Gamma-ray Burst 251215A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 15 Dec 25 04:21:40 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     787465286
GRB_RA:          114.433d {+07h 37m 44s} (J2000),
                 114.640d {+07h 38m 34s} (current),
                 114.035d {+07h 36m 08s} (1950)
GRB_DEC:         -43.683d {-43d 40' 59"} (J2000),
                 -43.743d {-43d 44' 35"} (current),
                 -43.569d {-43d 34' 07"} (1950)
GRB_ERROR:       17.20 [deg radius, statistical plus systematic]
GRB_INTEN:       69 [cnts/sec]
DATA_SIGNIF:     5.60 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        21024 TJD;   349 DOY;   25/12/15
GRB_TIME:        15681.57 SOD {04:21:21.57} UT
GRB_PHI:         260.00 [deg]
GRB_THETA:        30.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.30
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:       262.86d {+17h 31m 25s}  -23.27d {-23d 16' 20"}
SUN_DIST:        106.91 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      206.79d {+13h 47m 10s}  -15.00d {-14d 59' 46"}
MOON_DIST:        81.22 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      256.79,-10.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      132.25,-63.58 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_lc_medres34_bn251215181.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 0.70,24.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 15 Dec 25 04:22:50 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      119
TRIGGER_NUM:     787465286
GRB_RA:          121.217d {+08h 04m 52s} (J2000),
                 121.449d {+08h 05m 48s} (current),
                 120.770d {+08h 03m 05s} (1950)
GRB_DEC:         -39.117d {-39d 07' 00"} (J2000),
                 -39.192d {-39d 11' 30"} (current),
                 -38.973d {-38d 58' 23"} (1950)
GRB_ERROR:       6.85 [deg radius, statistical plus systematic]
GRB_INTEN:       265 [cnts/sec]
DATA_SIGNIF:     14.50 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        21024 TJD;   349 DOY;   25/12/15
GRB_TIME:        15681.57 SOD {04:21:21.57} UT
GRB_PHI:         252.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.69
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:       262.86d {+17h 31m 26s}  -23.27d {-23d 16' 21"}
SUN_DIST:        107.87 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
MOON_POSTN:      206.80d {+13h 47m 12s}  -15.00d {-15d 00' 00"}
MOON_DIST:        77.04 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      255.35, -4.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      138.34,-57.43 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_lc_medres34_bn251215181.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 0.70,24.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 15 Dec 25 04:21:58 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     787465286
GRB_RA:          124.380d {+08h 17m 31s} (J2000),
                 124.639d {+08h 18m 33s} (current),
                 123.881d {+08h 15m 31s} (1950)
GRB_DEC:         -31.670d {-31d 40' 11"} (J2000),
                 -31.752d {-31d 45' 06"} (current),
                 -31.514d {-31d 30' 49"} (1950)
GRB_ERROR:       2.95 [deg radius, statistical only]
DATA_SIGNIF:     7.80 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        21024 TJD;   349 DOY;   25/12/15
GRB_TIME:        15681.57 SOD {04:21:21.57} UT
GRB_PHI:         240.00 [deg]
GRB_THETA:        18.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       262.86d {+17h 31m 25s}  -23.27d {-23d 16' 21"}
SUN_DIST:        112.00 [deg]   Sun_angle= 9.2 [hr] (West of Sun)
MOON_POSTN:      206.79d {+13h 47m 10s}  -15.00d {-14d 59' 50"}
MOON_DIST:        75.62 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      250.53,  2.20 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      137.81,-49.56 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_lc_medres34_bn251215181.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_787465286.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 15 Dec 25 04:30:40 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     787465286
GRB_RA:          112.820d {+07h 31m 17s} (J2000),
                 113.025d {+07h 32m 06s} (current),
                 112.425d {+07h 29m 42s} (1950)
GRB_DEC:         -43.690d {-43d 41' 23"} (J2000),
                 -43.746d {-43d 44' 46"} (current),
                 -43.583d {-43d 34' 57"} (1950)
GRB_ERROR:       7.57 [deg radius, statistical only]
GRB_DATE:        21024 TJD;   349 DOY;   25/12/15
GRB_TIME:        15681.57 SOD {04:21:21.57} UT
GRB_PHI:         259.00 [deg]
GRB_THETA:        31.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       262.86d {+17h 31m 27s}  -23.27d {-23d 16' 22"}
SUN_DIST:        107.49 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      206.86d {+13h 47m 27s}  -15.03d {-15d 01' 36"}
MOON_DIST:        82.38 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      256.26,-11.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      129.79,-64.01 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_lc_medres34_bn251215181.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_locplot_all_bn251215181.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.

GCN Circular #43104
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:21:21 UT on 15 Dec 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251215A (trigger 787465286.567966 / 251215181).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 112.8, Dec = -43.7 (J2000 degrees, equivalent to J2000 07h 31m, -43d 42'), with a statistical uncertainty of 7.6 degrees.
The angle from the Fermi LAT boresight is 31.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_skymap_all_bn251215181.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_healpix_all_bn251215181.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251215181/quicklook/glg_lc_medres34_bn251215181.gif
GCN Circular #43114
Samuele Ronchini (GSSI), James DeLaunay (PSU), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report:
Swift/BAT did not localize GRB 251215A onboard (T0: 2025-12-15T04:21:21.57 UTC, Fermi GCN 43104).
