GRB 160220A

A. Y. Lien (GSFC/UMBC), P.A. Evans (U Leicester), J. A. Kennea (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 01:25:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160220A (trigger=674670).  Swift could not immediately
slew to the burst. 
The BAT on-board calculated location is 
RA, Dec 236.925, -18.555 which is 
   RA(J2000) = 15h 47m 42s
   Dec(J2000) = -18d 33' 17"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 15 sec.  The peak count rate
was ~500 counts/sec (15-350 keV), at ~5 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+50.1
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 
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.)

S. Campana (INAF-OAB), G. Cusumano (INAF-IASF PA), P.A. Evans (U.
Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU) and J.A.
Kennea (PSU) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 160220A at 02:19:23.8 UT,
3238.1 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 236.95167,
-18.56501 which is equivalent to:
   RA(J2000)  = 15h 47m 48.40s
   Dec(J2000) = -18d 33' 54.0"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 97 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 consistent with the Galactic value of 1.09
x 10^21 cm^-2 (Willingale et al. 2013).

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

Using 1730 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 160220A, 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 = 236.95288, -18.56605 which is equivalent
to:

RA (J2000): 15h 47m 48.69s
Dec (J2000): -18d 33' 57.8"

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.

C. M. Hui (NASA/MSFC) and E. Burns (UAH)
report on behalf of the Fermi GBM Team:

"At 01:25:26.968 UT on 20 February 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160220A (trigger 477624330 / 160220059), which
was also detected by the Swift/BAT (Lien et al. 2016, GCN 19023
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 ).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 46
degrees.

The GBM light curve shows a single peak
with a duration (T90) of about 9 s (50-300 keV).
The time-averaged spectrum from T0-3.072 s to T0+9.216 s is
best fit by a simple power law function with index -1.5 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(1.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.43 s in the 10-1000 keV band
is 1.7 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

P. Wiseman, F. Knust, J. Greiner (all MPE Garching) report on behalf of
the GROND team:

We observed the field of GRB 160220A (Swift trigger 674670; Lien et al.,
GCN #19023
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at  05:46 UT on 2016-02-20, 4.5 hrs after the GRB
trigger. They were performed at an average seeing of 1.5" and at an
average airmass of 1.6.

We do not find any single point source within the 1.9" Enhanced Swift-XRT
error circle reported by Evans et al. (GCN #19025
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 ). Based on 36.00 min of
total exposures in g'r'i'z' and 30.00 min in JHK, at a mid-time of 06:49
UT, we estimate preliminary upper limiting magnitudes (AB system) of

g' > 23.4 mag,
r' > 23.9 mag,
i' > 23.6 mag,
z' > 23.3 mag,
J  > 21.6 mag,
H  > 20.9 mag, and
K  > 18.0 mag.

Given limits are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.12 mag in the
direction of the burst (Schlafly & Finkbeiner 2011).

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

A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda
Blagoveschensk Educational State University, Blagoveschensk

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, 
A.Kuznetsov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

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-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the  GRB160220A (Lien et al., GCN #19023
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 ) 
22 sec after notice time and 65 
sec after trigger time at 2016-02-20 01:26:34 UT. On our first (10s 
exposure)  set we haven`t found optical transient  within SWIFT error-box 
(ra=15 47 41 dec=-18 33 16 r=0.050000).
The 5-sigma upper limit has been about 15.5mag
The automatically generated table image limits you can see below:


Pro.ID Pro.type      time      Exp.	Limit	Filt.   Tube
                        UT        s       mag  polaroid

162238	Alert 	    01:26:34	10	15.5	P/	EAST
162239	Alert       01:26:34	10      15.5	P\	WEST
162240	Alert 	    01:26:56	20	14.8	P/	EAST
162241  Alert       01:26:56    20      14.8    P\      WEST
162241  Alert       01:26:56    20      14.8    P\      WEST
162242  Alert       01:27:29    20      16.7    P/      EAST
162243  Alert       01:27:29    20      16.6    P\      WEST
162244  Alert       01:28:02    30      17.9    P/      EAST
162245  Alert       01:28:02    30      17.9    P\      WEST
162246  Alert       01:28:44    40      16.5    P/      EAST
162247 	Alert 	    01:28:44 	40 	16.4 	P\ 	WEST
162264 SumAlert     01:26:56    70      17.7    P/      EAST
162265 SumAlert     01:26:56    70      17.8    P\      WEST
162266 SumAlert     01:28:44   150      18.2    P/      EAST
162267 SumAlert     01:28:44   150      18.3    P\      WEST
162323 SumAlert     01:26:56   670	19.3	P/	EAST
162321 SumAlert     01:26:56   670	19.1	P\	WEST
........

