Gamma-ray Burst 200409A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Thu 09 Apr 20 03:20:20 UT 
NOTICE_TYPE:     Swift-BAT GRB Position 
TRIGGER_NUM:     965484,   Seg_Num: 0 
GRB_RA:           60.553d {+04h 02m 13s} (J2000), 
                  60.695d {+04h 02m 47s} (current), 
                  60.204d {+04h 00m 49s} (1950) 
GRB_DEC:         -50.247d {-50d 14' 49"} (J2000), 
                 -50.192d {-50d 11' 29"} (current), 
                 -50.385d {-50d 23' 04"} (1950) 
GRB_ERROR:       3.00 [arcmin radius, statistical only] 
GRB_INTEN:       1850 [cnts]    Image_Peak=116 [image_cnts] 
TRIGGER_DUR:     0.512 [sec]  
TRIGGER_INDEX:   121     E_range: 15-50 keV 
BKG_INTEN:       19466 [cnts] 
BKG_TIME:        11983.25 SOD {03:19:43.25} UT 
BKG_DUR:         8 [sec]
BKG_DUR:         8 [sec] 
GRB_DATE:        18948 TJD;   100 DOY;   20/04/09 
GRB_TIME:        11999.77 SOD {03:19:59.77} UT 
GRB_PHI:         -69.33 [deg] 
GRB_THETA:        19.52 [deg] 
SOLN_STATUS:     0x3 
RATE_SIGNIF:     16.55 [sigma] 
IMAGE_SIGNIF:    7.58 [sigma] 
MERIT_PARAMS:     +1  +0  +0  -1  +1  -2  +0  +0 -36  +0  
SUN_POSTN:        18.23d {+01h 12m 55s}   +7.72d {+07d 43' 17"} 
SUN_DIST:         68.61 [deg]   Sun_angle= -2.8 [hr] (East of Sun) 
MOON_POSTN:      213.73d {+14h 14m 54s}   -9.06d {-09d 03' 22"} 
MOON_DIST:       116.27 [deg] 
MOON_ILLUM:      98 [%] 
GAL_COORDS:      258.83,-47.19 [deg] galactic lon,lat of the burst (or transient) 
ECL_COORDS:       33.12,-67.95 [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 = 201.05,-18.14 [deg].

red DSS finding chart ps-file

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Thu 09 Apr 20 03:21:23 UT 
NOTICE_TYPE:     Swift-XRT Nack-Position 
TRIGGER_NUM:     965484,   Seg_Num: 0 
POINT_RA:         60.569d {+04h 02m 17s} (J2000) 
POINT_DEC:       -50.269d {-50d 16' 06"} (J2000) 
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09 
IMG_START_TIME:  12073.17 SOD {03:21:13.17} UT,   73.4 [sec] since BAT Trigger Time 
COUNTS:          1    Min_needed= 20 
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec] 
PH2_ITER:        0    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:     Thu 09 Apr 20 03:24:06 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.570d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.269d {-50d 16' 06"} (J2000)
POINT_ROLL:      314.207d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12077.68 SOD {03:21:17.68} UT,   77.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.970
N_STARS:         32
X_OFFSET:        670 [pixels]
Y_OFFSET:        530 [pixels]
X_MAX:           1629 [pixels]
Y_MAX:           1489 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00965484000msufc0077.fits
SUN_POSTN:        18.23d {+01h 12m 55s}   +7.72d {+07d 43' 20"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.76d {+14h 15m 03s}   -9.07d {-09d 04' 15"}
MOON_DIST:       116.24 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:24:24 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.570d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.269d {-50d 16' 06"} (J2000)
POINT_ROLL:      314.207d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12077.68 SOD {03:21:17.68} UT,   77.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.970
N_STARS:         32
X_OFFSET:        670 [pixels]
Y_OFFSET:        530 [pixels]
X_MAX:           1629 [pixels]
Y_MAX:           1489 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00965484000msufc0077.fits
SUN_POSTN:        18.23d {+01h 12m 55s}   +7.72d {+07d 43' 20"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.77d {+14h 15m 04s}   -9.07d {-09d 04' 19"}
MOON_DIST:       116.24 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [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:     Thu 09 Apr 20 03:25:34 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.570d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.269d {-50d 16' 06"} (J2000)
ROLL:            314.207d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12077.68 SOD {03:21:17.68} UT,   77.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     608095302
X_OFFSET:        989 [pixels]
Y_OFFSET:        849 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1149
Y_GRB_POS:       1009
BINNING_INDEX:   1
IM_URL:          sw00965484000msuni0102.fits
SUN_POSTN:        18.23d {+01h 12m 56s}   +7.72d {+07d 43' 22"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.78d {+14h 15m 06s}   -9.08d {-09d 04' 35"}
MOON_DIST:       116.24 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [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:     Thu 09 Apr 20 03:25:40 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     965484,   Seg_Num: 0
GRB_RA:           60.553d {+04h 02m 13s} (J2000),
                  60.695d {+04h 02m 47s} (current),
                  60.204d {+04h 00m 49s} (1950)
GRB_DEC:         -50.247d {-50d 14' 49"} (J2000),
                 -50.192d {-50d 11' 29"} (current),