The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
The position is found with the newly developed pipeline BAT-GLIMPSE: Gamma-ray Localization using Imaging and Mosaic techniques for Pointing and Slew Epochs (Ronchini et. al, in prep). The pipeline makes use of the tools from BatAnalysis ([Parsotan et al. 2025](https://iopscience.iop.org/article/10.3847/1538-4357/ade240)). The source was detected with an SNR = 6.5 in a 16.384 s analysis time bin starting at t0 - 4.096 s.
Independently, the BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), confirms the detection of the burst in a 16.384 s analysis time bin starting at T0 - 4.096 s with a sqrt(TS) of 14.6. An arcminute localization is found with DeltaLLHOut of 63.97 and a DeltaLLHPeak of 36.66. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The NITRATES and BAT-GLIMPSE positions are compatible.
Moreover, at T0: 2025-12-15T04:23:36.28 UTC, also a CALET trigger (trig number 1449807236) activated GUANO. A signal is found by BAT-GLIMPSE during Swift slew using a mosaic technique. The source is found with an SNR = 27.1. The position is compatible with the one found by BAT-GLIMPSE and NITRATES for the Fermi-GBM trigger. Hence we conclude that the two signals are associated to the same GRB.
The BAT position is: RA, Dec = 122.6526, -36.7395 deg which is
```
RA(J2000) = 08h 10m 36.62s 
Dec(J2000) = -36d 44’ 22.2″
```
with an estimated uncertainty of 3 arcmin radius.
More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=787465318
XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars.
GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/
GCN Circular #43118
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Swift/BAT-detected event GRB 251215A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021894 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Swift/BAT event. 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.
GCN Circular #43133
C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251215A, which was also detected by Fermi/GBM (GCN 43104), Swift/BAT-GUANO (GCN 43114), and CALET (trigger 1449807236).
Glowbug was in the SAA at the time of the GBM T0 (04:21:21) and recorded data beginning at T0+20s, initially with high background rates as it was exiting the SAA. Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-12-15 04:22:25.800 with a duration of 76.0 s and a total significance of about 23.8 sigma. The burst originated toward the Nadir side of Glowbug and was detected despite passing through the passive material from the H9 pallet and internal passive material/shielding within Glowbug.
The Glowbug onset is 64.8 s after the GBM T0, and the Glowbug light curve comprises three peaks at ~T0+1s, ~T0+25s, and ~T0+72s; the T0+72s peak matches the CALET trigger time (04:23:36.282).
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12.
```
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108
```
Distribution Statement A: Approved for public release. Distribution is unlimited.

GCN Circular #43136
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251215A ( Fermi GBM team, GCN 43104) errorbox 708 sec after notice time and 729 sec after trigger time at 2025-12-15 04:33:30 UT, with upper limit up to 20.3 mag. The observations began at zenith distance = 25 deg. The sun altitude is -35.7 deg.
The galactic latitude b = -12 deg., longitude l = 256 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3071404
We obtain a following upper limits.

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     759 | 2025-12-15 04:33:30 |         MASTER-OAFA | (07h 21m 38.63s , -44d 11m 53.3s) |   C |    60 | 19.8 |        
     836 | 2025-12-15 04:34:47 |         MASTER-OAFA | (07h 32m 44.70s , -44d 12m 40.8s) |   C |    60 | 19.7 |        
    1278 | 2025-12-15 04:42:09 |         MASTER-OAFA | (07h 21m 33.82s , -44d 13m 28.4s) |   C |    60 | 20.1 |        
    1356 | 2025-12-15 04:43:27 |         MASTER-OAFA | (07h 32m 50.29s , -44d 13m 23.2s) |   C |    60 | 20.0 |        
