Gamma-ray Burst 220305A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 16:13:24 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1095215,   Seg_Num: 0
GRB_RA:          107.584d {+07h 10m 20s} (J2000),
                 107.778d {+07h 11m 07s} (current),
                 107.149d {+07h 08m 36s} (1950)
GRB_DEC:         -37.708d {-37d 42' 29"} (J2000),
                 -37.746d {-37d 44' 44"} (current),
                 -37.625d {-37d 37' 30"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2074 [cnts]    Image_Peak=94 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   148     E_range: 25-100 keV
BKG_INTEN:       12155 [cnts]
BKG_TIME:        58371.27 SOD {16:12:51.27} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19643 TJD;    64 DOY;   22/03/05
GRB_TIME:        58388.61 SOD {16:13:08.61} UT
GRB_PHI:         -67.88 [deg]
GRB_THETA:        38.12 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.00 [sigma]
IMAGE_SIGNIF:    7.18 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -3  +0  +0 +34  +0 
SUN_POSTN:       346.25d {+23h 05m 00s}   -5.88d {-05d 52' 53"}
SUN_DIST:        110.40 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.06d {+01h 24m 14s}   +5.92d {+05d 55' 20"}
MOON_DIST:        91.04 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.99,-12.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.05,-59.45 [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 = 177.89,-20.42 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 16:17:21 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1095215,   Seg_Num: 0
GRB_RA:          107.584d {+07h 10m 20s} (J2000),
                 107.778d {+07h 11m 07s} (current),
                 107.149d {+07h 08m 36s} (1950)
GRB_DEC:         -37.708d {-37d 42' 29"} (J2000),
                 -37.746d {-37d 44' 44"} (current),
                 -37.625d {-37d 37' 30"} (1950)
GRB_DATE:        19643 TJD;    64 DOY;   22/03/05
GRB_TIME:        58388.61 SOD {16:13:08.61} UT
TRIGGER_INDEX:   148
GRB_PHI:         -67.88 [deg]
GRB_THETA:        38.12 [deg]
DELTA_TIME:      25.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.00 [sigma]
IMAGE_SIGNIF:    7.18 [sigma]
LC_URL:          sw01095215000msb.lc
SUN_POSTN:       346.25d {+23h 05m 01s}   -5.88d {-05d 52' 49"}
SUN_DIST:        110.40 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.09d {+01h 24m 21s}   +5.94d {+05d 56' 16"}
MOON_DIST:        91.03 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.99,-12.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.05,-59.45 [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 = 177.89,-20.42 [deg].

GCN Circular #31684
R. Caputo (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil Gehrels Swift Observatory Team:
At 16:13:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 220305A (trigger=1095215). Due to a viewing constraint, Swift did not immediately slew. The BAT on-board calculated location is RA, Dec 107.584, -37.708 which is
```
   RA(J2000) = 07h 10m 20s
   Dec(J2000) = -37d 42' 29"
```
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 ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+46.5 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is R. Caputo (regina.caputo 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:     Sat 05 Mar 22 17:03:32 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1095215,   Seg_Num: 0
POINT_RA:        107.555d {+07h 10m 13s} (J2000)
POINT_DEC:       -37.691d {-37d 41' 26"} (J2000)
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61405.55 SOD {17:03:25.55} UT,   3016.9 [sec] since BAT Trigger Time
COUNTS:          17    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        2    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 17:06:20 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1095215,   Seg_Num: 0
POINT_RA:        107.555d {+07h 10m 13s} (J2000)
POINT_DEC:       -37.691d {-37d 41' 27"} (J2000)
POINT_ROLL:      244.992d
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61409.90 SOD {17:03:29.90} UT,   3021.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.595
N_STARS:         77
X_OFFSET:        299 [pixels]
Y_OFFSET:        432 [pixels]
X_MAX:           1258 [pixels]
Y_MAX:           1391 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01095215000msufc3021.fits
SUN_POSTN:       346.28d {+23h 05m 08s}   -5.87d {-05d 52' 02"}
SUN_DIST:        110.37 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.49d {+01h 25m 56s}   +6.13d {+06d 07' 48"}
MOON_DIST:        90.81 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.96,-12.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      117.99,-59.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 17:06:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1095215,   Seg_Num: 0
POINT_RA:        107.555d {+07h 10m 13s} (J2000)
