Gamma-ray Burst 160228A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:34:53 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     676595,   Seg_Num: 0
GRB_RA:          107.322d {+07h 09m 17s} (J2000),
                 107.573d {+07h 10m 18s} (current),
                 106.546d {+07h 06m 11s} (1950)
GRB_DEC:         +26.956d {+26d 57' 23"} (J2000),
                 +26.929d {+26d 55' 46"} (current),
                 +27.037d {+27d 02' 15"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       5040 [cnts]    Image_Peak=270 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   155     E_range: 50-350 keV
BKG_INTEN:       25263 [cnts]
BKG_TIME:        63256.09 SOD {17:34:16.09} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17446 TJD;    59 DOY;   16/02/28
GRB_TIME:        63272.47 SOD {17:34:32.47} UT
GRB_PHI:          35.34 [deg]
GRB_THETA:        21.68 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     29.91 [sigma]
IMAGE_SIGNIF:    10.09 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +3  +0  +0  +0 +58  +0 
SUN_POSTN:       341.12d {+22h 44m 30s}   -7.98d {-07d 58' 57"}
SUN_DIST:        125.98 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.56d {+14h 54m 14s}  -12.17d {-12d 10' 03"}
MOON_DIST:       118.51 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.57 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      105.44,  4.44 [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 = 64.17,-20.37 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:36:21 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     676595,   Seg_Num: 0
GRB_RA:          107.3180d {+07h 09m 16.31s} (J2000),
                 107.5686d {+07h 10m 16.46s} (current),
                 106.5420d {+07h 06m 10.06s} (1950)
GRB_DEC:         +26.9282d {+26d 55' 41.5"} (J2000),
                 +26.9012d {+26d 54' 04.4"} (current),
                 +27.0093d {+27d 00' 33.3"} (1950)
GRB_ERROR:       5.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.37e-09 [erg/cm2/sec]
GRB_SIGNIF:      6.70 [sigma]
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63345.58 SOD {17:35:45.58} UT,   73.1 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.25 261.68 243.67
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       341.13d {+22h 44m 30s}   -7.98d {-07d 58' 56"}
SUN_DIST:        125.98 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.57d {+14h 54m 17s}  -12.17d {-12d 10' 13"}
MOON_DIST:       118.53 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.25, 15.56 [deg] galactic lon,lat of the burst
ECL_COORDS:      105.44,  4.41 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.71 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:36:31 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     676595,   Seg_Num: 0
GRB_RA:          107.3180d {+07h 09m 16.3s} (J2000),
                 107.5686d {+07h 10m 16.4s} (current),
                 106.5420d {+07h 06m 10.0s} (1950)
GRB_DEC:         +26.9282d {+26d 55' 41.5"} (J2000),
                 +26.9012d {+26d 54' 04.4"} (current),
                 +27.0093d {+27d 00' 33.3"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       45 [cnts]
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63345.58 SOD {17:35:45.58} UT,   73.1 [sec] since BAT Trigger Time
CENTROID_X:      314.88,  raw= 315  [pixels]
CENTROID_Y:      328.55,  raw= 329  [pixels]
ROLL:            280.06 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   72.48
GRB_POS_XRT_Z:   22.59
IMAGE_URL:       sw00676595000msxps_rw.img
SUN_POSTN:       341.13d {+22h 44m 30s}   -7.98d {-07d 58' 56"}
SUN_DIST:        125.98 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.57d {+14h 54m 18s}  -12.17d {-12d 10' 14"}
MOON_DIST:       118.53 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.25, 15.56 [deg] galactic lon,lat of the burst
ECL_COORDS:      105.44,  4.41 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:36:43 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     676595,   Seg_Num: 0
GRB_RA:          107.3180d {+07h 09m 16.3s} (J2000),
                 107.5686d {+07h 10m 16.4s} (current),
                 106.5420d {+07h 06m 10.0s} (1950)
GRB_DEC:         +26.9282d {+26d 55' 41.5"} (J2000),
                 +26.9012d {+26d 54' 04.4"} (current),
                 +27.0093d {+27d 00' 33.3"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       45 [cnts]
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63345.58 SOD {17:35:45.58} UT,   73.1 [sec] since BAT Trigger Time
CENTROID_X:      314.88,  raw= 315  [pixels]
CENTROID_Y:      328.55,  raw= 329  [pixels]
ROLL:            280.06 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   72.48
GRB_POS_XRT_Z:   22.59