    1537 | 2025-12-15 04:46:28 |         MASTER-OAFA | (07h 21m 36.90s , -44d 13m 08.5s) |   C |    60 | 20.2 |        
    1616 | 2025-12-15 04:47:47 |         MASTER-OAFA | (07h 28m 30.24s , -42d 18m 18.6s) |   C |    60 | 19.8 |        
    1692 | 2025-12-15 04:49:03 |         MASTER-OAFA | (07h 39m 20.70s , -42d 17m 18.4s) |   C |    60 | 19.5 |        
    1768 | 2025-12-15 04:50:19 |         MASTER-OAFA | (07h 28m 37.49s , -42d 18m 11.5s) |   C |    60 | 19.8 |        
    1844 | 2025-12-15 04:51:35 |         MASTER-OAFA | (07h 39m 20.66s , -42d 19m 12.0s) |   C |    60 | 19.5 |        
    1920 | 2025-12-15 04:52:51 |         MASTER-OAFA | (07h 28m 37.47s , -42d 18m 57.2s) |   C |    60 | 19.8 |        
    1998 | 2025-12-15 04:54:09 |         MASTER-OAFA | (07h 14m 43.71s , -46d 06m 35.4s) |   C |    60 | 20.3 |        
    2073 | 2025-12-15 04:55:24 |         MASTER-OAFA | (07h 26m 20.85s , -46d 05m 09.8s) |   C |    60 | 20.3 |        
    2149 | 2025-12-15 04:56:40 |         MASTER-OAFA | (07h 14m 41.57s , -46d 05m 53.1s) |   C |    60 | 20.3 |        
    2225 | 2025-12-15 04:57:56 |         MASTER-OAFA | (07h 26m 14.02s , -46d 04m 51.5s) |   C |    60 | 20.3 |        
    4916 | 2025-12-15 05:42:47 |         MASTER-OAFA | (07h 32m 47.05s , -44d 22m 53.9s) |   C |    60 | 20.1 |        
    4992 | 2025-12-15 05:44:03 |         MASTER-OAFA | (07h 32m 47.23s , -44d 24m 00.4s) |   C |    60 | 20.1 |        
    5071 | 2025-12-15 05:45:22 |         MASTER-OAFA | (07h 32m 50.60s , -44d 22m 25.2s) |   C |    60 | 20.1 |        
    5147 | 2025-12-15 05:46:38 |         MASTER-OAFA | (07h 21m 35.26s , -44d 22m 27.4s) |   C |    60 | 20.3 |        
    5224 | 2025-12-15 05:47:55 |         MASTER-OAFA | (07h 21m 40.10s , -44d 23m 25.8s) |   C |    60 | 20.2 |        
    5301 | 2025-12-15 05:49:12 |         MASTER-OAFA | (07h 21m 35.65s , -44d 24m 24.1s) |   C |    60 | 20.2 |        
    5377 | 2025-12-15 05:50:28 |         MASTER-OAFA | (07h 39m 26.43s , -42d 29m 44.8s) |   C |    60 | 19.6 |        
    5454 | 2025-12-15 05:51:45 |         MASTER-OAFA | (07h 39m 23.79s , -42d 28m 14.2s) |   C |    60 | 19.6 |        
    5530 | 2025-12-15 05:53:01 |         MASTER-OAFA | (07h 39m 23.97s , -42d 29m 57.9s) |   C |    60 | 19.6 |        
    5607 | 2025-12-15 05:54:18 |         MASTER-OAFA | (07h 28m 37.31s , -42d 28m 27.7s) |   C |    60 | 19.8 |        
    5746 | 2025-12-15 05:56:37 |         MASTER-OAFA | (07h 28m 32.75s , -42d 29m 10.7s) |   C |    60 | 19.8 |        
    5832 | 2025-12-15 05:58:03 |         MASTER-OAFA | (07h 28m 33.73s , -42d 28m 08.7s) |   C |    60 | 19.8 |        
    8125 | 2025-12-15 06:36:16 |         MASTER-OAFA | (07h 26m 26.02s , -46d 16m 45.3s) |   C |    60 | 20.1 |        
    8202 | 2025-12-15 06:37:33 |         MASTER-OAFA | (07h 26m 23.77s , -46d 15m 06.7s) |   C |    60 | 20.1 |        
    8279 | 2025-12-15 06:38:50 |         MASTER-OAFA | (07h 26m 24.09s , -46d 16m 48.0s) |   C |    60 | 20.1 |        
    8360 | 2025-12-15 06:40:11 |         MASTER-OAFA | (07h 14m 56.32s , -46d 15m 39.0s) |   C |    60 | 20.1 |        
    8435 | 2025-12-15 06:41:26 |         MASTER-OAFA | (07h 14m 50.27s , -46d 16m 09.0s) |   C |    60 | 20.1 |        
    8510 | 2025-12-15 06:42:42 |         MASTER-OAFA | (07h 14m 49.98s , -46d 15m 07.3s) |   C |    60 | 20.2 |        
    9066 | 2025-12-15 06:51:57 |         MASTER-OAFA | (07h 32m 54.70s , -44d 21m 49.3s) |   C |    60 | 20.1 |        
    9146 | 2025-12-15 06:53:17 |         MASTER-OAFA | (07h 32m 54.52s , -44d 20m 48.2s) |   C |    60 | 20.1 |        
    9222 | 2025-12-15 06:54:33 |         MASTER-OAFA | (07h 33m 00.52s , -44d 21m 46.6s) |   C |    60 | 20.0 |        
    9300 | 2025-12-15 06:55:51 |         MASTER-OAFA | (07h 21m 52.29s , -44d 22m 38.3s) |   C |    60 | 20.1 |        
    9375 | 2025-12-15 06:57:06 |         MASTER-OAFA | (07h 21m 49.58s , -44d 21m 12.2s) |   C |    60 | 20.1 |        
