GRB 190903A

The Fermi GBM team reports the detection of a likely SHORT GRB

At 17:19:36 UT on 3 Sep 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190903A (trigger 589223981.255486 / 190903722).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 62.4, Dec = -64.9 (J2000 degrees, equivalent to J2000 04h 09m, -64d 54'), with a statistical uncertainty of 6.3 degrees.

The angle from the Fermi LAT boresight is 86.0 degrees.

The skymap can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190903722/quicklook/glg_skymap_all_bn190903722.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190903722/quicklook/glg_healpix_all_bn190903722.fit

The GBM light curve can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190903722/quicklook/glg_lc_medres34_bn190903722.gif

B. Mailyan (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 17:19:36.26 UT on 3 September 2019, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 190903A (trigger 589223981/190903722).

The on-ground calculated location, using the GBM trigger
data, is RA = 62.43 , DEC = -64.86  (J2000 degrees,
equivalent to 11h 32m, -17d 46'), with an uncertainty
of 6.3 degrees (radius, 1-sigma containment).

The angle from the Fermi LAT boresight is 86  degrees.

The GBM light curve consists of a single short spike
with a duration (T90) of about 0.27s (50-300 keV).
The time-averaged spectrum from T0-0.064s to T0+0.128s is
adequately fit by a Band function with Epeak = 824 +/- 308 keV,
alpha = -0.79 +/- 0.13, and beta = -2.15 +/- 0.36

The event fluence (10-1000 keV) in this time interval is
 (7.8 +/- 0.65)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.38s in the 10-1000 keV band is 3.01 +/- 0.23 ph/s/cm^2."

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info,
please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/

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

K. Hurley, on behalf of the IPN,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,

and

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

The short-duration GRB 190903A
(Fermi-GBM detection: Fermi GBM Team, GCN Circ. 25633
Loading...
 
 ;
Mailyan and Meegan, GCN Circ. 25636
Loading...
 
 )
was detected by Fermi (GBM trigger 589223981), INTEGRAL (SPI-ACS),
and Konus-Wind, at about 62376 s UT (17:19:36).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    63.950 (04h 15m 48s) -59.485 (-59d 29' 04")
  Corners:
    62.459 (04h 09m 50s) -49.304 (-49d 18' 15")
    66.042 (04h 24m 10s) -66.310 (-66d 18' 34")
    64.926 (04h 19m 42s) -65.995 (-65d 59' 43")
    61.374 (04h 05m 30s) -46.559 (-46d 33' 33")
  ---------------------------------------------
The error box area is about 7.5 sq. deg, and its maximum
dimension is 19.9 deg (the minimum one is 27.5 arcmin).
The Sun distance was 100 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of, the 
Fermi-GBM one.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB190903_T62377/IPN/

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