Gamma-ray Burst 210912A

(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 12 Sep 21 11:01:24 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1072990,   Seg_Num: 0
GRB_RA:          129.769d {+08h 39m 04s} (J2000),
                 130.529d {+08h 42m 07s} (current),
                 127.983d {+08h 31m 56s} (1950)
GRB_DEC:         +79.194d {+79d 11' 38"} (J2000),
                 +79.116d {+79d 06' 58"} (current),
                 +79.369d {+79d 22' 08"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1652 [cnts]    Image_Peak=113 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       17278 [cnts]
BKG_TIME:        39660.28 SOD {11:01:00.28} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19469 TJD;   255 DOY;   21/09/12
GRB_TIME:        39671.54 SOD {11:01:11.54} UT
GRB_PHI:         -153.63 [deg]
GRB_THETA:         7.63 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.84 [sigma]
IMAGE_SIGNIF:    7.29 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -3  +0  +0 -20  +0 
SUN_POSTN:       170.73d {+11h 22m 54s}   +4.00d {+03d 59' 45"}
SUN_DIST:         77.74 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.43d {+15h 57m 42s}  -20.10d {-20d 05' 50"}
MOON_DIST:       113.26 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.25, 31.56 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      102.92, 57.55 [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 = 318.62,6.07 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:02:36 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1072990,   Seg_Num: 0
GRB_RA:          129.8850d {+08h 39m 32.39s} (J2000),
                 130.6454d {+08h 42m 34.90s} (current),
                 128.0984d {+08h 32m 23.60s} (1950)
GRB_DEC:         +79.2225d {+79d 13' 20.9"} (J2000),
                 +79.1444d {+79d 08' 39.9"} (current),
                 +79.3977d {+79d 23' 51.7"} (1950)
GRB_ERROR:       6.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       6.40e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.74 [sigma]
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39724.13 SOD {11:02:04.13} UT,   52.6 [sec] since BAT Trigger Time
TAM[0-3]:        327.68 237.23 261.62 243.41
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       170.73d {+11h 22m 54s}   +4.00d {+03d 59' 44"}
SUN_DIST:         77.75 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.44d {+15h 57m 45s}  -20.10d {-20d 06' 02"}
MOON_DIST:       113.23 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.21, 31.57 [deg] galactic lon,lat of the burst
ECL_COORDS:      102.93, 57.59 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 2.15 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:02:46 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1072990,   Seg_Num: 0
GRB_RA:          129.8850d {+08h 39m 32.3s} (J2000),
                 130.6454d {+08h 42m 34.9s} (current),
                 128.0984d {+08h 32m 23.6s} (1950)
GRB_DEC:         +79.2225d {+79d 13' 20.9"} (J2000),
                 +79.1444d {+79d 08' 39.9"} (current),
                 +79.3977d {+79d 23' 51.7"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       33 [cnts]
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39724.13 SOD {11:02:04.13} UT,   52.6 [sec] since BAT Trigger Time
CENTROID_X:      310.77,  raw= 311  [pixels]
CENTROID_Y:      355.94,  raw= 356  [pixels]
ROLL:            138.00 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   136.35
GRB_POS_XRT_Z:   7.95
IMAGE_URL:       sw01072990000msxps_rw.img
SUN_POSTN:       170.73d {+11h 22m 54s}   +4.00d {+03d 59' 44"}
SUN_DIST:         77.75 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.44d {+15h 57m 45s}  -20.10d {-20d 06' 04"}
MOON_DIST:       113.24 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.21, 31.57 [deg] galactic lon,lat of the burst
ECL_COORDS:      102.93, 57.59 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:02:49 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1072990,   Seg_Num: 0
GRB_RA:          129.8850d {+08h 39m 32.3s} (J2000),
                 130.6454d {+08h 42m 34.9s} (current),
                 128.0984d {+08h 32m 23.6s} (1950)
GRB_DEC:         +79.2225d {+79d 13' 20.9"} (J2000),
                 +79.1444d {+79d 08' 39.9"} (current),
                 +79.3977d {+79d 23' 51.7"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       33 [cnts]
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39724.13 SOD {11:02:04.13} UT,   52.6 [sec] since BAT Trigger Time
CENTROID_X:      310.77,  raw= 311  [pixels]
CENTROID_Y:      355.94,  raw= 356  [pixels]
ROLL:            138.00 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   136.35
