Gamma-ray Burst 180325A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:53:17 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     817564,   Seg_Num: 0
GRB_RA:          157.432d {+10h 29m 44s} (J2000),
                 157.683d {+10h 30m 44s} (current),
                 156.742d {+10h 26m 58s} (1950)
GRB_DEC:         +24.439d {+24d 26' 21"} (J2000),
                 +24.345d {+24d 20' 43"} (current),
                 +24.696d {+24d 41' 44"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1734 [cnts]    Image_Peak=158 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       16699 [cnts]
BKG_TIME:        6771.32 SOD {01:52:51.32} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18202 TJD;    84 DOY;   18/03/25
GRB_TIME:        6782.84 SOD {01:53:02.84} UT
GRB_PHI:         137.94 [deg]
GRB_THETA:        15.61 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.64 [sigma]
IMAGE_SIGNIF:    10.22 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  +0  +0  +0 +80  +0 
SUN_POSTN:         4.01d {+00h 16m 04s}   +1.74d {+01d 44' 17"}
SUN_DIST:        143.48 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.67d {+06h 42m 40s}  +20.25d {+20d 14' 56"}
MOON_DIST:        52.55 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.68, 58.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      150.01, 13.92 [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 = 277.06,8.22 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:54:40 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     817564,   Seg_Num: 0
GRB_RA:          157.4281d {+10h 29m 42.74s} (J2000),
                 157.6792d {+10h 30m 43.01s} (current),
                 156.7380d {+10h 26m 57.11s} (1950)
GRB_DEC:         +24.4627d {+24d 27' 45.7"} (J2000),
                 +24.3689d {+24d 22' 08.0"} (current),
                 +24.7191d {+24d 43' 08.8"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       4.68e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.04 [sigma]
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6856.22 SOD {01:54:16.22} UT,   73.4 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.16 261.57 243.70
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 19"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.68d {+06h 42m 44s}  +20.25d {+20d 14' 56"}
MOON_DIST:        52.53 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.64, 58.09 [deg] galactic lon,lat of the burst
ECL_COORDS:      150.00, 13.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.42 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:54:52 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     817564,   Seg_Num: 0
GRB_RA:          157.4281d {+10h 29m 42.7s} (J2000),
                 157.6792d {+10h 30m 43.0s} (current),
                 156.7380d {+10h 26m 57.1s} (1950)
GRB_DEC:         +24.4627d {+24d 27' 45.7"} (J2000),
                 +24.3689d {+24d 22' 08.0"} (current),
                 +24.7191d {+24d 43' 08.8"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       145 [cnts]
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6856.22 SOD {01:54:16.22} UT,   73.4 [sec] since BAT Trigger Time
CENTROID_X:      306.45,  raw= 306  [pixels]
CENTROID_Y:      278.27,  raw= 278  [pixels]
ROLL:            311.62 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -47.44
GRB_POS_XRT_Z:   0.13
IMAGE_URL:       sw00817564000msxps_rw.img
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 19"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.68d {+06h 42m 44s}  +20.25d {+20d 14' 56"}
MOON_DIST:        52.53 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.64, 58.09 [deg] galactic lon,lat of the burst
ECL_COORDS:      150.00, 13.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:54:50 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     817564,   Seg_Num: 0
GRB_RA:          157.4281d {+10h 29m 42.7s} (J2000),
                 157.6792d {+10h 30m 43.0s} (current),
                 156.7380d {+10h 26m 57.1s} (1950)
GRB_DEC:         +24.4627d {+24d 27' 45.7"} (J2000),
                 +24.3689d {+24d 22' 08.0"} (current),
                 +24.7191d {+24d 43' 08.8"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       145 [cnts]
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6856.22 SOD {01:54:16.22} UT,   73.4 [sec] since BAT Trigger Time
CENTROID_X:      306.45,  raw= 306  [pixels]
CENTROID_Y:      278.27,  raw= 278  [pixels]
ROLL:            311.62 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -47.44
GRB_POS_XRT_Z:   0.13
