Gamma-ray Burst 250706A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:49:24 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1330958,   Seg_Num: 0
GRB_RA:          284.007d {+18h 56m 02s} (J2000),
                 284.247d {+18h 56m 59s} (current),
                 283.538d {+18h 54m 09s} (1950)
GRB_DEC:         +32.287d {+32d 17' 13"} (J2000),
                 +32.322d {+32d 19' 18"} (current),
                 +32.221d {+32d 13' 15"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       14208 [cnts]    Image_Peak=275 [image_cnts]
TRIGGER_DUR:     8.192 [sec] 
TRIGGER_INDEX:   490     E_range: 50-350 keV
BKG_INTEN:       97208 [cnts]
BKG_TIME:        56820.08 SOD {15:47:00.08} UT
BKG_DUR:         64 [sec]
GRB_DATE:        20862 TJD;   187 DOY;   25/07/06
GRB_TIME:        56910.96 SOD {15:48:30.96} UT
GRB_PHI:         138.72 [deg]
GRB_THETA:        39.25 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.48 [sigma]
IMAGE_SIGNIF:    8.16 [sigma]
MERIT_PARAMS:     +1  +0  +0  +3  +3  -2  +0  +0 +57  +0 
SUN_POSTN:       106.10d {+07h 04m 23s}  +22.61d {+22d 36' 38"}
SUN_DIST:        125.04 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.41d {+15h 33m 38s}  -23.91d {-23d 54' 42"}
MOON_DIST:        74.27 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.68, 13.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      290.75, 54.72 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 182.38,19.96 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:51:31 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1330958,   Seg_Num: 0
GRB_RA:          284.0189d {+18h 56m 04.5s} (J2000),
                 284.2586d {+18h 57m 02.0s} (current),
                 283.5492d {+18h 54m 11.8s} (1950)
GRB_DEC:         +32.3214d {+32d 19' 17.0"} (J2000),
                 +32.3561d {+32d 21' 21.9"} (current),
                 +32.2551d {+32d 15' 18.2"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       25 [cnts]
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57053.14 SOD {15:50:53.14} UT,   142.2 [sec] since BAT Trigger Time
CENTROID_X:      261.78,  raw= 262  [pixels]
CENTROID_Y:      272.13,  raw= 272  [pixels]
ROLL:            357.62 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -62.62
GRB_POS_XRT_Z:   -117.43
IMAGE_URL:       sw01330958000msxps_rw.img
SUN_POSTN:       106.10d {+07h 04m 23s}  +22.61d {+22d 36' 37"}
SUN_DIST:        125.01 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.43d {+15h 33m 43s}  -23.92d {-23d 54' 59"}
MOON_DIST:        74.29 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.72, 13.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      290.78, 54.75 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:51:29 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1330958,   Seg_Num: 0
GRB_RA:          284.0189d {+18h 56m 04.5s} (J2000),
                 284.2586d {+18h 57m 02.0s} (current),
                 283.5492d {+18h 54m 11.8s} (1950)
GRB_DEC:         +32.3214d {+32d 19' 17.0"} (J2000),
                 +32.3561d {+32d 21' 21.9"} (current),
                 +32.2551d {+32d 15' 18.2"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       25 [cnts]
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57053.14 SOD {15:50:53.14} UT,   142.2 [sec] since BAT Trigger Time
CENTROID_X:      261.78,  raw= 262  [pixels]
CENTROID_Y:      272.13,  raw= 272  [pixels]
ROLL:            357.62 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -62.62
GRB_POS_XRT_Z:   -117.43
IMAGE_URL:       sw01330958000msxps_rw.img
SUN_POSTN:       106.10d {+07h 04m 23s}  +22.61d {+22d 36' 37"}
SUN_DIST:        125.01 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.43d {+15h 33m 43s}  -23.92d {-23d 54' 59"}
MOON_DIST:        74.29 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.72, 13.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      290.78, 54.75 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:51:19 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1330958,   Seg_Num: 0
GRB_RA:          284.0189d {+18h 56m 04.53s} (J2000),
                 284.2586d {+18h 57m 02.06s} (current),
                 283.5492d {+18h 54m 11.81s} (1950)
GRB_DEC:         +32.3214d {+32d 19' 17.0"} (J2000),
                 +32.3561d {+32d 21' 21.9"} (current),
                 +32.2551d {+32d 15' 18.2"} (1950)
GRB_ERROR:       6.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.25e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.00 [sigma]
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57053.14 SOD {15:50:53.14} UT,   142.2 [sec] since BAT Trigger Time
TAM[0-3]:        327.61 237.17 261.41 243.86
