GRB 150212A

K. L. Page (U Leicester), A. Amaral-Rogers (U Leicester),
S. D. Barthelmy (GSFC), M. M. Chester (PSU),
P. A. Evans (U Leicester), F. E. Marshall (NASA/GSFC),
C. J. Mountford (U Leicester) and P. T. O'Brien (U Leicester) report
on behalf of the Swift Team:

At 10:57:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150212A (trigger=630876).  The Swift slew was delayed by 4.7 min
due to an observing constraint.  The BAT on-board calculated location is 
RA, Dec 285.521, +47.407 which is 
   RA(J2000)  =  19h 02m 05s
   Dec(J2000) = +47d 24' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single FRED peak
with a duration of about 10 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to an observing constraint, Swift did not slew until T0+4.7
minutes. By this time Swift had entered the South Atlantic Anomaly,
from which it will emerge at 11:26 UT. There will be no XRT or UVOT
data until this time. 

Burst Advocate for this burst is K. L. Page (kpa AT star.le.ac.uk). 
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. B. Cenko (NASA/GSFC) reports on behalf of a larger collaboration:

We have imaged the field of the Swift GRB150212A (Page et al., GCN 17449
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 ) with the robotic Palomar 60 inch telescope.  Observations were obtained in the Sloan riz filters beginning at 11:12 UT (~ 15 min after the Swift trigger).  We identify a bright source in the BAT error circle not present in archival DSS imaging of the field in all 3 filters:

   RA: 19:01:53.92
   Dec: +47:26:10.7

We measure a preliminary magnitude of r = 16.8 at ~ 15 min after the Swift trigger (calibration performed with respect to nearby point sources from the APASS catalog).  While we have not yet confirmed fading, we consider this source to be the likely optical afterglow of GRB150212A.

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

The XRT began observing the field at 11:03:12.7 UT, 353.7 seconds after
the BAT trigger. Due to passage of the spacecraft through the South 
Atlantic Anomaly, no XRT data were collected until T0+1805 s.

Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 285.48092, 47.36602 which is equivalent
to:
    RA(J2000)  = 19h 01m 55.42s
    Dec(J2000) = +47d 21' 57.7"
with an uncertainty of 4.3 arcseconds (radius, 90% containment). This
location is 176 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 5.20
x 10^20 cm^-2 (Willingale et al. 2013).

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

S. B. Cenko (NASA/GSFC) reports on behalf of a larger collaboration:

We have obtained further imaging of the field the Swift GRB 150212A (Page et al., 17449) with the robotic Palomar 60 inch telescope.  The candidate afterglow we previously identified (GCN 17451
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 ) has remained at a constant brightness over the course of the last hour, and is well offset from the candidate XRT afterglow (Evans et al., GCN 17452
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 ).  Further inspection of archival catalogs indicates this object is likely to be a high proper motion star.  We apologize for any inconvenience this may have caused.

M. M. Chester (Penn State), K. L. Page (U Leicester), and A. Amaral-Rogers 
(U Leicester) report on behalf of the Swift/UVOT team:


UVOT took a finding chart exposure of 150 seconds with the White filter
starting 1811 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
none of the XRT error circle. 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.

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

E. Gorbovskoy, V. Lipunov,  M.Pruzhinskaya, V.Kornilov, D.Kuvshinov, 
N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, 
D.Denisenko, A.Sankovich
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, Kourovka

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

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)



MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka was pointed to the  GRB150212A (Page et. al. GCN 17449
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 ) 
32 sec after notice time and 47 sec after trigger time at 2015-02-12 
10:58:06 UT in two polarization. Unfortunately we were unable to obtain 
satisfactory data on the first images due to clouds and high zenith 
distance (z~75 d).

In the process of further observations we do not see the optical transient 
and obtained the following upper limits:

T_start   T-Tmid Expt.   Mlimit
11:08:50  761     140      11.5
11:11:52  958     170      11.5
11:15:26  1177    180      12.5
11:26:34  1845    180 	   12.6
11:32:12  2183    180      15.0
11:32:12  3447   1800      16.7
11:35:58  2641    540      16.1

So weak upper limits associated with the observation through clouds and 
large zenith distance of the object.