IMAGE_URL:       sw00817564000msxps_rw.img
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 19"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.68d {+06h 42m 44s}  +20.25d {+20d 14' 56"}
MOON_DIST:        52.53 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.64, 58.09 [deg] galactic lon,lat of the burst
ECL_COORDS:      150.00, 13.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:56:38 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     817564,   Seg_Num: 0
GRB_RA:          157.432d {+10h 29m 44s} (J2000),
                 157.683d {+10h 30m 44s} (current),
                 156.742d {+10h 26m 58s} (1950)
GRB_DEC:         +24.439d {+24d 26' 21"} (J2000),
                 +24.345d {+24d 20' 43"} (current),
                 +24.696d {+24d 41' 44"} (1950)
GRB_DATE:        18202 TJD;    84 DOY;   18/03/25
GRB_TIME:        6782.84 SOD {01:53:02.84} UT
TRIGGER_INDEX:   124
GRB_PHI:         137.94 [deg]
GRB_THETA:        15.61 [deg]
DELTA_TIME:      -31.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.64 [sigma]
IMAGE_SIGNIF:    10.22 [sigma]
LC_URL:          sw00817564000msb.lc
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 21"}
SUN_DIST:        143.48 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.70d {+06h 42m 49s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.52 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.68, 58.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      150.01, 13.92 [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 = 277.06,8.22 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:57:10 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.418d {+10h 29m 40s} (J2000)
POINT_DEC:       +24.453d {+24d 27' 09"} (J2000)
POINT_ROLL:      311.623d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6865.18 SOD {01:54:25.18} UT,   82.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.180
N_STARS:         23
X_OFFSET:        352 [pixels]
Y_OFFSET:        600 [pixels]
X_MAX:           1311 [pixels]
Y_MAX:           1559 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00817564000msufc0082.fits
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 21"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.71d {+06h 42m 50s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.50 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.99, 13.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 01:57:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.418d {+10h 29m 40s} (J2000)
POINT_DEC:       +24.453d {+24d 27' 09"} (J2000)
POINT_ROLL:      311.623d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6865.18 SOD {01:54:25.18} UT,   82.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.180
N_STARS:         23
X_OFFSET:        352 [pixels]
Y_OFFSET:        600 [pixels]
X_MAX:           1311 [pixels]
Y_MAX:           1559 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00817564000msufc0082.fits
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 21"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.71d {+06h 42m 50s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.50 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.99, 13.93 [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 25 Mar 18 01:58:35 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.418d {+10h 29m 40s} (J2000)
POINT_DEC:       +24.453d {+24d 27' 09"} (J2000)
ROLL:            311.623d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6865.18 SOD {01:54:25.18} UT,   82.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     543635685
X_OFFSET:        837 [pixels]
Y_OFFSET:        951 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       997
Y_GRB_POS:       1111
BINNING_INDEX:   1
IM_URL:          sw00817564000msuni0103.fits
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 23"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.72d {+06h 42m 53s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.49 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.99, 13.93 [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 25 Mar 18 01:58:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.418d {+10h 29m 40s} (J2000)
POINT_DEC:       +24.453d {+24d 27' 09"} (J2000)
ROLL:            311.623d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6865.18 SOD {01:54:25.18} UT,   82.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     543635685
X_OFFSET:        837 [pixels]
Y_OFFSET:        951 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       997
Y_GRB_POS:       1111