POINT_DEC:       -37.691d {-37d 41' 27"} (J2000)
POINT_ROLL:      244.992d
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61409.90 SOD {17:03:29.90} UT,   3021.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.595
N_STARS:         77
X_OFFSET:        299 [pixels]
Y_OFFSET:        432 [pixels]
X_MAX:           1258 [pixels]
Y_MAX:           1391 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01095215000msufc3021.fits
SUN_POSTN:       346.28d {+23h 05m 08s}   -5.87d {-05d 52' 02"}
SUN_DIST:        110.37 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.49d {+01h 25m 57s}   +6.13d {+06d 07' 53"}
MOON_DIST:        90.81 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.96,-12.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      117.99,-59.44 [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:     Sat 05 Mar 22 17:07:44 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1095215,   Seg_Num: 0
POINT_RA:        107.555d {+07h 10m 13s} (J2000)
POINT_DEC:       -37.691d {-37d 41' 27"} (J2000)
ROLL:            244.992d
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61409.90 SOD {17:03:29.90} UT,   3021.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     668192638
X_OFFSET:        618 [pixels]
Y_OFFSET:        751 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       778
Y_GRB_POS:       911
BINNING_INDEX:   1
IM_URL:          sw01095215000msuni3050.fits
SUN_POSTN:       346.29d {+23h 05m 09s}   -5.87d {-05d 52' 01"}
SUN_DIST:        110.37 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.50d {+01h 25m 59s}   +6.14d {+06d 08' 08"}
MOON_DIST:        90.80 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.96,-12.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      117.99,-59.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 17:07:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1095215,   Seg_Num: 0
POINT_RA:        107.555d {+07h 10m 13s} (J2000)
POINT_DEC:       -37.691d {-37d 41' 27"} (J2000)
ROLL:            244.992d
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61409.90 SOD {17:03:29.90} UT,   3021.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     668192638
X_OFFSET:        618 [pixels]
Y_OFFSET:        751 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       778
Y_GRB_POS:       911
BINNING_INDEX:   1
IM_URL:          sw01095215000msuni3050.fits
SUN_POSTN:       346.29d {+23h 05m 09s}   -5.87d {-05d 52' 00"}
SUN_DIST:        110.37 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.50d {+01h 26m 00s}   +6.14d {+06d 08' 11"}
MOON_DIST:        90.80 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.96,-12.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      117.99,-59.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 17:07:12 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1095215,   Seg_Num: 0
GRB_RA:          107.5974d {+07h 10m 23.37s} (J2000),
                 107.7906d {+07h 11m 09.75s} (current),
                 107.1618d {+07h 08m 38.82s} (1950)
GRB_DEC:         -37.6809d {-37d 40' 51.2"} (J2000),
                 -37.7184d {-37d 43' 06.3"} (current),
                 -37.5977d {-37d 35' 51.8"} (1950)
GRB_ERROR:       4.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61415.00 SOD {17:03:35.00} UT,   3026.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       346.29d {+23h 05m 08s}   -5.87d {-05d 52' 01"}
SUN_DIST:        110.41 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.49d {+01h 25m 58s}   +6.13d {+06d 08' 00"}
MOON_DIST:        90.84 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.97,-12.74 [deg] galactic lon,lat of the burst
ECL_COORDS:      118.05,-59.42 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
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 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 05 Mar 22 17:44:23 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1095215,   Seg_Num: 0
GRB_RA:          107.5983d {+07h 10m 23.59s} (J2000),
                 107.7915d {+07h 11m 09.96s} (current),
                 107.1627d {+07h 08m 39.04s} (1950)
GRB_DEC:         -37.6801d {-37d 40' 48.3"} (J2000),
                 -37.7176d {-37d 43' 03.4"} (current),
                 -37.5969d {-37d 35' 48.9"} (1950)
GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19643 TJD;    64 DOY;   22/03/05
IMG_START_TIME:  61415.00 SOD {17:03:35.00} UT,   3026.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       346.31d {+23h 05m 14s}   -5.86d {-05d 51' 25"}
SUN_DIST:        110.40 [deg]   Sun_angle= -8.1 [hr] (East of Sun)
MOON_POSTN:       21.79d {+01h 27m 10s}   +6.28d {+06d 16' 44"}
MOON_DIST:        90.69 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      248.97,-12.74 [deg] galactic lon,lat of the burst
ECL_COORDS:      118.05,-59.42 [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 0.58% < P(seren) < 1.1%.

