Gamma-ray Burst 160225A

(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:     Thu 25 Feb 16 14:24:01 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     675998,   Seg_Num: 0
GRB_RA:          164.242d {+10h 56m 58s} (J2000),
                 164.482d {+10h 57m 56s} (current),
                 163.496d {+10h 53m 59s} (1950)
GRB_DEC:         +53.655d {+53d 39' 19"} (J2000),
                 +53.569d {+53d 34' 07"} (current),
                 +53.923d {+53d 55' 22"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       99383 [cnts]    Image_Peak=964 [image_cnts]
TRIGGER_DUR:     26.880 [sec] 
TRIGGER_INDEX:   480     E_range: 25-100 keV
BKG_INTEN:       225352 [cnts]
BKG_TIME:        51544.10 SOD {14:19:04.10} UT
BKG_DUR:         64 [sec]
GRB_DATE:        17443 TJD;    56 DOY;   16/02/25
GRB_TIME:        51656.42 SOD {14:20:56.42} UT
GRB_PHI:          19.99 [deg]
GRB_THETA:        41.58 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.81 [sigma]
IMAGE_SIGNIF:    8.62 [sigma]
MERIT_PARAMS:     +1  +0  +0  +5  +2  -1  +0  +0 +71  +0 
SUN_POSTN:       338.17d {+22h 32m 41s}   -9.16d {-09d 09' 24"}
SUN_DIST:        135.30 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.70d {+12h 30m 47s}   -1.64d {-01d 38' 29"}
MOON_DIST:        58.50 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.55, 56.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      140.63, 42.45 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 14.35,10.64 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Feb 16 14:25:04 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     675998,   Seg_Num: 0
GRB_RA:          164.242d {+10h 56m 58s} (J2000),
                 164.482d {+10h 57m 56s} (current),
                 163.496d {+10h 53m 59s} (1950)
GRB_DEC:         +53.655d {+53d 39' 19"} (J2000),
                 +53.569d {+53d 34' 07"} (current),
                 +53.923d {+53d 55' 22"} (1950)
GRB_DATE:        17443 TJD;    56 DOY;   16/02/25
GRB_TIME:        51656.42 SOD {14:20:56.42} UT
TRIGGER_INDEX:   480
GRB_PHI:          19.99 [deg]
GRB_THETA:        41.58 [deg]
DELTA_TIME:      -31.00 [sec]
TRIGGER_DUR:     26.880 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.81 [sigma]
IMAGE_SIGNIF:    8.62 [sigma]
LC_URL:          sw00675998000msb.lc
SUN_POSTN:       338.17d {+22h 32m 41s}   -9.16d {-09d 09' 23"}
SUN_DIST:        135.30 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.70d {+12h 30m 49s}   -1.64d {-01d 38' 38"}
MOON_DIST:        58.50 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.55, 56.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      140.63, 42.45 [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 = 14.35,10.64 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Feb 16 14:34:57 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     675998,   Seg_Num: 0
POINT_RA:        164.227d {+10h 56m 55s} (J2000)
POINT_DEC:       +53.637d {+53d 38' 14"} (J2000)
IMG_START_DATE:  17443 TJD;    56 DOY;   16/02/25
IMG_START_TIME:  52490.62 SOD {14:34:50.62} UT,   834.2 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Feb 16 14:37:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     675998,   Seg_Num: 0
POINT_RA:        164.227d {+10h 56m 55s} (J2000)
POINT_DEC:       +53.637d {+53d 38' 12"} (J2000)
POINT_ROLL:      8.492d
IMG_START_DATE:  17443 TJD;    56 DOY;   16/02/25
IMG_START_TIME:  52495.52 SOD {14:34:55.52} UT,   839.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.636
N_STARS:         74
X_OFFSET:        640 [pixels]
Y_OFFSET:        519 [pixels]
X_MAX:           1599 [pixels]
Y_MAX:           1478 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00675998000msufc0839.fits
SUN_POSTN:       338.18d {+22h 32m 43s}   -9.15d {-09d 09' 11"}
SUN_DIST:        135.31 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.80d {+12h 31m 13s}   -1.68d {-01d 40' 37"}
MOON_DIST:        58.55 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.58, 56.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      140.63, 42.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Feb 16 14:38:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     675998,   Seg_Num: 0
POINT_RA:        164.227d {+10h 56m 55s} (J2000)
POINT_DEC:       +53.637d {+53d 38' 12"} (J2000)
POINT_ROLL:      8.492d
IMG_START_DATE:  17443 TJD;    56 DOY;   16/02/25