BINNING_INDEX:   1
IM_URL:          sw00817564000msuni0103.fits
SUN_POSTN:         4.02d {+00h 16m 04s}   +1.74d {+01d 44' 23"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.73d {+06h 42m 54s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.49 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.99, 13.93 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 02:00:45 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     817564,   Seg_Num: 0
GRB_RA:          157.4274d {+10h 29m 42.57s} (J2000),
                 157.6785d {+10h 30m 42.84s} (current),
                 156.7373d {+10h 26m 56.94s} (1950)
GRB_DEC:         +24.4634d {+24d 27' 48.2"} (J2000),
                 +24.3696d {+24d 22' 10.5"} (current),
                 +24.7198d {+24d 43' 11.3"} (1950)
GRB_ERROR:       0.8 [arcsec radius, statistical only]
GRB_MAG:         18.45 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  6862.00 SOD {01:54:22.00} UT,   79.2 [sec] since BAT Trigger Time
SUN_POSTN:         4.02d {+00h 16m 05s}   +1.74d {+01d 44' 25"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.75d {+06h 42m 59s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.48 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.64, 58.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      150.00, 13.94 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 3.2 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 02:03:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.419d {+10h 29m 41s} (J2000)
POINT_DEC:       +24.454d {+24d 27' 14"} (J2000)
POINT_ROLL:      311.626d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  7078.23 SOD {01:57:58.23} UT,   295.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.392
N_STARS:         7
X_OFFSET:        517 [pixels]
Y_OFFSET:        631 [pixels]
X_MAX:           1476 [pixels]
Y_MAX:           1590 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00817564000msufc0295.fits
SUN_POSTN:         4.02d {+00h 16m 05s}   +1.74d {+01d 44' 27"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.77d {+06h 43m 05s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.45 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      150.00, 13.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 02:03:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.419d {+10h 29m 41s} (J2000)
POINT_DEC:       +24.454d {+24d 27' 14"} (J2000)
POINT_ROLL:      311.626d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  7078.23 SOD {01:57:58.23} UT,   295.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.392
N_STARS:         7
X_OFFSET:        517 [pixels]
Y_OFFSET:        631 [pixels]
X_MAX:           1476 [pixels]
Y_MAX:           1590 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00817564000msufc0295.fits
SUN_POSTN:         4.02d {+00h 16m 05s}   +1.74d {+01d 44' 27"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.77d {+06h 43m 06s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.44 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      150.00, 13.93 [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 Circular #22532
E. Troja (NASA/GSFC/UMCP), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC), J. A. Kennea (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 01:53:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180325A (trigger=817564). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 157.432, +24.439 which is
```
   RA(J2000) = 10h 29m 44s
   Dec(J2000) = +24d 26' 21"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a ~10 second FRED peak (~3000 counts/s) which is followed by brighter peak
```
which reaches a maximum of ~11000 counts/sec (15-350 keV), at ~81
after the trigger, for a total duration of ~120 seconds. 
```
The XRT began observing the field at 01:54:16.2 UT, 73.4 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 157.4281, 24.4627 which is equivalent to:
```
   RA(J2000)  = +10h 29m 42.74s
   Dec(J2000) = +24d 27' 45.7"
```
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 86 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 82 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	10:29:42.59 = 157.42746
  DEC(J2000) = +24:27:48.5  =  24.46347
```
with a 90%-confidence error radius of about 0.76 arc sec. This position is 3.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.45 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
We note that the second peak seen by BAT occurs during the early UVOT and XRT images, so these sample the prompt GRB emission.
