GRB 160227A

M. H. Siegel (PSU), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC),
L. M. McCauley (PSU), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf
of the Swift Team:

At 19:32:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160227A (trigger=676423).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 194.788, +78.639 which is 
   RA(J2000) = 12h 59m 09s
   Dec(J2000) = +78d 38' 21"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a early complex
structure followed by a stronger peak at around 100 s after the trigger,
for a total duration of at least 160 s.  The peak count rate
was ~700 counts/sec (15-350 keV), at ~100 sec after the trigger. 

The XRT began observing the field at 19:34:39.9 UT, 151.8 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 194.7974, 78.6768 which is equivalent to:
   RA(J2000)  = +12h 59m 11.38s
   Dec(J2000) = +78d 40' 36.5"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 136 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 2.67e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 161 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	12:59:13.84 = 194.80767
  DEC(J2000) = +78:40:44.9  =  78.67913
with a 90%-confidence error radius of about 0.77 arc sec. This position is 11.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.32 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.05. 

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.)

E. Gorbovskoy, V. Lipunov,N.Tyurina, 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

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

D.Buckley, S. Potter, M.Kotze
South African Astronomical Observatory


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Ural was pointed to the  GRB160227A 30 after 
notice time and 115 sec after trigger time at 2016-02-27 19:34:03 UT. On 
our first (20s exposure)  set we  found 1 optical transient within SWIFT 
error-box (ra=12 59 08 dec=+78 38 19 r=0.050000) brighter then 17.6.


RA 12h 59m 14.13s
DEC +78d 40m 44.2s
  mag~17.36

The 5-sigma upper limit has been about 18.0
The message may be cited.

M. Andreev (Terskol Branch of INASAN), E. Mazaeva (IKI), V. Kozlov (IC 
AMER, NASU), A. Sergeev (Terskol Branch of INASAN), A. Pozanenko (IKI) 
report on behalf of larger GRB follow-up collaboration:

We observed the field of GRB 160227A (Siegel et al., GCN 19098
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 ) with 
Zeiss-600 telescope of Mt. Terskol observatory in R-filter starting on 
Feb. 27 (UT) 19:45:26. We obtained several images in R-filter. We 
clearly detect source in coordinates (J2000) 12 59 13.7 +78 40 44.9 
which is apparently the afterglow of GRB GRB 160227A (Siegel et al., GCN 
19098
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 ; Gorbovskoy et al., GCN 19099
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 ). The afterglow is clearly detected 
in a single images of 30 s exposure with brightness of ~19.0 magnitude 
in R-filter at Feb. 27 (UT) 19:49:36.

V. Nevskiy (ISON), V. Vikhrov(ISON), K. Polyakov (ISON), N. Rudenko 
(IAON), A. Kalinichenko (ISON), E. Mazaeva (IKI), I. Molotov (KIAM), A. 
Pozanenko (IKI) report on  behalf of larger collaboration:


We observed the field of GRB 160227A (Siegel et al., GCN 19098
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 ) with
HGB-500  telescope (0.5-m, f/2) of ISON-Kislovodsk observatory  starting 
on Feb. 27 (UT) 19:38:53, i.e. ~400 s after burst trigger. We obtained 
several unfiltered images of 60 s exposure. We clearly detect  the 
afterglow of GRB 160227A (Siegel et al., GCN 19098
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 ; Gorbovskoy et al., 
GCN 19099
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 ; Andreev et al., GCN 19100
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 ). The afterglow brightness is 
~18.0 magnitude at Feb. 27 (UT) 19:38:53.

