GRB 230723B

K. L. Page (U Leicester), J.D. Gropp (PSU), H. A. Krimm (NSF),
T. M. Parsotan (GSFC/UMBC/CRESSTII) and M. H. Siegel (PSU) report on
behalf of the Neil Gehrels Swift Observatory Team:

At 11:42:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230723B (trigger=1180410).  
The BAT on-board calculated location is 
RA, Dec 250.379, -5.327 which is 
   RA(J2000) = 16h 41m 31s
   Dec(J2000) = -05d 19' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~2200 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+50.2
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)

S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri
(INAF-OAB) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 230723B at 12:37:27.6 UT,
3294.7 seconds after the BAT trigger. No source was detected in 807 s
of promptly downlinked data, which covered 88% of the BAT error circle.
We are waiting for the full dataset to detect and localise the XRT
counterpart.

K.L. Page and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT
team:

We have analysed 1.0 ks of XRT data for GRB 230723B, from 3.3 ks to 4.4
ks after the  BAT trigger. The data are entirely in Photon Counting
(PC) mode. The refined XRT position is RA, Dec = 250.3798, -5.3348
which is equivalent to:

RA (J2000): 16 41 31.15
Dec(J2000): -05 20 05.2

with an uncertainty of 4.1 arcsec (radius, 90% confidence).

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

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 230723B ( K. L. Page et al., GCN 34234
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 ) errorbox  18882 sec after notice time and 18900 sec after trigger time at 2023-07-23 16:57:33 UT, with upper limit up to  19.3 mag. Observations started at twilight.  The observations began at zenith distance = 42 deg. The sun  altitude  is -13.0 deg. 

The galactic latitude b = 25 deg., longitude l = 12 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2243736

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   18990 |         MASTER-SAAO |   C |   180 | 18.1 |        
   18990 |         MASTER-SAAO |   C |   180 | 19.1 |        
   19201 |         MASTER-SAAO |   C |   180 | 18.4 |        
   19201 |         MASTER-SAAO |   C |   180 | 19.3 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

M. H. Siegel (PSU) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230723B
3298 s after the BAT trigger (Page et al., GCN Circ. 34234
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 ).
No optical afterglow consistent with the XRT position (Page and Evans, 
GCN Circ. 34238
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 )  is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          3298         3448          147         >20.6
white             3298         4680          344         >20.9
v                 3456         3655          197         >19.1
b                 4276         4475          197         >20.1
u                 4070         4270          197         >20.0
w1                3866         4065          197         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.411 in the direction of the burst
(Schlegel et al. 1998).

J.F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C.C. Thoene (ASU-CAS), M. Blazek (CAHA) report:

We observed the field of GRB 230723B (Page et al. GCN 34234
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 ) with CAFOS at the 2.2m CAHA telescope, at Calar Alto Observatory, in Almeria (Spain). The observation consisted of 9x360s exposures in i-band, starting at 20:34 UT and with mean epoch on 0.389 days after the burst. We do not see any new source within the XRT error box (Page & Evans, GCN 34238
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 ) down to a 3-sigma limit of 23.0 mag. We do notice that there is a faint object at the Eastern edge of the XRT error box with a magnitude of 22.4 mag, with coordinates (J2000): 16:41:31.43, -5:20:05.7, but that seems to be also there, at a similar magnitude, in the PanSTARRS images. It is not possible at this time to determine if this object could be the host galaxy of GRB 230723B.

C. Adami (LAM), J.-C. Cuillandre (CEA Paris-Saclay), M. Ollivier, H. Dole (IAS, Université Paris-Saclay), T. Adami (ENS Paris-Saclay), A. de Ugarte Postigo (OCA/CNRS), E. Le Floc’h, D. Götz (CEA Paris-Saclay), A.Saccardi, S.Vergani (GEPI, Obs. de Paris), S. Basa (LAM), report on behalf of a larger collaboration :

We observed the field of GRB 230723B (Page et al. GCN 34234
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 ) using the T193cm and T120cm telescopes at Observatoire de Haute-Provence (France). We obtained 26 exposures in the r’-band (4x30sec + 22x150sec) with MISTRAL on the T193cm for a total exposure time of 57min, starting at 20:54 UT with a mean epoch at ~0.42days after trigger. At the same time we also obtained 10 exposures of 6min in the I-band at T120cm (total time of 1h). In the r’-band and I-band combined frames, we do not detect any new source within the XRT error box (Page & Evans, GCN 34238
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 ). Our photometric calibration was performed using nearby stars from the PanSTARRS catalog, leading to the following lower limits :

r’ > 21 mag (AB, 3 sigma)
I > 19.25 mag (AB, 3 sigma)

These non-detections are consistent with the CAHA deeper observations in the i-band reported earlier by Agui Fernandez et al. (GCN 34241
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 ).

