- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Wed 18 Mar 15 07:06:15 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 635289, Seg_Num: 0
GRB_RA: 324.971d {+21h 39m 53s} (J2000),
325.255d {+21h 41m 01s} (current),
324.031d {+21h 36m 08s} (1950)
GRB_DEC: -61.477d {-61d 28' 35"} (J2000),
-61.407d {-61d 24' 25"} (current),
-61.703d {-61d 42' 11"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 50678 [cnts] Image_Peak=844 [image_cnts]
TRIGGER_DUR: 16.384 [sec]
TRIGGER_INDEX: 479 E_range: 25-100 keV
BKG_INTEN: 181032 [cnts]
BKG_TIME: 25394.67 SOD {07:03:14.67} UT
BKG_DUR: 64 [sec]
GRB_DATE: 17099 TJD; 77 DOY; 15/03/18
GRB_TIME: 25493.29 SOD {07:04:53.29} UT
GRB_PHI: 148.32 [deg]
GRB_THETA: 33.51 [deg]
SOLN_STATUS: 0x3
RATE_SIGNIF: 10.09 [sigma]
IMAGE_SIGNIF: 9.87 [sigma]
MERIT_PARAMS: +1 +0 +0 +4 +2 +0 +0 +0 -41 +0
SUN_POSTN: 357.58d {+23h 50m 20s} -1.05d {-01d 02' 48"}
SUN_DIST: 65.14 [deg] Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN: 328.77d {+21h 55m 05s} -9.01d {-09d 00' 49"}
MOON_DIST: 52.46 [deg]
MOON_ILLUM: 7 [%]
GAL_COORDS: 332.05,-43.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 303.05,-44.19 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This Notice was delayed by more than 60 sec past the end of the trigger integration interval;
COMMENTS: probably due to it occurring during a Malindi downlink session.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 84.79,-19.93 [deg].
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Wed 18 Mar 15 07:07:48 UT
NOTICE_TYPE: Swift-XRT Position
TRIGGER_NUM: 635289, Seg_Num: 0
GRB_RA: 325.0056d {+21h 40m 01.34s} (J2000),
325.2893d {+21h 41m 09.42s} (current),
324.0667d {+21h 36m 16.01s} (1950)
GRB_DEC: -61.4559d {-61d 27' 21.2"} (J2000),
-61.3864d {-61d 23' 11.1"} (current),
-61.6827d {-61d 40' 57.5"} (1950)
GRB_ERROR: 4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 8.33e-09 [erg/cm2/sec]
GRB_SIGNIF: 15.36 [sigma]
IMG_START_DATE: 17099 TJD; 77 DOY; 15/03/18
IMG_START_TIME: 25634.57 SOD {07:07:14.57} UT, 141.3 [sec] since BAT Trigger Time
TAM[0-3]: 327.67 237.21 261.53 243.64
AMPLIFIER: 2
WAVEFORM: 134
SUN_POSTN: 357.58d {+23h 50m 20s} -1.05d {-01d 02' 47"}
SUN_DIST: 65.12 [deg] Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN: 328.79d {+21h 55m 09s} -9.01d {-09d 00' 33"}
MOON_DIST: 52.44 [deg]
MOON_ILLUM: 7 [%]
GAL_COORDS: 332.07,-43.31 [deg] galactic lon,lat of the burst
ECL_COORDS: 303.08,-44.18 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: The XRT position is 1.60 arcmin from the BAT position.
COMMENTS: The object found at this position is either a very bright burst or a cosmic ray hit.
COMMENTS: Examine the XRT Image to differentiate (CRs are much more compact); see examples at:
COMMENTS: http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .
- GCN Circular #17599
C. Pagani (U Leicester), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
H. A. Krimm (CRESST/GSFC/USRA), C. J. Mountford (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:
At 07:04:53 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150318A (trigger=635289). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 324.971, -61.477d which is
RA(J2000) = 21h 39m 53s
Dec(J2000) = -61d 28' 35"
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 80 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~4 sec after the trigger.
The XRT began observing the field at 07:07:14.5 UT, 141.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 325.0056, -61.4559 which is equivalent to:
RA(J2000) = +21h 40m 1.34s
Dec(J2000) = -61d 27' 21.2"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 96 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.
UVOT took a finding chart exposure of 150 seconds with the white filter
starting 164 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 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
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
0.04.
Burst Advocate for this burst is C. Pagani (cp232 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.)
- GCN Circular #17600
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 669 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150318A, 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 = 325.00597, -61.45674 which is equivalent
to:
RA (J2000): 21h 40m 1.43s
Dec (J2000): -61d 27' 24.3"
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.
- GCN Circular #17602
P. Wiseman, K. Varela, M. Salvato and J. Greiner (all MPE Garching) report
on behalf of the GROND team:
We observed the field of GRB 150318A (SWIFT-635289; Pagani et al.,
GCN#17599) 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 on March 18rd, 2015, at 08:27 UT,
83 minutes after the GRB trigger. They were performed at an average seeing
of 1.3" and at an average airmass of 2.0.