T. Yoshii (Tokyo Tech), M. Nakajima, H. Negoro (Nihon U.),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, M. Arimoto, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
K. Tanaka, T. Masumitsu (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.),
Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (Chuo U.),
M. Yamauchi, D. Itoh, K. Furuya (Miyazaki U.),
K. Yamaoka (Nagoya U.),
M. Morii (ISM)

report on behalf of the MAXI team:

The MAXI/GSC detected an uncatalogued X-ray transient source at 19:35:13 UT on 2016 February 27.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (192.924 deg, 78.686 deg) = (12 51 41, +78 41 09) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.39 deg and 0.38 deg, respectively.
The roll angle of long axis from the north direction is 46.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 130 +- 27 mCrab
(4-10keV, 1 sigma error).
Without assumptions on the source constancy,we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (197.530 deg, 78.335 deg) = (13 10 07, +78 20 05) (J2000)
(R.A., Dec) = (194.899 deg, 77.788 deg) = (12 59 35, +77 47 15) (J2000)
(R.A., Dec) = (185.390 deg, 79.282 deg) = (12 21 33, +79 16 55) (J2000)
(R.A., Dec) = (187.705 deg, 79.931 deg) = (12 30 49, +79 55 52) (J2000)

The position is consistent with that of GRB 160227A (Siegel et al., GCN 19098
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 ),
and the detected time is 185 sec after the BAT trigger.

There was no significant excess flux in the previous transit at 
18:02 UT on 2016 February 27 and in the next transit at 
21:07 UT on 2016 February 27 with an upper limit of 20 mCrab for each.

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1604 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 160227A, 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 = 194.80719, +78.67917 which is equivalent
to:

RA (J2000): 12h 59m 13.73s
Dec (J2000): +78d 40' 45.0"

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.

P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A.
D'Ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A.
Kennea (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester)
and M.H. Siegel report on behalf of the Swift-XRT team:

We have analysed 6.9 ks of XRT data for GRB 160227A (Siegel et al. GCN
Circ. 19098
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 ), from 147 s to 31.1 ks after the  BAT trigger. The data
comprise 691 s in Windowed Timing (WT) mode (the first 3 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 Osborne et
al. (GCN Circ. 19104
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 ).

The late-time light curve (from T0+5.9 ks) can be modelled with a
power-law decay with a decay index of alpha=0.41 (+0.11, -0.10).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.79 (+/-0.03). The
best-fitting absorption column is  7.3 (+0.9, -0.8) x 10^20 cm^-2, in
excess of the Galactic value of 4.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.76 (+/-0.10) and a
best-fitting absorption column of 6.6 (+2.8, -2.5) x 10^20 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.8 x 10^-11 (4.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.6 (+2.8, -2.5) x 10^20 cm^-2
Galactic foreground: 4.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.76 (+/-0.10)

If the light curve continues to decay with a power-law decay index of
0.41, the count rate at T+24 hours will be 0.15 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x
10^-12 (6.3 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00676423.

This circular is an official product of the Swift-XRT team.

T. Sakamoto (AGU), 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), 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+800 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160227A (trigger #676423)
(Siegel et al., GCN Circ. 19098
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 ).  The BAT ground-calculated position is
RA, Dec = 195.034, 78.672 deg which is
  RA(J2000)  =  13h 00m 08.1s
  Dec(J2000) = +78d 40' 19.9"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~ T0-100 s and ends at ~ T0+270 s. There are roughly four pulses with peaks
at ~ T0-100 s, ~ T0-20 s, ~ T0+100 s, and ~ T0+200 s, respectively.
T90 (15-350 keV) is 316.5 +- 75.4 sec (estimated error including systematics).

