Gamma-ray Burst 210307A

(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 07 Mar 21 08:43:08 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1036139,   Seg_Num: 0
GRB_RA:          119.190d {+07h 56m 46s} (J2000),
                 119.219d {+07h 56m 53s} (current),
                 119.120d {+07h 56m 29s} (1950)
GRB_DEC:         -66.963d {-66d 57' 45"} (J2000),
                 -67.020d {-67d 01' 12"} (current),
                 -66.827d {-66d 49' 36"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       5449 [cnts]    Image_Peak=211 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   262     E_range: 25-100 keV
BKG_INTEN:       54046 [cnts]
BKG_TIME:        31325.37 SOD {08:42:05.37} UT
BKG_DUR:         24 [sec]
GRB_DATE:        19280 TJD;    66 DOY;   21/03/07
GRB_TIME:        31358.39 SOD {08:42:38.39} UT
GRB_PHI:          -8.06 [deg]
GRB_THETA:        29.98 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.39 [sigma]
IMAGE_SIGNIF:    7.90 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +2  -2  +0  +0 +17  +0 
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 56"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.89d {+18h 15m 33s}  -24.95d {-24d 56' 56"}
MOON_DIST:        86.08 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.56,-18.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      195.41,-78.58 [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 = 226.53,0.59 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 08:44:46 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1036139,   Seg_Num: 0
GRB_RA:          119.2432d {+07h 56m 58.3s} (J2000),
                 119.2723d {+07h 57m 05.3s} (current),
                 119.1724d {+07h 56m 41.3s} (1950)
GRB_DEC:         -66.9692d {-66d 58' 09.1"} (J2000),
                 -67.0268d {-67d 01' 36.5"} (current),
                 -66.8333d {-66d 50' 00.0"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       92 [cnts]
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31449.27 SOD {08:44:09.27} UT,   90.9 [sec] since BAT Trigger Time
CENTROID_X:      324.97,  raw= 325  [pixels]
CENTROID_Y:      321.30,  raw= 321  [pixels]
ROLL:            229.59 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   54.70
GRB_POS_XRT_Z:   41.42
IMAGE_URL:       sw01036139000msxps_rw.img
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 55"}
SUN_DIST:        100.01 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.90d {+18h 15m 37s}  -24.95d {-24d 57' 00"}
MOON_DIST:        86.07 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.58,-18.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      195.46,-78.56 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 08:44:44 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1036139,   Seg_Num: 0
GRB_RA:          119.2432d {+07h 56m 58.3s} (J2000),
                 119.2723d {+07h 57m 05.3s} (current),
                 119.1724d {+07h 56m 41.3s} (1950)
GRB_DEC:         -66.9692d {-66d 58' 09.1"} (J2000),
                 -67.0268d {-67d 01' 36.5"} (current),
                 -66.8333d {-66d 50' 00.0"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       92 [cnts]
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31449.27 SOD {08:44:09.27} UT,   90.9 [sec] since BAT Trigger Time
CENTROID_X:      324.97,  raw= 325  [pixels]
CENTROID_Y:      321.30,  raw= 321  [pixels]
ROLL:            229.59 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   54.70
GRB_POS_XRT_Z:   41.42
IMAGE_URL:       sw01036139000msxps_rw.img
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 55"}
SUN_DIST:        100.01 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.90d {+18h 15m 37s}  -24.95d {-24d 57' 00"}
MOON_DIST:        86.07 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.58,-18.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      195.46,-78.56 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 08:44:34 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1036139,   Seg_Num: 0
GRB_RA:          119.2432d {+07h 56m 58.36s} (J2000),
                 119.2723d {+07h 57m 05.34s} (current),
                 119.1724d {+07h 56m 41.38s} (1950)
GRB_DEC:         -66.9692d {-66d 58' 09.1"} (J2000),
                 -67.0268d {-67d 01' 36.5"} (current),
                 -66.8333d {-66d 50' 00.0"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       2.73e-09 [erg/cm2/sec]
GRB_SIGNIF:      9.59 [sigma]
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31449.27 SOD {08:44:09.27} UT,   90.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.64 237.12 261.67 243.71
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 55"}
SUN_DIST:        100.01 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.90d {+18h 15m 36s}  -24.95d {-24d 56' 59"}