IMG_START_TIME:  52495.52 SOD {14:34:55.52} UT,   839.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.636
N_STARS:         74
X_OFFSET:        640 [pixels]
Y_OFFSET:        519 [pixels]
X_MAX:           1599 [pixels]
Y_MAX:           1478 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00675998000msufc0839.fits
SUN_POSTN:       338.18d {+22h 32m 43s}   -9.15d {-09d 09' 11"}
SUN_DIST:        135.31 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.81d {+12h 31m 14s}   -1.68d {-01d 40' 42"}
MOON_DIST:        58.55 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.58, 56.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      140.63, 42.43 [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:     Thu 25 Feb 16 14:38:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     675998,   Seg_Num: 0
GRB_RA:          164.2284d {+10h 56m 54.81s} (J2000),
                 164.4683d {+10h 57m 52.38s} (current),
                 163.4821d {+10h 53m 55.70s} (1950)
GRB_DEC:         +53.6699d {+53d 40' 11.6"} (J2000),
                 +53.5833d {+53d 34' 59.9"} (current),
                 +53.9373d {+53d 56' 14.3"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17443 TJD;    56 DOY;   16/02/25
IMG_START_TIME:  52500.00 SOD {14:35:00.00} UT,   843.6 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       338.18d {+22h 32m 43s}   -9.15d {-09d 09' 10"}
SUN_DIST:        135.28 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.81d {+12h 31m 15s}   -1.68d {-01d 40' 46"}
MOON_DIST:        58.58 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.54, 56.11 [deg] galactic lon,lat of the burst
ECL_COORDS:      140.61, 42.46 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Feb 16 14:39:11 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     675998,   Seg_Num: 0
POINT_RA:        164.227d {+10h 56m 55s} (J2000)
POINT_DEC:       +53.637d {+53d 38' 12"} (J2000)
ROLL:            8.492d
IMG_START_DATE:  17443 TJD;    56 DOY;   16/02/25
IMG_START_TIME:  52495.52 SOD {14:34:55.52} UT,   839.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478103711
X_OFFSET:        959 [pixels]
Y_OFFSET:        838 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1119
Y_GRB_POS:       998
BINNING_INDEX:   1
IM_URL:          sw00675998000msuni0855.fits
SUN_POSTN:       338.18d {+22h 32m 43s}   -9.15d {-09d 09' 10"}
SUN_DIST:        135.31 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.82d {+12h 31m 16s}   -1.68d {-01d 40' 50"}
MOON_DIST:        58.56 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.58, 56.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      140.63, 42.43 [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:     Thu 25 Feb 16 14:39:33 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     675998,   Seg_Num: 0
POINT_RA:        164.227d {+10h 56m 55s} (J2000)
POINT_DEC:       +53.637d {+53d 38' 12"} (J2000)
ROLL:            8.492d
IMG_START_DATE:  17443 TJD;    56 DOY;   16/02/25
IMG_START_TIME:  52495.52 SOD {14:34:55.52} UT,   839.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478103711
X_OFFSET:        959 [pixels]
Y_OFFSET:        838 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1119
Y_GRB_POS:       998
BINNING_INDEX:   1
IM_URL:          sw00675998000msuni0855.fits
SUN_POSTN:       338.18d {+22h 32m 43s}   -9.15d {-09d 09' 09"}
SUN_DIST:        135.31 [deg]   Sun_angle= 11.6 [hr] (West of Sun)
MOON_POSTN:      187.82d {+12h 31m 16s}   -1.68d {-01d 40' 53"}
MOON_DIST:        58.56 [deg]
MOON_ILLUM:      93 [%]
GAL_COORDS:      153.58, 56.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      140.63, 42.43 [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 #19075
M. H. Siegel (PSU), A. P. Beardmore (U Leicester), P.A. Evans (U Leicester), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), L. M. McCauley (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), T. G. R. Roegiers (PSU), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team:
At 14:20:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160225A (trigger=675998). Swift's slew was briefly delayed due to an observing constraint. The BAT on-board calculated location is RA, Dec 164.242, +53.655 which is
```
  RA(J2000) = 10h 56m 58s
  Dec(J2000) = +53d 39' 19"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed multiple spikes over a 50 second interval. The peak count rate was ~1500 counts/sec (15-350 keV) at ~3 sec after the trigger.