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/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Mar 18 02:04:32 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.419d {+10h 29m 41s} (J2000)
POINT_DEC:       +24.454d {+24d 27' 14"} (J2000)
ROLL:            311.626d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  7078.23 SOD {01:57:58.23} UT,   295.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     543635898
X_OFFSET:        837 [pixels]
Y_OFFSET:        951 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       997
Y_GRB_POS:       1111
BINNING_INDEX:   1
IM_URL:          sw00817564000msuni0316.fits
SUN_POSTN:         4.02d {+00h 16m 05s}   +1.74d {+01d 44' 29"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.79d {+06h 43m 08s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.43 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      150.00, 13.93 [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 25 Mar 18 02:04:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     817564,   Seg_Num: 0
POINT_RA:        157.419d {+10h 29m 41s} (J2000)
POINT_DEC:       +24.454d {+24d 27' 14"} (J2000)
ROLL:            311.626d
IMG_START_DATE:  18202 TJD;    84 DOY;   18/03/25
IMG_START_TIME:  7078.23 SOD {01:57:58.23} UT,   295.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     543635898
X_OFFSET:        837 [pixels]
Y_OFFSET:        951 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       997
Y_GRB_POS:       1111
BINNING_INDEX:   1
IM_URL:          sw00817564000msuni0316.fits
SUN_POSTN:         4.02d {+00h 16m 05s}   +1.74d {+01d 44' 29"}
SUN_DIST:        143.46 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      100.79d {+06h 43m 09s}  +20.25d {+20d 14' 57"}
MOON_DIST:        52.43 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:      209.65, 58.08 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      150.00, 13.93 [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 #22534
C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath),=20 A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large=20 collaboration report:
The 2-m Liverpool Telescope automatically began observing Swift GRB=20 180325A (Troja et al. GCN 22532) on March 25, 01:55:25 UT (143 seconds=20 since the GRB trigger time) with the RINGO3 polarimeter and the IO:O=20 camera in the SDSS-R filter. We clearly detect the optical afterglow=20 (Troja et al.) with the following magnitude:
Mid Time from GRB=A0 Exposure=A0=A0=A0=A0=A0=A0 Filter=A0=A0=A0=A0=A0=A0 = Magnitude (AB) (min)=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 (s) ------------------------------------------------------------- 35.1=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 6x10=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0 SDSS-R=A0=A0=A0=A0=A0=A0 19.02 +- 0.05 -------------------------------------------------------------
as calibrated against nearby SDSS objects.
GCN Circular #22535
K. E. Heintz (Univ. Iceland and DAWN/NBI), J. P. U. Fynbo (DAWN/NBI), D. Malesani (DAWN/NBI and DARK/NBI), report on behalf of a larger collaboration:
We observed the optical counterpart of GRB 180325A (Troja et al., GCN 22532; Guidorzi et al., GCN 22534) with the 2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC, starting at 02:02:30 UT on 25 March 2018. We obtained 3x100 s in the r-band and measure a magnitude of m(r) = 18.61 +/- 0.03 mag at a mean post-explosion epoch of 11 minutes. The calibration was performed using local Pan-STARRS stars in the GRB field. This apparent magnitude is not corrected for foreground extinction.
We subsequently obtained spectroscopy for a total of 3x600 s, using grism #4 and covering the wavelength range 3650-9450 AA. In our low-resolution spectrum we identify several absorption features, including Mg II, Fe II, Al II, C IV, Si II at a common redshift of z = 2.25. The 2175 AA bump is clearly visible at this redshift. We also note the presence of a strong intervening system at z = 2.04, as revealed by Mg II and Fe II absorption features.
Further observations are in progress.
GCN Circular #22536
P. D'Avanzo, A. Melandri, S. Covino, D. Fugazza (INAF/OAB) report on behalf of the REM team:
We observed the field of the GRB 180325A (Troja et al., GCN 22532) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations started on 25-03-2018 at 01:53:52 UT, 50s after the burst, and were carried in the g, r, i, z, J, H and K bands.
A preliminary analysis shows that the optical counterpart (Troja et al., GCN 22532; Guidorzi et al. GCN 22534; Heintz et al. GCN 22535) is well detected and at a mid time of 123 seconds after the burst it was:
```
r = 17.2 +/- 0.2 (AB)
H = 12.7 +/- 0.1 (Vega)
```
Magnitudes are calibrated against the SDSS (optical) and 2MASS (NIR) catalogues.
GCN Circular #22537
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 180325A (Troja et al., GCN 22532) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2018/03 25.12 to 2018/03 25.23 UTC (1.02 to 3.67 hours after the BAT trigger), obtaining a total of 1.47 hours exposure in the r and i bands and hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 catalog, we obtain the following detections:
```
  r	=3D 19.79 +/- 0.02
  i	=3D 19.38 +/- 0.01
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #22538
C. Littlefield and P. Garnavich (Notre Dame) report:
We observed the field of GRB 180325A (GCN 22532) with the 0.8-m Sarah L. Krizmanich Telescope at the University of Notre Dame. Unfiltered CCD images were obtained under hazy conditions beginning 1.5 hours after the burst. We calibrated the afterglow in SDSS-r using a nearby star in the Pan-STARRS catalog and constructed the following light curve:
```
DateAge     SDSS-r err
(UT)          (hours)
March 25.1403  1.483    19.29  0.14
March 25.1626  2.018    19.52  0.18
March 25.227    3.564    20.1   0.3
```
Based on SDSS-r magnitudes reported by Heintz et al. (GCN 22535) and Guidorzi et al. (GCN 22534), we obtain a rather shallow power-law decay index of 0.31+/-0.05 between 0.5 hours and 2 hours after the burst.
