GRB 160630A

H. A. Krimm (CRESST/GSFC/USRA), P. D'Avanzo (INAF-OAB),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 04:04:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160630A (trigger=702252).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 198.239, -56.069 which is 
   RA(J2000) = 13h 12m 57s
   Dec(J2000) = -56d 04' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 160 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 04:05:33.0 UT, 83.1 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 198.2584, -56.0420
which is equivalent to:
   RA(J2000)  = 13h 13m 02.03s
   Dec(J2000) = -56d 02' 31.3"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 104 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 3.89
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 87 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 0.48. 

Burst Advocate for this burst is H. A. Krimm (hans.krimm 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.)

D. A. Kann (TLS Tautenburg), T. Kruehler (MPE Garching),  S. Schmidl (TLS
Tautenburg), J. Bolmer, and J. Greiner (both MPE Garching) report on
behalf of the GROND team.

We observed the field of GRB 160630A (Swift trigger 702252; Krimm et al.,
GCN #19624
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 04:10:58 UT, 6.8 minutes after the GRB trigger.
They were performed at an average seeing of 2".1 and at an average airmass
of 1.8.

In an image with exposure time 66 s in g'r'i'z' taken at a mid-time of 7.3
min after the trigger, we detect a source at the edge of the 1".8 XRT
error circle at position:

RA (J2000) = 13:13:02.04

Dec. (J2000) = -56:02:29.8

(with an error of 0".3) with (AB magnitudes):

g' > 21.0 mag,
r' = 20.4 +/- 0.1 mag,
i' = 19.5 +/- 0.1 mag,
z' = 18.7 +/- 0.1 mag.

The source faded by about 1.5 magnitudes within the next quarter hour. We
therefore propose this source to be the afterglow of GRB 160630A.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction E_(B-V) = 0.43 mag in the direction of the burst (Schlafly &
Finkbeiner, 2011).

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

Using 2865 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 160630A, 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 = 198.25909, -56.04183 which is equivalent
to:

RA (J2000): 13h 13m 2.18s
Dec (J2000): -56d 02' 30.6"

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.

A. Melandri, D. Fugazza, P. D'Avanzo, S. Covino (INAF/OAB) report on behalf of the REM team:

We observed the field of GRB 160630A (Krimm et al., GCN 19624
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 ) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations started at 04:05:13 UT, ~65 seconds after the burst, and were carried out simultaneously in the g, r, i, z and H bands.

A preliminary photometry indicates that the optical afterglow (Kann et al., GCN 16625
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 ) is detected with a magnitude H = 14.9 +/- 0.2, about 100 sec after the burst.

Further analysis is in progress.

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), L.M. McCauley (PSU), J.A.
Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), B. Mingo (U. Leicester), A.
Maselli  (INAF-IASFPA) and H.A. Krimm report on behalf of the Swift-XRT
team:

We have analysed 8.2 ks of XRT data for GRB 160630A (Krimm et al. GCN
Circ. 19624
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 ), from 69 s to 24.5 ks after the  BAT trigger. The data
comprise 7 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Goad et al. (GCN Circ. 19626
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 ).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.3 (+4.7, -1.1). At T+110 s  the decay
flattens to an alpha of 0.20 (+/-0.14) before breaking again at T+2108
s to a final decay with index alpha=1.31 (+0.12, -0.11).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.74 (+0.13, -0.12). The
best-fitting absorption column is  4.5 (+0.8, -0.6) x 10^21 cm^-2,
consistent with the Galactic value of 3.9 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 4.6 x 10^-11 (6.4 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     4.5 (+0.8, -0.6) x 10^21 cm^-2
Galactic foreground: 3.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.74 (+0.13, -0.12)

If the light curve continues to decay with a power-law decay index of
1.31, the count rate at T+24 hours will be 8.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x
10^-13 (5.6 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/00702252.

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

S. J. LaPorte (PSU) and H. A. Krimm (CRESST/GSFC/USRA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160630A
87 s after the BAT trigger (Krimm et al., GCN Circ. 19624
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 ).
No optical afterglow consistent with the enhanced XRT position
(Goad et al., GCN Circ 19626
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 ) or the optical/IR position
(Kann et al. GCN Circ. 19625
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 ) 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            87          237          147         >20.6
u_FC               300          550          246         >19.9
white               87         6366          530         >21.7
v                  630         6777          439         >20.2
b                  555         6161          236         >20.5
u                  300         5956          462         >20.6
w1                 680         7042          290         >19.7
m2                 655         6982          432         >20.9
w2                 606         6572          255         >19.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.48 in the direction of the burst
(Schlegel et al. 1998).

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 160630A detected by SWIFT
(trigger 702252) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 33s after the GRB trigger
(15s after the notice). The elevation of the field decreased from
34 degrees above horizon and weather conditions
were good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+33s to t0+93s : Rlim = 16.4

The second image is 30.0s exposure in tracking mode:
t0+107s to t0+137s : Rlim = 17.5

We co-added a series of exposures:
t0+107s to t0+302s : Rlim = 18.0

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

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.),
Coward, D. McPherson, D. Williams A., Martin R.,
Moore J., Dodson R. (UWA) report:

We imaged the field of GRB 160630A detected by SWIFT
(trigger 702252) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 6.4h after the GRB trigger.
The elevation of the field increased from
64 degrees above horizon and weather conditions
were good.

We co-added a series of exposures:
t0+6.4h to t0+8.0h : Rlim = 21.0

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

A. Trotter, D. Reichart, J. Haislip, J. Moore, N. Frank, M. Maples, D. Dutton, R. Gao, R. Joyner, J. Martin, M. Paggen, J. A. Crain, K. Ivarsen, A. LaCluyze, and M. Nysewander report:

Skynet observed the Swift BAT/XRT localization of GRB 160630A (Krimm et al., GCN 19624
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 , Swift trigger=702252) with with two 16" telescopes (P5, P6), and two 24" telescopes (P1, P8) of the PROMPT array at CTIO, Chile. Starting at 2016-06-30 04:05 UT and continuing until 07:02 UT (t=60s-3h post-trigger), Skynet took a total of 452 2.5-160s exposures in the I band (P1, P5), V band (P6) and B band (P8).  

We detect a fading optical afterglow in stacked I-band images at the OT position reported by Kann et al. (GCN 19625
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 ) and Melandri et al. (GCN 19627
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 ), with I~17.4 at t=5m and I~18.6 at t=23m. 

A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb160630a.png

Preliminary magnitudes are in the Vega System, calibrated to 9 APASS DR9 stars in the field.  Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.43 (Schlafly & Finkbeiner 2011).

No further Skynet observations are scheduled.

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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160630A (trigger #702252)
(Krimm, et al., GCN Circ. 19624
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 ).  The BAT ground-calculated position is
RA, Dec = 198.238, -56.029 deg which is
  RA(J2000)  =  13h 12m 57.0s
  Dec(J2000) = -56d 01' 44.3"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 51%.

The mask-weighted light curve shows a single-peaked structure that starts
at ~T-1 s, peaks at ~T0, and ends at ~T+35 s. T90 (15-350 keV)
is 29.50 +- 5.51 sec (estimated error including systematics).

The time-averaged spectrum from T-1.00 to T+34.89 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.32 +- 0.14.  The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.42 sec in the 15-150 keV band
is 1.2 +- 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/702252/BA/