IMAGE_URL:       sw00676595000msxps_rw.img
SUN_POSTN:       341.13d {+22h 44m 30s}   -7.98d {-07d 58' 56"}
SUN_DIST:        125.98 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.57d {+14h 54m 18s}  -12.17d {-12d 10' 16"}
MOON_DIST:       118.53 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.25, 15.56 [deg] galactic lon,lat of the burst
ECL_COORDS:      105.44,  4.41 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:38:35 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     676595,   Seg_Num: 0
GRB_RA:          107.322d {+07h 09m 17s} (J2000),
                 107.573d {+07h 10m 18s} (current),
                 106.546d {+07h 06m 11s} (1950)
GRB_DEC:         +26.956d {+26d 57' 23"} (J2000),
                 +26.929d {+26d 55' 46"} (current),
                 +27.037d {+27d 02' 15"} (1950)
GRB_DATE:        17446 TJD;    59 DOY;   16/02/28
GRB_TIME:        63272.47 SOD {17:34:32.47} UT
TRIGGER_INDEX:   155
GRB_PHI:          35.34 [deg]
GRB_THETA:        21.68 [deg]
DELTA_TIME:      -37.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     29.91 [sigma]
IMAGE_SIGNIF:    10.09 [sigma]
LC_URL:          sw00676595000msb.lc
SUN_POSTN:       341.13d {+22h 44m 30s}   -7.98d {-07d 58' 54"}
SUN_DIST:        125.97 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.59d {+14h 54m 22s}  -12.17d {-12d 10' 29"}
MOON_DIST:       118.54 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.57 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      105.44,  4.44 [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 = 64.17,-20.37 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:38:56 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.316d {+07h 09m 16s} (J2000)
POINT_DEC:       +26.949d {+26d 56' 57"} (J2000)
POINT_ROLL:      280.056d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63355.68 SOD {17:35:55.68} UT,   83.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.869
N_STARS:         151
X_OFFSET:        365 [pixels]
Y_OFFSET:        462 [pixels]
X_MAX:           1324 [pixels]
Y_MAX:           1421 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw00676595000msufc0083.fits
SUN_POSTN:       341.13d {+22h 44m 30s}   -7.98d {-07d 58' 53"}
SUN_DIST:        125.97 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.59d {+14h 54m 22s}  -12.18d {-12d 10' 31"}
MOON_DIST:       118.55 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:39:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.316d {+07h 09m 16s} (J2000)
POINT_DEC:       +26.949d {+26d 56' 57"} (J2000)
POINT_ROLL:      280.056d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63355.68 SOD {17:35:55.68} UT,   83.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.869
N_STARS:         151
X_OFFSET:        365 [pixels]
Y_OFFSET:        462 [pixels]
X_MAX:           1324 [pixels]
Y_MAX:           1421 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw00676595000msufc0083.fits
SUN_POSTN:       341.13d {+22h 44m 30s}   -7.98d {-07d 58' 53"}
SUN_DIST:        125.97 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.60d {+14h 54m 23s}  -12.18d {-12d 10' 34"}
MOON_DIST:       118.55 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 28 Feb 16 17:41:39 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.316d {+07h 09m 16s} (J2000)
POINT_DEC:       +26.949d {+26d 56' 57"} (J2000)
ROLL:            280.056d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63355.68 SOD {17:35:55.68} UT,   83.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478373771
X_OFFSET:        685 [pixels]
Y_OFFSET:        782 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       845
Y_GRB_POS:       942
BINNING_INDEX:   1
IM_URL:          sw00676595000msuni0099.fits
SUN_POSTN:       341.13d {+22h 44m 31s}   -7.98d {-07d 58' 51"}
SUN_DIST:        125.97 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.62d {+14h 54m 28s}  -12.18d {-12d 10' 50"}
MOON_DIST:       118.57 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 28 Feb 16 17:41:56 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.316d {+07h 09m 16s} (J2000)
POINT_DEC:       +26.949d {+26d 56' 57"} (J2000)
ROLL:            280.056d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63355.68 SOD {17:35:55.68} UT,   83.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478373771
X_OFFSET:        685 [pixels]
Y_OFFSET:        782 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       845
Y_GRB_POS:       942
BINNING_INDEX:   1
IM_URL:          sw00676595000msuni0099.fits
SUN_POSTN:       341.13d {+22h 44m 31s}   -7.98d {-07d 58' 51"}
SUN_DIST:        125.97 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.62d {+14h 54m 28s}  -12.18d {-12d 10' 52"}