GRB_POS_XRT_Z:   7.95
IMAGE_URL:       sw01072990000msxps_rw.img
SUN_POSTN:       170.73d {+11h 22m 54s}   +4.00d {+03d 59' 44"}
SUN_DIST:         77.75 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.44d {+15h 57m 45s}  -20.10d {-20d 06' 05"}
MOON_DIST:       113.24 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.21, 31.57 [deg] galactic lon,lat of the burst
ECL_COORDS:      102.93, 57.59 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:04:48 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1072990,   Seg_Num: 0
GRB_RA:          129.769d {+08h 39m 04s} (J2000),
                 130.529d {+08h 42m 07s} (current),
                 127.983d {+08h 31m 56s} (1950)
GRB_DEC:         +79.194d {+79d 11' 38"} (J2000),
                 +79.116d {+79d 06' 58"} (current),
                 +79.369d {+79d 22' 08"} (1950)
GRB_DATE:        19469 TJD;   255 DOY;   21/09/12
GRB_TIME:        39671.54 SOD {11:01:11.54} UT
TRIGGER_INDEX:   124
GRB_PHI:         -153.63 [deg]
GRB_THETA:         7.63 [deg]
DELTA_TIME:      -5.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.84 [sigma]
IMAGE_SIGNIF:    7.29 [sigma]
LC_URL:          sw01072990000msb.lc
SUN_POSTN:       170.73d {+11h 22m 55s}   +4.00d {+03d 59' 42"}
SUN_DIST:         77.74 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.46d {+15h 57m 50s}  -20.11d {-20d 06' 25"}
MOON_DIST:       113.27 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.25, 31.56 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      102.92, 57.55 [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 = 318.62,6.07 [deg].

GCN Circular #30820
E. Troja (NASA/GSFC/UMCP), A. P. Beardmore (U Leicester), R. Caputo (NASA/GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 11:01:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210912A (trigger=1072990). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 129.769, +79.194 which is
```
   RA(J2000) = 08h 39m 04s
   Dec(J2000) = +79d 11' 38"
```
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 40 sec. The peak count rate was ~2800 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 11:02:04.1 UT, 52.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 129.88358, 79.22292 which is equivalent to:
```
   RA(J2000)  = 08h 39m 32.06s
   Dec(J2000) = +79d 13' 22.5"
```
with an uncertainty of 7.5 arcseconds (radius, 90% containment). This location is 129 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 2.40 x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 6.40e-10 erg cm^-2 s^-1 (0.2-10 keV).
There are no UVOT data available.
Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 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 12 Sep 21 11:30:24 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1072990,   Seg_Num: 0
POINT_RA:        129.736d {+08h 38m 57s} (J2000)
POINT_DEC:       +79.195d {+79d 11' 42"} (J2000)
ROLL:            137.989d
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39731.30 SOD {11:02:11.30} UT,   59.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     653137359
X_OFFSET:        646 [pixels]
Y_OFFSET:        632 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       806
Y_GRB_POS:       792
BINNING_INDEX:   1
IM_URL:          sw01072990000msuni0087.fits
SUN_POSTN:       170.74d {+11h 22m 58s}   +3.99d {+03d 59' 18"}
SUN_DIST:         77.76 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.72d {+15h 58m 52s}  -20.18d {-20d 10' 49"}
MOON_DIST:       113.40 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.25, 31.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      102.91, 57.55 [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 12 Sep 21 11:30:33 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1072990,   Seg_Num: 0
POINT_RA:        129.736d {+08h 38m 57s} (J2000)
POINT_DEC:       +79.195d {+79d 11' 42"} (J2000)
ROLL:            137.989d
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39731.30 SOD {11:02:11.30} UT,   59.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     653137359
X_OFFSET:        646 [pixels]
Y_OFFSET:        632 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       806
Y_GRB_POS:       792
BINNING_INDEX:   1
IM_URL:          sw01072990000msuni0087.fits
SUN_POSTN:       170.74d {+11h 22m 58s}   +3.99d {+03d 59' 18"}
SUN_DIST:         77.76 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.72d {+15h 58m 53s}  -20.18d {-20d 10' 50"}
MOON_DIST:       113.40 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      134.25, 31.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      102.91, 57.55 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:40:26 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1072990,   Seg_Num: 0