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       106.10d {+07h 04m 23s}  +22.61d {+22d 36' 37"}
SUN_DIST:        125.01 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.43d {+15h 33m 42s}  -23.92d {-23d 54' 57"}
MOON_DIST:        74.29 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.72, 13.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      290.78, 54.75 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 2.14 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:52:40 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1330958,   Seg_Num: 0
GRB_RA:          284.007d {+18h 56m 02s} (J2000),
                 284.247d {+18h 56m 59s} (current),
                 283.538d {+18h 54m 09s} (1950)
GRB_DEC:         +32.287d {+32d 17' 13"} (J2000),
                 +32.322d {+32d 19' 18"} (current),
                 +32.221d {+32d 13' 15"} (1950)
GRB_DATE:        20862 TJD;   187 DOY;   25/07/06
GRB_TIME:        56910.96 SOD {15:48:30.96} UT
TRIGGER_INDEX:   490
GRB_PHI:         138.72 [deg]
GRB_THETA:        39.25 [deg]
DELTA_TIME:      32.00 [sec]
TRIGGER_DUR:     8.192 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.48 [sigma]
IMAGE_SIGNIF:    8.16 [sigma]
LC_URL:          sw01330958000msb.lc
SUN_POSTN:       106.10d {+07h 04m 23s}  +22.61d {+22d 36' 37"}
SUN_DIST:        125.04 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.44d {+15h 33m 45s}  -23.92d {-23d 55' 08"}
MOON_DIST:        74.26 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.68, 13.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      290.75, 54.72 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 182.38,19.96 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:55:29 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1330958,   Seg_Num: 0
POINT_RA:        284.000d {+18h 56m 00s} (J2000)
POINT_DEC:       +32.288d {+32d 17' 16"} (J2000)
POINT_ROLL:      357.625d
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57058.06 SOD {15:50:58.06} UT,   147.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.676
N_STARS:         190
X_OFFSET:        248 [pixels]
Y_OFFSET:        352 [pixels]
X_MAX:           1687 [pixels]
Y_MAX:           1791 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01330958000msufc0147.fits
SUN_POSTN:       106.10d {+07h 04m 24s}  +22.61d {+22d 36' 36"}
SUN_DIST:        125.04 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.46d {+15h 33m 51s}  -23.93d {-23d 55' 31"}
MOON_DIST:        74.24 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.68, 13.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      290.74, 54.72 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:55:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1330958,   Seg_Num: 0
POINT_RA:        284.000d {+18h 56m 00s} (J2000)
POINT_DEC:       +32.288d {+32d 17' 16"} (J2000)
POINT_ROLL:      357.625d
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57058.06 SOD {15:50:58.06} UT,   147.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.676
N_STARS:         190
X_OFFSET:        248 [pixels]
Y_OFFSET:        352 [pixels]
X_MAX:           1687 [pixels]
Y_MAX:           1791 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01330958000msufc0147.fits
SUN_POSTN:       106.10d {+07h 04m 24s}  +22.61d {+22d 36' 36"}
SUN_DIST:        125.04 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.46d {+15h 33m 52s}  -23.93d {-23d 55' 33"}
MOON_DIST:        74.24 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.68, 13.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      290.74, 54.72 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:56:52 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1330958,   Seg_Num: 0
POINT_RA:        284.000d {+18h 56m 00s} (J2000)
POINT_DEC:       +32.288d {+32d 17' 16"} (J2000)
ROLL:            357.625d
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57058.06 SOD {15:50:58.06} UT,   147.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     773509893
X_OFFSET:        1055 [pixels]
Y_OFFSET:        869 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1215
Y_GRB_POS:       1029
BINNING_INDEX:   1
IM_URL:          sw01330958000msuni0183.fits
SUN_POSTN:       106.10d {+07h 04m 24s}  +22.61d {+22d 36' 36"}
SUN_DIST:        125.04 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.47d {+15h 33m 54s}  -23.93d {-23d 55' 42"}
MOON_DIST:        74.24 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.68, 13.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      290.74, 54.72 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 15:57:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1330958,   Seg_Num: 0