We do not detect a source inside the 1.9 arcsec error circle reported by
Evans et al. (GCN #17600). Based on a total exposure of 0.67 hours in
g'r'i'z'and 0.73 hours in JHK, we measure the following preliminary upper
limits (AB magnitudes system):
g' > 24.9 mag,
r' > 24.8 mag,
i' > 24.2 mag,
z' > 23.9 mag,
J > 21.4 mag,
H > 20.9 mag, and
K > 18.9 mag.
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) = 0.03 mag in the
direction of the burst (Schlegel et al. 1998).
- GCN Circular #17603
A. A. Breeveld (UCL-MSSL) and C. Pagani (U Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150318A
151 s after the BAT trigger (Pagani et al., GCN Circ. 17599).
No optical afterglow consistent with the XRT position (Evans et al. GCN
Circ. 17600) 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 151 300 147 >20.8
u_FC 308 558 246 >19.8
white 151 5695 530 >21.4
v 638 6106 432 >20.0
b 736 6762 252 >20.4
u 308 6721 659 >20.4
w1 687 6516 413 >20.2
m2 4676 6311 393 >20.1
w2 4266 5901 393 >20.8
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.04 in the direction of the
burst (Schlegel et al. 1998).
- GCN Circular #17604
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), C. Pagani (U. Leicester), 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 150318A (trigger #635289)
(Pagani, et al., GCN Circ. 17599). The BAT ground-calculated position is
RA, Dec = 324.990, -61.461 deg, which is
RA(J2000) = 21h 39m 57.6s
Dec(J2000) = -61d 27' 41.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 44%.
The mask-weighted light curve shows two very broad peaks. The first one runs
from about T-10 sec to T+50 sec, and the second, brighter peak starts at T+50 sec,
peaks at ~T+65 sec and decays to background by T+120 sec.
T90 (15-350 keV) is 83.88 +- 12.57 sec (estimated error including systematics).
The time-averaged spectrum from T-6.60 to T+98.58 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.00 +- 0.12. The fluence in the 15-150 keV band is 2.5 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+66.62 sec in the 15-150 keV band
is 1.1 +- 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/635289/BA/
- GCN Circular #17605
A. Trotter, D. Reichart, J. Haislip, A. Aji, R. Beauchemin, T. Berger, A. Dow, A. Foster,
N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M. Maples, J. Moore, M. Nysewander, C. Salemi,
L. Zbinden, and J. A. Crain report:
Skynet observed the Swift BAT/XRT localization of GRB 150318A (Pagani et al., GCN 17599, Swift
trigger=635289) with with one 24" telescope (PROMPT 8; I band) and four 16" telescopes
(PROMPT 1,3,4,5; V,B,R,I bands) of the PROMPT array at CTIO, Chile.
Starting at 2015-03-18 06:06:54 UT and continuing until 09:52 UT (t=2m-2.8h post-trigger),
Skynet took a total of 376 exposures ranging from 10-160s. We stacked subsets of these images
to maximize the S/N ratio, and detected no optical source in any band at the XRT position.
Our 3-sigma limiting magnitudes are:
==============================================
tmid scope band exposures lim mag
----------------------------------------------
104m PROMPT8 I 69 x 80s >20.9
104m PROMPT5 I 43 x 160s >20.9
78m PROMPT4 R 37 x 80s >20.9
104m PROMPT1 V 42 x 160s >21.6
125m PROMPT3 B 18 x 160s >21.1
Limiting magnitudes are in the Vega System, calibrated to 3 APASS stars in the field. Magnitudes
have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.03
(Schlafly & Finkbeiner 2011).
No further Skynet observations are scheduled.
- GCN Circular #17608
P.A. Evans (U. Leicester), A. Amaral-Rogers (U. Leicester), A. Maselli
(INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A.
Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.P.
Osborne (U. Leicester) and C. Pagani report on behalf of the Swift-XRT
team:
We have analysed 6.3 ks of XRT data for GRB 150318A (Pagani et al. GCN
Circ. 17599), from 130 s to 40.1 ks after the BAT trigger. The data
comprise 191 s in Windowed Timing (WT) mode (the first 9 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. 17600).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.25 (+0.23, -0.29). At T+187 s the decay
steepens to an alpha of 5.30 (+/-0.18) before breaking again at T+628 s
to a final decay with index alpha=0.94 (+0.19, -0.21).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.46 (+/-0.06). The
best-fitting absorption column is 3.17 (+0.22, -0.21) x 10^21 cm^-2,
in excess of the Galactic value of 3.3 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 2.9 x 10^-11 (5.8 x 10^-11) erg
cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
Total column: 3.17 (+0.22, -0.21) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 21.9 sigma
Photon index: 2.46 (+/-0.06)
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 1.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.4 x
10^-14 (8.7 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00635289.
This circular is an official product of the Swift-XRT team.
Previous IAU Circulars 