                 -50.385d {-50d 23' 04"} (1950)
GRB_DATE:        18948 TJD;   100 DOY;   20/04/09
GRB_TIME:        11999.77 SOD {03:19:59.77} UT
TRIGGER_INDEX:   121
GRB_PHI:         -69.33 [deg]
GRB_THETA:        19.52 [deg]
DELTA_TIME:      -50.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     16.55 [sigma]
IMAGE_SIGNIF:    7.58 [sigma]
LC_URL:          sw00965484000msb.lc
SUN_POSTN:        18.23d {+01h 12m 56s}   +7.72d {+07d 43' 22"}
SUN_DIST:         68.61 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.78d {+14h 15m 07s}   -9.08d {-09d 04' 37"}
MOON_DIST:       116.26 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.83,-47.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       33.12,-67.95 [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 = 201.05,-18.14 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:25:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.570d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.269d {-50d 16' 06"} (J2000)
ROLL:            314.207d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12077.68 SOD {03:21:17.68} UT,   77.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     608095302
X_OFFSET:        989 [pixels]
Y_OFFSET:        849 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1149
Y_GRB_POS:       1009
BINNING_INDEX:   1
IM_URL:          sw00965484000msuni0102.fits
SUN_POSTN:        18.23d {+01h 12m 56s}   +7.72d {+07d 43' 22"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.78d {+14h 15m 07s}   -9.08d {-09d 04' 39"}
MOON_DIST:       116.24 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [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:     Thu 09 Apr 20 03:25:36 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     965484,   Seg_Num: 0
GRB_RA:           60.5380d {+04h 02m 09.11s} (J2000),
                  60.6797d {+04h 02m 43.13s} (current),
                  60.1889d {+04h 00m 45.33s} (1950)
GRB_DEC:         -50.2253d {-50d 13' 31.0"} (J2000),
                 -50.1699d {-50d 10' 11.7"} (current),
                 -50.3630d {-50d 21' 46.6"} (1950)
GRB_ERROR:       4.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12086.00 SOD {03:21:26.00} UT,   86.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        18.23d {+01h 12m 56s}   +7.72d {+07d 43' 22"}
SUN_DIST:         68.58 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.78d {+14h 15m 06s}   -9.08d {-09d 04' 36"}
MOON_DIST:       116.29 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.80,-47.21 [deg] galactic lon,lat of the burst
ECL_COORDS:       33.13,-67.93 [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:     Thu 09 Apr 20 03:27:47 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     965484,   Seg_Num: 0
GRB_RA:           60.5364d {+04h 02m 08.73s} (J2000),
                  60.6781d {+04h 02m 42.75s} (current),
                  60.1873d {+04h 00m 44.94s} (1950)
GRB_DEC:         -50.2245d {-50d 13' 28.1"} (J2000),
                 -50.1691d {-50d 10' 08.8"} (current),
                 -50.3622d {-50d 21' 43.8"} (1950)
GRB_ERROR:       0.8 [arcsec radius, statistical only]
GRB_MAG:         19.13 +/- 0.16 [mag]
FILTER:          10, White
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12074.00 SOD {03:21:14.00} UT,   74.2 [sec] since BAT Trigger Time
SUN_POSTN:        18.23d {+01h 12m 56s}   +7.72d {+07d 43' 24"}
SUN_DIST:         68.58 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.80d {+14h 15m 12s}   -9.09d {-09d 05' 06"}
MOON_DIST:       116.29 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.80,-47.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       33.13,-67.93 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:32:39 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.570d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.272d {-50d 16' 17"} (J2000)
POINT_ROLL:      314.207d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12291.04 SOD {03:24:51.04} UT,   291.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.406
N_STARS:         93
X_OFFSET:        430 [pixels]
Y_OFFSET:        290 [pixels]
X_MAX:           1869 [pixels]
Y_MAX:           1729 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00965484000msufc0291.fits
SUN_POSTN:        18.24d {+01h 12m 57s}   +7.72d {+07d 43' 28"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.85d {+14h 15m 23s}   -9.10d {-09d 06' 15"}
MOON_DIST:       116.23 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:32:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.570d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.272d {-50d 16' 17"} (J2000)
POINT_ROLL:      314.207d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12291.04 SOD {03:24:51.04} UT,   291.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.406
N_STARS:         93
X_OFFSET:        430 [pixels]
Y_OFFSET:        290 [pixels]
X_MAX:           1869 [pixels]
Y_MAX:           1729 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00965484000msufc0291.fits