MOON_DIST:       118.57 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 #19107
D. Malesani (DARK/NBI), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), L. M. McCauley (PSU), D. M. Palmer (LANL), T. G. R. Roegiers (PSU) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:
At 17:34:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160228A (trigger=676595). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 107.322, +26.956 which is
```
   RA(J2000)  =  07h 09m 17s
   Dec(J2000) = +26d 57' 23"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several separated peaks with a total duration of about 30 sec. The peak count rate was ~4200 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 17:35:45.5 UT, 73.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 107.31671, 26.93103 which is equivalent to:
```
   RA(J2000)  = 07h 09m 16.01s
   Dec(J2000) = +26d 55' 51.7"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 91 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 consistent with the Galactic value of 9.03 x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 1.37e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of nominal 150.000 seconds with the White filter starting 83 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. Data from the 2.7'x2.7' sub-image are not available at this time. 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 0.06.
Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 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 28 Feb 16 17:47:43 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
POINT_ROLL:      280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63568.34 SOD {17:39:28.34} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.771
N_STARS:         81
X_OFFSET:        365 [pixels]
Y_OFFSET:        462 [pixels]
X_MAX:           1324 [pixels]
Y_MAX:           1421 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00676595000msufc0295.fits
SUN_POSTN:       341.13d {+22h 44m 32s}   -7.98d {-07d 58' 45"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.66d {+14h 54m 40s}  -12.19d {-12d 11' 32"}
MOON_DIST:       118.62 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:48:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
POINT_ROLL:      280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63568.34 SOD {17:39:28.34} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.771
N_STARS:         81
X_OFFSET:        365 [pixels]
Y_OFFSET:        462 [pixels]
X_MAX:           1324 [pixels]
Y_MAX:           1421 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00676595000msufc0295.fits
SUN_POSTN:       341.13d {+22h 44m 32s}   -7.98d {-07d 58' 45"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.67d {+14h 54m 40s}  -12.19d {-12d 11' 35"}
MOON_DIST:       118.63 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 28 Feb 16 17:48:30 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     676595,   Seg_Num: 0
GRB_RA:          107.3161d {+07h 09m 15.86s} (J2000),
                 107.5667d {+07h 10m 16.01s} (current),
                 106.5400d {+07h 06m 09.60s} (1950)
GRB_DEC:         +26.9316d {+26d 55' 53.7"} (J2000),
                 +26.9046d {+26d 54' 16.6"} (current),
                 +27.0127d {+27d 00' 45.5"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63482.00 SOD {17:38:02.00} UT,   209.5 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       341.13d {+22h 44m 32s}   -7.98d {-07d 58' 44"}
SUN_DIST:        125.97 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.67d {+14h 54m 41s}  -12.19d {-12d 11' 38"}
MOON_DIST:       118.63 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.25, 15.56 [deg] galactic lon,lat of the burst
ECL_COORDS:      105.44,  4.42 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:48:54 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
ROLL:            280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63568.34 SOD {17:39:28.34} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     478373984
X_OFFSET:        685 [pixels]
Y_OFFSET:        782 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       845
Y_GRB_POS:       942
BINNING_INDEX:   1
IM_URL:          sw00676595000msuni0311.fits
SUN_POSTN:       341.13d {+22h 44m 32s}   -7.98d {-07d 58' 44"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.67d {+14h 54m 42s}  -12.19d {-12d 11' 41"}
MOON_DIST:       118.63 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 28 Feb 16 17:49:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
ROLL:            280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  63568.34 SOD {17:39:28.34} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     478373984
X_OFFSET:        685 [pixels]