The XRT began observing the field at 14:34:50.6 UT, 834.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 164.22846, 53.66991 which is equivalent to:
```
   RA(J2000)  = 10h 56m 54.83s
   Dec(J2000) = +53d 40' 11.7"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 60 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (9.69 x 10^19 cm^-2, Willingale et al. 2013), with an excess column of 3.8 (+4.26/-3.38) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 839 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 0.01.
Burst Advocate for this burst is M. H. Siegel (siegel 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 Circular #19076
A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, N.Tyurina, V. Lipunov, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University
D.Buckley, S. Potter, M.Kotze South African Astronomical Observatory
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
R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB160225A 20 sec after notice time and 204 sec after Swift BAT trigger time at 2016-02-25 14:24:20 UT (Siegel et al, 19075). On our first (40s exposure) set we haven`t found optical transient within SWIFT error-box (ra=10 56 58 dec=+53 39 17 r=0.050000). The 5-sigma upper limit has been about 17.5 mag
The message may be cited.
GCN Circular #19077
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 2168 s of XRT Photon Counting mode data and 1 UVOT images for GRB 160225A, 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 = 164.22971, +53.66998 which is equivalent to:
```
RA (J2000): 10h 56m 55.13s
Dec (J2000): +53d 40' 11.9"
```
with an uncertainty of 1.7 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 #19078
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the Swift GRB 160225A (Siegel et al., GCN 19075) with Zeiss-1000 (West) 1-m telescope of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on Feb. 25 (UT) 14:46:05. In the first images we do not detect any optical source within enhanced Swift-XRT position (Goad et al., GCN 19077). Preliminary photometry of one of single 90 s image is following
```
Date        UT start   t-T0    Filter  Exp.   UL (3sigma)
                       (mid, days)     (s)

2016-02-25 14:47:35   0.01903  R      1*90    18.90
```
GCN Circular #19080
T. Yoshii, Y.Saito, T.Fujiwara, Y. Tachibana, Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 160225A (M. H. Siegel et al., GCN Circular #19075) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2016-01-04 14:24:14 UT (198 sec after the burst) and we detected the optical counterpart in Rc and Ic band. The measured magnitudes were listed as follows.
We obtained following limits for the magnitudes.
```
T0+[sec]    MID-UT      T-EXP[sec]         g'              Rc                      Ic
-------------------------------------------------------------------------------------------
378        14:27:14       270            > 19.4        18.2 +/- 0.1        17.1 +/- 0.2 
-------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used GSC2.3 catalog for flux calibration.
GCN Circular #19081
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of MITSuME and OISTER collaboration:
We observed the field of GRB 160225A (Siegel et al., GCNC 19075) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2016-02-25 14:26:51 UT (~5.9 min after the burst). We detected the previously reported afterglow (Yoshii et al., GCNC 19080) in Rc and Ic bands.
Photometric results and three sigma upper limit of the OT are listed below. We used SDSS-DR7 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc  Rc_err  Ic  Ic_err
------------------------------------------------------------------
0.00777    14:32:08     540.0   >19.4   18.6 0.2    17.8 0.2
------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #19082
K. Wiersema, N. Tanvir (U. of Leicester), A. Levan (U. of Warwick) and G. Pugliese (API/UvA) report:
We observed the position of GRB 160225A (Siegel et al. GCN 19075) with the 4.2m William Herschel Telescope (WHT). Using the LIRIS instrument we obtained 20x60 sec in Y band, 20x60 sec in J band and 60x20 sec in Ks band. Observations started at 19:57 UT on 25 February 2016 (i.e. 5.62 hours after burst). A point source is clearly detected near the enhanced XRT position (Goad et al. GCN 19077), at position:
```
RA (J2000):  10 56 55.18
Dec (J2000): +53 40 13.7
```
with an uncertainty of 0.5 arc seconds. The source is seen in all three filters, and has magnitudes J~20.6 mag and Ks~19.2 mag (Vega magnitudes, calibrated using 2MASS objects in the field).
We acknowledge excellent support from Raine Karjalainen (ING).
GCN Circular #19083
D. Xu (NAOC/CAS), D. Malesani (DARK/NBI), N. Tanvir (U. of Leicester), A. Kvammen (NOT) report on behalf of a large collaboration:
We observed the field of GRB 160225A (Siegel et al. GCN 19075) using the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 23:31:27 UT on 2016-02-25 (i.e., 8.56 hr post-burst) and 9x200s exposures were obtained in the Sloan r- and i-band, respectively.