POINT_RA:        219.004d {+14h 36m 01s} (J2000)
POINT_DEC:       +58.804d {+58d 48' 14"} (J2000)
POINT_ROLL:      238.768d
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39943.86 SOD {11:05:43.86} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.736
N_STARS:         27
X_OFFSET:        326 [pixels]
Y_OFFSET:        312 [pixels]
X_MAX:           1285 [pixels]
Y_MAX:           1271 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01072990000msufc0272.fits
SUN_POSTN:       170.75d {+11h 23m 00s}   +3.99d {+03d 59' 08"}
SUN_DIST:         66.21 [deg]   Sun_angle= -3.2 [hr] (East of Sun)
MOON_POSTN:      239.82d {+15h 59m 17s}  -20.21d {-20d 12' 32"}
MOON_DIST:        80.74 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      100.37, 53.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      174.16, 66.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:40:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1072990,   Seg_Num: 0
POINT_RA:        219.004d {+14h 36m 01s} (J2000)
POINT_DEC:       +58.804d {+58d 48' 14"} (J2000)
POINT_ROLL:      238.768d
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39943.86 SOD {11:05:43.86} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.736
N_STARS:         27
X_OFFSET:        326 [pixels]
Y_OFFSET:        312 [pixels]
X_MAX:           1285 [pixels]
Y_MAX:           1271 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01072990000msufc0272.fits
SUN_POSTN:       170.75d {+11h 23m 00s}   +3.99d {+03d 59' 08"}
SUN_DIST:         66.21 [deg]   Sun_angle= -3.2 [hr] (East of Sun)
MOON_POSTN:      239.82d {+15h 59m 17s}  -20.21d {-20d 12' 34"}
MOON_DIST:        80.75 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      100.37, 53.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      174.16, 66.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 12 Sep 21 11:41:47 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1072990,   Seg_Num: 0
POINT_RA:        129.736d {+08h 38m 57s} (J2000)
POINT_DEC:       +79.195d {+79d 11' 42"} (J2000)
ROLL:            137.989d
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39943.86 SOD {11:05:43.86} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     653137571
X_OFFSET:        646 [pixels]
Y_OFFSET:        632 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       806
Y_GRB_POS:       792
BINNING_INDEX:   1
IM_URL:          sw01072990000msuni0300.fits
SUN_POSTN:       170.75d {+11h 23m 00s}   +3.99d {+03d 59' 07"}
SUN_DIST:         77.76 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.83d {+15h 59m 20s}  -20.21d {-20d 12' 46"}
MOON_DIST:       113.45 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      134.25, 31.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      102.91, 57.55 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The Pointing RA,Dec,Roll values came from the 1st Image Notice.  
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 12 Sep 21 11:41:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1072990,   Seg_Num: 0
POINT_RA:        129.736d {+08h 38m 57s} (J2000)
POINT_DEC:       +79.195d {+79d 11' 42"} (J2000)
ROLL:            137.989d
IMG_START_DATE:  19469 TJD;   255 DOY;   21/09/12
IMG_START_TIME:  39943.86 SOD {11:05:43.86} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     653137571
X_OFFSET:        646 [pixels]
Y_OFFSET:        632 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       806
Y_GRB_POS:       792
BINNING_INDEX:   1
IM_URL:          sw01072990000msuni0300.fits
SUN_POSTN:       170.75d {+11h 23m 00s}   +3.99d {+03d 59' 07"}
SUN_DIST:         77.76 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:      239.84d {+15h 59m 21s}  -20.21d {-20d 12' 47"}
MOON_DIST:       113.45 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      134.25, 31.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      102.91, 57.55 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #30823
Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, R. Sanchez-Ramirez and M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:
The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 13 s to the Swift trigger for GRB 210912A (Troja et al., GCNC 30820). In the co-added clear image (30 x 1 s), we find an uncataloged optical source at (J2000) coordinates RA: 8:39:34.30, DEC:+79:13:17.5, which is located at the edge of the XRT error box (Troja et al., GCNC 30820) and for which we measure R = 18.5 mag. We propose this source to be the GRB 210219A optical afterglow, pending confirmation of its variability. Further observations are ongoing.