Y_OFFSET:        782 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       845
Y_GRB_POS:       942
BINNING_INDEX:   1
IM_URL:          sw00676595000msuni0311.fits
SUN_POSTN:       341.13d {+22h 44m 32s}   -7.98d {-07d 58' 44"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.68d {+14h 54m 42s}  -12.20d {-12d 11' 43"}
MOON_DIST:       118.63 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 28 Feb 16 17:52:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
POINT_ROLL:      280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  64146.81 SOD {17:49:06.81} UT,   874.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.399
N_STARS:         190
X_OFFSET:        125 [pixels]
Y_OFFSET:        222 [pixels]
X_MAX:           1564 [pixels]
Y_MAX:           1661 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00676595000msufc0874.fits
SUN_POSTN:       341.14d {+22h 44m 33s}   -7.98d {-07d 58' 41"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.70d {+14h 54m 49s}  -12.20d {-12d 12' 06"}
MOON_DIST:       118.66 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 28 Feb 16 17:52:28 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
POINT_ROLL:      280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  64146.81 SOD {17:49:06.81} UT,   874.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.399
N_STARS:         190
X_OFFSET:        125 [pixels]
Y_OFFSET:        222 [pixels]
X_MAX:           1564 [pixels]
Y_MAX:           1661 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00676595000msufc0874.fits
SUN_POSTN:       341.14d {+22h 44m 33s}   -7.98d {-07d 58' 41"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.70d {+14h 54m 49s}  -12.20d {-12d 12' 06"}
MOON_DIST:       118.66 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 28 Feb 16 17:53:21 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
ROLL:            280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  64146.81 SOD {17:49:06.81} UT,   874.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478374562
X_OFFSET:        684 [pixels]
Y_OFFSET:        781 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       844
Y_GRB_POS:       941
BINNING_INDEX:   1
IM_URL:          sw00676595000msuni0890.fits
SUN_POSTN:       341.14d {+22h 44m 33s}   -7.98d {-07d 58' 40"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.71d {+14h 54m 51s}  -12.20d {-12d 12' 12"}
MOON_DIST:       118.67 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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:     Sun 28 Feb 16 17:53:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     676595,   Seg_Num: 0
POINT_RA:        107.314d {+07h 09m 15s} (J2000)
POINT_DEC:       +26.948d {+26d 56' 52"} (J2000)
ROLL:            280.055d
IMG_START_DATE:  17446 TJD;    59 DOY;   16/02/28
IMG_START_TIME:  64146.81 SOD {17:49:06.81} UT,   874.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478374562
X_OFFSET:        684 [pixels]
Y_OFFSET:        781 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       844
Y_GRB_POS:       941
BINNING_INDEX:   1
IM_URL:          sw00676595000msuni0890.fits
SUN_POSTN:       341.14d {+22h 44m 33s}   -7.98d {-07d 58' 40"}
SUN_DIST:        125.96 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      223.71d {+14h 54m 51s}  -12.20d {-12d 12' 14"}
MOON_DIST:       118.67 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      190.23, 15.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.43,  4.43 [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 #19108
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 160228A, we find an enhanced XRT position of the afterglow: RA, Dec: 107.3162, 26.9317 which is equivalent to:
```
   RA (J2000)  = 07 09 15.90
   Dec (J2000) = +26 55 54.0
```
with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/676595.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #19110
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 732 s of XRT Photon Counting mode data and 1 UVOT images for GRB 160228A, 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 = 107.31636, +26.93173 which is equivalent to:
```
RA (J2000): 07h 09m 15.93s
Dec (J2000): +26d 55' 54.2"
```
with an uncertainty of 1.9 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 #19112
K. Wiersema (University of Leicester) reports on behalf of the Oadby Transients Team:
We observed the field of GRB 160228A (Malesani et al. GCN 19107) using the 0.5m telescope at the observatory of the University of Leicester, at Oadby (UK). In a series of V band exposures, starting at 19:52 UT on 28 February 2016 (~2.3 hours after burst), we find no source in or near the XRT error circle (Beardmore et al. GCN 19110) to a limit of V<19.5 mag.
