Gamma-ray Burst 180510B

(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 10 May 18 20:16:27 UT
NOTICE_TYPE:     Swift-BAT GRB Position 
TRIGGER_NUM:     831816,   Seg_Num: 0   
GRB_RA:           77.989d {+05h 11m 57s} (J2000),
                  78.033d {+05h 12m 08s} (current),
                  77.868d {+05h 11m 28s} (1950)
GRB_DEC:         -62.335d {-62d 20' 05"} (J2000),
                 -62.314d {-62d 18' 49"} (current),
                 -62.393d {-62d 23' 35"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       11349 [cnts]    Image_Peak=347 [image_cnts]
TRIGGER_DUR:     4.096 [sec]    
TRIGGER_INDEX:   300     E_range: 25-100 keV
BKG_INTEN:       98014 [cnts]
BKG_TIME:        72883.07 SOD {20:14:43.07} UT
BKG_DUR:         40 [sec]
GRB_DATE:        18248 TJD;   130 DOY;   18/05/10
GRB_TIME:        72942.27 SOD {20:15:42.27} UT
GRB_PHI:         -103.85 [deg]
GRB_THETA:        29.63 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     9.64 [sigma]
IMAGE_SIGNIF:    9.44 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  +0  +0  +0 -11  +0
SUN_POSTN:        47.68d {+03h 10m 43s}  +17.77d {+17d 46' 19"}
SUN_DIST:         83.60 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.15d {+23h 32m 36s}   -6.60d {-06d 35' 54"}
MOON_DIST:        81.78 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.86,-35.28 [deg] galactic lon,lat of the burst (or transient)      
ECL_COORDS:       33.67,-83.33 [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 = 1.87,3.35 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 10 May 18 20:19:36 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     831816,   Seg_Num: 0
GRB_RA:           77.989d {+05h 11m 57s} (J2000),
                  78.033d {+05h 12m 08s} (current),
                  77.868d {+05h 11m 28s} (1950)
GRB_DEC:         -62.335d {-62d 20' 05"} (J2000),
                 -62.314d {-62d 18' 49"} (current),
                 -62.393d {-62d 23' 35"} (1950)
GRB_DATE:        18248 TJD;   130 DOY;   18/05/10
GRB_TIME:        72942.27 SOD {20:15:42.27} UT
TRIGGER_INDEX:   300
GRB_PHI:         -103.85 [deg]
GRB_THETA:        29.63 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     9.64 [sigma]
IMAGE_SIGNIF:    9.44 [sigma]
LC_URL:          sw00831816000msb.lc
SUN_POSTN:        47.68d {+03h 10m 43s}  +17.77d {+17d 46' 21"}
SUN_DIST:         83.60 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.18d {+23h 32m 43s}   -6.59d {-06d 35' 20"}
MOON_DIST:        81.78 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.86,-35.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       33.67,-83.33 [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 = 1.87,3.35 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 10 May 18 21:05:01 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     831816,   Seg_Num: 0
POINT_RA:         77.977d {+05h 11m 54s} (J2000)
POINT_DEC:       -62.330d {-62d 19' 47"} (J2000)
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75892.40 SOD {21:04:52.40} UT,   2950.1 [sec] since BAT Trigger Time
COUNTS:          2    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    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 10 May 18 21:09:31 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     831816,   Seg_Num: 0
POINT_RA:         77.977d {+05h 11m 54s} (J2000)
POINT_DEC:       -62.330d {-62d 19' 46"} (J2000)
POINT_ROLL:      331.179d
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75896.00 SOD {21:04:56.00} UT,   2953.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.663
N_STARS:         37
X_OFFSET:        446 [pixels]
Y_OFFSET:        611 [pixels]
X_MAX:           1405 [pixels]
Y_MAX:           1570 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw00831816000msufc2953.fits
SUN_POSTN:        47.71d {+03h 10m 52s}  +17.78d {+17d 46' 53"}
SUN_DIST:         83.59 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.60d {+23h 34m 23s}   -6.44d {-06d 26' 26"}
MOON_DIST:        81.71 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.86,-35.29 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.67,-83.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 10 May 18 21:08:52 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     831816,   Seg_Num: 0
GRB_RA:           77.9668d {+05h 11m 52.03s} (J2000),
                  78.0115d {+05h 12m 02.76s} (current),
                  77.8459d {+05h 11m 23.02s} (1950)
GRB_DEC:         -62.3224d {-62d 19' 20.6"} (J2000),
                 -62.3011d {-62d 18' 04.0"} (current),
                 -62.3807d {-62d 22' 50.6"} (1950)