We thak the staff at San Pedro Martir for their support.
GCN Circular #30824
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210912A ( E. Troja et al., GCN 30820) errorbox 19826 sec after notice time and 19878 sec after trigger time at 2021-09-12 16:32:29 UT, with upper limit up to 15.0 mag. Observations started at twilight. The observations began at zenith distance = 57 deg. The sun altitude is -12.6 deg.
The galactic latitude b = 32 deg., longitude l = 134 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1718486
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    5800 |             MASTER- |   C |    25 | 13.0 |        
    8423 |             MASTER- |   C |    20 | 17.6 |        
    8423 |             MASTER- |   C |    20 | 13.9 |        
   19968 |   MASTER-Kislovodsk |   C |   180 | 15.0 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #30825
N. Pankov (HSE), S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of GRB IKI FuN:
We observed the field of GRB 210912A (Troja et al., GCN 30820) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-09-12(UT) 12:57:48. We obtained 30 images in R-filter. We confirm the fading object suggested by Hu et al. (GCN 30823) as the optic afterglow of GRB 210912A. Preliminary photometry of the object in stacked images is following
```
Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-09-12 12:57:48  0.10112    R     29*120   21.33 0.14  22.5
```
The photometry is based on the nearby USNO-B1.0 stars
```
RA DEC R2
08:39:12.26208 +79:12:37.1304 15.88
08:39:10.94880 +79:16:33.8916 15.26
```
GCN Circular #30829
D. A. Kann (HETH/IAA-CSIC) reports:
At the afterglow position (Hu et al., GCN #30823, see also Pankov et al., GCN #30825) of the Swift GRB 210912A (Troja et al., GCN #30820), an object is visible in Pan-STARRS pre-imaging at position (J2000):
```
RA = 129.89171813
Dec. = +79.22157927
```
in agreement with the position given by Hu et al., GCN #30823,
with magnitudes:
```
g' = 23.19 +/- 0.23 mag,
r' = 23.09 +/- 0.36 mag,
i' = 22.48 +/- 0.13 mag,
z' = 22.43 +/- 0.25 mag.
```
It is undetected in Y.
We suggest this object to be the host galaxy of GRB 210912A. This may be indicative that this is a low-redshift event which may be followed by a detectable supernova.
Further follow-up despite the very northerly position is warranted.
GCN Circular #30830
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 526 s of XRT Photon Counting mode data and 1 UVOT images for GRB 210912A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 129.88990, +79.22148 which is equivalent to:
```
RA (J2000): 08h 39m 33.58s
Dec (J2000): +79d 13' 17.3"
```
with an uncertainty of 2.6 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #30832
N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210912A 60 s after the BAT trigger (Troja et al., GCN Circ. 30820). A source consistent with the optical position (Hu et al. GCN Circ. 30823) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  08:39:34.27 = 129.89280 (deg.)
    Dec (J2000) = +79:13:17.1  =  79.22141 (deg.)
```
with an estimated uncertainty of 0.47 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               60          209          147         18.73 +/- 0.08
v                  602          621           19        >17.8
b                  528          547           19        >18.3
u                  272          490          214         19.56 +/- 0.31
w2                 577          597           19        >18.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.027 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #30833
A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and E. Troja report on behalf of the Swift-XRT team:
We have analysed 4.1 ks of XRT data for GRB 210912A (Troja et al. GCN Circ. 30820), from 46 s to 29.0 ks after the BAT trigger. The data comprise 32 s in Windowed Timing (WT) mode (the first 5 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 30830).
The light curve can be modelled with an initial power-law decay with an index of alpha=3.4 (+/-0.4), followed by a break at T+140 s to an alpha of 0.68 (+/-0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.67 (+0.25, -0.23). The best-fitting absorption column is 1.2 (+0.9, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.2 (+0.9, -0.7) x 10^21 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index:	     1.67 (+0.25, -0.23)
```
If the light curve continues to decay with a power-law decay index of 0.68, the count rate at T+24 hours will be 0.014 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x 10^-13 (6.6 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01072990.
This circular is an official product of the Swift-XRT team.