GCN Circular #19113
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), 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 160228A (trigger #676595) (Malesani et al., GCN Circ. 19107). The BAT ground-calculated position is RA, Dec = 107.311, 26.946 deg which is
```
  RA(J2000)  =  07h 09m 14.6s
  Dec(J2000) = +26d 56' 45.3"
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%.
The mask-weighted light curve shows a short spike from ~T0 to ~T+3 s, followed by an extended emission till ~T+120 s. This structure is similar to those short GRBs with extended emission (e.g., Norris et al. 2006). T90 (15-350 keV) is 98.36 +- 23.35 sec (estimated error including systematics).
The time-averaged spectrum from T-0.01 to T+116.104 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.31 +- 0.11. The fluence in the 15-150 keV band is (2.0 +- 0.1) x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band is 1.2 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
Moreover, spectral analyses for the short pulse and extended emission intervals show that the short pulse is harder than the extended emission. Both the short-pulse spectrum (T0-0.008 to T0+3.188 s) and the extended-emission spectrum (T0+3.188 to T0+116.104 s) are best fit by the simple power-law model, with the power-law index of (0.88 +/- 0.17) and (1.35 +/- 0.12), respectively.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/676595/BA/
GCN Circular #19114
C. Delvaux, T. Schweyer (both MPE Garching), D. A. Kann (TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 160228A (Swift trigger 676595; Malesani et al., GCN #19107) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO La Silla Observatory (Chile).
Observations started at 00:02 UT on 2016-02-29, 6.4h after the GRB trigger. They were performed at an average seeing of 1.2" and at an average airmass of 1.9.
We detect a single source at the edge of the Swift-XRT error circle reported by Beardmore et al. (GCN #19110) at
```
RA (J2000.0) = 07h09m15.82s
Dec. (J2000.0) = +26d55'53.8"
```
with an uncertainty of 0.2" in each coordinate.
Based on 132 min of exposure in g'r'i'z' and 110 min in JHK, at a mid-time of 01:46 UT, we derive the following preliminary magnitudes and upper limits (in AB system):
```
g' = 24.4 +/- 0.1 mag,
r' = 24.4 +/- 0.1 mag,
i' = 23.8 +/- 0.2 mag,
z' = 24.1 +/- 0.3 mag,
J > 22.3 mag,
H > 21.6 mag, and
K > 19.4 mag.
```
We note the presence of a very close-by (separation < 2") extended bluish object, lying outside the Swift-XRT error circle, which could be the host galaxy of the candidate. Another host could be a larger, brighter galaxy lying at the north of the Swift-XRT error circle (separation ~ 6.6").
We found no evidence of fading of the candidate. Therefore, we cannot affirm the detected source is the optical afterglow.
Given detections and upper limits are calibrated against GROND zeropoints as well as 2MASS field stars. No correction for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.056 mag in the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.
GCN Circular #19117
B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), T.G.R. Roegiers (PSU) and D. Malesani report on behalf of the Swift-XRT team:
We have analysed 5.9 ks of XRT data for GRB 160228A (Malesani et al. GCN Circ. 19107), from 63 s to 40.4 ks after the BAT trigger. The data comprise 129 s in Windowed Timing (WT) mode (the first 8 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 Beardmore et al. (GCN Circ. 19108).