The optical afterglow is detected at the WHT position (Wiersema et al., GCN 19082) and presumably also the MITSuME position (Yoshii et al. GCN 19080). We measured m(r)=23.25 +/- 0.15 at 8.86 hr post-burst and m(i) = 22.55 +/- 0.07 at 9.48 hr post-burst, calibrated with nearby SDSS stars.
GCN Circular #19084
J.A. Kennea (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU) and M.H. Siegel report on behalf of the Swift-XRT team:
We have analysed 9.4 ks of XRT data for GRB 160225A (Siegel et al. GCN Circ. 19075), from 841 s to 31.8 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 19077).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.91 (+/-0.06).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.11 (+/-0.14). The best-fitting absorption column is 5.7 (+3.0, -2.7) x 10^20 cm^-2, in excess of the Galactic value of 9.7 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.0 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     5.7 (+3.0, -2.7) x 10^20 cm^-2
Galactic foreground: 9.7 x 10^19 cm^-2
Excess significance: 2.9 sigma
Photon index:	     2.11 (+/-0.14)
```
If the light curve continues to decay with a power-law decay index of 0.91, the count rate at T+24 hours will be 0.013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x 10^-13 (4.5 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/00675998.
This circular is an official product of the Swift-XRT team.
GCN Circular #19086
L. P. Xin, X. F. Wang, J. Y. Wei, X. H. Han, Y. L. Qiu, J. Wang, C. Wu, J. S. Deng report:
We observed GRB 160225A (Siegel et al. GCN 19075) with 80cm TNT telescope, located at Xinglong obervatory, China, at 14:24:26 UT, about 3.5 min after the burst. The optical afterglow (Wiersema et al., GCN 19082) near the enhanced XRT errorbox (Goad et al., GCN 19082) was detected in our white and R-band images.
The brightness of the optical afterglow is about 17.58 mag at the mid time of 3.67 min afer the burst, calibrated by the USNO B1.0 star (RA=10:56:59.4 DEC=+53:40:45 R2=15.26mag).
We thank excellent support of the Xinglong 80cm TNT staff, particularly YunPeng Wang.
The message may be cited.
GCN Circular #19087
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160225A 839 s after the BAT trigger (Siegel et al., GCN Circ. 19075). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 19077) or the previously reported optical position (Wierema, et al., GCN Circ. 19082) 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) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           839          989          147         >20.7
white              839         2657          342         >21.1
v                 1121         2708          194         >19.9
b                 1047         2632          194         >20.8
u                 1022         2608          156         >19.9
w1                 998         3036          311         >20.1
m2                1494         2912          236         >20.2
w2                1446         2683           78         >20.0
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #19088
Nat Butler (ASU), Alan M. Watson (UNAM), 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=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 160225A (Siegel, et al., GCN 19075) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2016/02 26.13 to 2016/02 26.28 UTC (12.72 to 16.34 hours after the BAT trigger), obtaining a total of 2.47 hours exposure in the r and i bands and 1.04 hours exposure in the Z, Y, J, and H bands.
We detect the WHT afterglow candidate (Wiersema, et al., GCN 19082), and find it to have faded. In comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections and upper limits (3-sigma):
```
  r > 24.09
  i =3D 23.03 +/- 0.16
  Z =3D 22.17 +/- 0.19
  Y > 22.35
  J =3D 22.06 +/- 0.33
  H > 21.74
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The r-band faintness suggests that this may be a moderate to high-z source. Fitting Milky Way, LMC, and SMC Exctinction Laws in Addition to the IGM (see, Littlejohns, et al. 2014), we find a photo-z of 5.54 (+0.35,-5.11; 90% conf.). Hence, a high-z solution is preferred, but a low-z origin is not ruled out.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #19089
N.Tyurina, E. Gorbovskoy, V. Lipunov, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University
A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda Blagoveschensk Educational State University, Blagoveschensk
D.Buckley, S. Potter, M.Kotze South African Astronomical Observatory
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
R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB160225A 20 sec after notice time and 204 sec after Swift BAT trigger (Siegel et al, 19075) time at 2016-02-25 14:24:20 UT (Gabovich et al, 19076).
We did not see any OT brighter 2-sigma. Our unfiltered camera sensitive up to 10 mk.
```
  Id 	 t_start-t_trigger    t_mean-t_trig   Exp.time  	Limit
                   s                 s            s            unfiltered

767291		204                224          40	        17.4
767293          256                281          50              17.6 
767295          318                348          60              17.0
769139          318                768         600              18.7 
769244          318               1187	      1200 	        19.0
```
Our unfiltered magnitude calibrated to USNOB1 stars as m =0.2B + 0.8R .
