////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  8311
SUBJECT: Trigger 330353: Swift detection of a Galactic short soft burst
DATE:    08/10/03 10:18:48 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

H. A. Krimm (CRESST/GSFC/USRA), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), M. Capalbi (ASDC), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), O. Godet (U Leicester),
C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC),
S. D. Hunsberger (PSU), J. A. Kennea (PSU), J. Mao (INAF-OAB),
C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester),
S. R. Oates (UCL-MSSL), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (INAF-IASFPA),
B. Sbarufatti (INAF-IASFPA), R. L. C. Starling (U Leicester),
G. Tagliaferri (INAF-OAB) and E. Troja (INAF-IASFPA) report on behalf
of the Swift Team:

At 09:28:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short, soft burst (trigger=330353).  Swift slewed 
immediately to the location.  The BAT on-board calculated location is 
RA, Dec 237.711, -54.319 which is 
   RA(J2000) = 15h 50m 51s
   Dec(J2000) = -54d 19' 08"
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 less than 0.1 sec, with most of the flux
below 100 keV.  The peak count rate was ~4000 counts/sec (15-350 keV), 
at ~0 sec after the trigger. 

The XRT began observing the field at 09:29:26.6 UT, 77.9 seconds after
the BAT trigger. Using promptly downlinked data we find an X-ray source
with an enhanced position: RA, Dec 237.72546, -54.30659 which is
equivalent to:
   RA(J2000)  = 15h 50m 54.11s
   Dec(J2000) = -54d 18' 23.7"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 54 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. 

This position is 1.5 arcsec from (and hence consistent with) a source in the
2XMM catalogue: 2XMM J155054.2-541824. The XRT count rate is significantly 
higher than that catalogued by XMM, however. 

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density. 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 82 seconds after the BAT trigger. No 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 18.5 mag. 
No correction has been made for the large, but uncertain extinction expected. 

The enhanced brightness of the 2XMM source immediately following
a BAT detection argues that this is the correct source identification. 
However, we note that there are additional catalogued X-ray sources in 
the BAT error circle which are also plausible candidates for the
burst source.  Given the location of the burst, within 0.14 degrees
of the Galactic plane, these are all expected to be Galactic sources. 

Because this is a short soft burst from a Galactic source,
this may be a magnetar, such as an Soft Gamma Repeater (SGR) or
an Anomalous X-ray Pulsar (AXP). 

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  8312
SUBJECT: Swift discovery of a new Soft Gamma Repeater SGR 1550-5418
DATE:    08/10/03 11:46:01 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

H. A. Krimm (CRESST/GSFC/USRA), A. P. Beardmore (U Leicester),
N. Gehrels (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), R. L. C. Starling (U Leicester) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 11:16:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short soft burst (trigger=330367).   The BAT on-board 
calculated location is RA, Dec 237.704, -54.308 which is 
   RA(J2000) = 15h 50m 49s
   Dec(J2000) = -54d 18' 29"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  This is consistent with the location
of the trigger 330353, 108 minutes earlier.  The BAT light curve 
showed a single-peaked structure with a duration of about 0.750 sec, 
mostly below 100 keV.  The peak count rate was ~20000 counts/sec 
(15-350 keV), at ~0 sec after the trigger. 

Swift was already observing this source when BAT triggered. Hence, no XRT or UVOT
data will be downlinked via TDRSS, but will be available after the next Malindi pass. 

The earlier BAT trigger 330353 (Krimm et al. GCN 8311) showed
additional bursts at T+110s and T+520s, giving a total of
four known bursts from this source in under two hours.  Therefore
we believe that this is a new Soft Gamma Repeater, 
which we name SGR 1550-5418.  It is possible that this SGR
is the same source as the Anomalous X-ray Pulsar 1E1547.0-5408
(Gelfand & Gaensler 2007; Camilo et al. 2008; Halpern et al. 2008). 
This possible identification will be confirmed or refuted
when the XRT position data becomes available. 

Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.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.)

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  8313
SUBJECT: SGR 1550-5418 = AXP 1E1547.0-5408 (Trigger 330353)
DATE:    08/10/03 14:26:07 GMT
FROM:    Nanda Rea at U of Amsterdam  <nrea@science.uva.nl>

N. Rea (U. Amsterdam), P. Esposito (INAF-IASF, Milan), H. A. Krimm
(CRESST/GSFC/USRA), D. M. Palmer (LANL), S. Mereghetti, A. Tiengo
(INAF-IASF, Milan), G.L. Israel (INAF-OAR)

Swift-BAT triggered today on several Galactic short bursts (Krimm et al.
GCN 8311, 8312), which were claimed to come from a new Soft Gamma Repeater
SGR 1550-5418. However, given the positional coincidence of this new
putative SGR 1550-5418 with the Anomalous X-ray Pulsar (AXP) 1E1547.0-5408
(Gelfand & Gaensler 2007; Camilo et al. 2008; Halpern et al. 2008), and
the enhanced X-ray flux observed from promptly downlinked XRT data from
this source (Krimm et al. 8311), we now identify the source of these
bursts being the AXP 1E1547.0-5408.

