GRB 170210A

O.J. Roberts (USRA/NASA) and B. Mailyan (UAH)
report on behalf of the Fermi GBM Team:

"At 02:47:36.58 UT on February 10th 2017, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 170210A (trigger 508387661 / 170210116). The
on-ground calculated location using the GBM trigger
data is,

RA = 232.56, DEC = -58.59 (J2000 degrees), equivalent to
J2000 15h 30m, -58d 35',

with an uncertainty of 1 degree (radius, 1-sigma
containment, statistical only; there is additionally
a systematic error which we have characterized as a
core-plus-tail model, with 90% of GRBs having a 3.7 deg.
error and a small tail suffering a larger than 10 deg.
systematic error [Connaughton et al. 2015, ApJS, 216, 32]).

The initial angle from the Fermi-LAT boresight to the GBM
ground-location is 109 degrees.

The GBM light curve shows a long burst with multiple
episodes of bright emission over a duration (T90) of about
79 s (50-300 keV). The time-averaged spectrum from T0+9 s
to T0+84 s is best fit by a Band function with
alpha= -0.90 +/- 0.02, beta= -2.28 +/- 0.08 and Epeak
is 361.5 +/- 14.1 keV.

The event fluence (10-1000 keV) in this time interval is
(1.10 +/- 0.2) E-04 erg/cm^2. The 1s peak photon flux
measured starting from T0+41.7 s in the 10-1000 keV band is
32.8 +/- 0.6 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

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,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

S. Barthelmy, J. Cummings, N. Gehrels, 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:


The long-duration GRB 170210A (Roberts and Mailyan, GCN Circ. 20660
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 ) has 
been detected by Fermi(GBM), Konus-Wind, Mars-Odyssey (HEND), and Swift 
(BAT), so far, at about 10056 s UT (02:47:36).
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:
    226.055 (15h 04m 13s) -65.101 (-65d 06' 02")
   Corners:
    228.764 (15h 15m 03s) -63.914 (-63d 54' 51")
    228.302 (15h 13m 12s) -64.342 (-64d 20' 31")
    223.147 (14h 52m 35s) -66.193 (-66d 11' 35")
    223.706 (14h 54m 49s) -65.801 (-65d 48' 04")
   ---------------------------------------------
The error box area is 1731 sq. arcmin, and its maximum
dimension is 3.28 deg (the minimum one is 10.1 arcmin).
The Sun distance was 80 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170210_T10092/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.

Y.H. Wang (IHEP), M.Z. Feng (IHEP), Y. Zhao (IHEP), 
report on behalf of the POLAR collaboration:

At 2017-02-10T02:47:37 UT (T0), during a routine on-ground 
search of data, POLAR detected the long-duration GRB 170210A, 
which was also reported by the 
Fermi/GBM (O.J. Roberts et al, GCN Circ. 20660
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 ) and 
IPN Triangulation(K. Hurley et al, GCN Circ. 20661
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 ), and also 
detected by Konus-Wind.

The POLAR light curve shows a long burst consists of multiple peaks,
with a duration (T90) of 62.27 s measured from T0+13.12 s.
The 1-s peak rate measured from T0+41.0 s is 6673.75cnts/s.
The total counts is about 106099 cnts.
LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170210A/lc/POLAR_lc_grb170210A.png

The above results are not dead time corrected. The above 
measurements are in the energy range of about 20-500 keV.

Using the best location from the IPN Triangulation, which is (J2000):
RA:     226.055   [deg]
Dec:    -65.101   [deg]
Err:    1731      [sq. arcmin](3 sigma)

the incident angle in POLAR coordinate at T0 is:
theta:  80.6      [deg]
phi:    130.9     [deg]

The Minimum Detectable Polarization(MDP) for this burst is
estimated to be ~7.3% [1-sigma, statistical only]. 

All analysis results presented above are preliminary.

POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.

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

The long-duration, bright GRB 170210A
(Fermi-GBM detection: Roberts and Mailyan, GCN Circ. 20660
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 ;
IPN Triangulation: Hurley et al., GCN Circ. 20661
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 ;
POLAR detection: Wang et al., GCN Circ. 20665
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 )
triggered Konus-Wind at T0=10092.18 s UT (02:48:12.180).

The burst light curve shows a multipeaked structure which
starts at ~T0-41 s and has a total duration of ~124 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170210_T10092/

As observed by Konus-Wind, the burst
had a fluence of 1.40(-0.16,+0.16)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+7.152 s,
of 1.83(-0.33,+0.33)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+86.528 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.99(-0.06,+0.07),
the high energy photon index beta = -2.55(-0.68,+0.26),
the peak energy Ep = 392(-40,+45) keV
(chi2 = 105/97 dof)

The spectrum near the maximum count rate
(measured from T0+5.888 to T0+7.680 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.63(-0.14,+0.17),
the high energy photon index beta = -2.30(-0.39,+0.21),
the peak energy Ep = 410(-76,+90) keV
(chi2 = 70/65 dof)

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