Gamma-ray Burst 180905A

(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:     Wed 05 Sep 18 13:59:00 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     859421,   Seg_Num: 0
GRB_RA:           91.035d {+06h 04m 08s} (J2000),
                  91.266d {+06h 05m 04s} (current),
                  90.417d {+06h 01m 40s} (1950)
GRB_DEC:          -4.591d {-04d 35' 27"} (J2000),
                  -4.593d {-04d 35' 35"} (current),
                  -4.588d {-04d 35' 15"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1573 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        18366 TJD;   248 DOY;   18/09/05
GRB_TIME:        50266.45 SOD {13:57:46.45} UT
GRB_PHI:         162.21 [deg]
GRB_THETA:        42.86 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.32 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +0  +0  +0 -27  +0 
SUN_POSTN:       164.30d {+10h 57m 11s}   +6.69d {+06d 41' 30"}
SUN_DIST:         73.76 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.56d {+07h 06m 13s}  +20.93d {+20d 55' 36"}
MOON_DIST:        29.60 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.65,-12.61 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       91.17,-28.03 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 263.24,-6.55 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 05 Sep 18 14:00:46 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     859421,   Seg_Num: 0
GRB_RA:           91.0602d {+06h 04m 14.4s} (J2000),
                  91.2912d {+06h 05m 09.8s} (current),
                  90.4419d {+06h 01m 46.0s} (1950)
GRB_DEC:          -4.5724d {-04d 34' 20.6"} (J2000),
                  -4.5745d {-04d 34' 28.3"} (current),
                  -4.5688d {-04d 34' 07.5"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       56 [cnts]
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50412.31 SOD {14:00:12.31} UT,   145.9 [sec] since BAT Trigger Time
CENTROID_X:      252.60,  raw= 253  [pixels]
CENTROID_Y:      313.53,  raw= 314  [pixels]
ROLL:            81.67 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   35.68
GRB_POS_XRT_Z:   -126.81
IMAGE_URL:       sw00859421000msxps_rw.img
SUN_POSTN:       164.30d {+10h 57m 11s}   +6.69d {+06d 41' 28"}
SUN_DIST:         73.74 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.57d {+07h 06m 18s}  +20.93d {+20d 55' 34"}
MOON_DIST:        29.58 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.58 [deg] galactic lon,lat of the burst
ECL_COORDS:       91.20,-28.01 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 05 Sep 18 14:00:48 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     859421,   Seg_Num: 0
GRB_RA:           91.0602d {+06h 04m 14.4s} (J2000),
                  91.2912d {+06h 05m 09.8s} (current),
                  90.4419d {+06h 01m 46.0s} (1950)
GRB_DEC:          -4.5724d {-04d 34' 20.6"} (J2000),
                  -4.5745d {-04d 34' 28.3"} (current),
                  -4.5688d {-04d 34' 07.5"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       56 [cnts]
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50412.31 SOD {14:00:12.31} UT,   145.9 [sec] since BAT Trigger Time
CENTROID_X:      252.60,  raw= 253  [pixels]
CENTROID_Y:      313.53,  raw= 314  [pixels]
ROLL:            81.67 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   35.68
GRB_POS_XRT_Z:   -126.81
IMAGE_URL:       sw00859421000msxps_rw.img
SUN_POSTN:       164.30d {+10h 57m 11s}   +6.69d {+06d 41' 28"}
SUN_DIST:         73.74 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.57d {+07h 06m 18s}  +20.93d {+20d 55' 34"}
MOON_DIST:        29.58 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.58 [deg] galactic lon,lat of the burst
ECL_COORDS:       91.20,-28.01 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 05 Sep 18 14:00:37 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     859421,   Seg_Num: 0
GRB_RA:           91.0602d {+06h 04m 14.44s} (J2000),
                  91.2912d {+06h 05m 09.88s} (current),
                  90.4419d {+06h 01m 46.06s} (1950)
GRB_DEC:          -4.5724d {-04d 34' 20.6"} (J2000),
                  -4.5745d {-04d 34' 28.3"} (current),
                  -4.5688d {-04d 34' 07.5"} (1950)
GRB_ERROR:       5.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       2.03e-09 [erg/cm2/sec]
GRB_SIGNIF:      7.48 [sigma]
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50412.31 SOD {14:00:12.31} UT,   145.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.21 261.63 243.49
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       164.30d {+10h 57m 11s}   +6.69d {+06d 41' 28"}
SUN_DIST:         73.74 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.57d {+07h 06m 17s}  +20.93d {+20d 55' 34"}
MOON_DIST:        29.58 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.58 [deg] galactic lon,lat of the burst
ECL_COORDS:       91.20,-28.01 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 05 Sep 18 14:01:58 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     859421,   Seg_Num: 0
GRB_RA:           91.035d {+06h 04m 08s} (J2000),
                  91.266d {+06h 05m 04s} (current),
                  90.417d {+06h 01m 40s} (1950)
GRB_DEC:          -4.591d {-04d 35' 27"} (J2000),
                  -4.593d {-04d 35' 35"} (current),
                  -4.588d {-04d 35' 15"} (1950)
GRB_DATE:        18366 TJD;   248 DOY;   18/09/05
GRB_TIME:        50266.45 SOD {13:57:46.45} UT
TRIGGER_INDEX:   20000
GRB_PHI:         162.21 [deg]
GRB_THETA:        42.86 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.32 [sigma]
