POLAR Observation: R. Marcinkowski et al., GCN Circ. 20387) in the 40-200
keV energy range. The light curve shows a single peak structure with main peak at 06:14:06 UT in the quadrant A and B only, ~1 sec before the
POLAR trigger at 06:14:07 UT. The measured peak count rate is 305.46 counts/sec above the background in combined data of four quadrants, with a
total of 762 counts. The local mean background count rate was 287.54 counts/sec. Using cumulative rates, we measure a T90 of 2.86 secs.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium
of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated
the project.
GCN Circular 20412
Subject
GRB170105A: AstroSat CZTI localisation
Date
2017-01-10T05:46:39Z (8 years ago)
From
Varun Bhalerao at IUCAA <varunb@iucaa.in>
V. Bhalerao and D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Detailed analysis of AstroSat CZTI data for GRB170105A (POLAR Observation: R. Marcinkowski et al., GCN Circ. 20387; CZTI detection: Sharma et al., GCN Circ. 20389) was carried out for localising the GRB. We modelled the counts in various quadrants using a raytracing code based on the instrument geometry. The GRB is localised to a 550 sq. deg. area, centred roughly on RA, Dec = 60, +80. While spectral fits are not possible at the current stage, the data indicate a rather soft spectrum, with strongest detection around 60-80 keV and almost no counts above 100 keV. Along with the T90 measurement in Sharma et al., GCN Circ. 20389, this suggests that GRB170501A was a long GRB.
A pdf showing the localisation region is available at:
http://www.iucaa.in/~astrosat/czti_grb/GRB170105A/heal/GRB170105A_localisation.pdf
A healpix map with the localisation region is available at: http://www.iucaa.in/~astrosat/czti_grb/GRB170105A/heal/GRB170105A_localisation.fits
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.