GCN Circular #22539
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 2783 s of XRT Photon Counting mode data and 7 UVOT images for GRB 180325A, 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 = 157.42735, +24.46361 which is equivalent to:
```
RA (J2000): 10h 29m 42.56s
Dec (J2000): +24d 27' 49.0"
```
with an uncertainty of 1.5 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 #22540
K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and E. Troja report on behalf of the Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 180325A (Troja et al. GCN Circ. 22532), from 61 s to 29.3 ks after the BAT trigger. The data comprise 329 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 22539).
The late-time light curve (from T0+4.8 ks) can be modelled with a power-law decay with a decay index of alpha=2.02 (+0.09, -0.08).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.60 (+/-0.09). The best-fitting absorption column is 1.7 (+0.6, -0.5) x 10^22 cm^-2, at a redshift of 2.25, in addition to the Galactic value of 1.3 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.85 (+/-0.09) and a best-fitting absorption column of 1.3 (+/-0.4) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 1.3 x 10^20 cm^-2
Intrinsic column:    1.3 (+/-0.4) x 10^22 cm^-2 at z=2.25
Photon index:	     1.85 (+/-0.09)
```
If the light curve continues to decay with a power-law decay index of 2.02, 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 2.5 x 10^-13 (2.9 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/00817564.
This circular is an official product of the Swift-XRT team.
GCN Circular #22541
Jan Strobl, Martin Jelinek and Rene Hudec (ASU CAS Ondrejov)
report
We observed the field of the Swift GRB 180325A (Troja et al., GCNC 22532) with the 0.5m telescope D50 in Ondrejov (Czech Republic), starting at 01:53:47.1 UT, i.e. 44.3s after the trigger.
The observation consisted of a series of 10 s unfiltered exposures, covering the peak of the optical emission at mag ~16.3. The maximum seems to be somewhat delayed with respect to the bright peak in gamma-rays.
This message can be cited.
GCN Circular #22542
Klotz A., Noysena K., Atteia J.L. (CNRS-OMP-IRAP), Boer M., Eymar L. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report:
We imaged the field of GRB 180325A detected by SWIFT (trigger 817564) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France.
The observations started 26s after the GRB trigger (14s after the notice). The elevation of the field decreased from 37 degrees above horizon and weather conditions were excellents.
We detect clearly the optical transcient (OT) reported by Troja et al. (GCN 22532), Guidorzi et al. (GCN 22534), Heintz et al. GCN 22535), D'Avanzo et al. (GCNC 22536), Watson et al. (GCNC 22537), Garnavich et al. (GCNC 22538), Strobl et al. (GCNC 22541).
The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We detect the OT at a magnitude of: t0+26s to t0+86s : r(AB) = 17.2 +/- 0.3
It is important to notice that a bright gamma flash in Swift-BAT data occured between 70 and 92 seconds. We do not detect any significant optical flux increase during the range 70 to 86 seconds of the first TAROT exposure.
After an overhead time of 13 seconds the second image of 30s exposure in tracking mode started 99 seconds after the trigger. In this image the OT has brightened by about 1 magnitude. The third image shows a rapid decrease of 1 magnitude compatible with a decay index of about 3 followed by a mean decay of 0.45 until 1.7 hour after the trigger confirming the small decay value published by Littlefield and Garnavich (GCNC 22538).