LC_URL:          sw00859421000msb.lc
SUN_POSTN:       164.30d {+10h 57m 11s}   +6.69d {+06d 41' 27"}
SUN_DIST:         73.76 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.59d {+07h 06m 21s}  +20.93d {+20d 55' 33"}
MOON_DIST:        29.62 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.65,-12.61 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       91.17,-28.03 [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 an image 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 = 263.24,-6.55 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 05 Sep 18 14:03:05 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     859421,   Seg_Num: 0
POINT_RA:         91.027d {+06h 04m 06s} (J2000)
POINT_DEC:        -4.587d {-04d 35' 12"} (J2000)
POINT_ROLL:      81.670d
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50420.41 SOD {14:00:20.41} UT,   154.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.071
N_STARS:         79
X_OFFSET:        536 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1495 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00859421000msufc0153.fits
SUN_POSTN:       164.30d {+10h 57m 12s}   +6.69d {+06d 41' 26"}
SUN_DIST:         73.77 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.60d {+07h 06m 24s}  +20.93d {+20d 55' 32"}
MOON_DIST:        29.62 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.61 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       91.16,-28.02 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 05 Sep 18 14:03:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     859421,   Seg_Num: 0
POINT_RA:         91.027d {+06h 04m 06s} (J2000)
POINT_DEC:        -4.587d {-04d 35' 12"} (J2000)
POINT_ROLL:      81.670d
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50420.41 SOD {14:00:20.41} UT,   154.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.071
N_STARS:         79
X_OFFSET:        536 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1495 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00859421000msufc0153.fits
SUN_POSTN:       164.30d {+10h 57m 12s}   +6.69d {+06d 41' 26"}
SUN_DIST:         73.77 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.60d {+07h 06m 25s}  +20.93d {+20d 55' 32"}
MOON_DIST:        29.62 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.61 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       91.16,-28.02 [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:     Wed 05 Sep 18 14:05:45 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     859421,   Seg_Num: 0
POINT_RA:         91.027d {+06h 04m 06s} (J2000)
POINT_DEC:        -4.587d {-04d 35' 12"} (J2000)
ROLL:            81.670d
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50420.41 SOD {14:00:20.41} UT,   154.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     557848841
X_OFFSET:        973 [pixels]
Y_OFFSET:        681 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1133
Y_GRB_POS:       841
BINNING_INDEX:   1
IM_URL:          sw00859421000msuni0175.fits
SUN_POSTN:       164.30d {+10h 57m 12s}   +6.69d {+06d 41' 24"}
SUN_DIST:         73.77 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.63d {+07h 06m 31s}  +20.92d {+20d 55' 29"}
MOON_DIST:        29.64 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.61 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       91.16,-28.02 [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:     Wed 05 Sep 18 14:05:58 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     859421,   Seg_Num: 0
POINT_RA:         91.027d {+06h 04m 06s} (J2000)
POINT_DEC:        -4.587d {-04d 35' 12"} (J2000)
ROLL:            81.670d
IMG_START_DATE:  18366 TJD;   248 DOY;   18/09/05
IMG_START_TIME:  50420.41 SOD {14:00:20.41} UT,   154.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     557848841
X_OFFSET:        973 [pixels]
Y_OFFSET:        681 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1133
Y_GRB_POS:       841
BINNING_INDEX:   1
IM_URL:          sw00859421000msuni0175.fits
SUN_POSTN:       164.30d {+10h 57m 12s}   +6.69d {+06d 41' 23"}
SUN_DIST:         73.77 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      106.63d {+07h 06m 31s}  +20.92d {+20d 55' 29"}
MOON_DIST:        29.64 [deg]
MOON_ILLUM:      23 [%]
GAL_COORDS:      211.64,-12.61 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       91.16,-28.02 [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 Circular #23201
V. D'Elia (SSDC), A. D'Ai (INAF-IASFPA), J.D. Gropp (PSU), J. A. Kennea (PSU), M. J. Moss (George Washington University), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 13:57:46 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180905A (trigger=859421). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 91.035, -4.591 which is
```
   RA(J2000) = 06h 04m 08s
   Dec(J2000) = -04d 35' 27"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger, no obvious variation is visible in the immediately-available lightcurve.
The XRT began observing the field at 14:00:12.3 UT, 145.9 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 91.0602, -4.5724 which is equivalent to:
```
   RA(J2000)  = 06h 04m 14.45s
   Dec(J2000) = -04d 34' 20.6"
```
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This location is 112 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.
The initial flux in the 2.5 s image was 2.03e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 135 seconds with the White filter starting 153 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.60.