See http://staff.science.uva.nl/~nrea/1E1546_XMM_CXO_GCNs.jpg for an
X-ray image of the field with superimposed the Swift-BAT and XRT
error circles from Krimm et al. (GCN 8311, 8312).

////////////////////////////////////////////////////////////////////////
ATEL #1756                                                           ATEL #1756

Title:          The new SGR 1550-5418 is the old AXP 1E1547.0-5408
Author: N. Rea (U. Amsterdam), P. Esposito (INAF-IASF, Milan), H.
                A. Krimm (CRESST/GSFC/USRA), D. M. Palmer (LANL), S. Mereghetti, A.
                Tiengo (INAF-IASF, Milan), G.L. Israel (INAF-OAR)
Queries:        N.Rea@uva.nl
Posted: 3 Oct 2008;  14:34  UT
Subjects:       X-ray, Request for Observations, Neutron Stars, Pulsars,
                Soft Gamma-ray Repeaters, Transients

N. Rea (U. Amsterdam), P. Esposito (INAF-IASF, Milan), H. A. Krimm
(CRESST/GSFC/USRA), D. M. Palmer (LANL), S. Mereghetti, A. Tiengo (INAF-IASF,
Milan), G.L. Israel (INAF-OAR)   

Swift-BAT triggered today on several Galactic short bursts (Krimm et
al. GCN 8311, 8312), which were claimed to come from a new Soft Gamma Repeater
SGR 1550-5418. However, given the positional coincidence of this new putative
SGR 1550-5418 with the Anomalous X-ray Pulsar (AXP) 1E1547.0-5408 (Gelfand
& Gaensler 2007; Camilo et al. 2008; Halpern et al. 2008), and the enhanced
X-ray flux observed from promptly downlinked XRT data of this source (Krimm
et al. 8311), we now identify the source of these bursts being the AXP
1E1547.0-5408.   

See http://staff.science.uva.nl/~nrea/1E1546_XMM_CXO_GCNs.jpg for an
X-ray image of the field with superimposed the Swift-BAT and XRT error
circles from Krimm et al. (GCN 8311, 8312).    

XMM-Newton and Chandra field of AXP 1E1547.0-5408: http://staff.science.uva.nl/~nrea/1E1546_XMM_CXO_GCNs.jpg

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  8315
SUBJECT: AXP 1E1547.0-5408 (SGR 1550-5418): Fermi GBM detection
DATE:    08/10/03 15:08:39 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) and M.S. Briggs (UAH) report on behalf of the Fermi GBM
Team: 

"On 3 October 2008 the Fermi Gamma-ray Burst Monitor triggered and located
three bursts from the Galatic source, reported by SWIFT (H. A. Krimm  et
al., GCN Circ. 8311, GCN Circ. 8312). Later the source of this burst was
identified being the AXP 1E1547.0-5408 (N. Rea et al., GCN Circ. 8313).

GBM triggered at: 

09:03:06 UT (trigger 244717387; GBM 081003.377)in the 25 to 50 keV energy
band with an integration time of 32 ms.

09:14:00 UT (trigger 244718041; GBM 081003.385)in the 25 to 50 keV energy
band with an integration time of 64 ms.

10:42:53 UT (trigger 244723369; GBM 081003.446)in the 50 to 300 keV energy
band with an integration time of 64 ms.

The GBM on-board locations are all consistent with the AXP 1E1547.0-5408
position.

The GBM triggers are not coincident in time with the Swift triggers, so
there are a total of seven bursts from this AXP.

The on-ground improved locations and results of spectral analysis will be
reported soon."

////////////////////////////////////////////////////////////////////////
ATEL #1758                                                           ATEL #1758

Title:          Possible NIR counterpart to the AXP 1E 1547.0-5408
Author: R. P. Mignani (UCL-MSSL), N. Rea (U. Amsterdam), G.L. Israel,
                V. Testa (INAF-OAR), P. Esposito (INAF-IASF) on behalf of a larger
                collaboration
Queries:        n.rea@uva.nl
Posted: 3 Oct 2008;  22:37  UT
Subjects:       Infra-Red, Request for Observations, Pulsars, Transients

On 2008 October 3rd, Swift-BAT triggered on several short bursts from
the direction of the Anomalous X-ray Pulsar (AXP) 1E1547.0-5408 (Krimm
et al. GCN 8311, 8312; Rea et al. Atel #1756). This is the second known
transient radio AXP discovered to date (Gelfand & Gaensler 2007; Camilo
et al. 2007), and it showed the previous X-ray outburst around June 2007
(Halpern et al. 2008).   