The light curve can be modelled with an initial power-law decay with an index of alpha=1.01 (+0.26, -0.32), followed by a break at T+125 s to an alpha of 2.94 (+0.16, -0.14).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.22 (+0.18, -0.16). The best-fitting absorption column is 2.6 (+1.8, -1.3) x 10^21 cm^-2, in excess of the Galactic value of 9.0 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.63 (+0.30, -0.28) and a best-fitting absorption column of 1.8 (+1.4, -0.9) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.4 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.8 (+1.4, -0.9) x 10^21 cm^-2
Galactic foreground: 9.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.63 (+0.30, -0.28)
```
If the light curve continues to decay with a power-law decay index of 2.94, the count rate at T+24 hours will be 7.1 x 10^-8 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.1 x 10^-18 (3.7 x 10^-18) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00676595.
This circular is an official product of the Swift-XRT team.
GCN Circular #19118
A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda Blagoveschensk Educational State University, Blagoveschensk
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University
V.Krushinski, I.Zalozhnich, A. Popov Ural State University, Kourovka
K.Ivanov, N.M.Budnev, O.Gres, V.A.Poleshchuk Irkutsk State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
MASTER-Amur robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB160228A 20 sec after notice time and 40 sec after trigger time at 2016-02-28 17:35:12 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (Malesani et al., GCN 19107) and at GROND OT position (Delvaux et al., GCN 19114). The 5-sigma upper limit has been about 15.1 mag (unfilterd).
We have 3 images during extended emission (Stamatikos et al., GCN 19113) with limit 15.2 .
The message may be cited.
GCN Circular #19119
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 (GSFC/STScI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos=C3=A9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=C3=BAs Gonz=C3=A1= lez (UNAM), Carlos Rom=C3=A1n-Z=C3=BA=C3=B1iga (UNAM), Neil Gehrels (GSFC), Harvey Mo= seley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 160228A (Malesani et al., GCN Circular 19107= ) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.or= g) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=C3=B3mico Nacional on Sierra San Pedro M=C3=A1rtir from 2016/02 29.12 to 2016/02 29= .38 UTC (9.23 to 15.50 hours after the BAT trigger), obtaining a total of 4.27 hours exposure in the r and i bands and 1.79 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following 3-sigma upper limits:
```
  r > 24.46
  i > 24.39
  Z > 23.21
  Y > 22.76
  J > 22.43
  H > 22.10
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We do not detect the candidate afterglow seen by Delvaux et al. (GCN Circ 19114) with GROND. Our upper-limits in rZJH are above their detections. However, there is weak evidence for fading in i, since GROND detected i =3D 23.8 =C2=B1 0.2 at about 7.5 hours and we obtain i > 24.4 at 12.4 hours.
We see suggestions of the "extended bluish object=E2=80=9D mentioned by D= elvaux et al. in our r-band image. We also clearly detect the "larger, brighter galaxy=E2=80=9D at 07:09:15.89 +26:55:59.3 (=C2=B10.5=E2=80=9D) with:
```
  r =3D 22.64 =C2=B1 0.07
  i =3D 22.17 =C2=B1 0.05
  Z =3D 22.07 =C2=B1 0.13
  Y =3D 21.69 =C2=B1 0.14
  J =3D 21.60 =C2=B1 0.17
  H =3D 21.64 =C2=B1 0.24
```
We thank the staff of the Observatorio Astron=C3=B3mico Nacional in San Pedro M=C3=A1rtir.
GCN Circular #19120
E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of Swift GRB 160228A (Malesani et al., GCN 19107) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Feb.28 (UT) 18:31:31. Within enhanced XRT position (Beardmore et al., GCN 19110) we do not detect any optical object. In particular we do not detect candidate of optical afterglow (Delvaux et al., GCN 19114). We barely detect extended bluish object mentioned in (Delvaux et al., GCN 19114). Preliminary photometry of a combined image is following
```
Date        UT start   t-T0    Filter   Exp.   UL (3sigma)
                       (mid, days)       (s)
```
2016-02-28 18:31:31 0.06044 R 60*60 22.2
Photometry is base on nearby USNO-B1.0 stars
```
USNO-B.1_id     R2
1169-0155723    18.59
1169-0155657    19.12
1169-0155662    18.92
1168-0146568    18.65
1169-0155709    19.49
```
GCN Circular #19121
J. P. Norris (BSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC), N. Gehrels (GSFC), D. Malesani (DARK/NBI), T. Sakamoto (AGU), and E. Troja (GSFC/UMCP) report:
We report on the spectral lag analysis of the initial pulse and extended emission measurements of GRB 160228A (Malesani et al., GCN Circ. 19107).