The photometric analysis of the TAROT images are given:
```
t1(h)  t2(h)  r(AB) 1sig
0.0277 0.0361 16.24 0.09
0.0391 0.0474 17.22 0.20
0.0504 0.0815 17.68 0.19
0.0843 0.1093 18.02 0.30
0.2062 0.2872 18.56 0.30
0.2951 0.4364 18.78 0.39
0.4392 1.1843 18.94 0.22
1.2400 1.6746 19.26 0.36
```
Magnitudes were estimated with the nearby star NOMAD-1 1144-0181799 R=14.440 (V-R)=0.65, converted into r(AB) system and are not corrected for galactic dust extinction.
Note that the TAROT light curve is compatible with an optical flash occuring with a lag of 20 +/- 10 seconds after the bright gamma emission peak as mentioned by Strobl et al. (GCNC 22541).
GCN Circular #22543
V. Lipunov, E.Gorbovskoy, N.Tyurina, V.Kornilov, D.Zimnukhov, V.Vladimirov, A.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.Chazov, D. Kuvshinov (Lomonosov Moscow State University, SAI),
R.Podesta, C.Lopez, F. Podesta (Observatorio Astronomico Felix Aguilar (OAFA),National University of San Juan, Argentina),
H. Levato, C. Saffe (Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina),
R. Rebolo, M. Serra-Ricart, G.Israelyan (The Instituto de Astrofisica de Canarias),
D.Buckley, S. Potter (South African Astronomical Observatory),
O.Gres, N.M.Budnev (Irkutsk State University),
A. Tlatov, V.Senik, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory)
V.Yurkov, A.Gabovich, Yu.Sergienko (Blagoveschensk Educational State University, Blagoveschensk),
MASTER-OAFA and MASTER-IAC automatically pointed to GRB 180314A (Eleonora Troja et al. GCN 22532) with optical transient detection by MASTER auto-detection system. We confirm Swift, LT, NOT, REM, RATIR, SLKT, D50 GROND OT (GCN 22532, 22534, 22535, 22536, 22537, 22538, 22541) but observed before.
MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA (Argentina,http://oafa.master.sai.msu.ru:49001/) was pointed to the GRB180325.08 38 sec after trigger time at 2018-03-25 01:53:40 UT. On our second (20s exposure) set robot automaticaly found 1 optical transient within SWIFT error-box (ra=157.429 dec=24.4389 r=0.05) brighter then 16.7 .
```
  T-Ttrig  Date      Time       Expt.        Ra              Dec        Mag
-------|-------------------|-------|-----------------|---------------|-------
    88   2018-03-25 01:54:31    20    ( 10h 29m 42.7s , +24d 27m 49.3s)  16
```
The 5-sigma upper limit has been about 17.3mag
====================================================================
The observations made on zenit distance = 58 degrees, galaxy latitude b = 59 degree. The moon (55 % bright part) is 25 degrees above the horizon. The distance between moon and object is 53 The sun altitude is -40.3 degree. The object can be observed till 2018-03-25 07:53:41 UT.
MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC (Tenerife, Tejde Observatory) was pointed to the GRB180325.08 63 sec after trigger time at 2018-03-25 01:54:09 UT. On our second (20s exposure) set robot automaticaly found 1 optical transient within SWIFT error-box (ra=157.429 dec=24.4386 r=0.05) brighter then 17.0.
```
  T-Ttrig     Date   Time       Expt.        Ra                Dec         Mag
-------|-------------------|-------|-----------------|-----------------|-------
   119   2018-03-25 01:55:01    20     ( 10h 29m 42.6s , +24d 27m 48.3s)  16.50
```
The 5-sigma upper limit has been about 17.5 mag The message may be cited.
====================================================================
The observations made on zenit distance = 34 degrees, galaxy latitude b = 59 degree. The moon (55 % bright part) is 6 degrees above the horizon. The distance between moon and object is 53 The sun altitude is -58.3 degree. The object can be observed till 2018-03-25 06:24:39 with good limit.
This message can be cited.