GCN Circular #30834
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), and S. Gongora (CAHA) report:
We observed GRB 210912A (Swift detection: Troja et al., GCN #30820) with CAFOS mounted on the 2.2m CAHA telescope at Calar Alto, Almeria, Spain. We obtained 7 x 60 s in the SDSS i' band under passing clouds, starting at 20:04:34 UT (9.056 hrs after the trigger; further observations at a later time were prevented by cloud cover). The afterglow (Hu et al., GCN #30823; Pankov et al., GCN #30825; Kuin & Troja, GCN #30832) is faintly detected in the stacked image.
Compared to a nearby Pan-STARRS comparison star, we measure (AB mag) i' = 21.66 +/- 0.15 mag at 0.38146 d after the GRB, further confirming the decaying afterglow. This is still significantly brighter than the potential underlying host galaxy (Kann, GCN #30829).
GCN Circular #30837
A. Nicuesa Guelbenzu, S. Klose, S. Melnikov, B. Stecklum, C. Hoegner (all TLS Tautenburg) report:
We observed the field of GRB 210912A (Troja et al., GCN 30820) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD camera and the Sloan r-band filter.
Observations were performed on September 12, at a midtime of 19.33 UT, 22.17 UT, and 02:36 UT (Sep 13). The optical transient (Hu et al., GCN 30823; Pankov et al., GCN 30825; Kuin & Troja, GCN 30832; Kann et al. GCN 30833) is detected with the following preliminary AB magnitudes:
```
r_1 = 21.95 +- 0.19,
r_2 = 22.17 +- 0.19,
r_3 = 22.53 +- 0.19.
```
Magnitudes are calibrated against the Pan-STARRS catalogue.
A comparison with the previous observations suggests that around 0.6 days the decay index of the light curve has increased from a rather modest value of alpha = 0.4 to alpha about 1. Further observations are required in order to provide a more precise decay index.
GCN Circular #30839
M. Stamatikos (OSU), 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. Sakamoto (AGU), (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210912A (trigger #1072990) (Troja et al., GCN Circ. 30820). The BAT ground-calculated position is RA, Dec = 129.874, 79.216 deg which is
```
   RA(J2000)  =  08h 39m 29.7s
   Dec(J2000) = +79d 12' 59.3"
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.
The BAT light curve showed a complex structure with a duration of about ~30 sec. T90 (15-350 keV) is 28.35 +- 14.34 sec (estimated error including systematics).
The time-averaged spectrum from T-23 to T+25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.61 +- 0.13. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.23 sec in the 15-150 keV band is 1.7 +- 0.2 ph/cm2/sec. 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/1072990/BA/
GCN Circular #30844
Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, R. Sanchez-Ramirez and M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:
The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 13 s to the Swift trigger for GRB 210912A (Troja et al., GCNC 30820). In the co-added clear image (30 x 1 s), we find an uncataloged optical source at (J2000) coordinates RA: 8:39:34.30, DEC:+79:13:17.5, which is located at the edge of the XRT error box (Troja et al., GCNC 30820) and for which we measure R = 18.5 mag. We propose this source to be the GRB 210912A optical afterglow, pending confirmation of its variability. Further observations are ongoing.
We thank the staff at San Pedro Martir for their support.
In the GCNC 30823, we have a typo of the GRB name in the text and it was corrected now. We apologize for the possible confusion and inconvenience.
GCN Circular #30861
A. Rossi (INAF-OAS Bologna) report on behalf of the CIBO collaboration:
We observed the field of GRB 210912A (Troja et al., GCN 30820) in the r' band with the LBC imager mounted on LBT (Mt Graham, AZ, USA). We obtained 10min of imaging at the midtime 11:20 UT on 2021-09-17 (~5 days after the burst trigger).
We clearly detect the optical afterglow (Hu et al., GCN 30823; Pankov et al., GCN 30825; Kuin & Troja, GCN 30832; Kann et al. GCN 30834; Nicuesa Guelbenzu et al. GCN 30837) with the following preliminary AB magnitude:
r = 22.73 +- 0.05
calibrated against Pan-STARRS field stars. It is likely that this flux is significantly affected by host galaxy contamination (Kann et al. GCN 30829).
We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly A. Cardwell, J. Williams and D. Paris, in obtaining these observations.

Back to JG's homepage

Jochen Greiner, last update: 22-Sep-2021 [Disclaimer]