Using a 32-ms binned light curve (which is the shortest time bin possible for the lag analysis in this case), the lag of the initial pulse (~T0 to ~T0+2 s) for the 100-350 keV to 25-50 keV bands is estimated as 75 (+100/-60) ms (with 1-sigma error).
Despite the large error bars, the lag is inconsistent with zero, and thus the lag of the initial pulse is much more consistent with those from a long GRBs rather than short bursts (e.g., Norris et al. 2006).
Moreover, further analysis of the initial pulse intensity shows that it is only a factor of several more intense than the extended emission in both the 1-s binned and 32-ms binned light curves, which is much less prominent than the usual short GRBs with extended emission (e.g., Norris et al. 2006).
GCN Circular #19123
F. E. Marshall (NASA/GSFC) and D. Malesani (DARK/NBI) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160228A 83 s after the BAT trigger (Malesani et al., GCN Circ. 19107). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 19110) or the position of the GROND optical afterglow candidate (Delvaux et al. GCN Circ. 19114) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposures and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            83          233          147         >20.2
u_FC               296          546          246         >19.5
white               83        10111          342         >20.5
v                  625         5975          236         >19.0
b                  551         6695          138         >19.8
u                  296         6589          462         >20.2
w1                 675         6385          235         >19.8
m2                 650         6179          236         >19.9
w2                 601         5770          235         >19.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.06 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #19186
T. Kruehler (MPE Garching), D. Malesani (DARK/NBI), D. Xu (NAOC/CAS), J. Bolmer (MPE Garching), J. P. U. Fynbo, D. Perley (both DARK/NBI), D. A. Kann (TLS Tautenburg), J. Greiner and J. F. Graham (both MPE Garching) report on behalf of a larger collaboration:
We re-observed the field of GRB 160228A (Swift-trigger 676595, Malesani et al. GCN #19107) with GROND mounted at the 2.2m MPG telescope at ESO La Silla observatory. Simultaneous observations in seven filters (g'r'i'z'JHK) started at 01:13 UT on 2016-03-03 (80 h after the GRB) and consisted of images with a total integration time of 72 minutes in g'r'i'z' and 60 minutes in JHK.
The source reported as candidate afterglow in our earlier imaging (Delvaux et al. GCN #19114) has faded beyond the detection limit of the new data (r' > 25.1 mag in the AB system), confirming it as the optical afterglow of GRB 160228A.
The nearby source (angular separation of 1.7") mentioned in Delvaux et al. (GCN #19114) is still clearly present and located at
```
RA (J2000.0) = 07:09:15.79
Dec. (J2000.0) = +26:55:52.4
```
with a preliminary brightness of r' = 24.2 +/- 0.3 mag.
The chance coincidence probability of finding an unrelated object of this magnitude within a distance of 1.7" is 0.04 (following Bloom et al. 2002, AJ, 123, 1111), and we hence consider this object as a host galaxy candidate of GRB 160228A. While the chance coincidence probability is quite low, we note that the angular separation would be unusually large for long GRBs.
A spectrum of the possible host was taken on 2016-03-12 with the VLT equipped with the X-shooter spectrograph. The spectrum covers the wavelength range 3000-20000 AA and has an exposure time of 4x1200 s. In the red part of the spectrum, we detect two emission lines which we interpret as [O III] (5007) and Halpha at a common redshift z = 1.64.
We acknowledge excellent support from the observing staff at La Silla and Paranal, in particular Giovanni Carraro, Boris Haeussler, Jose Velasquez, and Willem-Jan de Wit.

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Jochen Greiner, last update: 14-Mar-2016 [Disclaimer]