SUN_POSTN:        18.24d {+01h 12m 57s}   +7.72d {+07d 43' 28"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.85d {+14h 15m 24s}   -9.11d {-09d 06' 18"}
MOON_DIST:       116.23 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [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:     Thu 09 Apr 20 03:33:04 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     965484,   Seg_Num: 0
GRB_RA:           60.5365d {+04h 02m 08.75s} (J2000),
                  60.6782d {+04h 02m 42.77s} (current),
                  60.1874d {+04h 00m 44.97s} (1950)
GRB_DEC:         -50.2250d {-50d 13' 30.0"} (J2000),
                 -50.1696d {-50d 10' 10.6"} (current),
                 -50.3627d {-50d 21' 45.6"} (1950)
GRB_ERROR:       2.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12086.00 SOD {03:21:26.00} UT,   86.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        18.24d {+01h 12m 57s}   +7.72d {+07d 43' 29"}
SUN_DIST:         68.58 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.85d {+14h 15m 24s}   -9.11d {-09d 06' 21"}
MOON_DIST:       116.29 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.80,-47.21 [deg] galactic lon,lat of the burst
ECL_COORDS:       33.13,-67.93 [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:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN Circular #27509
J.D. Gropp (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 03:19:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200409A (trigger=965484). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 60.553, -50.247, which is
```
   RA(J2000)  =  04h 02m 13s
   Dec(J2000) = -50d 14' 49"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows multiple peaks with a total duration of about 20 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 03:21:13.1 UT, 73.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 60.53820, -50.22509 which is equivalent to:
```
   RA(J2000)  = 04h 02m 09.17s
   Dec(J2000) = -50d 13' 30.3"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 85 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.27 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 5 (+4.06/-3.42) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 77 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	04:02:08.75 =  60.53646
  DEC(J2000) = -50:13:28.4  = -50.22455
```
with a 90%-confidence error radius of about 0.77 arc sec. This position is 4.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.14 with a 1-sigma error of about 0.16. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01.
Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 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:     Thu 09 Apr 20 03:35:33 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:          0.000d {+00h 00m 00s} (J2000)
POINT_DEC:        +0.000d {+00d 00' 00"} (J2000)
ROLL:            -50.272d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12658.72 SOD {03:30:58.72} UT,   658.9 [sec] since BAT Trigger Time
FILTER:          0, illegal value
EXPOSURE_ID:     65537
X_OFFSET:        911 [pixels]
Y_OFFSET:        1275 [pixels]
WIDTH:           386 [pixels]
HEIGHT:          1063 [pixels]
X_GRB_POS:       0
Y_GRB_POS:       0
BINNING_INDEX:   0
IM_URL:          sw00965484000msuni0316.fits
SUN_POSTN:        18.24d {+01h 12m 57s}   +7.73d {+07d 43' 31"}
SUN_DIST:         19.47 [deg]   Sun_angle= 1.2 [hr] (West of Sun)
MOON_POSTN:      213.87d {+14h 15m 30s}   -9.12d {-09d 06' 55"}
MOON_DIST:       145.34 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:       96.34,-60.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.00,  0.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        WARNING: This Notice was received with 1 (or more) critical values out of range.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 1x1 binning (ie no compression).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:35:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:          0.000d {+00h 00m 00s} (J2000)
POINT_DEC:        +0.000d {+00d 00' 00"} (J2000)
ROLL:            -50.272d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12658.72 SOD {03:30:58.72} UT,   658.9 [sec] since BAT Trigger Time
FILTER:          0, illegal value
EXPOSURE_ID:     65537
X_OFFSET:        911 [pixels]
Y_OFFSET:        1275 [pixels]
WIDTH:           386 [pixels]
HEIGHT:          1063 [pixels]
X_GRB_POS:       0
Y_GRB_POS:       0
BINNING_INDEX:   0
IM_URL:          sw00965484000msuni0316.fits
SUN_POSTN:        18.24d {+01h 12m 57s}   +7.73d {+07d 43' 31"}
SUN_DIST:         19.47 [deg]   Sun_angle= 1.2 [hr] (West of Sun)
MOON_POSTN:      213.88d {+14h 15m 30s}   -9.12d {-09d 06' 58"}
MOON_DIST:       145.34 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:       96.34,-60.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.00,  0.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        WARNING: This Notice was received with 1 (or more) critical values out of range.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 1x1 binning (ie no compression).  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:38:54 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.571d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.272d {-50d 16' 18"} (J2000)