    9449 | 2025-12-15 06:58:20 |         MASTER-OAFA | (07h 21m 49.84s , -44d 22m 43.6s) |   C |    60 | 20.1 |        
    9528 | 2025-12-15 06:59:39 |         MASTER-OAFA | (07h 39m 36.92s , -42d 26m 56.9s) |   C |    60 | 19.5 |        
    9602 | 2025-12-15 07:00:53 |         MASTER-OAFA | (07h 39m 31.12s , -42d 27m 41.8s) |   C |    60 | 19.5 |        
    9685 | 2025-12-15 07:02:16 |         MASTER-OAFA | (07h 39m 30.42s , -42d 26m 40.3s) |   C |    60 | 19.5 |        
    9761 | 2025-12-15 07:03:32 |         MASTER-OAFA | (07h 28m 49.41s , -42d 27m 49.0s) |   C |    60 | 19.8 |        
    9836 | 2025-12-15 07:04:47 |         MASTER-OAFA | (07h 28m 43.69s , -42d 28m 48.0s) |   C |    60 | 19.8 |        
    9911 | 2025-12-15 07:06:02 |         MASTER-OAFA | (07h 28m 49.61s , -42d 28m 43.1s) |   C |    60 | 19.8 |        
    9989 | 2025-12-15 07:07:20 |         MASTER-OAFA | (07h 08m 14.54s , -42d 29m 07.5s) |   C |    60 | 20.1 |        
   10066 | 2025-12-15 07:08:37 |         MASTER-OAFA | (07h 19m 05.86s , -42d 26m 59.3s) |   C |    60 | 19.9 |        
   10144 | 2025-12-15 07:09:55 |         MASTER-OAFA | (07h 08m 12.74s , -42d 28m 07.0s) |   C |    60 | 20.1 |        
   10220 | 2025-12-15 07:11:11 |         MASTER-OAFA | (07h 19m 01.00s , -42d 26m 52.3s) |   C |    60 | 19.9 |        
   10296 | 2025-12-15 07:12:27 |         MASTER-OAFA | (07h 08m 18.47s , -42d 28m 04.8s) |   C |    60 | 20.0 |        
   10373 | 2025-12-15 07:13:44 |         MASTER-OAFA | (07h 26m 28.67s , -46d 16m 19.5s) |   C |    60 | 20.2 |        
   10447 | 2025-12-15 07:14:58 |         MASTER-OAFA | (07h 26m 35.57s , -46d 16m 13.5s) |   C |    60 | 20.2 |        
   10523 | 2025-12-15 07:16:14 |         MASTER-OAFA | (07h 26m 32.19s , -46d 14m 44.0s) |   C |    60 | 20.2 |        
   10599 | 2025-12-15 07:17:30 |         MASTER-OAFA | (07h 15m 01.09s , -46d 16m 24.8s) |   C |    60 | 20.2 |        
   10676 | 2025-12-15 07:18:47 |         MASTER-OAFA | (07h 15m 04.61s , -46d 14m 26.7s) |   C |    60 | 20.2 |        
   10752 | 2025-12-15 07:20:03 |         MASTER-OAFA | (07h 14m 57.99s , -46d 15m 24.1s) |   C |    60 | 20.2 |        
   11089 | 2025-12-15 07:25:40 |         MASTER-OAFA | (07h 33m 04.54s , -44d 22m 09.2s) |   C |    60 | 20.1 |        
   11164 | 2025-12-15 07:26:55 |         MASTER-OAFA | (07h 33m 08.71s , -44d 20m 17.2s) |   C |    60 | 20.0 |        
   11240 | 2025-12-15 07:28:11 |         MASTER-OAFA | (07h 33m 02.78s , -44d 21m 08.0s) |   C |    60 | 20.1 |        
   11321 | 2025-12-15 07:29:32 |         MASTER-OAFA | (07h 00m 48.69s , -44d 21m 46.6s) |   C |    60 | 20.3 |        
   11397 | 2025-12-15 07:30:48 |         MASTER-OAFA | (07h 11m 51.63s , -44d 22m 30.7s) |   C |    60 | 20.2 |        
   11473 | 2025-12-15 07:32:04 |         MASTER-OAFA | (07h 00m 48.56s , -44d 22m 37.0s) |   C |    60 | 20.2 |        
   11549 | 2025-12-15 07:33:20 |         MASTER-OAFA | (07h 11m 55.05s , -44d 20m 30.4s) |   C |    60 | 20.2 |        
   11626 | 2025-12-15 07:34:37 |         MASTER-OAFA | (07h 00m 46.36s , -44d 22m 19.2s) |   C |    60 | 20.2 |        
   11705 | 2025-12-15 07:35:56 |         MASTER-OAFA | (07h 39m 43.96s , -42d 26m 19.8s) |   C |    60 | 19.5 |        
   11780 | 2025-12-15 07:37:11 |         MASTER-OAFA | (07h 39m 37.07s , -42d 27m 04.2s) |   C |    60 | 19.4 |        
   11855 | 2025-12-15 07:38:26 |         MASTER-OAFA | (07h 39m 38.58s , -42d 26m 03.1s) |   C |    60 | 19.5 |        
   11935 | 2025-12-15 07:39:46 |         MASTER-OAFA | (07h 30m 51.44s , -48d 09m 35.4s) |   C |    60 | 20.1 |        
   12010 | 2025-12-15 07:41:01 |         MASTER-OAFA | (07h 42m 55.59s , -48d 09m 06.7s) |   C |    60 | 19.9 |        
   12087 | 2025-12-15 07:42:18 |         MASTER-OAFA | (07h 30m 55.70s , -48d 07m 49.7s) |   C |    60 | 20.0 |        
   12162 | 2025-12-15 07:43:34 |         MASTER-OAFA | (07h 42m 52.36s , -48d 09m 05.7s) |   C |    60 | 19.9 |        