GCN Circular #31685
D.N. Burrows (PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB), G. Cusumano (INAF-IASF PA), P.A. Evans (U. Leicester) and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 220305A at 17:03:25.5 UT, 3016.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 107.59841, -37.68016 which is equivalent to:
```
   RA(J2000)  = 07h 10m 23.62s
   Dec(J2000) = -37d 40' 48.6"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 108 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 in excess of the Galactic value (2.59 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.1 (+6.60/-5.31) x 10^21 cm^-2 (90% confidence).
GCN Circular #31686
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, 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 (Irkutsk State University, API),
B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez, M.L.H.Rodriguez (INAOE, OAGH)
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 220305A ( R. Caputo et al., GCN 31684) errorbox 5464 sec after notice time and 5486 sec after trigger time at 2022-03-05 17:44:35 UT, with upper limit up to 16.4 mag. Observations started at twilight. The observations began at zenith distance = 16 deg. The sun altitude is -8.2 deg.
The galactic latitude b = -12 deg., longitude l = 249 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1902942
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    5577 |         MASTER-SAAO | P\  |   180 | 16.0 |        
    5776 |         MASTER-SAAO | P\  |   180 | 16.4 |        
```
The observation and reduction will continue. The message may be cited.
GCN Circular #31688
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1712 s of XRT Photon Counting mode data and 5 UVOT images for GRB 220305A, 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 = 107.59853, -37.68033 which is equivalent to:
```
RA (J2000): 07h 10m 23.65s
Dec (J2000): -37d 40' 49.2"
```
with an uncertainty of 2.2 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 #31695
V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB) and R. Caputo report on behalf of the Swift-XRT team:
We have analysed 6.2 ks of XRT data for GRB 220305A (Caputo et al. GCN Circ. 31684), from 3.0 ks to 43.5 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 31688).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.22 (+0.11, -0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.34 (+0.28, -0.26). The best-fitting absorption column is 8.3 (+2.0, -1.8) x 10^21 cm^-2, in excess of the Galactic value of 2.6 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 (9.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     8.3 (+2.0, -1.8) x 10^21 cm^-2
Galactic foreground: 2.6 x 10^21 cm^-2
Excess significance: 5.3 sigma
Photon index:	     2.34 (+0.28, -0.26)
```
If the light curve continues to decay with a power-law decay index of 1.22, the count rate at T+24 hours will be 7.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x 10^-13 (6.3 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/01095215.
This circular is an official product of the Swift-XRT team.
GCN Circular #31696
J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team:
Swift-BAT detected GRB 220305A at 16:13:08 UT on 05 March, 2022 (Caputo et al. GCN 31684). There was no Fermi-GBM onboard trigger around the time of the event.
An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no counterparts.
The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 8.192 s timescale, with a location consistent with the Swift-BAT event and a signal-to-noise ratio of 17.8, using the standard search protocol. The GBM targeted search event was found with the highest significance with a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
This analysis is preliminary.
[1] Goldstein et al. 2019 arXiv:1903.12597
Note: Fermi-GBM also detected GRB 220305B at 11:33:20.48 UT on 05 March 2022 which was erroneously named GRB 220305A at the time of its initial publication (GCN 31689, 31690). GRB 220305B is a different burst than the one described here.
GCN Circular #31698
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. Parsotan (GSFC/UMBC), R. Caputo (GSFC), 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 220305A (trigger #1095215) (Caputo et al., GCN Circ. 31684). The BAT ground-calculated position is RA, Dec = 107.610, -37.703 deg which is
```
   RA(J2000)  =  07h 10m 26.4s
   Dec(J2000) = -37d 42' 09.2"
```
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 25%.
The mask-weighted light curve shows a single-pulse structure that starts at ~T-15 s, peaks at ~T0, and ends at ~T+11 s. The burst went out of the BAT FOV at T+225.7 s. T90 (15-350 keV) is 21.12 +- 3.65 sec (estimated error including systematics).
The time-averaged spectrum from T-15.04 to T+11.02 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 +- 0.15. The fluence in the 15-150 keV band is 2.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.16 sec in the 15-150 keV band is 2.1 +- 0.5 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/1095215/BA/

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Jochen Greiner, last update: 06-Mar-2022 [Disclaimer]