GCN Circular #22544
T. Schweyer (MPE), and D. A. Kann (HETH/IAA-CSIC) report:
We observed the field of GRB 180325A (Swift trigger 817564; E. Troja et al., GCN #22532) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 02:53 UTC on March 25, 1.0 hours after the GRB trigger. They were performed at an average seeing of 1".5 and at an average airmass of 1.7.
We clearly detect the NIR/optical transient of GRB 180325A within the enhanced XRT position (J. P. Osborne et al., GCN #22539), in agreement with the optical transient detected by UVOT (E. Troja et al., GCN #22532). Based on 7 minutes of exposure centered around 03:30 UTC, we measure the following magnitudes (all in AB system).
```
g' = 20.45 +/- 0.03 mag
r' = 19.57 +/- 0.02 mag
i' = 19.18 +/- 0.02 mag
z' = 18.30 +/- 0.02 mag
J = 17.42 +/- 0.02 mag
H = 16.85 +/- 0.02 mag
K = 16.34 +/ 0.03 mag
```
Given magnitudes are calibrated against SDSS in g'r'i'z' and 2MASS field stars in JHK, and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.015 in the direction of the burst (Schlafly & Finkbeiner 2011).
We acknowledge the excellent support from the TiO and the current observer at the 2.2m in La Silla, Angela Hempel and Victor Marian.
GCN Circular #22545
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+500 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180325A (trigger #817564) (Troja et al., GCN Circ. 22532). The BAT ground-calculated position is RA, Dec = 157.416, 24.461 deg which is
```
  RA(J2000)  =  10h 29m 39.9s
  Dec(J2000) = +24d 27' 39.7"
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%.
The mask-weighted light curve shows two separate pulses. The first pulse starts and peaks at ~T0, and ends at ~T+10 s. The second brighter pulse starts at ~T+70 s, peaks at ~T+80 s, and ends at ~T+110 s. T90 (15-350 keV) is 94.1 +- 1.5 sec (estimated error including systematics).
The time-averaged spectrum from T-0.0 to T+107.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.18 +- 0.05. The fluence in the 15-150 keV band is 6.5 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+80.75 sec in the 15-150 keV band is 9.4 +- 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/817564/BA/
GCN Circular #22546
D. Frederiks, S. Golenetskii, R.Aptekar, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report:
The long GRB 180325A (Swift-BAT trigger 817564: Troja et al., GCN 22532; Lien et al., GCN 22545) triggered Konus-Wind at T0=3D6866.876 s UT (01:54:26.876)
The burst light curve shows a single pulse, which started at ~T0-1 s and peaked at ~T0+1.7 s. The total duration of the burst is ~10 s. The emission is seen up to ~7 MeV.
As observed by Konus-Wind, the burst had a fluence of (1.9 =B1 0.3)x10^-5 erg/cm2 and a 64-ms peak energy flux, measured from T0+1.728, of (8.2 =B1 1.3)x10^-6 erg/cm2 (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+7.424 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.50 (-0.19,+0.21), the high energy photon index beta =3D -2.65 (-1.06,+0.31), the peak energy Ep =3D 306 (-39,+50) keV, chi2 =3D 99/92 dof.
Assuming the redshift z=3D2.25 (Heintz et al., GCN 22535) and a standard cosmology model with H_0 =3D 70 km/s/Mpc, Omega_M =3D 0.3, and Omega_Lambda =3D 0.7, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~2.3x10^53 erg, the peak luminosity L_iso is ~3.2x10^53 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,z, is ~995 keV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180325_T06866/
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
GCN Circular #22549
F. E. Marshall (NASA/GSFC) 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 180325A 82 s after the BAT trigger (Troja et al., GCN Circ. 22532). A fading source consistent with the enhanced XRT position (Osborne et al. GCN Circ. 22539) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  10:29:42.59 = 157.42744 (deg.)
    Dec (J2000) = +24:27:48.6  =  24.46349 (deg.)