   12240 | 2025-12-15 07:44:51 |         MASTER-OAFA | (07h 30m 58.65s , -48d 07m 43.9s) |   C |    60 | 20.0 |        
   12318 | 2025-12-15 07:46:09 |         MASTER-OAFA | (07h 19m 06.95s , -42d 27m 23.2s) |   C |    60 | 19.9 |        
   12395 | 2025-12-15 07:47:26 |         MASTER-OAFA | (07h 19m 08.53s , -42d 26m 22.2s) |   C |    60 | 19.9 |        
   12471 | 2025-12-15 07:48:42 |         MASTER-OAFA | (07h 19m 14.47s , -42d 27m 21.2s) |   C |    60 | 19.8 |        
   12546 | 2025-12-15 07:49:57 |         MASTER-OAFA | (07h 08m 19.27s , -42d 28m 36.9s) |   C |    60 | 20.1 |        
   12620 | 2025-12-15 07:51:11 |         MASTER-OAFA | (07h 08m 26.14s , -42d 28m 23.2s) |   C |    60 | 20.0 |        
   12694 | 2025-12-15 07:52:25 |         MASTER-OAFA | (07h 08m 23.68s , -42d 27m 05.0s) |   C |    60 | 20.0 |        
   12771 | 2025-12-15 07:53:42 |         MASTER-OAFA | (07h 26m 40.50s , -46d 15m 33.7s) |   C |    60 | 20.1 |        
   12850 | 2025-12-15 07:55:01 |         MASTER-OAFA | (07h 26m 43.84s , -46d 13m 52.0s) |   C |    60 | 20.1 |        
   12927 | 2025-12-15 07:56:18 |         MASTER-OAFA | (07h 26m 38.20s , -46d 14m 34.8s) |   C |    60 | 20.1 |        
   13003 | 2025-12-15 07:57:35 |         MASTER-OAFA | (07h 37m 07.47s , -46d 14m 21.4s) |   C |    60 | 20.0 |        
   13080 | 2025-12-15 07:58:51 |         MASTER-OAFA | (07h 48m 32.47s , -46d 15m 08.4s) |   C |    60 | 19.8 |        
   13155 | 2025-12-15 08:00:06 |         MASTER-OAFA | (07h 37m 06.85s , -46d 15m 15.8s) |   C |    60 | 20.0 |        
   13238 | 2025-12-15 08:01:29 |         MASTER-OAFA | (07h 48m 35.83s , -46d 13m 17.2s) |   C |    60 | 19.8 |        
   13314 | 2025-12-15 08:02:45 |         MASTER-OAFA | (07h 37m 05.08s , -46d 15m 00.9s) |   C |    60 | 19.9 |        
   13434 | 2025-12-15 08:04:46 |         MASTER-OAFA | (07h 11m 59.20s , -44d 06m 31.8s) |   C |    60 | 20.1 |        
   13510 | 2025-12-15 08:06:02 |         MASTER-OAFA | (07h 11m 53.69s , -44d 07m 07.7s) |   C |    60 | 20.1 |        
   13588 | 2025-12-15 08:07:19 |         MASTER-OAFA | (07h 11m 53.62s , -44d 06m 07.0s) |   C |    60 | 20.1 |        
   13663 | 2025-12-15 08:08:34 |         MASTER-OAFA | (07h 00m 50.69s , -44d 07m 25.0s) |   C |    60 | 20.1 |        
   13738 | 2025-12-15 08:09:49 |         MASTER-OAFA | (07h 00m 44.20s , -44d 08m 24.8s) |   C |    60 | 20.1 |        
   13812 | 2025-12-15 08:11:03 |         MASTER-OAFA | (07h 00m 49.56s , -44d 08m 05.9s) |   C |    60 | 20.0 |        
   13890 | 2025-12-15 08:12:21 |         MASTER-OAFA | (07h 15m 57.41s , -40d 19m 43.9s) |   C |    60 | 19.7 |        
   13966 | 2025-12-15 08:13:37 |         MASTER-OAFA | (07h 26m 31.11s , -40d 17m 39.3s) |   C |    60 | 19.5 |        
   14043 | 2025-12-15 08:14:54 |         MASTER-OAFA | (07h 15m 54.78s , -40d 18m 47.7s) |   C |    60 | 19.6 |        
   14120 | 2025-12-15 08:16:11 |         MASTER-OAFA | (07h 26m 24.87s , -40d 17m 30.7s) |   C |    60 | 19.4 |        
   14197 | 2025-12-15 08:17:28 |         MASTER-OAFA | (07h 16m 00.19s , -40d 18m 46.2s) |   C |    60 | 19.4 |        
   14275 | 2025-12-15 08:18:46 |         MASTER-OAFA | (07h 42m 53.06s , -47d 55m 28.5s) |   C |    60 | 19.4 |        
   14352 | 2025-12-15 08:20:03 |         MASTER-OAFA | (07h 42m 57.59s , -47d 55m 10.4s) |   C |    60 | 19.3 |        
   14427 | 2025-12-15 08:21:18 |         MASTER-OAFA | (07h 42m 55.69s , -47d 53m 44.8s) |   C |    60 | 19.3 |        
   14504 | 2025-12-15 08:22:35 |         MASTER-OAFA | (07h 30m 58.35s , -47d 55m 18.9s) |   C |    60 | 19.3 |        
   14579 | 2025-12-15 08:23:50 |         MASTER-OAFA | (07h 31m 01.75s , -47d 53m 57.1s) |   C |    60 | 19.3 |        
   14655 | 2025-12-15 08:25:06 |         MASTER-OAFA | (07h 30m 55.68s , -47d 54m 41.6s) |   C |    60 | 19.2 |        
   14732 | 2025-12-15 08:26:23 |         MASTER-OAFA | (07h 19m 09.09s , -42d 11m 42.9s) |   C |    60 | 18.9 |        
