GRB 230623A

Y. Hagiwara (Miyazaki U.), H. Negoro, M. Nakajima (Nihon U.), M. Serino (AGU),
K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.),
T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto (Chuo U.),
M. Shidatsu (Ehime U.),
I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA),
Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani (Kyoto U.),
M. Yamauchi, Y. Umeki, Y. Otsuki (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 07:23:37 UT on 23 June 2023.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (349.981 deg, -17.842 deg) = (23 19 55, -17 50 31) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.23 deg and 0.2 deg, respectively.
The roll angle of long axis from the north direction is 40.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 185 +- 29 mCrab
(4.0-10.0keV, 1 sigma error).
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (349.422, -18.340) deg = (23 17 41, -18 20 23) (J2000)
(R.A., Dec) = (349.773, -18.563) deg = (23 19 05, -18 33 46) (J2000)
(R.A., Dec) = (350.604, -17.375) deg = (23 22 24, -17 22 30) (J2000)
(R.A., Dec) = (350.255, -17.153) deg = (23 21 01, -17 09 10) (J2000)
There was no significant excess flux in the previous transit at 05:50 UT
and in the next transit at 08:56 UT with an upper limit of 20 mCrab for each.

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 230623A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00113

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.

V.Lipunov, A.Kuznetsov, N.Tiurina, E.Gorbovskoy, P.Balanutsa, K.Zhirkov, O.Gress,  A.Chasovnikov, G.Antipov, D.Vlasenko,
V.Senik, V.Topolev, Ya.Kechin, Yu.Tselik, Siyu Wu, D.Cheryasov, V.Shumkov, T.Pogrosheva (Lomonosov Moscow State University,SAI,Physics Department),
C.Francile, F. Podesta, C.Lopez, R. Podesta (Observatorio Astronomico Felix Aguilar OAFA),
D.Buckley (SAAO),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
N.M.Budnev, O.Ershova (ISU,API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University),
M.Gulyaev, E.Minkina (Lomonosov MSU)

MASTER-OAFA obotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)
pointed to MAXI/GSC GRB 230623A (Hagiwara et al. GCN 34068
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 ,
Trigger=2023-06-23 07:23:37 UT, not came in socket, Tnotice(GCN)=09:39:20)
at 2023-06-23 10:14:25UT through  clouds with  mlim=17.0 at first 6 images (sun alt.=-16 and sunrise), we don't find OT insode 0.23deg MAXI error-box by auto-detection system.

We also made the difference with old MASTER image and didn't find new optical sources, that can be connected with GRB.

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 230623A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00114

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.

S. Dichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), E. Ambrosi	(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M.
Perri (SSDC & INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf
of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 230623A in a series of observations tiled on the sky. The
total exposure time is 1.8 ks, distributed over 7 tiles; the maximum
exposure at a single sky location was 807 s. The data were collected
between T0+19.9 ks and T0+38.0 ks, and are entirely in Photon Counting
(PC) mode. 

No X-ray sources have been detected. The 3-sigma upper limit in the
field (not including the regions where the tiles overlap) ranges from
~0.02 to ~0.23 ct s^-1, corresponding to a 0.3-10 keV observed flux of
6.1e-13 to 9.1e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00113.

This circular is an official product of the Swift-XRT team.