J. R. Cummings (GSFC/UMBC), A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC), 
W. H. Baumgartner (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. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 150212A (trigger #630876)
(Page, et al., GCN Circ. 17449
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 ).  The BAT ground-calculated position is
RA, Dec = 285.497, 47.389 deg, which is 
   RA(J2000)  =  19h 01m 59.2s 
   Dec(J2000) = +47d 23' 19.1" 
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.
 
The mask-weighted light curve is FRED peak starting at ~T-1 sec, peaking
at ~T+1 sec, and ending at ~T+25 sec.  T90 (15-350 keV) is 11.4 +- 4.1 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.20 to T+19.66 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.50 +- 0.11.  The fluence in the 15-150 keV band is 8.9 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.82 sec in the 15-150 keV band
is 1.9 +- 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/630876/BA/

A. Trotter, D. Reichart, A. LaCluyze, J. Haislip, A. Smith, D. Caton, L. Hawkins, K. McLin, L. Cominsky, A. Aji, T. Berger, A. Dow, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, C. Salemi, and J. A. Crain report:

Skynet observed the Swift BAT/XRT localization of GRB 150212A (Page et al., GCN 17449
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 , Swift trigger=630876) with the 14" telescope at the Appalachian State University Dark Sky Observatory (DSO14) in NC, USA, and with the 14" GLAST Optical Robotic Telescope (GORT) at the Hume Observatory in CA, USA. DSO14 obtained exposures of the field starting at 2015-02-12 10:58:05 (t=46s post-trigger); GORT was delayed until 48m post-trigger due to clouds. Skynet took a total of 29 exposures ranging from 5s to 160s in the R and I bands. We do not detect any optical source at the XRT afterglow position reported by Evans (GCN 17452
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 ).

Our early-time DSO14 limiting magnitudes are:
==============================================
tmid    scope   band    exposures   lim mag
----------------------------------------------
48s     DSO14    I      1 x 5s      >15.2
102s    DSO14    I      2 x 10s     >16.4
108s    DSO14    R      1 x 5s      >16.0
==============================================

Stacked subsets of those images that maximize the S/N ratio give limiting magnitudes:
==============================================
tmid    scope   band    exposures   lim mag
----------------------------------------------
15.4m   DSO14    R      1 x 80s      >18.4
                        1 x 160s
16.1m   DSO14    I      1 x 80s      >18.4
                        1 x 160s                       
74m     GORT     R      4 x 160s     >17.2
84m     GORT     I      3 x 160s     >16.8
==============================================

Magnitudes are in the Vega System, calibrated to 10 APASS stars in the field.  Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.051 (Schlafly & Finkbeiner 2011).

No further Skynet observations are scheduled.

E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of 
Astronomy and Geophysics MAS), A. Volnova (IKI), I.Molotov (KIAM), A. 
Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of 150212A (Page et al., GCN 17449
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 ) with ORI-40 
telescope of Khureltogot observatory on Feb., 12 starting on (UT) 
11:32:28. We obtained 24 unfiltered images of 15 s exposure. We did not 
detect any optical counterpart in XRT error circle (Evans et al. GCN 
17452
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 ). Details of the photometry are following:

Date        UT start  t-T0    Filter Exp.  uplim (3 sigma)
                       (mid, days) (s)

2015-02-12  11:32:28  0.02739 none  24*15  15.8

The star mentioned by Cenko et al. (GCNs 17451
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 , 17454
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 ) is visible in our 
combined image and have a brightness of 15.85 +/- 0.25.

The photometry is based on R magnitudes of nearby USNO-B1.0 stars

USNO-B1_id    R2
1374-0373548  15.39
1374-0373502  14.41

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús
González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and
Harvey Moseley (GSFC) report:

We observed the field of GRB 150212A (Page, et al., GCN 17449
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 ) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on
Sierra San Pedro Mártir from 2015/02 12.51 to 2015/02 12.55 UTC (1.29 to
2.31 hours after the BAT trigger), obtaining a total of 0.89 hours exposure
in the r, i, and z bands.

