GRB 140408A

V. D'Elia (ASDC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC),
S. T. Holland (STScI), L. Izzo (URoma/ICRA), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU),
R. L. C. Starling (U Leicester) and C. A. Swenson (PSU) report on
behalf of the Swift Team:

At 13:15:54 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140408A (trigger=595141).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 290.685, -12.578 which is 
   RA(J2000)  =  19h 22m 44s
   Dec(J2000) = -12d 34' 40"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 10 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 13:17:40.2 UT, 105.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 290.71576, -12.59373 which is
equivalent to:
   RA(J2000)  = 19h 22m 51.78s
   Dec(J2000) = -12d 35' 37.4"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 122 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. No spectrum from the promptly downlinked
event data is yet available to determine the column density. 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 109 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. Because of the density of catalogued stars,  further
analysis is required to report an upper limit for any afterglow in the
region. No correction has been made for the expected extinction
corresponding  to E(B-V) of 0.19. 

Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). 
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.)

P. Jenke (UAH), G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team:

"At 13:15:55.24 UT on April 8 2014, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 140408A (trigger 418655758/140408553),
which was also detected by Swift (V. D'Elia et al. 2014, GCN 16082
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 ).  
The GBM on-ground location, using the Fermi GBM trigger
data, is consistent with the Swift/BAT location.

The angle of the burst direction to the Fermi LAT boresight is 90 degrees.

The GBM light curve consists of one main peak with a duration
 (T90) of about 13 s (50-300 keV).
The time-averaged spectrum from T0-4.1 s to T0+10.2s is
well fit by a power law with an index of -1.61 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(1.8 +/- 0.2)E-06 erg/cm^2. The 1.0-sec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 2.0 +/- 0.3 ph/s/cm^2.

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

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

Using 661 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 140408A, 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 = 290.71590, -12.59525 which is equivalent
to:

RA (J2000): 19h 22m 51.82s
Dec (J2000): -12d 35' 42.9"

with an uncertainty of 2.1 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.

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 collaboration:

We observed the field of GRB 140408A (D'Elia et al., GCNC 16082)
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 2014-04-08 17:47:44 UT (~4.5 h after the burst).
We did not find any new point source within the enhanced XRT circle
(Evans et al., GCNC 16085) in all the three bands.

Three sigma upper limits of the OT are listed below.
We used GSC2.3 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.21515    18:25:43    4200.0   >19.1  >18.9  >18.3
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

J.A. Kennea (PSU), V. Mangano (PSU), M.C. Stroh (PSU), B.P. Gompertz
(U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
A. Maselli  (INAF-IASFPA), A. Melandri (INAF-OAB) and V. D'Elia report
on behalf of the Swift-XRT team:

We have analysed 8.7 ks of XRT data for GRB 140408A (D'Elia  et al. GCN
Circ. 16082
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 ),  from 91 s to 29.8 ks after the  BAT trigger. The data
comprise 268 s in Windowed Timing (WT) mode (the first 8 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 Evans et
al. (GCN Circ. 16085
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 ).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.77 (+0.10, -0.09).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2 (+80, -1). The
best-fitting absorption column is  1.4 (+7.3, -1.2) x 10^22 cm^-2,
consistent with the Galactic value of 1.8 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 1.5 x 10^-11 (6.9 x
10^-11) erg cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     1.4 (+7.3, -1.2) x 10^22 cm^-2
Galactic foreground: 1.8 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2 (+80, -1)

If the light curve continues to decay with a power-law decay index of
0.77, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.1 x
10^-14 (1.5 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/00595141.

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

N. P. M. Kuin (UCL-MSSL) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140408A
109 s after the BAT trigger (D'Elia et al., GCN Circ. 16082
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 ).
No optical afterglow consistent with the XRT position (Evans et al.,
GCN Circ. 16085
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 ,) and with the non-detection reported by Kuroda et al.
(GCN Circ. 16086
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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           109          259          147         >20.9
u_FC               321          571          246         >20.5
white              109         1025          334         >21.2
v                  652         4403          236         >20.0
b                  577          769           39         >18.7
u                  321          745          265         >20.5
w1                 701          720           19         >18.1
m2                 676         4572          201         >19.9
w2                 627         1046           54         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst
(Schlegel et al. 1998).

GRB 140408A: GROND Detection of an Afterglow Candidate
  
K. Varela, C. Delvaux (both MPE Garching), D.A. Kann (TLS 
Tautenburg), and J. Greiner (MPE Garching) report on behalf of the
GROND team:
  
We observed the field of GRB 140408A (Swift trigger 595141; d'Elia et 
al., GCN #16082
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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 La
Silla Observatory (Chile).

Observations started at 06:16:31 UT on 8th April 2014, 0.709 days
after the  GRB trigger. They were performed at an average seeing of
0".9 and at an average airmass of 1.6.
  
We find a single point source within the 2".2 Swift-XRT error circle
reported by Evans et al. (GCN #16085
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 ) at 
  
RA (J2000.0) = 19h 22m 51.78s  
Dec. (J2000.0) = -12d 35' 40.9" 
  
with an uncertainty of 0".4 in each coordinate.
  
Based on a 7380 s exposure on g'r'i'z' , and a 6000 s exposure in
JHK, we estimate preliminary magnitudes (all in AB system) of
  
g' = 25.6 +- 0.3 mag,
r' = 23.7 +- 0.2 mag,
i' = 22.7 +- 0.2 mag,
z' = 22.8 +- 0.3 mag,
J > 22.0 mag,
H > 21.5 mag, and
K > 20.0 mag.

We propose this source to be a candidate afterglow for GRB 140408A.
At the moment, fading can not be established. If it is the afterglow,
the SED suggests a redshift of z ~ 4.