MOON_DIST:        86.06 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.58,-18.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      195.46,-78.56 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.30 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 08:46:11 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1036139,   Seg_Num: 0
GRB_RA:          119.190d {+07h 56m 46s} (J2000),
                 119.219d {+07h 56m 53s} (current),
                 119.120d {+07h 56m 29s} (1950)
GRB_DEC:         -66.963d {-66d 57' 45"} (J2000),
                 -67.020d {-67d 01' 12"} (current),
                 -66.827d {-66d 49' 36"} (1950)
GRB_DATE:        19280 TJD;    66 DOY;   21/03/07
GRB_TIME:        31358.39 SOD {08:42:38.39} UT
TRIGGER_INDEX:   262
GRB_PHI:          -8.06 [deg]
GRB_THETA:        29.98 [deg]
DELTA_TIME:      57.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.39 [sigma]
IMAGE_SIGNIF:    7.90 [sigma]
LC_URL:          sw01036139000msb.lc
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 53"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.92d {+18h 15m 40s}  -24.95d {-24d 57' 02"}
MOON_DIST:        86.08 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.56,-18.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      195.41,-78.58 [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 = 226.53,0.59 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 08:47:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.194d {+07h 56m 47s} (J2000)
POINT_DEC:       -66.964d {-66d 57' 51"} (J2000)
POINT_ROLL:      229.590d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31458.56 SOD {08:44:18.56} UT,   100.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.662
N_STARS:         146
X_OFFSET:        496 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1455 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01036139000msufc0100.fits
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 52"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.93d {+18h 15m 43s}  -24.95d {-24d 57' 04"}
MOON_DIST:        86.08 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.42,-78.58 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 08:47:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.194d {+07h 56m 47s} (J2000)
POINT_DEC:       -66.964d {-66d 57' 51"} (J2000)
POINT_ROLL:      229.590d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31458.56 SOD {08:44:18.56} UT,   100.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.662
N_STARS:         146
X_OFFSET:        496 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1455 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01036139000msufc0100.fits
SUN_POSTN:       348.04d {+23h 12m 10s}   -5.13d {-05d 07' 52"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.93d {+18h 15m 44s}  -24.95d {-24d 57' 05"}
MOON_DIST:        86.08 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.42,-78.58 [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 07 Mar 21 08:49:30 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.194d {+07h 56m 47s} (J2000)
POINT_DEC:       -66.964d {-66d 57' 51"} (J2000)
ROLL:            229.590d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31458.56 SOD {08:44:18.56} UT,   100.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636799485
X_OFFSET:        681 [pixels]
Y_OFFSET:        829 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       841
Y_GRB_POS:       989
BINNING_INDEX:   1
IM_URL:          sw01036139000msuni0127.fits
SUN_POSTN:       348.04d {+23h 12m 11s}   -5.13d {-05d 07' 50"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.95d {+18h 15m 49s}  -24.95d {-24d 57' 09"}
MOON_DIST:        86.08 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.42,-78.58 [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 07 Mar 21 08:49:41 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.194d {+07h 56m 47s} (J2000)
POINT_DEC:       -66.964d {-66d 57' 51"} (J2000)
ROLL:            229.590d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31458.56 SOD {08:44:18.56} UT,   100.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636799485
X_OFFSET:        681 [pixels]
Y_OFFSET:        829 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       841
Y_GRB_POS:       989
BINNING_INDEX:   1
IM_URL:          sw01036139000msuni0127.fits
SUN_POSTN:       348.04d {+23h 12m 11s}   -5.13d {-05d 07' 50"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      273.95d {+18h 15m 49s}  -24.95d {-24d 57' 09"}
MOON_DIST:        86.08 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.42,-78.58 [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 #29609
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-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 GRB210307.36 (trigger No 1036139,07h 56m 45.60s , -66d 57m 46.8s, R=0.05) errorbox 6 sec after notice time and 54 sec after trigger time at 2021-03-07 08:43:33 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 69 deg. The sun altitude is -22.8 deg.