The message may be cited.
GCN Circular #19091
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. H. Siegel (PSU), M. Stamatikos (OSU), 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 160225A (trigger #675998) (Siegel, et al., GCN Circ. 19075). The BAT ground-calculated position is RA, Dec = 164.217, 53.659 deg which is
```
   RA(J2000)  =  10h 56m 52.1s 
   Dec(J2000) = +53d 39' 33.6" 
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%.
The mask-weighted light curve shows a multiple peak structure starting at T0-30 sec and ending at T0+50 sec. Although there is a hint of a emission after T0+100 sec, no data are available after T0+150 sec because the spacecraft slewed away to the GRB. T90 (15-350 keV) is 157 +- 70 sec (estimated error including systematics).
The time-averaged spectrum from T-30.38 to T+135.29 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.55 +- 0.23. The fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+37.13 sec in the 15-150 keV band is 1.0 +- 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/675998/BA/
GCN Circular #19093
Nat Butler (ASU), Alan M. Watson (UNAM), 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=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 160225A (Siegel, et al., GCN 19075) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2016/02 26.13 to 2016/02 26.51 UTC (12.72 to 21.97 hours after the BAT trigger), obtaining a total of 6.38 hours exposure in the r and i bands and 2.68 hours exposure in the Z, Y, J, and H bands.
With continued exposure (see, Butler, et al., GCN 19088), we now detect the WHT afterglow candidate (Wiersema, et al., GCN 19082) in all bands. In comparison with the SDSS DR9 and 2MASS catalogs, we find:
```
 r =3D 23.84 +/- 0.18
 i =3D 23.13 +/- 0.11
 Z =3D 22.71 +/- 0.18
 Y =3D 22.40 +/- 0.22
 J =3D 22.44 +/- 0.26
 H =3D 22.04 +/- 0.26
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We have fitted our photometry with a power-law source and redshifted Milky Way, LMC, or SMC extinction laws and IGM extinction (see, Littlejohns, et al. 2014). The detection in r conclusively rules out solutions with z > 5. However, there are a range of solutions up to z ~ 4.5.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #19097
S. Jeong (SKKU/IAA-CSIC), M. Im (SNU), Y. Urata (NCU), I. H. Park (SKKU) on behalf of larger collaboration:
We observed the field of GRB 160225A (Siegel, et al., GCN 19075) with the 1m telescope of Mt. Lemmon Optical Astronomy Observatory (LOAO) in Arizona. The series of images are taken in R filter starting on Feb. 26 02:45:36 UT (~12.4 hr post burst). We do not detect any optical afterglow candidate within the XRT enhanced error circle (Goad et al., GCN 19077) down to the following magnitudes calibrated with the nearby USNO-B1.0 stars. The non-detection is consistent with the previous UL report in similar epoch (Butler, et al., GCN 19088).
```
Mid Time      Exposure       Filter       Magnitude
(hr)           (s)
-------------------------------------------------------
12.83         9x300            R          > 21.5
-------------------------------------------------------
USNO-B1.0_id   R1    R2       
1436-0208445 14.73 15.26  14.995
1436-0208447 13.55 13.74  13.645
```
GCN Circular #19102
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the Swift GRB 160225A (Siegel et al., GCN 19075) with Zeiss-1000 (West, East) 1-m telescopes of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on Feb. 25 (UT) 14:45:56. In the first images we do not detect any optical source (Mazaeva et al., GCN 19078). In combine images we detect afterglow (Yoshiiet al., GCN 19080; Kuroda al., GCN 19081; Wiersema al., GCN 19082). Preliminary photometry of combined images is following
```
Date       UT start   t-T0    Filter  Exp.   OT     Err.  UL
                       (mid, days)     (s)

*2016-02-25 14:45:56   0.07022 R       87*90 20.75    0.16  21.4
  2016-02-25 15:30:59   0.09576 R       77*90 21.36    0.20  21.9
  2016-02-25 17:58:10   0.18146 R       52*90  n/d     n/a   21.7

*) Zeiss-1000 West telescope observations
```
Photometry is based on SDSS-DR9 nearby stars
```
SDSS-DR9_id            R(Lupton)
J105614.20+533500.1    15.35
J105714.63+533304.9    14.36
J105658.91+533304.1    15.77
```

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Jochen Greiner, last update: 27-Feb-2016 [Disclaimer]