Given magnitudes 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)=0.16 
mag in the direction of the burst (Schlafly & Finkbeiner 2011).

[GCN OPS NOTE(10apr14): The missing minus sign on the Declination value
in the 3rd paragraph was added. Acknowledgement to F.Marshall.]

T. N. Ukwatta (MSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC),
(i.e. the Swift-BAT team):

Using the data set from T-180 to T+902 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140408A (trigger #595141)
(D'Elia, et al., GCN Circ. 16082
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 ).  The BAT ground-calculated position is
RA, Dec = 290.723, -12.585 deg which is
   RA(J2000)  =  19h 22m 53.5s
   Dec(J2000) = -12d 35' 07.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.

The mask-weighted light curve shows a single-pulse structure starts at ~T-1 sec,
peaks at ~ T+1 sec, and ends at ~T+4 sec. T90 (15-350 keV) is 4.00 +- 1.41 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.66 to T+3.34 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.49 +- 0.25.  The fluence in the 15-150 keV band is 3.1 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.34 sec in the 15-150 keV band
is 1.2 +- 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/595141/BA/

Owen Littlejohns (ASU), 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), 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 140408A (D'Elia, et al., GCN 16082
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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 2014/04 9.41 to 2014/04 9.48
UTC (20.52 to 22.37 hours after the BAT trigger), obtaining a total of
1.42 hours exposure in the r and i bands.

For a source within the Swift-XRT error circle we obtain the following
upper limits (3-sigma):

  r     > 22.84
  i     > 22.53

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. These upper limits are consistent
with the previously reported GROND afterglow candidate (Varela, et al.,
GCN 16089
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 ).

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

H. Ohuchi, T. Yoshii, Y. Saito, Y. Tachibana, S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 140408A (V. D'Elia et al., GCN Circular #16082
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 ) 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 2014-04-08 17:03:08.6 UT ( 3.8h after the burst).
We did not find any new point source within the enhanced XRT circle (Evans et al., GCNC 16085) in all the three bands.
The measured magnitudes were listed below.

T0+[sec]    MID-UT    T-EXP[sec]    g'         Rc         Ic
$B!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=(B-
17105     18:00:59     6300        >20.1    >19.6     >19.1
$B!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=!=(B-
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.

S. Jeong, S. R. Oates, J. C. Tello, J. Gorosabel, A. Sota and A. J.
Castro-Tirado (IAA-CSIC), on behalf of a larger collaboration, report:

"Following the detection of GRB140408A by Swift (D'Elia et al., GCNC
16082), we observed the field of GRB 140408A with the 1.5 m OSN telescope
at Observatorio de Sierra Nevada in the R and I-bands. The observation
started on Apr 9, 04:01:16 UT (i.e. ~0.62 d post burst). No optical
afterglow is found at the position of the optical candidate reported by
Varela et al. (GCNC 16089) in the median combined images (6 x 300s)
down to 21.7 mag (I band) and 22.5 mag (R band) (3-sigma upper limits,
with all magnitudes in Vega system and no correction for the Galaxy
reddening)."

GRB 140408A: Withdrawal of afterglow candidate

F. Knust, K. Varela, C. Delvaux (all MPE Garching), D.A. Kann (TLS
Tautenburg) and J. Greiner (MPE Garching)  report on behalf of the GROND
team: 

We observed the GRB 140408A field again on further three epochs,
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).


The afterglow candidate reported in Varela et al. (GCN #16089
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 ) remained
constant, thus this source is a fore- or background source and not the
afterglow of GRB 140408A.

For the first epoch as reported in Varela et al. (GCN #16089
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 ), no other
source is seen in the 1".8 Swift-XRT refined error circle
(http://www.swift.ac.uk/xrt_positions/00595141/) down to limiting magnitudes
(all in the AB system) of

g' > 25.8 mag, 
r' > 25.6 mag, 
i' > 25.0 mag, 
z' > 25.0 mag, 
J > 22.1 mag, 
H > 21.5 mag, and 
K > 20.0 mag.

The given limits are based on calibrating the images against GROND
zeropoints and 2MASS field stars, and are not corrected for the Galactic
foreground extinction corresponding to a reddening of E_(B-V)= 0.16 in the
direction of the burst (Schlegel et al. 1998).

S. Sugita (AGU), H. Negoro, M. Nakajima, W. Maruyama, M. Aoki, K.
Kobayashi (Nihon U.),
S. Nakahira, T. Mihara, M. Matsuoka (RIKEN),
T. Sakamoto, M. Serino, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
M. Shidatsu (Ehime U.),
N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita, M. Oeda, K. Shiraishi
(Tokyo Tech),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N.Isobe, R. Shimomukai,
M. Tominaga (JAXA),
Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, S. Ogawa (Kyoto U.),
H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.),
M. Yamauchi, S. Iwahori, Y. Kurihara (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray
transient source at UT 2019/04/08 18:06:19.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (47.342 deg, 1.758 deg) = (03 09 22, +01 45 28) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.52 deg and 0.22 deg, respectively.
The roll angle of long axis from the north direction is 145.0 deg
counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90%
containment radius).
The X-ray flux averaged over the scan was 189 +- 35 mCrab
(2.0-4.0keV, 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) = (46.050, 1.531) deg = (03 04 11, +01 31 51) (J2000)
(R.A., Dec) = (46.579, 0.646) deg = (03 06 18, +00 38 45) (J2000)
(R.A., Dec) = (48.900, 2.032) deg = (03 15 35, +02 01 55) (J2000)
(R.A., Dec) = (48.371, 2.917) deg = (03 13 29, +02 55 01) (J2000)
There was no significant excess flux in the previous transit at UT 16:33
and in the next transit at UT 19:39 with an upper limit of 20 mCrab for each.