POINT_RA:        284.000d {+18h 56m 00s} (J2000)
POINT_DEC:       +32.288d {+32d 17' 16"} (J2000)
ROLL:            357.625d
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57058.06 SOD {15:50:58.06} UT,   147.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     773509893
X_OFFSET:        1055 [pixels]
Y_OFFSET:        869 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1215
Y_GRB_POS:       1029
BINNING_INDEX:   1
IM_URL:          sw01330958000msuni0183.fits
SUN_POSTN:       106.10d {+07h 04m 24s}  +22.61d {+22d 36' 36"}
SUN_DIST:        125.04 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.48d {+15h 33m 54s}  -23.93d {-23d 55' 44"}
MOON_DIST:        74.23 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.68, 13.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      290.74, 54.72 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #40988
M. J. Moss (GSFC), E. Ambrosi (INAF-IASFPA), R. Gupta (NASA GSFC), J. A. Kennea (PSU), A. Melandri (INAF-OAR), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 15:48:30.96 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250706A (trigger=1330958). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 284.007, +32.287 which is
```
   RA(J2000) = 18h 56m 1.6s
   Dec(J2000) = +32d 17' 13"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 35 sec. The peak count rate was ~750 counts/sec (15-350 keV), at ~7 sec after the trigger.
The XRT began observing the field at 15:50:53.1 UT, 142.2 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 284.01755, 32.32120 which is equivalent to:
```
   RA(J2000)  = 18h 56m 04.21s
   Dec(J2000) = +32d 19' 16.3"
```
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 127 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.20 x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 5.25e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 147 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.093.
Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com). 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/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Jul 25 16:13:46 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1330958,   Seg_Num: 0
GRB_RA:          284.0175d {+18h 56m 04.19s} (J2000),
                 284.2572d {+18h 57m 01.72s} (current),
                 283.5478d {+18h 54m 11.47s} (1950)
GRB_DEC:         +32.3211d {+32d 19' 15.9"} (J2000),
                 +32.3558d {+32d 21' 20.8"} (current),
                 +32.2548d {+32d 15' 17.1"} (1950)
GRB_ERROR:       3.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20862 TJD;   187 DOY;   25/07/06
IMG_START_TIME:  57346.00 SOD {15:55:46.00} UT,   435.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       106.11d {+07h 04m 27s}  +22.61d {+22d 36' 32"}
SUN_DIST:        125.01 [deg]   Sun_angle= -11.9 [hr] (East of Sun)
MOON_POSTN:      233.62d {+15h 34m 29s}  -23.97d {-23d 58' 00"}
MOON_DIST:        74.20 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       62.72, 13.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      290.77, 54.75 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #40990
T. Mohan, A.P. Saikia, A. Salgundi, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team:
We observed the field of Swift GRB 250706A (Moss et al., GCN 40988), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2025-07-06 16:04:55 UT, i.e., 16.4 min after the GRB trigger. We obtained multiple exposures each in r' and g' filters. After performing image subtraction using PanSTARRS reference images, we do not detect any afterglow candidates at the XRT localization. The photometric upper limits are as follows:
```
| MJD (mid)    | Filter | tmid-t0 (min) | Exposure Time (sec) | Upper limit (AB) |
| ------------ | ------ | ------------- | ------------------- | ---------------- |
| 60862.670081 | r'     | 18.9          | 300                 | 20.0             |
| 60862.682546 | g'     | 34.4          | 300                 | 20.3             |
| 60862.699537 | r'     | 61.3          | 300                 | 20.5             |
```
The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The result is consistent with Swift UVOT upper limit (Moss et al., GCN 40988).
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular #40998
Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei, Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC) report on behalf of the SVOM/C-GFT team:
We observed the field of GRB250706A detected by Swift/BAT (GCN 40988) with LATIOS on SVOM/C-GFT. Observations started at 2025-07-06T15:49:56 UTC, ~85 seconds after the trigger.