POINT_ROLL:      314.208d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12868.67 SOD {03:34:28.67} UT,   868.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.278
N_STARS:         57
X_OFFSET:        430 [pixels]
Y_OFFSET:        290 [pixels]
X_MAX:           1869 [pixels]
Y_MAX:           1729 [pixels]
DET_THRESH:      5
PHOTO_THRESH:    2
SL_URL:          sw00965484000msufc0868.fits
SUN_POSTN:        18.24d {+01h 12m 58s}   +7.73d {+07d 43' 34"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.91d {+14h 15m 38s}   -9.13d {-09d 07' 42"}
MOON_DIST:       116.23 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:39:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.571d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.272d {-50d 16' 18"} (J2000)
POINT_ROLL:      314.208d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12868.67 SOD {03:34:28.67} UT,   868.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.278
N_STARS:         57
X_OFFSET:        430 [pixels]
Y_OFFSET:        290 [pixels]
X_MAX:           1869 [pixels]
Y_MAX:           1729 [pixels]
DET_THRESH:      5
PHOTO_THRESH:    2
SL_URL:          sw00965484000msufc0868.fits
SUN_POSTN:        18.24d {+01h 12m 58s}   +7.73d {+07d 43' 34"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.91d {+14h 15m 38s}   -9.13d {-09d 07' 46"}
MOON_DIST:       116.23 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Apr 20 03:39:51 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.571d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.272d {-50d 16' 18"} (J2000)
ROLL:            314.208d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12868.67 SOD {03:34:28.67} UT,   868.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     608096093
X_OFFSET:        989 [pixels]
Y_OFFSET:        849 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1149
Y_GRB_POS:       1009
BINNING_INDEX:   1
IM_URL:          sw00965484000msuni0893.fits
SUN_POSTN:        18.24d {+01h 12m 58s}   +7.73d {+07d 43' 35"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.92d {+14h 15m 40s}   -9.13d {-09d 07' 56"}
MOON_DIST:       116.23 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [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:     Thu 09 Apr 20 03:40:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     965484,   Seg_Num: 0
POINT_RA:         60.571d {+04h 02m 17s} (J2000)
POINT_DEC:       -50.272d {-50d 16' 18"} (J2000)
ROLL:            314.208d
IMG_START_DATE:  18948 TJD;   100 DOY;   20/04/09
IMG_START_TIME:  12868.67 SOD {03:34:28.67} UT,   868.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     608096093
X_OFFSET:        989 [pixels]
Y_OFFSET:        849 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1149
Y_GRB_POS:       1009
BINNING_INDEX:   1
IM_URL:          sw00965484000msuni0893.fits
SUN_POSTN:        18.24d {+01h 12m 58s}   +7.73d {+07d 43' 35"}
SUN_DIST:         68.63 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:      213.92d {+14h 15m 41s}   -9.13d {-09d 08' 00"}
MOON_DIST:       116.23 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      258.86,-47.18 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.11,-67.98 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #27510
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 2685 s of XRT Photon Counting mode data and 6 UVOT images for GRB 200409A, 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 = 60.53633, -50.22498 which is equivalent to:
```
RA (J2000): 04h 02m 8.72s
Dec (J2000): -50d 13' 29.9"
```
with an uncertainty of 1.6 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #27511
D.N. Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J.A. Kennea (PSU) and J.D. Gropp report on behalf of the Swift-XRT team:
We have analysed 7.6 ks of XRT data for GRB 200409A (Gropp et al. GCN Circ. 27509), from 59 s to 18.1 ks after the BAT trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 27510).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.8 (+5.2, -0.8). At T+123 s the decay flattens to an alpha of -0.2 (+0.4, -0.7) before breaking again at T+441 s to a final decay with index alpha=0.80 (+0.34, -0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.94 (+0.17, -0.16). The best-fitting absorption column is 3.2 (+3.7, -1.9) x 10^20 cm^-2, consistent with the Galactic value of 1.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.2 (+3.7, -1.9) x 10^20 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.94 (+0.17, -0.16)
```
If the light curve continues to decay with a power-law decay index of 0.80, the count rate at T+24 hours will be 9.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-13 (3.2 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/00965484.