The time-averaged spectrum from T-99.8 to T+236.2 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.75 +- 0.51,
and Epeak of 65.8 +- 16.4 keV (chi squared 40.42 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 3.1 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+198.62 sec in the 15-150 keV band is
0.6 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.65 +- 0.10 (chi squared 51.62 for 57 d.o.f.).  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/676423/BA/

D. Xu (NAOC/CAS), J. P. U. Fynbo, D. Malesani (DARK/NBI), A. de Ugarte 
Postigo (IAA-CSIC, DARK/NBI), T. Petrushevska (Stockholm U.), P. M. 
Sorensen, J. Saario, J. Telting (NOT) report on behalf of a larger 
collaboration:

We observed the field of GRB 160227A (Siegel et al., GCN 19098
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 ) using 
the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC 
camera. Observations started at 20:19:12 UT on 2016-02-27 (i.e., 0.784 
hr post-burst) and 2x120s R-band frames were obtained, followed by 
2x1800s+1x1200s spectroscopy (i.e., at a median time of ~1.87 hr 
post-burst) covering 3200A - 9000A, all in a seeing of ~2.0 arcsec.

The previously reported optical afterglow (e.g., Siegel et al., GCN 
19098
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 ; Gorbovskoy et al., GCN 19099
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 ) is clearly detected in our stacked 
R-band image, with R~19.3 mag calibrated with nearby USNO B1 stars.

Preliminary analysis of the spectrum shows a clear trough at the blue 
end of the spectral continuum, indicating Ly-alpha absorption from H I. 
We also detect several narrow absorption features, though at low 
signal-to-noise, which we interpret as due to, e.g., C II, Si II, O I, C 
II, Fe II, all consistent with a redshift of z = 2.38.

Y. Kitaoka, T. Sakamoto, A. Yoshida (AGU)

We observed the field of GRB 160227A detected by Swift (trigger #676423; 
Siegel et al., GCN Circ. 19098
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 ) with the 12-inch AGU Robotic Optical 
Monitor for Astrophysical object - Narrow (AROMA-N) located at 
the Sagamihara campus of Aoyama Gakuin University.  

10 images of 60 sec exposures and 5 images of 180 sec exposures 
were taken in the R filter starting from February 27 19:36:28 (UT) 
about 260 seconds after the trigger and stopped on February 27 20:02:05 (UT).  
Because the target was a low elevation (44.4 deg at the start time) and 
the telescope was slightly out of focus, the quality of the obtained images 
was not ideal.  We do not detect the optical afterglow both in the individual 
images and the stacked image.  The estimated five sigma upper limit of 
the combined image (total exposure of 1500 sec) is ~16.4 mag using 
the USNO-B1 catalog.

V.Krushinski, I.Zalozhnich, A. Popov
Ural State University, Kourovka

E. Gorbovskoy, V. Lipunov, N.Tyurina, 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

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


Five telescopes of  MASTER Net of   robotic telescope   participated in 
the observation of the GRB 160227A. Two telescopes  detected 
prompt  optical emission. We discovery very strong OT variations with time 
~100 sec correlated with gamma ray flux (Sakamoto et al., 19106).

MASTER-Ural  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Ural was pointed to the  GRB160227A 30 sec after notice time 
and 115 sec after trigger time at 2016-02-27 19:34:03 UT. On our first 
(20s exposure)  set we  found 1 optical transient within SWIFT error-box 
(Siegel et al GCN 19098
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 ; Gorbovskoy et al GCN 19099
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 ) at a position:
RA   12h 59m 14.13s
Dec +78d 40m 44.2s
With magnitude automatical magnitude ~ 17.3
We definetly see OT  at a number of single and coadd images. OT was 
observed during ~ 1 hours. We see OT decay from 17.0 to 19.1 mag in the 
time interval from 115 to 2647 sec atger the trigger.
The 5-sigma upper limit has been about 17.5 mag on first single image and 
up to 19.5 mag at on coadd images in later time.

MASTER-Kislovodsk  robotic telescope (MASTER-Net: 
http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB160227A  (Siegel et al GCN 
19098
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 ) 52 sec after notice time and 137 sec after trigger time at 
2016-02-27 19:34:25 UT. On our first (30s exposure)  set we  marginaly see 
optical transient (Siegel et al GCN 19098
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 , Gorbovskoy et al GCN 19099
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 ) 
within SWIFT error-box.  OT also definetly seen at a number of coadd 
images. OT was observed for about 4 hours. We see OT decay from 18.1 to ~ 
20.5 mag in the time interval from 152 to 12900 sec atger the trigger.
The 5-sigma upper limit has been about 17.5 mag on first single image and 
up to 21.0 mag at on coadd images in later time.