We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Yoann Degot-Longhi, and we also thank Alice Morel.

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (SSDC
& INAF-OAR), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), D.N.
Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), 
 and P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 230723B, from 3.3 ks to
28.6 ks after the  BAT trigger. The data are entirely in Photon
Counting (PC) mode. Using 1149 s of PC mode data and 3 UVOT images, we
find an enhanced XRT position (using the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
250.37810, -5.33463 which is equivalent to:

RA (J2000): 16h 41m 30.74s
Dec(J2000): -05d 20' 04.7"

with an uncertainty of 2.4 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.6 (+0.6, -0.4).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.4 (+0.6, -0.5). The
best-fitting absorption column is  6.8 (+4.5, -3.3) x 10^21 cm^-2, in
excess of the Galactic value of 2.2 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.0 x 10^-11 (9.4 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.8 (+4.5, -3.3) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^21 cm^-2
Excess significance: 2.3 sigma
Photon index:	     2.4 (+0.6, -0.5)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01180410.

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

J.Mangan (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

At 11:42:33.03 UT on 23 July 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230723B (trigger 711805358 / 230723488),
which was also detected by Swift BAT (K. L. Page et al. 2023, GCN 34234
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 ).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 78 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 10 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+9 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.9 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 59.1 +/- 2.7 keV.

The event fluence (10-1000 keV) in this time interval is
(3.8 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.2 s in the 10-1000 keV band
is 7.8 +/- 0.4 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/

U.Quadri and  L.Strabla (Bassano Bresciano Astronomical Observatory),
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We imaged the field of GRB 230723B detected by SWIFT(trigger 1180410)
with the robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
GAC - Gruppo Astrofili Cremonesi.

The observations started 518 min after the GRB trigger, at the end of twilight, 
with our Newton telescope D=250 mm F/D=4.8.

Weather conditions were medium.

We co-added 70 exposures of 120 sec each.

Start T0+      End T0+       R lim
518.43 min   598.40 min      19

We did not found any optical counterpart in the error box of the XRTcandidate.
Page et al. GCN 34234
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Magnitudes were estimated with the Gaia DR2 cat. and 
are not corrected for galactic dust extinction.

Reference:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.

J.F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C.C. Thoene (ASU-CAS), M. Blazek and Ana Guijarro Roman (CAHA) report:

After XRT delivered its refined analysis and updated GRB localisation (Osborne et al. GCN 34248
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 ) we noticed that the new localisation has very little overlap with the fist one. The revised localisation is no longer consistent with the object mentioned in our previous GCN (Agui Fernandez et al. GCN 34241
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 ). However, within the new localisation circle and outside the original one, we detect an object at coordinates (J2000): 16:41:30.65 -5:20:04.5 with an AB magnitude of i =  22.4+/-0.2 mag as compared to PanSTARRS field objects. No object is detected in PanSTARRS at this position. Further observations will be needed to confirm the object variability and its possible identification as the optical counterpart of GRB 230723A.

S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez and L. Bellizzi (Montarrenti Observatory, Siena, Italy) report:

We observed the field of the GRB 230723B (Trigger 1180410, K.L. Page et al., GCN 34234
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 , V. Lipunov, GCN 34239
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 ; J.F. Agui Fernandez, GCN 34241
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 ; C. Adami, GCN 34247
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 ; U. Quadri, GCN 34250
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 ; J.F. Agui Fernandez, GCN 34251
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 ) with the automatic 0.53m Ritchey-Chretien telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88).

The observations were started under good weather conditions at 2023-07-23 21:13:37 UT (approximately 9.5 hours after notice) stacking 30x30s clear filter CCD exposures.

We have not found optical transient within the error-box of the Neil Gehrels Swift Observatory position (RA 16h 41m 30.74s, Dec. -05d 20m 04.7s - J2000).  
Mag. upper limit R = 20.83 +/-0.14

Magnitudes were obtained from USNO-B1 catalogue and are not corrected for galactic extinction.

Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We image the field of GRB 230723B detected by SWIFT(trigger 1180410)
with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione

The observations started at 19:19 UT of  2023/07/23, after 7,40 hours after the GRB trigger, at the end of twilight
with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 32 image of 60 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software
We have not detected any clearly visible sources, up to 20th magnitude with clear skies.
   Start T0+                  End T0+        Rlim
19:19:39 UT            19:54:47 UT      20

We did not found any optical counterpart in the error box of the XRTcandidate.
Page et al. GCN 34234
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Magnitudes were estimated with the Gaia DR2 cat. and 
are not corrected for galactic dust extinction.



The message may be cited.

E. Pavoni and L. Moretti (Leavitt Observatory), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We imaged the field of GRB 230723B detected by SWIFT(trigger 1180410)
with telescope of Leavitt Observatory, Italy. Member of: 
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
ATA - Associazione Tuscolana di Astronomia.

The observations began at 21:31 UT on 2023/07/23, 577 min after the GRB trigger, with our RC telescope D=250 mm F/D=8.

Weather conditions were medium.

We took 30 images of 120 sec each. All images are unfiltered, calibrated with master dark and master flat, stacked with ASTAP software.

We have not detected any clearly visible sources, up to 19.9th magnitude with clear sky at 
RA(J2000)  = 16h 41m 43.83s
Dec(J2000) = -05d 17' 16.04"

on a field of view 31.1 x 26.8 arcmin

Start                End              Rlim
577 min         637 min      19.9

Magnitudes were estimated with the Gaia DR3 cat. and are not corrected for galactic dust extinction.

The message may be cited.

Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, Italy)
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
Unione Astrofili Italiani (UAI)
report: 
 
We imaged the field of GRB 230723B detected by SWIFT(trigger 1180410)
with the telescope LX200 12” of GAD Observatory, La Spezia, Italy
Member of: 
 
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
GAD - Gruppo Astronomia Digitale.
 
The observations started 557 min after the GRB trigger, at the end of twilight, 
with a Shmidt-Cassegrain telescope D=304 mm with reducer F/D=4.75.
 
Weather conditions were medium.
 
We co-added 42 exposures of 120 sec each.
 
 
Start T0+      End T0+       R lim
557 min        641 min         19
 
We did not found any optical counterpart in the error box of the XRT candidate.
Page et al. GCN 34234
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Magnitudes were estimated with the Gaia EDR3 cat. and 
are not corrected for galactic dust extinction.
 
Reference:
https://www.parcodellestelle.com/
 
The message may be cited.

G. E. Anderson (Curtin), A. Gulati (USyd), J. K. Leung (USyd), A. J. van der Horst (GWU), L. Rhodes (Oxford), S. Chastain (UNM) on behalf of the PanRadio GRB collaboration

The Australia Telescope Compact Array (ATCA) performed rapid-response follow-up observations of the long GRB 230723B (Page et al. GCN 34234
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 ) at 5.5, 9, 16.7, and 21.2 GHz as part of the Large ATCA “PanRadio GRB” follow-up programme C3542 (PI. Anderson). ATCA was on target observing at  2023-07-23 11:51 UT,  just 9 minutes post-burst and observed for 4 hrs. There is no radio source coincident with the enhanced XRT position (Page et al. GCN 34238
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 ) with 3 sigma upper limits of 150, 90, 90 and 150 microJy/beam at 5.5, 9.0, 16.7 and 21.2 GHz, respectively. Further observations are planned.

We thank the CSIRO Space and Astronomy staff for supporting these observations and maintaining the ATCA rapid-response observing mode.

We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.

M. Sasada, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, N. Higuchi, H. Takei, H. Seki, Y. Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on behalf of the MITSuME collaboration:

We observed the field of GRB 230723B (Page et al. GCN Circular #34234
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 , Campana et al. #34236, Page et al. #34238, Lipunov et al. #34239, Siegle et al. #34240, Agui Fernandez et al. #34241, Adami et al. #34247, Osborne et al. #34248, Mangan et al. #34249, Quadri et al. #34250, Agui Fernandez et al. #34251, Leonini et al. #34252, Ruocco et al. #34253, Pavoni et al. #34254, Lopresti et al. #34259, Anderson et al. #34267) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.

The observation with a series of 10 sec exposures started at 2023-07-23 11:43:20 UT (48 seconds after the Swift/BAT detection). We stacked the images with good conditions. In the stacked image at 454 seconds after the burst, we detected an object of Ic=17.1+/-0.2 at the coordinate reported by Agui Fernandez et al. #34251. We also report the g’-, Rc- and Ic-band 3-sigma upper limits of the stacked images.

