Gamma-ray Burst 220730A

(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 30 Jul 22 15:49:06 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1118357,   Seg_Num: 0
GRB_RA:          225.021d {+15h 00m 05s} (J2000),
                 225.549d {+15h 02m 12s} (current),
                 223.862d {+14h 55m 27s} (1950)
GRB_DEC:         -69.497d {-69d 29' 48"} (J2000),
                 -69.585d {-69d 35' 06"} (current),
                 -69.298d {-69d 17' 52"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       849 [cnts]    Image_Peak=102 [image_cnts]
TRIGGER_DUR:     0.064 [sec] 
TRIGGER_INDEX:   10427     E_range: 50-350 keV
BKG_INTEN:       16957 [cnts]
BKG_TIME:        56922.41 SOD {15:48:42.41} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19790 TJD;   211 DOY;   22/07/30
GRB_TIME:        56934.89 SOD {15:48:54.89} UT
GRB_PHI:         -155.38 [deg]
GRB_THETA:        37.44 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     55.93 [sigma]
IMAGE_SIGNIF:    10.00 [sigma]
MERIT_PARAMS:     +1  +0  +0  -4  +3  +0  +0  +1 +32  +0 
SUN_POSTN:       129.88d {+08h 39m 31s}  +18.40d {+18d 23' 60"}
SUN_DIST:        109.18 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      152.90d {+10h 11m 35s}  +16.45d {+16d 27' 01"}
MOON_DIST:        99.53 [deg]
MOON_ILLUM:      3 [%]
GAL_COORDS:      313.83, -9.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      247.57,-49.54 [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 = 102.00,-20.26 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Jul 22 15:50:57 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1118357,   Seg_Num: 0
POINT_RA:        225.010d {+15h 00m 02s} (J2000)
POINT_DEC:       -69.486d {-69d 29' 09"} (J2000)
IMG_START_DATE:  19790 TJD;   211 DOY;   22/07/30
IMG_START_TIME:  57043.08 SOD {15:50:43.08} UT,   108.2 [sec] since BAT Trigger Time
COUNTS:          40    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        4    Max_iter_allowed= 4
ERROR_CODE:      2
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        Algorithm did not converge; too many iterations.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Jul 22 15:53:11 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1118357,   Seg_Num: 0
GRB_RA:          225.021d {+15h 00m 05s} (J2000),
                 225.549d {+15h 02m 12s} (current),
                 223.862d {+14h 55m 27s} (1950)
GRB_DEC:         -69.497d {-69d 29' 48"} (J2000),
                 -69.585d {-69d 35' 06"} (current),
                 -69.298d {-69d 17' 52"} (1950)
GRB_DATE:        19790 TJD;   211 DOY;   22/07/30
GRB_TIME:        56935.00 SOD {15:48:55.00} UT
TRIGGER_INDEX:   10427
GRB_PHI:         -155.38 [deg]
GRB_THETA:        37.44 [deg]
DELTA_TIME:      20.00 [sec]
TRIGGER_DUR:     0.064 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     55.93 [sigma]
IMAGE_SIGNIF:    10.00 [sigma]
LC_URL:          sw01118357000msb.lc
SUN_POSTN:       129.88d {+08h 39m 32s}  +18.40d {+18d 23' 57"}
SUN_DIST:        109.18 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      152.93d {+10h 11m 43s}  +16.44d {+16d 26' 15"}
MOON_DIST:        99.51 [deg]
MOON_ILLUM:      3 [%]
GAL_COORDS:      313.83, -9.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      247.57,-49.54 [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 = 102.00,-20.26 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Jul 22 15:54:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1118357,   Seg_Num: 0
POINT_RA:        225.010d {+15h 00m 02s} (J2000)
POINT_DEC:       -69.486d {-69d 29' 09"} (J2000)
POINT_ROLL:      271.892d
IMG_START_DATE:  19790 TJD;   211 DOY;   22/07/30
IMG_START_TIME:  57046.42 SOD {15:50:46.42} UT,   111.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.712
N_STARS:         190
X_OFFSET:        415 [pixels]
Y_OFFSET:        491 [pixels]
X_MAX:           1374 [pixels]
Y_MAX:           1450 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01118357000msufc0111.fits
SUN_POSTN:       129.88d {+08h 39m 32s}  +18.40d {+18d 23' 57"}
SUN_DIST:        109.17 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      152.94d {+10h 11m 45s}  +16.43d {+16d 26' 05"}
MOON_DIST:        99.50 [deg]
MOON_ILLUM:      3 [%]
GAL_COORDS:      313.83, -9.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      247.56,-49.53 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Jul 22 15:55:39 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1118357,   Seg_Num: 0
POINT_RA:        225.010d {+15h 00m 02s} (J2000)
POINT_DEC:       -69.486d {-69d 29' 09"} (J2000)
ROLL:            271.892d
IMG_START_DATE:  19790 TJD;   211 DOY;   22/07/30
IMG_START_TIME:  57046.42 SOD {15:50:46.42} UT,   111.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     680889076
X_OFFSET:        734 [pixels]
Y_OFFSET:        810 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       894
Y_GRB_POS:       970
BINNING_INDEX:   1
IM_URL:          sw01118357000msuni0141.fits
SUN_POSTN:       129.88d {+08h 39m 32s}  +18.40d {+18d 23' 56"}
SUN_DIST:        109.17 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      152.95d {+10h 11m 48s}  +16.43d {+16d 25' 48"}