   14811 | 2025-12-15 08:27:42 |         MASTER-OAFA | (07h 19m 16.77s , -42d 12m 42.0s) |   C |    60 | 18.8 |        
   14886 | 2025-12-15 08:28:57 |         MASTER-OAFA | (07h 19m 09.57s , -42d 13m 41.9s) |   C |    60 | 18.7 |        
   14967 | 2025-12-15 08:30:18 |         MASTER-OAFA | (07h 20m 16.60s , -47d 54m 16.6s) |   C |    60 | 18.7 |        
   15042 | 2025-12-15 08:31:33 |         MASTER-OAFA | (07h 20m 11.22s , -47d 54m 54.2s) |   C |    60 | 18.5 |        
   15122 | 2025-12-15 08:32:53 |         MASTER-OAFA | (07h 48m 34.22s , -45d 59m 04.2s) |   C |    60 | 18.2 |        
   15200 | 2025-12-15 08:34:11 |         MASTER-OAFA | (07h 48m 40.65s , -46d 00m 03.4s) |   C |    60 | 18.1 |        
   15278 | 2025-12-15 08:35:29 |         MASTER-OAFA | (07h 48m 34.37s , -46d 01m 03.0s) |   C |    60 | 18.0 |        
   15353 | 2025-12-15 08:36:44 |         MASTER-OAFA | (07h 37m 07.92s , -46d 01m 09.9s) |   C |    60 | 14.4 |        
   84349 | 2025-12-16 03:46:40 |         MASTER-OAFA | (06h 42m 04.68s , -46d 22m 13.0s) |   C |    60 | 20.1 |        
   84423 | 2025-12-16 03:47:55 |         MASTER-OAFA | (06h 42m 11.05s , -46d 21m 55.7s) |   C |    60 | 20.1 |        
   84501 | 2025-12-16 03:49:12 |         MASTER-OAFA | (06h 42m 08.07s , -46d 20m 26.7s) |   C |    60 | 20.1 |        
   85037 | 2025-12-16 03:58:08 |         MASTER-OAFA | (07h 03m 41.56s , -38d 45m 25.1s) |   C |    60 | 20.0 |        
   85111 | 2025-12-16 03:59:22 |         MASTER-OAFA | (07h 03m 39.52s , -38d 43m 41.8s) |   C |    60 | 20.0 |        
   85186 | 2025-12-16 04:00:37 |         MASTER-OAFA | (07h 03m 39.60s , -38d 45m 13.1s) |   C |    60 | 20.0 |        
   85269 | 2025-12-16 04:02:00 |         MASTER-OAFA | (07h 13m 56.14s , -38d 43m 24.5s) |   C |    60 | 19.9 |        
   85346 | 2025-12-16 04:03:17 |         MASTER-OAFA | (07h 13m 49.92s , -38d 44m 16.0s) |   C |    60 | 19.9 |        
   85426 | 2025-12-16 04:04:37 |         MASTER-OAFA | (07h 13m 50.59s , -38d 43m 13.4s) |   C |    60 | 19.9 |        
   86212 | 2025-12-16 04:17:43 |         MASTER-OAFA | (07h 00m 35.46s , -50d 09m 13.0s) |   C |    60 | 20.0 |        
   86286 | 2025-12-16 04:18:57 |         MASTER-OAFA | (07h 00m 41.92s , -50d 08m 46.7s) |   C |    60 | 19.9 |        
   86361 | 2025-12-16 04:20:12 |         MASTER-OAFA | (07h 00m 39.05s , -50d 07m 11.0s) |   C |    60 | 19.9 |        
   86437 | 2025-12-16 04:21:28 |         MASTER-OAFA | (07h 13m 05.48s , -50d 08m 41.6s) |   C |    60 | 19.9 |        
   86511 | 2025-12-16 04:22:42 |         MASTER-OAFA | (07h 13m 09.00s , -50d 07m 10.9s) |   C |    60 | 19.9 |        
   86586 | 2025-12-16 04:23:57 |         MASTER-OAFA | (07h 13m 03.32s , -50d 08m 00.5s) |   C |    60 | 19.9 |        
   87136 | 2025-12-16 04:33:07 |         MASTER-OAFA | (07h 11m 30.33s , -34d 54m 46.1s) |   C |    60 | 20.0 |        
   88145 | 2025-12-16 04:49:56 |         MASTER-OAFA | (06h 39m 07.90s , -44d 26m 10.3s) |   C |    60 | 20.2 |        
   88223 | 2025-12-16 04:51:14 |         MASTER-OAFA | (06h 39m 04.26s , -44d 24m 24.1s) |   C |    60 | 20.2 |        
   88298 | 2025-12-16 04:52:29 |         MASTER-OAFA | (06h 39m 04.43s , -44d 25m 58.7s) |   C |    60 | 20.2 |        
   88374 | 2025-12-16 04:53:45 |         MASTER-OAFA | (06h 50m 17.94s , -44d 24m 16.0s) |   C |    60 | 20.3 |        
   88449 | 2025-12-16 04:55:00 |         MASTER-OAFA | (06h 50m 11.51s , -44d 25m 01.4s) |   C |    60 | 20.3 |        
   88528 | 2025-12-16 04:56:19 |         MASTER-OAFA | (06h 50m 11.32s , -44d 23m 59.0s) |   C |    60 | 20.3 |        
   89158 | 2025-12-16 05:06:49 |         MASTER-OAFA | (06h 49m 31.52s , -50d 05m 36.2s) |   C |    60 | 20.0 |        
   89232 | 2025-12-16 05:08:03 |         MASTER-OAFA | (06h 49m 37.28s , -50d 06m 33.8s) |   C |    60 | 20.1 |        
   92863 | 2025-12-16 06:08:34 |         MASTER-OAFA | (07h 21m 43.31s , -44d 22m 47.0s) |   C |    60 | 20.3 |        