The galactic latitude b = -19 deg., longitude l = 280 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1562923
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      60 |         MASTER-OAFA |   C |    10 | 17.1 |        
      94 |         MASTER-OAFA |   C |    20 | 17.5 |        
     134 |         MASTER-OAFA |   C |    20 | 17.5 |        
     243 |         MASTER-OAFA |   C |    40 | 14.4 |        
     376 |         MASTER-OAFA |   C |    70 | 18.1 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29610
E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), N. J. Klingler (PSU), K. L. Page (U Leicester) and T. Sakamoto (AGU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 08:42:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210307A (trigger=1036139). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 119.190, -66.963 which is
```
   RA(J2000) = 07h 56m 46s
   Dec(J2000) = -66d 57' 45"
```
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 120 sec. The peak count rate was ~1300 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 96.2 s seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with a position: RA, Dec 119.239583, -66.969694 which is equivalent to:
```
   RA(J2000)  = 07 56 57.5
   Dec(J2000) = -66 58 10.9 
```
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 73.8 arcsec 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 http://www.swift.ac.uk/sper.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 100 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 19.6 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 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.138.
This source lies within the current (Sector 35) field-of-view of TESS camera 4.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it). 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 07 Mar 21 09:11:28 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.200d {+07h 56m 48s} (J2000)
POINT_DEC:       -66.966d {-66d 57' 58"} (J2000)
POINT_ROLL:      229.584d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31670.95 SOD {08:47:50.95} UT,   312.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.585
N_STARS:         128
X_OFFSET:        361 [pixels]
Y_OFFSET:        509 [pixels]
X_MAX:           1320 [pixels]
Y_MAX:           1468 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01036139000msufc0312.fits
SUN_POSTN:       348.06d {+23h 12m 14s}   -5.12d {-05d 07' 29"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      274.18d {+18h 16m 44s}  -24.96d {-24d 57' 53"}
MOON_DIST:        86.10 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.43,-78.58 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 07 Mar 21 09:11:39 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.200d {+07h 56m 48s} (J2000)
POINT_DEC:       -66.966d {-66d 57' 58"} (J2000)
POINT_ROLL:      229.584d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31670.95 SOD {08:47:50.95} UT,   312.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.585
N_STARS:         128
X_OFFSET:        361 [pixels]
Y_OFFSET:        509 [pixels]
X_MAX:           1320 [pixels]
Y_MAX:           1468 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01036139000msufc0312.fits
SUN_POSTN:       348.06d {+23h 12m 14s}   -5.12d {-05d 07' 29"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      274.18d {+18h 16m 44s}  -24.96d {-24d 57' 53"}
MOON_DIST:        86.10 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.43,-78.58 [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 07 Mar 21 09:12:36 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.200d {+07h 56m 48s} (J2000)
POINT_DEC:       -66.966d {-66d 57' 58"} (J2000)
ROLL:            229.584d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31670.95 SOD {08:47:50.95} UT,   312.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     636799697
X_OFFSET:        681 [pixels]
Y_OFFSET:        829 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       841
Y_GRB_POS:       989
BINNING_INDEX:   1
IM_URL:          sw01036139000msuni0339.fits
SUN_POSTN:       348.06d {+23h 12m 14s}   -5.12d {-05d 07' 28"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      274.19d {+18h 16m 47s}  -24.97d {-24d 57' 55"}
MOON_DIST:        86.10 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.43,-78.58 [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 07 Mar 21 09:12:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1036139,   Seg_Num: 0
POINT_RA:        119.200d {+07h 56m 48s} (J2000)
POINT_DEC:       -66.966d {-66d 57' 58"} (J2000)
ROLL:            229.584d
IMG_START_DATE:  19280 TJD;    66 DOY;   21/03/07
IMG_START_TIME:  31670.95 SOD {08:47:50.95} UT,   312.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     636799697
X_OFFSET:        681 [pixels]
Y_OFFSET:        829 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       841