MASTER-IAC  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was pointed to the  GRB160227A 49 sec after notice time and 
137 sec after trigger time at 2016-02-27 19:34:25 UT. On our first (30s 
exposure)  set we haven`t found optical transient  within SWIFT error-box. 
The observations started on evening sky (Sun altitude ~ -6 deg). 
Therefore, the first exposure upper limit is very low.  We definetly see 
OT  at a number of coadd images, starting ~ 1 hour after the trigger. OT 
was observed for about 2 hours. We see OT decay from 19.0 to 20.0 mag in 
the time interval from 3400 to 9200 sec atger the trigger.
The 5-sigma upper limit has been about 14.5 mag (due to bright evening sky 
) on first single image and up to 21.0 mag at on coadd images in later 
time.


MASTER-Tunka  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Astrophysical Center Tunka  was pointed to the  GRB160227A 17 
sec after notice time and 103 sec after trigger time at 2016-02-27 19:33:51 UT. On our first 
(20s exposure)  set we haven`t found optical transient  within SWIFT 
error-box. The observations made on not very well weather condition and 
was finished 10 after GRB, due to snow coming.
The 5-sigma upper limit has been about 15.3 mag on first single image.


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Blagoveschensk was pointed to the  GRB160227A  8 sec after 
notice time and 93 sec after trigger time at 2016-02-27 19:33:41 UT. On 
our first (20s exposure)  set we haven`t found optical transient  within 
SWIFT error-box.
The 5-sigma upper limit has been about 16.0 mag on first single image.


Out preliminary photometry results available at table 1
Light curve available here: http://master.sai.msu.ru/static/grb160227.png


Table 1.

T0-Tmig Expt.   Mag          Site            Coadd
-------|-------|------|---------------------|------
125     20      17.0     MASTER Ural
152     30      18.1     MASTER Kislovodsk
174     30      18.5     MASTER Ural
207     120     17.8     MASTER Kislovodsk     3
231     40      17.7     MASTER Ural
299     50      18.9     MASTER Ural
383     70      19.6     MASTER Ural
485     90      17.9     MASTER Ural
607     110     18.0     MASTER Ural
621     550     18.7     MASTER Kislovodsk     4
757     140     18.7     MASTER Ural
935     170     18.2     MASTER Ural
1133    180     19.1     MASTER Ural
1349    180     19.0     MASTER Ural
1566    180     18.9     MASTER Ural
1765    1080    18.9     MASTER Kislovodsk     6
1781    180     19.1     MASTER Ural
1998    180     19.1     MASTER Ural
2647    900     19.1     MASTER Ural           5
2789    360     19.7     MASTER Kislovodsk     2
3423    540     19.0     MASTER IAC            3
4261    900     19.2     MASTER IAC            5
4527    900     19.4     MASTER Kislovodsk     5
5966    1080    19.5     MASTER Kislovodsk     6
6401    1800    20.0     MASTER IAC           10
7771    3600    19.9     MASTER IAC           20
9196    1800    19.8     MASTER IAC           10
10608   1620    20.9     MASTER Kislovodsk     9
12824   1800    20.3     MASTER Kislovodsk    10


The message may be cited.

M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160227A
161 s after the BAT trigger (Siegel et al., GCN Circ. 19098
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 ).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 19104
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 )
is detected in the initial UVOT exposures but had faded away
in later exposures.