   92938 | 2025-12-16 06:09:49 |         MASTER-OAFA | (07h 32m 48.01s , -44d 23m 39.5s) |   C |    60 | 20.2 |        
   93015 | 2025-12-16 06:11:06 |         MASTER-OAFA | (07h 21m 44.03s , -44d 23m 25.4s) |   C |    60 | 20.2 |        
   93096 | 2025-12-16 06:12:27 |         MASTER-OAFA | (07h 32m 51.29s , -44d 21m 59.3s) |   C |    60 | 20.2 |        
   93171 | 2025-12-16 06:13:42 |         MASTER-OAFA | (07h 21m 42.00s , -44d 23m 19.6s) |   C |    60 | 20.3 |        
   94066 | 2025-12-16 06:28:37 |         MASTER-OAFA | (07h 28m 39.67s , -42d 29m 10.7s) |   C |    60 | 19.9 |        
   94142 | 2025-12-16 06:29:53 |         MASTER-OAFA | (07h 39m 31.59s , -42d 27m 32.3s) |   C |    60 | 19.6 |        
   94221 | 2025-12-16 06:31:12 |         MASTER-OAFA | (07h 28m 37.80s , -42d 28m 18.8s) |   C |    60 | 19.9 |        
   94300 | 2025-12-16 06:32:31 |         MASTER-OAFA | (07h 39m 25.23s , -42d 27m 09.1s) |   C |    60 | 19.6 |        
   94378 | 2025-12-16 06:33:49 |         MASTER-OAFA | (07h 28m 43.67s , -42d 28m 15.8s) |   C |    60 | 19.9 |        
   94457 | 2025-12-16 06:35:08 |         MASTER-OAFA | (07h 14m 55.59s , -46d 17m 09.1s) |   C |    60 | 20.3 |        
   94532 | 2025-12-16 06:36:23 |         MASTER-OAFA | (07h 26m 24.14s , -46d 15m 26.7s) |   C |    60 | 20.3 |        
   94618 | 2025-12-16 06:37:49 |         MASTER-OAFA | (07h 14m 52.84s , -46d 16m 51.5s) |   C |    60 | 20.3 |        
   94698 | 2025-12-16 06:39:09 |         MASTER-OAFA | (07h 26m 27.32s , -46d 15m 19.6s) |   C |    60 | 20.3 |        
   94777 | 2025-12-16 06:40:28 |         MASTER-OAFA | (07h 14m 49.66s , -46d 16m 04.5s) |   C |    60 | 20.3 |        
   94857 | 2025-12-16 06:41:48 |         MASTER-OAFA | (07h 24m 42.74s , -50d 03m 42.8s) |   C |    60 | 20.1 |        
   94933 | 2025-12-16 06:43:05 |         MASTER-OAFA | (07h 37m 02.25s , -50d 04m 35.0s) |   C |    60 | 20.1 |        
   95011 | 2025-12-16 06:44:22 |         MASTER-OAFA | (07h 24m 42.56s , -50d 04m 27.0s) |   C |    60 | 20.1 |        
   95086 | 2025-12-16 06:45:37 |         MASTER-OAFA | (07h 37m 05.24s , -50d 02m 34.5s) |   C |    60 | 20.1 |        
   95163 | 2025-12-16 06:46:54 |         MASTER-OAFA | (07h 24m 40.87s , -50d 04m 29.3s) |   C |    60 | 20.2 |        
   95241 | 2025-12-16 06:48:12 |         MASTER-OAFA | (07h 32m 59.73s , -44d 21m 03.7s) |   C |    60 | 20.2 |        
   95315 | 2025-12-16 06:49:26 |         MASTER-OAFA | (07h 32m 54.82s , -44d 21m 44.8s) |   C |    60 | 20.2 |        
   95481 | 2025-12-16 06:52:12 |             MASTER- | (07h 06m 46.38s , -42d 16m 40.2s) |   C |    60 | 17.9 |        
   95481 | 2025-12-16 06:52:12 |             MASTER- | (06h 57m 42.70s , -43d 15m 17.5s) |   C |    60 | 17.5 |        
   95552 | 2025-12-16 06:53:23 |             MASTER- | (06h 59m 10.83s , -44d 11m 26.1s) |   C |    60 | 17.7 |        
   95552 | 2025-12-16 06:53:23 |             MASTER- | (06h 49m 48.76s , -45d 10m 03.7s) |   C |    60 | 17.7 |        
   95627 | 2025-12-16 06:54:38 |             MASTER- | (07h 34m 21.14s , -40d 22m 55.6s) |   C |    60 | 17.7 |        
   95627 | 2025-12-16 06:54:38 |             MASTER- | (07h 25m 32.71s , -41d 21m 43.9s) |   C |    60 | 17.6 |        
   96781 | 2025-12-16 07:13:52 |             MASTER- | (07h 21m 39.36s , -44d 10m 20.1s) |   C |    60 | 17.6 |        
   96781 | 2025-12-16 07:13:53 |             MASTER- | (07h 09m 40.36s , -45d 07m 52.4s) |   C |    60 | 17.6 |        
   96854 | 2025-12-16 07:15:05 |             MASTER- | (06h 52m 49.25s , -46d 05m 58.2s) |   C |    60 | 17.9 |        
   96854 | 2025-12-16 07:15:05 |             MASTER- | (06h 40m 24.86s , -47d 03m 27.2s) |   C |    60 | 17.6 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html

GCN Circular #43137
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 251215A, collecting 5.2 ks of Photon Counting (PC) mode data between T0+32.0 ks and T0+49.6 ks.