GRB_ERROR:       4.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75915.00 SOD {21:05:15.00} UT,   2972.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        47.71d {+03h 10m 51s}  +17.78d {+17d 46' 53"}
SUN_DIST:         83.58 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.59d {+23h 34m 22s}   -6.44d {-06d 26' 33"}
MOON_DIST:        81.71 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.85,-35.30 [deg] galactic lon,lat of the burst
ECL_COORDS:       33.68,-83.32 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 10 May 18 21:09:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     831816,   Seg_Num: 0
POINT_RA:         77.977d {+05h 11m 54s} (J2000)
POINT_DEC:       -62.330d {-62d 19' 46"} (J2000)
POINT_ROLL:      331.179d
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75896.00 SOD {21:04:56.00} UT,   2953.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.663
N_STARS:         37
X_OFFSET:        446 [pixels]
Y_OFFSET:        611 [pixels]
X_MAX:           1405 [pixels]
Y_MAX:           1570 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw00831816000msufc2953.fits
SUN_POSTN:        47.72d {+03h 10m 52s}  +17.78d {+17d 46' 53"}
SUN_DIST:         83.59 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.60d {+23h 34m 24s}   -6.44d {-06d 26' 22"}
MOON_DIST:        81.71 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.86,-35.29 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.67,-83.33 [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 10 May 18 21:11:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     831816,   Seg_Num: 0
POINT_RA:         77.977d {+05h 11m 54s} (J2000)
POINT_DEC:       -62.330d {-62d 19' 46"} (J2000)
ROLL:            331.179d
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75896.00 SOD {21:04:56.00} UT,   2953.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     547679116
X_OFFSET:        765 [pixels]
Y_OFFSET:        930 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       925
Y_GRB_POS:       1090
BINNING_INDEX:   1
IM_URL:          sw00831816000msuni2974.fits
SUN_POSTN:        47.72d {+03h 10m 52s}  +17.78d {+17d 46' 54"}
SUN_DIST:         83.59 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.61d {+23h 34m 26s}   -6.44d {-06d 26' 10"}
MOON_DIST:        81.71 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.86,-35.29 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.67,-83.33 [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 10 May 18 21:11:16 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     831816,   Seg_Num: 0
POINT_RA:         77.977d {+05h 11m 54s} (J2000)
POINT_DEC:       -62.330d {-62d 19' 46"} (J2000)
ROLL:            331.179d
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75896.00 SOD {21:04:56.00} UT,   2953.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     547679116
X_OFFSET:        765 [pixels]
Y_OFFSET:        930 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       925
Y_GRB_POS:       1090
BINNING_INDEX:   1
IM_URL:          sw00831816000msuni2974.fits
SUN_POSTN:        47.72d {+03h 10m 52s}  +17.78d {+17d 46' 54"}
SUN_DIST:         83.59 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.61d {+23h 34m 27s}   -6.44d {-06d 26' 07"}
MOON_DIST:        81.71 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.86,-35.29 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       33.67,-83.33 [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 #22696
A. Tohuvavohu (PSU), A. Deich (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 20:15:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 180510B (trigger=831816). Due to an observing constraint Swift did not slew immediately to the burst.
The BAT on-board calculated location is RA, Dec 77.989, -62.335 which is
```
   RA(J2000) = 05h 11m 57s
   Dec(J2000) = -62d 20' 05"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 21:04:52.4 UT, 2950.1 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 77.96962, -62.32356 which is equivalent to:
```
   RA(J2000)  = 05h 11m 52.71s
   Dec(J2000) = -62d 19' 24.8"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 52 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 http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.54 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.8 (+3.31/-2.67) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 2953 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	05:11:52.64 =  77.96932
  DEC(J2000) = -62:19:26.3  = -62.32396
```
with a 90%-confidence error radius of about 0.76 arc sec. This position is 4.0 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.25 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03.
Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.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/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 10 May 18 21:31:30 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     831816,   Seg_Num: 0
GRB_RA:           77.9696d {+05h 11m 52.70s} (J2000),
                  78.0143d {+05h 12m 03.43s} (current),
                  77.8488d {+05h 11m 23.70s} (1950)
GRB_DEC:         -62.3235d {-62d 19' 24.6"} (J2000),
                 -62.3022d {-62d 18' 08.0"} (current),
                 -62.3818d {-62d 22' 54.5"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75915.00 SOD {21:05:15.00} UT,   2972.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        47.73d {+03h 10m 55s}  +17.79d {+17d 47' 07"}
SUN_DIST:         83.58 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.78d {+23h 35m 08s}   -6.38d {-06d 22' 30"}
MOON_DIST:        81.68 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.85,-35.30 [deg] galactic lon,lat of the burst
ECL_COORDS:       33.68,-83.32 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 10 May 18 21:46:38 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     831816,   Seg_Num: 0
GRB_RA:           77.9696d {+05h 11m 52.70s} (J2000),
                  78.0143d {+05h 12m 03.43s} (current),
                  77.8488d {+05h 11m 23.70s} (1950)
GRB_DEC:         -62.3235d {-62d 19' 24.6"} (J2000),
                 -62.3022d {-62d 18' 08.0"} (current),
                 -62.3818d {-62d 22' 54.5"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18248 TJD;   130 DOY;   18/05/10
IMG_START_TIME:  75915.00 SOD {21:05:15.00} UT,   2972.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        47.74d {+03h 10m 58s}  +17.79d {+17d 47' 17"}
SUN_DIST:         83.58 [deg]   Sun_angle= -2.0 [hr] (East of Sun)
MOON_POSTN:      353.91d {+23h 35m 38s}   -6.33d {-06d 19' 47"}
MOON_DIST:        81.66 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      271.85,-35.30 [deg] galactic lon,lat of the burst
ECL_COORDS:       33.68,-83.32 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #22698
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 2476 s of XRT Photon Counting mode data and 7 UVOT images for GRB 180510B, 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 = 77.96901, -62.32411 which is equivalent to:
```
RA (J2000): 05h 11m 52.56s
Dec (J2000): -62d 19' 26.8"
```
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 #22700
Klotz A., Noysena.K., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Eymar, L. (CNRS-ARTEMIS), Gendre B. (UWA - Univ. Western Australia) report:
We imaged the field of GRB 180510B detected by SWIFT (trigger 831816) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 2.88h after the GRB trigger just after the dusk. The elevation of the field decreased from 38 degrees above horizon weather conditions were good.
We co-added a series of exposures but we we cannot detect the OT reported by Tohuvavohu et al. (GCNC 22696) Preliminary analysis gives:
```
start  end    rlim(AB)
(hour) (hour)
2.88   3.62   19.0
```
Magnitudes were estimated with the nearby NOMAD1 stars and are not corrected for galactic dust extinction.
GCN Circular #22701
P. Schady (MPE, Garching) reports:
We observed the field of GRB 180510B (Swift trigger 831816; Tohuvavohu et al., GCN #22696) 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 23:14 UT on 10th May, 3.0 hours after the GRB trigger. They were performed at an average seeing of 1.3" and at an average airmass of 1.8.
A single point source is present within the 1.5" Swift-XRT error circle reported by Beardmore et al. (GCN #22698) at
```
RA (J2000.0) = 05:11:52.66
DEC (J2000.0) = -62:19:26.4
```
with an uncertainty of 0.2" in each coordinate.
Based on 6.6 min of total exposures in g'r'i'z' and 6 min in JHK, the estimated AB magnitudes are
```
g' = 20.5 +/- 0.1 mag
r' = 20.0 +/- 0.1 mag
i' = 19.8 +/- 0.1 mag
z' = 19.6 +/- 0.1 mag
J = 18.8 +/- 0.1 mag
H = 18.5 +/- 0.1 mag
K = 18.0 +/- 0.1 mag
```
Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.02 in the direction of the burst (Schlafly & Finkbeiner 2011).