A series of g, r, and i band images were obtained. No credible candidate was detected within the error box provided by XRT (GCN 40988) in our images after preliminary processing, the three sigma upper limits are:
```
| Date-Obs (mid-time) | Mid_t - T0 (s) | Exposure Time (s) | Band | Upper Limit (AB) |
|---------------------|----------------|-------------------|------|------------------|
| 2025-07-06T15:50:35 | 124            | 5×10              | i    | 19.31            |
| 2025-07-06T16:00:55 | 744            | 6×30              | g    | 20.66            |
| 2025-07-06T16:04:30 | 949            | 6×30              | r    | 20.37            |
```
The photometry was calibrated with nearby Pan-STARRS1 stars.
We thank the observation assistants Bowen Li & Yinhuai Hao at Jilin observatory for their excellent support.
The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching.
GCN Circular #41000
A. Moskvitin and O. Spiridonova (SAO RAS), report on behalf of a GRB follow-up collaboration.
We observed the field of the GRB 250706A (Moss et al., GCN 40988) with SAO RAS 1-m telescope Zeiss-1000 equipped with CCD-photometer. We obtained 20 x 300 sec. images in Rc band on July 6, 20:04:37--22:41:35 UT (t_mid - T0 = 5.5764 hours) under a good weather conditions and the seeing of 1".6.
In the XRT error circle (Moss et al., GCN 40988) we detected a bright stellar-like source with the coordinates R.A. = 18:56:04.3, Dec. = +32:19:13.5 (J2000.0) also presented in the archival images.
After the PSF subtraction of this bright star we did not detect any significant sources down to the limiting magnitude of R_lim = 23.0. (based on the nearby USNO-B1.0 stars and not corrected for the Galactic extinction)
Additionaly we divided whole set into two 10 x 300 sec. subsets (1st: t_mid - T0 = 4.9217 hours, 2nd: t_mid - T0 = 6.2393 hours) and found no significant residuals between two stacked images and no variability of the mentioned bright star within 0.01 mag. between two epochs.
This results are in agreement with OT non-detection by Moss et al. (GCN 40988); Mohan et al. (GCN 40990) and Wu et al. (GCN 40998).
GCN Circular #41001
Z.P. Zhu, S.Q. Jiang, X. Liu, J. An, L.B. He, D. Xu (NAOC), S.Y. Fu(HUST), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the field of GRB250706A detected by Swift/BAT (Moss et al., GCN 40988), using the 100cm-C telescope (100C) of the JinShan project, located at Altay, Xinjiang, China. Observations began at 15:55:19 UT on 2025-07-06, i.e., 6.8 minutes after the BAT trigger, and a series of frames were obtained in the Sloan r- and z-band.
No new optical source is detected within the XRT error circle (Moss et al., GCN 40988), consistent with the reported results (Mohan et al., GCN 40990; Wu et al., GCN 40998), down to 5-sigma upper limits of r ~ 21.4 and z ~21.1, calibrated with nearby Pan-STARRS stars and not corrected for Galactic extinction.
We acknowledge the excellent support from T.Q. Chen for enabling these observations.
GCN Circular #41002
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 (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 250706A ( M. J. Moss et al., GCN 40988) errorbox 46980 sec after notice time and 47035 sec after trigger time at 2025-07-07 04:52:26 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -81.1 deg.