MOON_DIST:        99.49 [deg]
MOON_ILLUM:      3 [%]
GAL_COORDS:      313.83, -9.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      247.56,-49.53 [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 30 Jul 22 15:54:24 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1118357,   Seg_Num: 0
POINT_RA:        225.010d {+15h 00m 02s} (J2000)
POINT_DEC:       -69.486d {-69d 29' 09"} (J2000)
POINT_ROLL:      271.892d
IMG_START_DATE:  19790 TJD;   211 DOY;   22/07/30
IMG_START_TIME:  57046.42 SOD {15:50:46.42} UT,   111.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.712
N_STARS:         190
X_OFFSET:        415 [pixels]
Y_OFFSET:        491 [pixels]
X_MAX:           1374 [pixels]
Y_MAX:           1450 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01118357000msufc0111.fits
SUN_POSTN:       129.88d {+08h 39m 32s}  +18.40d {+18d 23' 57"}
SUN_DIST:        109.17 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      152.94d {+10h 11m 46s}  +16.43d {+16d 26' 02"}
MOON_DIST:        99.50 [deg]
MOON_ILLUM:      3 [%]
GAL_COORDS:      313.83, -9.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      247.56,-49.53 [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 30 Jul 22 15:55:52 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1118357,   Seg_Num: 0
POINT_RA:        225.010d {+15h 00m 02s} (J2000)
POINT_DEC:       -69.486d {-69d 29' 09"} (J2000)
ROLL:            271.892d
IMG_START_DATE:  19790 TJD;   211 DOY;   22/07/30
IMG_START_TIME:  57046.42 SOD {15:50:46.42} UT,   111.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     680889076
X_OFFSET:        734 [pixels]
Y_OFFSET:        810 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       894
Y_GRB_POS:       970
BINNING_INDEX:   1
IM_URL:          sw01118357000msuni0141.fits
SUN_POSTN:       129.88d {+08h 39m 32s}  +18.40d {+18d 23' 56"}
SUN_DIST:        109.17 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      152.95d {+10h 11m 49s}  +16.43d {+16d 25' 45"}
MOON_DIST:        99.49 [deg]
MOON_ILLUM:      3 [%]
GAL_COORDS:      313.83, -9.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      247.56,-49.53 [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 Circular #32431
S. Dichiara (PSU), J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), A. Tohuvavohu (U Toronto) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 15:48:55 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 220730A (trigger=1118357). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 225.021, -69.497 which is
```
   RA(J2000) = 15h 00m 05s
   Dec(J2000) = -69d 29' 48"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single spike structure with a duration of about 0.2 sec. The peak count rate was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 15:50:43.0 UT, 108.2 seconds after the BAT trigger. No source was detected in 446 s of promptly downlinked data. We are waiting for the full dataset to detect and localise the XRT counterpart.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 111 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 25% of the BAT 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 91% of the BAT 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 0.161.
Burst Advocate for this burst is S. Dichiara (simonedichiara55 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 Circular #32432
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
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 220730A ( S. Dichiara et al., GCN 32431) errorbox 3555 sec after notice time and 3568 sec after trigger time at 2022-07-30 16:48:23 UT, with upper limit up to 17.7 mag. Observations started at twilight. The observations began at zenith distance = 38 deg. The sun altitude is -10.3 deg.
The galactic latitude b = -10 deg., longitude l = 314 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2044932
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    3659 |         MASTER-SAAO |   C |   180 | 17.4 |        
    3870 |         MASTER-SAAO |   C |   180 | 17.7 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN Circular #32434
A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and S. Dichiara (PSU) report on behalf of the Swift-XRT team:
We have analysed 5.7 ks of Photon Counting (PC) mode XRT data for the Swift-BAT-detected burst GRB 220730A (Dichiara et al. GCN Circ. 32431), collected between T0+3.8 ks and T0+51.6 ks.
Four uncatalogued X-ray sources have been detected consistent with being within 296 arcsec of the Swift-BAT position, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
Source 1:

  RA (J2000.0):  224.9153  =  14:59:39.66
  Dec (J2000.0): -69.5540  =  -69:33:14.4
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: (1.27 [+0.69, -0.53])e-3 ct s^-1	 
  Distance: 244 arcsec from Swift-BAT position.
  Flux: (4.0 [+2.2, -1.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:

  RA (J2000.0):  225.0143  =  15:00:3.43
  Dec (J2000.0): -69.4959  =  -69:29:45.4
  Error: 6.6 arcsec (radius, 90% conf.)
  Count-rate: (1.90 [+1.02, -0.77])e-3 ct s^-1	 
  Distance: 9 arcsec from Swift-BAT position.