Y_GRB_POS:       989
BINNING_INDEX:   1
IM_URL:          sw01036139000msuni0339.fits
SUN_POSTN:       348.06d {+23h 12m 14s}   -5.12d {-05d 07' 28"}
SUN_DIST:        100.00 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:      274.20d {+18h 16m 47s}  -24.97d {-24d 57' 55"}
MOON_DIST:        86.10 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      279.57,-18.76 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.43,-78.58 [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 #29613
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 210307A (Ambrosi et al., GCN 29610) with the LCO 1-m Sinistro instrument at the Sutherland Observatory, South Africa site, on March 7, from 09:28 to 09:59 UT (corresponding to 0.60 to 1.18 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 4x240s exposures in R and I. We do not detect an uncatalogued optical source in either band in single frames, or in stacked images at a location consistent the initial XRT detection (Ambrosi et al., GCN 29610). Using the USNO-B.1 catalog as reference, we calculate the following upper limits:
R > 20.72
I > 20.66
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682
GCN Circular #29624
A. D'Ai (INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and E. Ambrosi (INAF-IASFPA) report on behalf of the Swift-XRT team:
We have analysed 7.0 ks of XRT data for GRB 210307A (Ambrosi et al. GCN Circ. 29610), from 97 s to 40.0 ks after the BAT trigger. The data comprise 149 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. Using 2981 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 119.23831, -66.97092 which is equivalent to:
```
RA (J2000): 07h 56m 57.19s
Dec(J2000): -66d 58' 15.3"
```
with an uncertainty of 1.5 arcsec (radius, 90% confidence).
The light curve can be modelled with a series of power-law decays followed by a plateau. The initial decay index is alpha= : 2.11 (+0.10, -0.11). At T= T0+242.1 s the decay index is alpha=7.88 (+0.12, -2.58) before breaking again at T=T0+280.5 s with an index alpha= 3.2 (+0.6, -0.4). After T>T0+10^4 s the lightcurve is in a long lasting plateau phase.
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.520 (+0.035, -0.026). The best-fitting absorption column is consistent with the Galactic value of 1.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.75 (+0.16, -0.14) and a best-fitting absorption column of 1.75 (+0.61, -0.30) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (4.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.75 (+0.61, -0.30) x 10^21 cm^-2
Galactic foreground: 1.4 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.75 (+0.16, -0.14)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01036139.
This circular is an official product of the Swift-XRT team.
GCN Circular #29629
M. H. Siegel (PSU) and E. Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210307A 100 s after the BAT trigger (Ambrosi et al., GCN Circ. 29610). No optical afterglow consistent with the XRT position (Ambrosi et al. GCN Circ. 29610) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           100          250          147         >20.9
u_FC               313          562          246         >20.6
white              100          786          186         >21.1
v                  642          836           39         >19.3
b                  568          761           39         >19.9
u                  313          736          265         >20.6
w1                 692          711           19         >19.6
m2                 667          687           19         >18.7
w2                 618          812           39         >19.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.138 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #29632
C. B. Markwardt (GSFC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+700 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210307A (trigger #1036139) (Ambrosi, et al., GCN Circ. 29610). The BAT ground-calculated position is RA, Dec = 119.244, -66.965 deg which is
```
    RA(J2000)  =  07h 56m 58.5s
    Dec(J2000) = -66d 57' 54.3"
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 79%.
The mask-weighted light curve shows two isolated peaks. The initial peak starts at T-30 sec, peaks at T0 and ends at T+40 sec. The second peak starts at T+110 sec, peaks at T+118 sec and ends at T+150 sec. T90 (15-350 keV) is 262 +- 83 sec (estimated error including systematics).
The time-averaged spectrum from T-159.61 to T+174.53 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.56 +- 0.16. The fluence in the 15-150 keV band is 2.8 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.27 sec in the 15-150 keV band is 1.0 +- 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/1036139/BA/

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Jochen Greiner, last update: 09-Mar-2021 [Disclaimer]