We find one uncatalogued source within the Swift XRT error circle (Evans,
et al., GCN 17452
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 ) at a position RA, Dec = 285.48273,  47.36637 (+/- 0.5",
J2000) with magnitudes r = 23.1 +/- 0.4 and i = 21.4 +/- 0.1.  This source
does not appear to fade in time during our observation.  For other
potential sources within the XRT error circle, in comparison with USNO-B1
and 2MASS, we obtain the following upper limits (3-sigma):

  r > 23.1
  i > 23.3
  z > 19.6

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.

A. Amaral-Rogers (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page
(U. Leicester), M. de Pasquale (INAF-IASFPA), A. Maselli 
(INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU), J.A. Kennea
(PSU) and K. L. Page (U Leicester) report on behalf of the Swift-XRT
team:

We have analysed 4.1 ks of XRT data for GRB 150212A (Page et al. GCN
Circ. 17449
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 ), from 1.8 ks to 54.6 ks after the	BAT trigger. The data
are entirely in Photon Counting (PC) mode. The refined XRT position is
RA, Dec = 285.4799, +47.3656 which is equivalent to:

RA (J2000): 19 01 55.16
Dec(J2000): +47 21 56.3

with an uncertainty of 3.7 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.56 (+0.15, -0.14).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.3 (+/-0.4). The
best-fitting absorption column is  1.7 (+1.2, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 5.2 x 10^20 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 (4.4 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.7 (+1.2, -1.0) x 10^21 cm^-2
Galactic foreground: 5.2 x 10^20 cm^-2
Excess significance: 2.0 sigma
Photon index:	     2.3 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
0.56, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.5 x
10^-13 (5.2 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00630876.

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

M. H. Siegel, M. M. Chester (PSU), A. Amaral-Rogers (U Leicester)
and D. Malesani (DARK/NBI) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150212A
1812 s after the BAT trigger (Page et al. GCN Circ. 17449
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 ; Chester et al.
GCN Circ. 17455
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 ).  A cataloged optical source is detected
within the XRT error circle (Evans GCN Circ. 17452
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 ).  The measured
magnitudes are consistent with the cataloged values and no fading is
evident.

V.V. Golovnya (Main Astro Obs., Kyiv)
report: 
We have undertaken the review of the sky area of GRB 150212A (P.A. Evans
GCN Circ. 17452
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 ) on astronegatives, collected in Ukrainian plate archive
(1976-1996). All the plates with the possible object appearance are
digitized using Epson Expression 10000XL flatbed scanner and the images
have been placed into Golosiiv Plate Archive database DBGPA with open
access to them. The list of plates is given in the table:

yyyymmdd/TimeUT   ---Plates----- Exp. -Mag- --USNO-B1--
19840720/21:19:40 GUA040C000430A 22.5 15.93 1373-0374987
19770622/22:14:06 GUA040C000535B 60.0 17.17 1374-0373547
19860716/21:18:54 GUA040C000961  16.0 17.42 1373-0374984
19870701/22:16:16 GUA040C001064  16.0 17.42 1373-0374984
19870822/19:11:46 GUA040C001078A 16.0 16.33 1373-0374866

Plates:���the plates archive identifier of DWA D/F=400/2000, M=103"/mm
(Marsden's number - 83) the plate number [1].
Exp. - Duration of the maximum exposures (minutes).
Mag - Limited Bmag, derived in the 7 minutes area around the location
given in Evans GCN Circ. 17452
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 :
RA(J2000): 19h 01m 55.27s, Dec(J2000): +47d 21' 57.6".
USNO-B1 - Comparison star.
  The preview images of 5 areas together with the 7 min. of arc area
from Aladin can be found in
"http://gua.db.ukr-vo.org/img/grb/150212A/index.html".
The images with full resolution are available via e-mail on demand.

References:
1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0),
"http://gua.db.ukr-vo.org".