GRB 230111A

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

At 19:07:42 UT on 11 Jan 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230111A (trigger 695156867.898656 / 230111797).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 316.1, Dec = -22.5 (J2000 degrees, equivalent to J2000 21h 04m, -22d 30'), with a statistical uncertainty of 8.9 degrees.

The angle from the Fermi LAT boresight is 100.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230111797/quicklook/glg_skymap_all_bn230111797.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230111797/quicklook/glg_healpix_all_bn230111797.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230111797/quicklook/glg_lc_medres34_bn230111797.gif

K. Setoguchi(Kyoto U.), T. Mihara (RIKEN), M. Serino (AGU),
H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima (Nihon U.),
T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, J. Kohara, S. Urabe, S. Nawa, N. Nemoto (Chuo U.),
M. Shidatsu, M. Iwasaki (Ehime U.),
N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Kurihara (JAXA),
Y. Ueda, S. Ogawa, T. Yoshitake, K. Inaba, Y. Nakatani (Kyoto U.),
M. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC) ,
W. Iwakiri (Chiba U.)

report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 19:07:37 UT on 11 Jan 2023.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (320.188 deg, -30.577 deg) = (21 20 45, -30 34 36) (J2000)
with a 90% C.L. statistical error of 0.22 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners.
(319.214, -30.721) deg = (21 16 51, -30 43 15) (J2000)
(319.406, -31.127) deg = (21 17 37, -31 07 37) (J2000)
(321.653, -30.323) deg = (21 26 36, -30 19 22) (J2000)
(321.454, -29.920) deg = (21 25 48, -29 55 12) (J2000)
The X-ray flux averaged over the scan was 230 +- 30 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 17:34 UT
and in the next transit at 20:40 UT with an upper limit of 20 mCrab for each.

O.J. Roberts (USRA) and C. Meegan (UAH) report on
behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 19:07:42.90 UT on 11 January 2023, the Fermi
Gamma-ray Burst Monitor (GBM) triggered and located
GRB 230111A (trigger 695156867/230111797), which was
also detected by MAXI (K. Setoguchi et al. 2023, GCN 33157
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 ).
The Fermi GBM Localization reported in GCN 33156
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  is consistent
with the MAXI location.

The angle from the Fermi LAT boresight is 108 degrees.

The GBM light curve consists of a single peak with a duration (T90)
of about 9 s (50-300 keV). The time-averaged spectrum
from T0-3.6 to T0+4.8 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.31 +/- 0.30 and the cutoff energy,
parameterized as Epeak, is 122 +/- 16 keV.

The event fluence (10-1000 keV) in this time interval is
(1.16 +/- 0.12)E-06 erg/cm^2. The measured 1-s peak photon flux
starting from T0-0.9 s in the 10-1000 keV band is 2.6 +/- 0.3 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/"