GRB 170529A

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

A long-duration, GRB 170529A has been detected by
Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift (BAT),
so far, at about 25538 s UT (07:05:38).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   164.499 (10h 58m 00s) -17.934 (-17d 56' 01")
  Corners:
   163.130 (10h 52m 31s) -20.393 (-20d 23' 34")
   163.049 (10h 52m 12s) -20.800 (-20d 48' 01")
   165.951 (11h 03m 48s) -15.216 (-15d 12' 59")
   166.065 (11h 04m 15s) -14.719 (-14d 43' 08")
  ---------------------------------------------
The error box area is 2644 sq. arcmin, and its maximum
dimension is 6.7 deg (the minimum one is 7.1 arcmin).
The Sun distance was 103 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170529_T25541/IPN/

The time history and spectrum will be given in forthcoming GCN Circulars.

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170529A
(IPN triangulation: Hurley et al., GCN 21165
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 )
triggered Konus-Wind at T0=25541.567 s UT (07:05:41.567).

The burst light curve shows two separate multipeaked episodes: the first
from ~T0-6 s to ~T0+52 s and the second weaker/softer
from ~T0+176 s to ~T0+220 s. The total duration of the burst is ~226 s.
The emission is seen up to 20 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.73(-0.40,+0.62)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+7.504 s,
of 1.54(-0.27,+0.28)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+222.464 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.96(-0.16,+0.46),
the high energy photon index beta = -2.23(-1.36,+0.41),
the peak energy Ep = 422(-188,+142) keV
(chi2 = 89/98 dof).

The spectrum near the maximum count rate
(measured from T0+6.656 to T0+11.008 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.49(-0.10,+0.11),
the high energy photon index beta = -2.41(-0.28,+0.18),
the peak energy Ep = 486(-54,+59) keV
(chi2 = 75/87 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170529_T25541/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

Analysis of Astrosat data showed the CZTI detection of a long bright GRB 170529A, which was also detected by IPN triangulation(Hurley et al., GCN 21165
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 ) and Konus-wind(Kozlova A., GCN 21167
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 ).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks emission with the strongest peak at 07:05:48.567 UT, ~7 s after the Konus-wind Trigger. The measured peak count rate is 1508.5 cts/s above the background in combined data of four quadrants, with a total of 17280 cts. The local mean background count rate was 390.5 cts/s. Using cumulative rates, we measure a T90 of 33.5 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as in the 100-500 keV energy range.

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.