During the decay of the 2007 X-ray outburst we observed 1E 1547.0-5408
in the Ks band (on 2007 July 8th, 12th, and August 17th) with the NAOS
-CONICA  (NACO) instrument mounted at the ESO- VLT (Mignani, Rea, Testa,
et al., 2008 submitted). We have detected four objects  close to the source
error circle (labeled 1-4 in the finding chart available at http://staff.science.uva.nl/~nrea/ESO_VLT_1E1547.png
). The brightest one (object #3) has K= 16.22 +/-0.06, while objects #2
and #4 have K=18.51+/-0.06 and K=18.54+/-0.06,  respectively. None of them
was found to vary in the three nights. The faintest object, #1 (Ks = 20.3
+/- 0.07), was detected on the night of July 12th, 2007 only, although
we could not claim any significant variability because the July 8th and
August 17th observations were highly affected by bad atmospheric conditions.
The source brightness is consistent with that of typical NIR counterparts
of AXPs.   

Given the X-ray re-activation of the AXP 1E1547.0-5408, NIR follow-ups
would be crucial to assess with higher significance the possible variability
of source #1, a candidate NIR counterpart to this transient AXP. 

ESO-VLT NIR finding chart for the AXP 1E1547.0-5408: http://staff.science.uva.nl/~nrea/ESO_VLT_1E1547.png

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  8318
SUBJECT: Swift-BAT refined analysis of AXP 1E1547.0-5408 (Trigger 330353)
DATE:    08/10/03 23:29:59 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC),
T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+829 sec from recent telemetry downlinks,
we report further analysis of BAT trigger 330353 (Krimm, et al.,
GCN Circ. 8312).   We are not quoting the usual refined ground position
at this time because the automated processing did not choose an optimum
time interval for the position analysis.  Howver, it is consistant
with the catalog position of the 1E1547.0-5408 source.
The partial coding was 95%.
 
The mask-weighted light curve shows a spike with a duration of about 64 msec
at the time of the trigger.  There were multiple spikes from this source:
a smaller one at T-2.45 sec, slightly larger ones at ~T+105 and ~T+290 sec,
and much larger ones at ~T+420 and ~T+520 sec.
 
The time-averaged spectrum from T-0.016 to T+0.080 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index -0.11 +- 0.79,
and Epeak of 21.9 +- 9.5 keV (chi squared 43.1 for 49 d.o.f.).
A simple power law fit yields and index 1.81 +- 0.15.

////////////////////////////////////////////////////////////////////////
ATEL #1761                                                           ATEL #1761

Title:    AXP 1E1547.0-5408: Swift-XRT analysis
Author:   K.L. Page, A.P. Beardmore (U. Leicester) and H.A. Krimm (CRESST/GSFC/USRA)
Queries:  kpa@star.le.ac.uk
Posted:   4 Oct 2008;  14:21  UT
Subjects: X-ray

Swift-XRT started observing the field of the AXP 1E1547.0-5408 82 seconds
after the first BAT trigger (Krimm et al., <a href='http://gcn.gsfc.nasa.gov/gcn3/8311.gcn3'>GCN
Circ. 8311</a>) and a clear   X-ray source was found. Using 84 s of XRT
Photon Counting mode data and 1 UVOT images, we find an astrometrically
corrected X-ray position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue) of RA, Dec = 237.72433, -54.30643
which is equivalent to:   

RA (J2000):   15 50 53.84
Dec (J2000): -54 18 23.2   

with an uncertainty of 1.4 arcsec (radius, 90% confidence). This position
is 2.5 arcsec from CXOU J155054.1-541824 (<a href='http://ukads.nottingham.ac.uk/abs/2007ApJ...667.1111G'>Gelfand
& Gaensler 2007</a>), which   they identify with 1E1547.0-5408.   

The XRT detected an increased count rate at around 520 s, coincident
with one of the BAT spikes mentioned in Krimm et al. (GCN Circ. 8318);
similarly a brightening was seen at the time of the second trigger  
reported in <a href='http://gcn.gsfc.nasa.gov/gcn3/8312.gcn3'>GCN Circ.
8312</a>.  In both cases, the XRT registered a single, bright 2.5 s frame
of data.   

The spectrum from the first two orbits of PC data can be modelled by
a   highly-absorbed power-law, with Gamma = 2.33 +0.31/-0.29 and NH = (4.9
+0.8/-0.7) x 10^22 cm^-2.