The galactic latitude b = 13 deg., longitude l = 63 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2927564
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   47126 |         MASTER-OAFA |   C |   180 | 17.7 |        
   47319 |         MASTER-OAFA |   C |   180 | 17.8 |        
   49913 |         MASTER-OAFA |   C |   180 | 18.0 |        
   50108 |         MASTER-OAFA |   C |   180 | 18.0 |        
   51188 |         MASTER-OAFA |   C |   180 | 17.8 |        
   51392 |         MASTER-OAFA |   C |   180 | 17.9 |        
   52485 |         MASTER-OAFA |   C |   180 | 17.8 |        
   52679 |         MASTER-OAFA |   C |   180 | 17.6 |        
   53664 |         MASTER-OAFA |   C |   180 | 17.6 |        
   53965 |         MASTER-OAFA |   C |   180 | 17.7 |        
   54883 |         MASTER-OAFA |   C |   180 | 17.7 |        
   55239 |         MASTER-OAFA |   C |   180 | 17.7 |        
   56730 |         MASTER-OAFA |   C |   180 | 17.4 |        
   56924 |         MASTER-OAFA |   C |   180 | 17.2 |        
   57911 |         MASTER-OAFA |   C |   180 | 17.4 |        
   58211 |         MASTER-OAFA |   C |   180 | 17.1 |        
   59205 |         MASTER-OAFA |   C |   180 | 16.4 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #41005
Q. C. Liu (THU), J. W. Hu, D. Y. Li, B. B. Zhang (NAO,CAS), Y. H. Cheng (YNU), P. Y. Han (HUST), W. Yuan (NAO,CAS) on behalf of the Einstein Probe team
We report on the detection of a fast X-ray transient, designated EP250706a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient event started at 2025-07-06T15:48:25 (UTC). The position of the source is R.A. = 284.02 deg, DEC = 32.329 deg (J2000) with an uncertainty of 2.2 arcmin in radius (90% C.L. statistical and systematic). The trigger time and position of this X-ray transient are consistent with that of GRB 250706A (#GCN 40988, #GCN 40990, #GCN 40998, #GCN 41000, #GCN 41001).
The transient event lasts for more than 250 seconds. No automated follow-up X-ray observation was performed due to that EP was performing a ToO observation of higher priority. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a photon index of 2.7 (+1.2/-1.0) with a column density value of 0.7 (+0.4/-0.3) x 10^22 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 0.8 (+1.0/-0.3) x 10^-9 erg/s/cm^2. The peak flux is around 4.6 x 10^-9 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
GCN Circular #41006
R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 250706A detected by Swift/BAT (Moss et al., GCN 40988) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, and H bands, started on 2025 July 07 at 06:21:07 UT (i.e. 14.5 hr after the burst), and lasted for about 1 hour.
From preliminary inspection, we do not detect any optical/NIR counterpart within the Swift/XRT error region down to the following 3sigma limits:
r > 19.8 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 15.1 hr after the trigger;
H > 15.3 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 14.6 hr after the trigger.
GCN Circular #41008
M. H. Siegel (PSU) and M. J. Moss (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250706A 147 s after the BAT trigger (Moss et al., GCN Circ. 40988). No optical afterglow consistent with the XRT position 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

u_FC               147          397          246         >19.5
v                  453          473           19         >16.8
b                  403          423           19         >18.0
u                  147          397          246         >19.5
w1                 502          509            6         >18.2
m2                 477          497           19         >17.9
w2                 429          449           19         >19.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.093 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #41010
R. Brivio (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 5.7 ks of XRT data for GRB 250706A, from 131 s to 55.6 ks after the trigger. The data comprise 285 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 284.0176, +32.3216 which is equivalent to:
```
RA (J2000): 18 56 04.22
Dec(J2000): +32 19 17.6
```
with an uncertainty of 3.5 arcsec (radius, 90% confidence).
The light curve can be modelled with an initial power-law decay with an index of alpha=0.76 (+0.12, -0.13), followed by a break at T+427 s to an alpha of 2.27 (+0.18, -0.14).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.87 (+/-0.09). The best-fitting absorption column is 2.6 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 1.2 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 3.8 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
```
Total column:	     2.6 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^21 cm^-2
Excess significance: 6.4 sigma
Photon index:	     1.87 (+/-0.09)
```
If the light curve continues to decay with a power-law decay index of 2.27, the count rate at T+24 hours will be 3.3 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x 10^-15 (1.7 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01330958.
This circular is an official product of the Swift-XRT team.
GCN Circular #41083
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250706A (trigger #1330958) (Moss, et al., GCN Circ. 40988). The BAT ground-calculated position is RA, Dec = 284.011, 32.327 deg which is
```
   RA(J2000)  =  18h 56m 02.7s
   Dec(J2000) = +32d 19' 36.8"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%.
The mask-weighted light curve shows a single-peak structure that starts at ~T-1 s, peaks at ~T+2 s, and ends at ~T+40 s. T90 (15-350 keV) is 31.9 +- 7.2 sec (estimated error including systematics).
The time-averaged spectrum from T0 to T+40 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.34 +- 0.17. The fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.93 sec in the 15-150 keV band is 1.3 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1330958

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Jochen Greiner, last update: 13-Jul-2025 [Disclaimer]