This circular is an official product of the Swift-XRT team.
GCN Circular #27512
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),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
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-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 200409A ( J.D. Gropp et al., GCN 27509) errorbox 49717 sec after notice time and 49742 sec after trigger time at 2020-04-09 17:09:01 UT, with upper limit up to 19.1 mag. Observations started at twilight. The observations began at zenith distance = 44 deg. The sun altitude is -10.2 deg.
The galactic latitude b = -47 deg., longitude l = 259 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1333122
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   49832 |         MASTER-SAAO |   C |   180 | 19.1 |        
   49834 |         MASTER-SAAO |   C |   180 | 19.0 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #27514
E. Burns (GSFC), M. S. Briggs (UAH), C. M. Hui (MSFC), C. Malacaria (MSFC), and P. Veres (UAH) reports on behalf of the Fermi-GBM Team
Swift-BAT detected GRB 200409A at 03:19:59 UT (GCN 27509). There was no Fermi-GBM onboard trigger around the event.
An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified GRB 200904A with high reliability [1], with a localization consistent with the Swift-BAT location, and a discovery timescale of 0.703 s.
The GBM targeted search [2], the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around BAT trigger time. A transient source was identified whose most significant timescale according to the search is 1.024 s, with a log likelihood ratio of 62, with a consistent location, and is consistent with a soft spectrum for a GRB.
Preliminary spectral analysis statistically prefers a power-law fit over models that constrain Epeak. Using T0-0.320 to T0+0.320 as the source interval gives an alpha of -1.84 +/- 0.06, a photon flux of 3.3 +/- 0.4 ph/s/cm^2, and a fluence of (2.0+/-0.2)E-7 erg/s/cm^2.
```
[1] https://gcn.gsfc.nasa.gov/notices_gbm_sub/608095205.fermi
[2] Goldstein et al. 2019 arXiv:1903.12597
```
GCN Circular #27519
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), J.D. Gropp (PSU), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), 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-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200409A (trigger #965484) (Gropp et al., GCN Circ. 27509). The BAT ground-calculated position is RA, Dec = 60.555, -50.243 deg which is
```
   RA(J2000)  =  04h 02m 13.3s
   Dec(J2000) = -50d 14' 36.4"
```
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%.
The mask-weighted light curve shows several overlapping pulses that start at ~T0 and ends at~T+19 s. The main peak occurs at ~T0. T90 (15-350 keV) is 17.91 +- 5.20 sec (estimated error including systematics).
The time-averaged spectrum from T+0.01 to T+19.01 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.14 +- 0.44. The fluence in the 15-150 keV band is 2.3 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.01 sec in the 15-150 keV band is 1.2 +- 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/965484/BA/
GCN Circular #27521
Dougal Dobie (USYD/CSIRO), Tara Murphy (USYD), David Kaplan (UWM)
While performing follow-up of GRB 200405B (GCN 27497, 27516) we received notification of the detection of GRB 200409A and the associated optical and X-ray candidate counterpart (GCN 27509). We added it to our schedule and carried out observations of it from 2020-04-09 07:00-09:30 UTC, approximately 5 hours post-burst.
We make no detection of radio emission at 5.5 or 9 GHz with 3-sigma upper limits of 90 uJy and 81 uJy respectively.
Thank you to CSIRO staff for supporting these observations during these especially difficult times.

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Jochen Greiner, last update: 10-Apr-2020 [Disclaimer]