```
with an estimated uncertainty of 0.44 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               82          232          147         18.48 +/- 0.05
white             5039         5239          197         20.75 +/- 0.23
v                 5450         5650          197        >18.8
b                 4834         6385          309        >20.1
u                  295         6265          353        >20.0
w1                5860         6060          197        >20.1
m2                5654         5854          197        >19.4
w2                5245        12343          980        >20.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22551
Daniele Malesani (DAWN/NBI and DARK/NBI) and Johan P.U. Fynbo (DAWN/NBI) report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 180325A (Troja et al., GCN 22532) using the Nordic Optical Telescope (NOT) equipped with the AlFOSC imaging camera. The seeing in our observations was not good, around 2". 4 and 2 exposures by 600 s were obtained in the R and I filters, respectively.
The afterglow was not detected in R, and marginally (if at all) in I. The following magnitudes were computed with respect to nearby Pan-STARRS reference stars, and are therefore in the AB system.
```
Time (UT)    Time since GRB (hr) Filter  Magnitude
-----------------------------------------------------
Mar 25.856   18.65                r       >22.6
Mar 25.871   18.92                i       22.9 +- 0.3
```
These values are significantly fainter than the extrapolation based on the earlier measurements (Guidorzi et al., GCN 22534; Heintz et al., GCN 22535; D'Avanzo et al., GCN 22536; Watson et al., GCN 22536; Littlefield & Garnavich, GCN 22538; Strobl et al., GCN 22541; Klotz et al., GCN 22542; Lipunov et al., GCN 22543; Schweyer & Kann, GCN 22544) and indicate a break in the afterglow light curve.
GCN Circular #22555
P. D=E2=80=99Avanzo (INAF-OAB), J. Bolmer (ESO/MPE), V. D=E2=80=99Elia (ASI-SSDC), J. P. U. Fynbo (DAWN/NBI), K. E. Heintz (U. Iceland, DAWN/NBI), L. Izzo (HETH/IAA-CSIC), J. Japelj (API, U. Amsterdam), D. A. Kann (HETH/IAA-CSIC), D. Malesani (DAWN/NBI and DARK/NBI), J. Selsing (DARK/NBI), N. R. Tanvir (Univ. Leicester), T. Zafar (AAO), S. Campana (INAF-OAB), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), J. Hjorth (DARK/NBI), L. Kaper (Univ. Amsterdam), A. Melandri (INAF-OAB), A. Smette (ESO), report on behalf of the Stargate Consortium:
We observed the optical afterglow of GRB 180325A (Troja et al. GCN 22532) with the ESO VLT/X-shooter spectrograph, covering the wavelength range 3000-25000 AA. Spectroscopy started at 03:20:45 UT on 2018-03-25 (i.e., ~1.5 hr after the GRB) and consisted of 8 exposures of 600 s.
The spectrum exhibits a red continuum with several absorption features, including Ly-alpha and different metal and fine-structure lines, together with [OII], [OIII] and Halpha emission lines, all at a common redshift of z=3D2.248. At the same redshift, we also note the presence of a clear continuum depression corresponding to the 2175 AA bump. Finally, the spectrum shows the presence of a strong double intervening system at z =3D 2.041/2.043.
The above results are in agreement with the findings of Heintz et al. (GCN 22535).
We acknowledge the excellent support from the ESO staff, particularly Luca Sbordone, Jose Velasquez and Zahed Wahhaj in obtaining these observations.
GCN Circular #22557
V. Sharma (IUCAA), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 180325A, which was also detected by Swift (Troja E. et al., GCN 22532), Swift-BAT (Lien A. Y. et al., GCN 22454), Swift-XRT (Page K.L. et al., GCN 22540) and Konus-Wind (Frederiks D. et al., GCN 22546).
The source was clearly detected in the 40-200 keV energy range. The light curve shows single peak of emission at 01:54:23.0 UT, ~81 s after Swift-BAT trigger time. The measured peak count rate is 1093.8 cts/s above the background in combined data of four quadrants, with a total of 5294 cts. The local mean background count rate was 510.2 cts/s. Using cumulative rates, we measure a T90 of 15.7 s. In Preliminary analysis, we find that 495.2 compton events are associated with this event.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.

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Jochen Greiner, last update: 29-Mar-2018 [Disclaimer]