I would like to thank Markus Rabus for his excellent support from La Silla.
GCN Circular #22702
J. Palmerio (IAP, Paris), A. Rossi (INAF-OAS), D. Malesani (DAWN/NBI and DARK/NBI), N. R. Tanvir (Univ. Leicester), V. D'Elia (ASI-SSDC), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), S. D. Vergani (GEPI/Obs. Paris), D. Xu (NAOC), D. A. Kann (HETH/IAA-CSIC), J.P.U. Fynbo (DAWN/NBI), and B. Sbarufatti (PSU), report on behalf of the Stargate Consortium:
We observed the optical afterglow of GRB 180510B (Tohuvavohu et al., GCN 22696; Schady et al., GCN 22701) with the ESO VLT/X-shooter spectrograph, covering the wavelength range 3000-21000 AA. The afterglow is clearly detected in the 10s acquisition images taken starting at 23:09 UT (~3.7 hours after the GRB trigger) with brightness R~19.8 (Vega), calibrated against USNO-B1 stars in the field. Spectroscopy started at 23:19 UT on 2018-05-10 (~3.9 hours after the GRB trigger) and consisted of 2 exposures of 600 s.
Preliminary analysis of the spectrum reveals continuum flux down to 3600 AA, which sets an upper limit to the redshift z <~ 2 via the lack of any obvious DLA feature. In addition, we identify several absorption lines at a common redshift of z=1.305, the most prominent being ZnII/CrII, FeII, MgII, and MgI. Moreover, we also identify another absorption system at z=0.63 based on the detection of the MgII doublet. Therefore, we propose the most probable redshift of the GRB to be z=1.305, with an intervening system at 0.638.
We acknowledge the excellent support from the ESO staff, particularly Boris Haeussler, Karleyne Silva and Emanuela Pompei in obtaining these observations.
GCN Circular #22703
S. R. Oates (U.Warwick) and A. Tohuvavohu (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180510B 2954 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 22696). A source consistent with the XRT position (Beardmore et al. GCN Circ. 22698) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
  RA  (J2000) =  05:11:52.60 =  77.96918 (deg.)
  Dec (J2000) = -62:19:26.7  = -62.32408 (deg.)
```
with an estimated uncertainty of 0.47 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 (FC)        2954         3103          147         18.29 +/- 0.09
white             4135         4335          196         18.81 +/- 0.12
v                 3111         3310          197         18.00 +/- 0.19
b                 3931         4130          197         18.99 +/- 0.29
u                 3725         3925          197         17.96 +/- 0.16
w1                3520         3720          197         18.82 +/- 0.31
m2                3315        10201          663         19.75 +/- 0.30
w2                4341         4541          197        >19.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22705
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), A. Tohuvavohu (PSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180510B (trigger #831816) (Tohuvavohu et al. GCN Circ. 22696). The BAT ground-calculated position is RA, Dec = 77.965, -62.320 deg which is
```
  RA(J2000)  =  05h 11m 51.6s
  Dec(J2000) = -62d 19' 13.0"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 41%.
The mask-weighted light curve shows a weak pulse that starts at ~T-20 s and peaks at ~T+1 s. The main pulse ends at ~ T+40 s, and there is some low-level emission that lasts until ~T+140 s. T90 (15-350 keV) is 134.3 +- 48.2 sec (estimated error including systematics).
The time-averaged spectrum from T-19.92 to T+137.10 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.00 +- 0.17. The fluence in the 15-150 keV band is 2.1 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.96 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/831816/BA/
GCN Circular #22708
B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and A. Tohuvavohu report on behalf of the Swift-XRT team:
We have analysed 2.6 ks of XRT data for GRB 180510B (Tohuvavohu et al. GCN Circ. 22696), from 3.0 ks to 10.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 22698).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.48 (+/-0.12).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.83 (+/-0.12). The best-fitting absorption column is 1.3 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 2.5 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 3.7 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.3 (+0.4, -0.3) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index:	     1.83 (+/-0.12)
```
If the light curve continues to decay with a power-law decay index of 1.48, the count rate at T+24 hours will be 9.2 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x 10^-13 (4.1 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/00831816.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 11-May-2018 [Disclaimer]