Four uncatalogued X-ray sources have been detected within the estimated 3-sigma Swift/BAT error region (493 arcsec), however none of them is above historical upper limits, or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
Source 2:
```
  RA (J2000.0):  122.5523  =  08h 10m 12.54s
  Dec (J2000.0): -36.6697  =  -36d 40' 10.8"
  Error: 3.9 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (9.7 [+1.8, -1.7])e-3 ct s^-1   
  Distance: 383 arcsec from Swift/BAT position.
  Flux: (4.47 [+0.81, -0.77])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
Source 5:
```
  RA (J2000.0):  122.6189  =  08h 10m 28.54s
  Dec (J2000.0): -36.7427  =  -36d 44' 33.6"
  Error: 5.7 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (5.0 [+1.3, -1.2])e-3 ct s^-1   
  Distance: 97 arcsec from Swift/BAT position.
  Flux: (1.96 [+0.50, -0.47])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
Source 6:
```
  RA (J2000.0):  122.6954  =  08h 10m 46.90s
  Dec (J2000.0): -36.6198  =  -36d 37' 11.5"
  Error: 7.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (3.44 [+1.20, -0.99])e-3 ct s^-1	 
  Distance: 448 arcsec from Swift/BAT position.
  Flux: (2.87 [+1.00, -0.83])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
Source 8:
```
  RA (J2000.0):  122.6662  =  08h 10m 39.88s
  Dec (J2000.0): -36.6483  =  -36d 38' 53.8"
  Error: 5.9 arcsec (radius, 90% conf.)
  Count-rate: (1.81 [+0.92, -0.72])e-3 ct s^-1	 
  Distance: 330 arcsec from Swift/BAT position.
  Flux: (3.7 [+1.9, -1.5])e-10 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
A catalogued source was also detected within the estimated 3-sigma Swift/BAT error region (493 arcsec).
Two uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates.
The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021894.
This circular is an official product of the Swift-XRT team.
GCN Circular #43140
Stéphane Basa (UAR Pytheas), Leonardo García García (UNAM), Benjamin Schneider (LAM), Noémie Globus (UNAM), Jean-Luc Atteia (IRAP), William H. Lee (UNAM), Alan M. Watson (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Enrique Moreno Méndez (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Nikos Mandarakas (LAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM).
We imaged the field of GRB 251215A detected by Fermi (Fermi GBM team, GCN Circ. 43104) and confirmed by Swift/BAT-GUANO (Ronchini et al., GCN Circ. 43114) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-12-15 at 11:27:37.35 to 12:06:41.62 UTC (from 7.10 to 7.76 hr after the Fermi trigger) and obtained 31 minutes of simultaneous exposure in the r and z filters. Observations were obtained at a relatively high airmass (~3.0), and we also noted that the Galactic extinction is significant at the Swift/BAT-GUANO localization (Av= ~2.8).
The data were reduced, coadded and analyzed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the SkyMapper-DR4 catalog, is in the AB system, and was not corrected for Galactic extinction.
In the stacked image, we do not detect any new source associated with the candidates reported by Swift-XRT (Osborne et al., GCN Circ. 43137) down to the following 5-sigma limit:
```
  r > 21.8
  z > 20.5
```
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular #43144
P. Veres (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 04:21:21.57 UT on 15 December 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251215A (trigger 787465286/251215181), which was also detected by Swift-BAT-GUANO (Ronchini et al. 2025, GCN 43114), Swift-XRT (Osborne et al. 2025, GCN 43137) and Glowbug (Cheung et al. 2025, GCN 43133). The real-time Fermi GBM location (GCN 43104) is consistent with the Swift-BAT position.
The GBM light curve consists of multiple overlapping pulses with a duration (T90) of about 143 s (50-300 keV). The time-averaged spectrum from T0-37 to T0+162 s is best fit by a Band function with Epeak = 35 +/- 7 keV, alpha = -1 +/- 0.3, and beta = -1.97 +/- 0.03.
The event fluence (10-1000 keV) in this time interval is (2.05 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+64 s in the 10-1000 keV band is 5.7 +/- 0.2 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/"
GCN Circular #43145
S. R. Oates (Lancaster U.) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251215A 32 ks after the Fermi/GBM trigger (Fermi GBM team, GCN Circ. 43104). No optical afterglow is found in the initial UVOT exposures. The UVOT exposures include the positions of XRT sources 2, 5, 6 and 8 (Osborne et al., GCN 43137). The positions of XRT sources 2, 6, and 8 are consistent with known USNO-B1 sources. No optical source is found consistent with XRT source 5.
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/3sigUL
white    31995          49531         4297       >22.4
```
The magnitudes in the table are not corrected for the Galactic extinction due to the significant reddening of E(B-V) = 0.87 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #43155
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the Swift/BAT-detected burst GRB 251215A. The observations now extend from T0+32.0 ks to T0+383.9 ks and have a total exposure time of 9.9 ks.
Of the sources previously reported, "Source 5" is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 1629 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 122.61893, -36.74266 which is equivalent to:
```
RA (J2000): 08h 10m 28.54s
Dec(J2000): -36d 44' 33.6"
```
with an uncertainty of 5.7 arcsec (radius, 90% confidence). This position is 97 arcsec from the Swift/BAT position. The source is fading with alpha >0.3.
The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/ToO_GRBs/00021894/Source5.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021894.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 20-Dec-2025 [Disclaimer]