The preliminary UVOT position is:
   RA  (J2000) =  12:59:13.80 = 194.80750 (deg.)
   Dec (J2000) = +78:40:45.1  =  78.67920 (deg.)
with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white (fc)         161          311          147         19.34 +/- 0.10
white              600         2418          341         19.80 +/- 0.13 
white             6755         8196          201        >20.82
v                  650         7366          400         19.40 +/- 0.25
b                  575         2393          194         19.71 +/- 0.35
b                 6550         8186          393        >20.10
u (fc)             319          569          245         19.44 +/- 0.20
u                  724         2368          174        >19.22
w1                 699         7776          540        >20.5
m2                1082         7570          432        >21.1
w2                1206         7161          294        >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).

Myungshin Im, Changsu Choi, Gu Lim (CEOU/SNU),
Soomin Jeong (SKKU/IAA-CSIC) on behalf of a larger collaboration

We observed the field of GRB 160227A (Palmer et al. GCN19098
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 ) using the
0.8m telescope at the McDonald Observatory. The observation started at
2016-02-28 03:03:38 UT, or about
7.5 hours after the BAT alert.
We identify the afterglow at the location of the UVOT detection,
and our preliminary analysis shows the afterglow
at R ~ 20.8 +- 0.15 mag in a stacked image of 21 x 3 min frames.
The mid-point of the observation is 2016-02-28 03:47.
The photometry is calibrated against a star at RA=194.74877
and Dec=78.68984 (J2000) with R=15.72, taken from APASS
catalog.
A second epoch data was taken at about 6 hours later, and the
analysis of the data is ongoing.

Soomin Jeong (SKKU/IAA-CSIC), Myungshin Im (SNU), Yuji Urata (NCU), Il H. Park (SKKU) on behalf of a larger collaboration:

We observed the field of GRB 160227A (Siegel, et al., GCN 19098
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 ) with the 1m telescope of Mt. Lemmon Optical Astronomy Observatory (LOAO) in Arizona. 
The series of images are taken in R- & B-filter starting on Feb. 28 05:11:27 UT (~ 9.7 hr post burst). 
The optical counterpart is clearly detected in a median combined image of R at the previously reported optical afterglow position 
(e.g., Siegel et al., GCN 19098
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 ; Gorbovskoy et al., GCN 19099
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 ; Mazaeva et al., GCN19102
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 ). We confirmed marginal detection of OT in a median combined B. 
The observed magnitudes are as following:
Mid Time(hr)     Exposure(s)       Filter       Magnitude
���������������������������������������������������������������������������������
10.19         12x300            R          21.16 +/- 0.14
10.15          4x300             B           22.19 +/- 0.41
���������������������������������������������������������������������������������
The fields are calibrated to the near by star at RA=194.74877, Dec=78.68984 (R2=15.84, USNO-B1.0).

Y.Ono (Tokyo Tech), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. E. Nakagawa, Y. Sugawara (JAXA), 
T. Mihara, M. Sugizaki, M. Serino, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), 
N. Kawai, N.Isobe, S.Sugita, T. Yoshii, Y. Tachibana, T. Fujiwara (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), 
H. Tsunemi, R.Imatani (Osaka U.), 
H. Negoro, M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), 
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.), 
Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), 
M. Yamauchi, K. Furuya (Miyazaki U.), 
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 2016-05-09T09:04:16.

Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (312.131 deg, 75.810 deg) = (20 48 31, +75 48 36) (J2000)
with a 90% C.L. statistical error of 0.06 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 1307 +- 69 mCrab
(4-10keV, 1 sigma error).
Without assumptions on the source constancy,we obtain a rectangular error
box for the transient source with the following corners:
(310.897 deg, 75.728 deg) = (20 43 35, +75 43 40) (J2000)
(311.105 deg, 75.626 deg) = (20 44 25, +75 37 34) (J2000)
(313.379 deg, 75.887 deg) = (20 53 30, +75 53 14) (J2000)
(313.181 deg, 75.991 deg) = (20 52 43, +75 59 27) (J2000)

There was no significant excess flux in the previous transit at UT 2016-0509T07:32
with an upper limit of 20 mCrab.