T0+[sec] |MID-UT | T-EXP[sec] | 3-sigma limits
------------------------------------------------------------------------------------------------
454  | 2023-07-23 11:50:06 | 220 | g’>18.0, Rc>17.8, Ic>17.6
1419 | 2023-07-23 12:06:11 | 1020 | g’>18.6, Rc>18.5, Ic>18.2
 3763 | 2023-07-23 12:45:15 | 1890 | g'>19.0, Rc>18.5, Ic>18.0
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 r and i bands were converted to our Rc- and Ic-band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).

J.F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C.C. Thoene (ASU-CAS), J. Flores and Ana Guijarro Roman (CAHA) report:

We have performed follow-up observations on the GRB 230723B field (Page et al. GCN 34324
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 , Osborne et al. GCN 34248
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 ) with CAFOS in the 2.2m telescope at the Calar Alto Observatory in Almeria, Spain. Observations consisted of 9x360s in i-band, starting at 2023-07-25T20:46:11 UT with a mean epoch 2.393 days after the burst. We detect the object reported in Agui Fernandez et al. (GCN 34251
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 ) at a magnitude consistent with our previous observation. 
The early optical detection of the transient at a consistent location by Sasada et al. (GCN 34268
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 ) indicates that the detection in the first Calar Alto observation was already dominated by the host galaxy contribution. The interpolation from the observation of Sasada et al. (GCN 34251
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 ) to the one of Agui Fernandez et al. (GCN 34251
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 ) indicates a decay rate of at least alpha=1.1 (where F_nu ~ t^-alpha). Extrapolating this, the GRB afterglow should be dimmer than 24 mag at the time of our follow-up observations. We do note, that the host galaxy should be in the range for emission line spectroscopy with 8-10m telescopes.

N. H. Hayatsu, H. Hanayama (NAOJ), M. Sasada, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, N. Higuchi, H. Takei, H. Seki, Y. Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on behalf of the MITSuME collaboration:

report:

We observed the field of GRB 230723B (Page et al. GCN Circular #34234
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 , Campana et al. #34236, Page et al. #34238, Lipunov et al. #34239, Siegle et al. #34240, Agui Fernandez et al. #34241, Adami et al. #34247, Osborne et al. #34248, Mangan et al. #34249, Quadri et al. #34250, Agui Fernandez et al. #34251, Leonini et al. #34252, Ruocco et al. #34253, Pavoni et al. #34254, Lopresti et al. #34259, Anderson et al. #34267, Sanada et al. #34268, and Agui Fernandez et al. #34271) with the optical three color (g', Rc, and Ic) CCD cameras attached to the 105 cm Murikabushi telescope of Ishigakijima Astronomical Observatory, Okinawa, Japan. 

The observation with a series of 60 sec exposures started at 2023-07-23 12:21:20.29 UT (2328 seconds after the Swift/BAT detection). In the stacked image at 3193 seconds after the burst, we detected an object of g'=20.5+/-0.2, Rc=19.4+/-0.1, and Ic=19.6+/-0.1 at the coordinate reported by Agui Fernandez et al. #34251. We also report the g’-, Rc- and Ic-band 5-sigma upper limits of the stacked images.

TT0+[sec] | MID-UT | T-EXP[sec] | candidate magnitudes | 5-sigma limits
------------------------------------------------------------------------------------------------
3193 | 2023-07-23 12:35:45 | 1080 | g'=20.5+/-0.2, Rc=19.4+/-0.1, Ic=19.6+/-0.1 | g'>20.6, Rc>21.2, Ic>20.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We used PS1 catalog for flux calibration. The conversion from PS1 r and i band to our Rc and Ic band is by the equation of Tonry et al. (2012), Table. 6. The magnitudes are expressed in the AB system. The images were processed through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), 
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+60 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230723B (trigger #1180410)
(Page, et al., GCN Circ. 34234
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 ).  The BAT ground-calculated position is
RA, Dec = 250.391, -5.319 deg which is 
   RA(J2000)  =  16h 41m 33.8s 
   Dec(J2000) = -05d 19' 08.1" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 39%.
 
The light curve shows a fast rise exponential decay type profile.
T90 (15-350 keV) is 6.64 +- 0.81 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.22 to T+7.94 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.09 +- 0.38, 
and Epeak of 65.9 +- 15.8 keV (chi squared 41.57 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.7 +- 0.1 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+1.64 sec in the 15-150 keV band is
5.1 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.77 +- 0.08 (chi squared 52.21 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1180410/BA/