Burst Advocate for this burst is V. D'Elia (delia AT ssdc.asi.it). 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 Circular #23207
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1840 s of XRT Photon Counting mode data and 4 UVOT images for GRB 180905A, 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 = 91.06265, -4.57015 which is equivalent to:
```
RA (J2000): 06h 04m 15.04s
Dec (J2000): -04d 34' 12.6"
```
with an uncertainty of 1.8 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 #23208
Y.-D. Hu, E. Fernandez-Garcia, J. C. Tello, A. Ayala and A. J. Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), M. D. Caballero-Garcia (ASU-CAS, CZ) and R. Querel (NIWA), on behalf of a larger collaboration, report:
The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) automatically responded to the Swift trigger of GRB 180905A (D'Elia et al. GCNC 23201) ~0.55 h after the burst as soon as it became few degrees above the horizon. The first image (clear filter) were obtained starting at 14:30:52 UT. At the position of the Swift/XRT enhanced X-ray position (Beardmore et al. GCNC 23207), no optical afterglow is detected down to 20 mag on a 720s co-added image at 14:38:31 (mid-exposure), in agreement with the non-detection by Swift/UVOT. Further analysis is ongoing.
We thank the staff at NIWA for its excellent support.
GCN Circular #23210
A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester) and V. D'Elia report on behalf of the Swift-XRT team:
We have analysed 9.0 ks of XRT data for GRB 180905A (D'Elia et al. GCN Circ. 23201), from 152 s to 35.0 ks after the BAT trigger. The data comprise 135 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 23207).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.556 (+0.029, -0.027).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.45 (+0.11, -0.10). The best-fitting absorption column is 5.7 (+1.1, -1.0) x 10^21 cm^-2, in excess of the Galactic value of 3.5 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.68 (+0.28, -0.26) and a best-fitting absorption column of 5.5 (+2.2, -1.8) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.0 x 10^-11 (6.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     5.5 (+2.2, -1.8) x 10^21 cm^-2
Galactic foreground: 3.5 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index:	     1.68 (+0.28, -0.26)
```
If the light curve continues to decay with a power-law decay index of 1.556, the count rate at T+24 hours will be 1.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x 10^-14 (1.2 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/00859421.
This circular is an official product of the Swift-XRT team.
GCN Circular #23211
M. Niwano, R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, K. Shiraishi, K. Iida, R. Adachi, M. Oeda, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 180905A (V. D'Elia et al., GCN Circular #23201) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2018-09-05 17:29:51.08 UT. We did not find any point source at the enhanced position of the XRT error circle (A.P. Beardmore et al., GCN Circular #23207) in all three bands. We obtained following 5-sigma upper limits for the magnitudes.
```
T0+[min]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
202.32     18:46:39  8,100   >18.9   >18.6   >18.4
-------------------------------------------------------------------------------------------------------
```
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used UCAC-4 catalog for flux calibration.
GCN Circular #23212
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�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 180905A (D'Elia et al., GCN Circ. 23201) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2018/09 6.42 to 2018/09 6.51 UTC (20.07 to 22.23 hours after the BAT trigger), obtaining a total of 1.17 hours exposure in the r and i bands and 0.57 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT enhanced error circle (Beardmore et al., GCN Circ. 23207), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):
```
  r	> 23.26
  i	> 23.10
  Z	> 22.21
  Y	> 22.06
  J	> 21.60
  H	> 21.25
```
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�mico Nacional in San Pedro M�rtir.
GCN Circular #23213
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), V. D'Elia (SSDC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+250 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180905A (trigger #859421) (D'Elia et al., GCN Circ. 23201). The BAT ground-calculated position is RA, Dec = 91.038, -4.592 deg which is
```
  RA(J2000)  =  06h 04m 09.2s
  Dec(J2000) = -04d 35' 31.9"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 29%.
The mask-weighted light curve shows a weak long pulse that starts at ~T-60 s and ends at ~T+150 s. Note that the burst came into the BAT field of view at T-84 s, and BAT entered the SAA after ~ T+250 s. Therefore, there might be additional burst emission before and after the available event data range. T90 (15-350 keV) is 165.3 +- 28.9 sec (estimated error including systematics).
The time-averaged spectrum from T-58.9 to T+146.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.12. The fluence in the 15-150 keV band is 4.2 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-2.09 sec in the 15-150 keV band is 1.0 +- 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/859421/BA/
GCN Circular #23215
M. H. Siegel (PSU) and V. D'Elia (SSDC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180905A 154 s after the BAT trigger (D'Elia et al., GCN Circ. 23201). No optical afterglow consistent with the XRT position (D'Elia et al. GCN Circ. 23201) is detected in the initial UVOT exposures, as confirmed by Bootes (Hu et al., GCN Circ. 23208), MITSUME (Niwano et al., GCN Circ. 23211) and RATIR (Watson et al., GCN Circ. 23212). Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           154          289          133         >20.4
white              154         6385          373         >21.1
v                 5316         5515          197         >19.1
b                 4700         6335          393         >20.5
u                 4495         6130          393         >20.3
w1                5726         5925          197         >19.6
m2                5520         5720          197         >19.8
w2                5111         5311          197         >19.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.60 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 09-Sep-2018 [Disclaimer]