  Flux: (4.0 [+2.2, -1.6])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 7:

  RA (J2000.0):  225.0749  =  15:00:17.98
  Dec (J2000.0): -69.4908  =  -69:29:26.9
  Error: 7.3 arcsec (radius, 90% conf.)
  Count-rate: (1.68 [+0.79, -0.62])e-3 ct s^-1	 
  Distance: 71 arcsec from Swift-BAT position.
  Flux: (1.12 [+0.53, -0.41])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 8:

  RA (J2000.0):  224.9654  =  14:59:51.71
  Dec (J2000.0): -69.5389  =  -69:32:20.2
  Error: 7.4 arcsec (radius, 90% conf.)
  Count-rate: (2.53 [+0.93, -0.76])e-3 ct s^-1	 
  Distance: 166 arcsec from Swift-BAT position.
  Flux: (3.13 [+1.15, -0.94])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Five uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates.
The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/01118357.
This circular is an official product of the Swift-XRT team.

GCN Circular #32435
N. P. M. Kuin (UCL-MSSL) and S. Dichiara (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220730A 112 s after the BAT trigger (Dichiara et al., GCN Circ. 32431). No optical afterglow consistent with any of the positions in GCN Circ. 32434 (D'Ai et al.) has been 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           112          261          147         >20.5
u_FC               324          574          246         >19.8
white              112          623          167         >20.6
v                  655          675           19         >17.8
b                  579          599           19         >18.7
u                  324          574          246         >19.8
w2                 630          650           19         >18.4
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.161 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #32436
S. Dichiara (PSU), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the Swift-BAT-detected burst GRB 220730A (Dichiara et al. GCN Circ. 32431). The observations now extend from T0+119 s to T0+124.8 ks.
Of the sources reported by D'Ai et al. (GCN Circ. 32434), "Source 5" is fading with >3-sigma significance and is believed to be the afterglow. The position of this source is RA, Dec=225.0143, -69.4959 which is equivalent to:
```
RA (J2000): 15:00:3.43
Dec(J2000): -69:29:45.4
```
with an uncertainty of 6.6 arcsec (radius, 90% confidence). This position is 9.3 arcsec from the Swift-BAT position.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01118357. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/01118357.
This circular is an official product of the Swift-XRT team.
GCN Circular #32437
S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 15:48:55.032 UT on 30 July 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220730A (trigger 680888940 / 220730659) which was also detected by the Swift/BAT (Dichiara et al. 2022, GCN 32431).
The angle from the Fermi LAT boresight at the GBM trigger time is 121 degrees.
The GBM light curve consists of a single peak followed by some extended emission with a duration (T90) of about 0.16 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.192 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.34 +/- 0.18 and the cutoff energy, parameterized as Epeak, is 488 +/- 84 keV. A Band function fits equally well, with Epeak = 412 +/- 97 keV, alpha = -0.21 +/- 0.25 and beta = -2.47 +/- 0.68.
The event fluence (10-1000 keV) in this time interval is (1.06 +/- 0.09)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0 s in the 10-1000 keV band is 24.9 +/- 2.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #32438
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), S. Dichiara (PSU), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+700 sec from the recent telemetry downlink, we report further analysis of BAT GRB 220730A (trigger #1118357) (Dichiara, et al., GCN Circ. 32431). The BAT ground-calculated position is RA, Dec = 224.988, -69.496 deg which is
```
   RA(J2000)  =  14h 59m 57.1s
   Dec(J2000) = -69d 29' 44.5"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask-weighted light curve shows a single FRED-shaped pulse from approximately T-0.05 to T+0.25 seconds. T90 (15-350 keV) is 0.19 +- 0.20 sec (estimated error including systematics). The time-averaged spectrum from T-0.04 to T+0.28 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.61 +- 0.25. The fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band is 1.6 +- 0.3 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/1118357/BA/
GCN Circular #32439
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The short GRB 220730A (Swift detection: Dichiara et al., GCN Circ 32431; Swift-BAT refined analysis: Markwardt et al., GCN Circ 32438; Fermi GBM detection: Poolakkil & Meegan, GCN Circ 32437) triggered Konus-Wind (KW) at T0=56937.381 s UT (15:48:57.381).
The burst light curve shows a single emission pulse which starts at ~T0-0.032 s and has a duration of ~0.1 s. The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB220730_T56937/
As observed by Konus-Wind, the burst had a total fluence of (1.20 � 0.38)x10^-6 erg/cm^2 and a 16-ms peak energy flux, measured from T0, of (1.62 � 0.51)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 15 MeV range by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.14(-0.34,+0.40) and Ep = 369(-59,+92) keV (pgstat = 50/54 dof). A Band function fits the spectrum equally well with alpha = -0.08 (-0.36,+0.42), beta = -2.61(-1.33, + 0.45), and Ep = 347 (-54, +86) keV (pgstat = 48/53 dof).
All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.

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Jochen Greiner, last update: 02-Aug-2022 [Disclaimer]