162338 SumAlert     01:40:23  1800	19.4	P/	EAST
162337 SumAlert     01:40:23  1800 	19.2 	P\ 	WEST

The message may be cited.

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 160220A detected by SWIFT
(trigger 674670) with the TAROT robotic telescopes (D=25cm)
located at the Calern observatory, France and
at the European Southern Observatory, La Silla
observatory, Chile.

The observations started 1.64h after the GRB trigger
at Calern and 4.00h after the GRB trigger at la Silla
(the field was not visible at the date of the trigger).
The elevation of the field increased from
20 degrees above horizon and weather conditions
were good.

We co-added a series of exposures. We do not detected the
X-ray couterpart mentioned by Campana et al. (GCNC 19024):

t1(h) t2(h)  Rmag_lim  Site
1.64 3.30    17.5      TAROT Calern
4.00 4.69    19.0      TAROT La Silla

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

M. De Pasquale (MSSL-UCL) and A. Lien (GSFC/UMBC) report
on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160220A
4.11 ks after the BAT trigger (Lien et al., GCN Circ. 19023
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 ).
No optical afterglow consistent with the XRT position (Evans et al.
GCN Circ. 19025
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 ) is detected in the UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the
summed UVOT exposures are:

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

white             4110         5493          344         >20.6
v                 4268        34517          903         >19.4
b                 5088         5288          197         >19.7
u                 4882        17290          424         >19.5

w1                4678        17052         1175         >20.3
m2                4472        11445         1271         >20.3
w2                5499        32840         1177         >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.13 in the direction of the burst
(Schlegel et al. 1998).

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160220A (trigger #674670)
(Lien, et al., GCN Circ. 19023
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 ).  The BAT ground-calculated position is
RA, Dec = 236.942, -18.539 deg which is
    RA(J2000)  =  15h 47m 46.2s
    Dec(J2000) = -18d 32' 20.6"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.

The mask-weighted light curve shows a single peak of about 20 seconds total
duration starting at ~0 sec.  The spacecraft slewed away
from the burst location at ~T+220 sec due to a pre-planned maneuver.
T90 (15-350 keV) is 8.3 +- 1.2 sec (estimated error including systematics).

The time-averaged spectrum from T-0.02 to T+8.99 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.55 +- 0.24.  The fluence in the 15-150 keV band is 5.2 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.33 sec in the 15-150 keV band
is 1.0 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/674670/BA/

A. Maselli  (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U.
Leicester), P. D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of
the Swift-XRT team:

We have analysed 7.7 ks of XRT data for GRB 160220A (Lien et al. GCN
Circ. 19023
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 ), from 4.1 ks to 63.2 ks after the	BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 19025
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.94 (+0.20, -0.18).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.67 (+0.37, -0.18). The
best-fitting absorption column is  consistent with the Galactic value
of 1.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 4.0 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.1 (+/-1.1) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.67 (+0.37, -0.18)

If the light curve continues to decay with a power-law decay index of
0.94, the count rate at T+24 hours will be 3.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x
10^-13 (1.8 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/00674670.

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

R. Starling, N. Tanvir, K. Wiersema (U. Leicester) and J. Bailey (UNSW) report on behalf of a larger collaboration:

We observed the field of GRB 160220A (Swift trigger 674670, Lien et al. GCN Circ. 19023
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 ; Fermi trigger 477624330/16022005, Hui & Burns GCN Circ. 19026
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 ) 
with the 4m Anglo Australian Telescope, AAT, at Siding Spring, Australia on 2016 February 20th, 14 hours after burst.

We obtained near-IR photometry with the Infrared Imager and Spectrograph, IRIS2, in the Ks band beginning at 15:35 UT and in the J band beginning 16:09 UT, 
and totalling 27 minutes exposure in each filter. No source was detected within the Swift XRT error circle (Evans et al. GCN Circ. 19025
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 ).
We find the following approximate limiting magnitudes (at 5-sigma in the Vega system):
J > 21 
Ks > 18

We acknowledge excellent support from the Australian Astronomical Observatory staff.