SGR 0501+4516

D.M. Palmer (LANL) and S.D. Barthelmy (GSFC)
report on behalf of the Swift Team:

At 17:29:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a third outburst from SGR 0501+4516 (trigger=321252).
Swift was already observing this source (from the previous triggers,
GCNs 8112
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  and 8113
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 ).  The BAT light curve again shows a single spike
with a duration less than 128 msec.  The peak count rate was ~4000 counts/sec
(15-350 keV), at ~0 sec after the trigger.

E. Gogus (Sabanci University), P. Woods (Dynetics), and C. Kouveliotou
(NASA/MSFC), report on behalf of a larger collaboration:

We triggered our SGR ToO Program with RXTE following the Swift detection
of a burst from the new Soft Gamma Repeater SGR 0501+4516 (Barthelmy et
al. 2008, GCN # 8113). A 600 s RXTE observation started on 2008 August
22, 16:39:09 UT. During this pointing we detected one short SGR
burst-like event in the PCA data (2-60 keV), confirming that the new
source was in the field of view. We searched for a spin period for the
new SGR in the 2.5-13.5 keV band PCA event mode data and detected a
coherent signal (barycenter corrected) at 0.17334 Hz, corresponding to a
spin period of 5.769 +- 0.004 s.

A longer RXTE observation of SGR 0501+4516 is currently underway.  We
thank the RXTE planner, Divya Pereira, for prompt scheduling.

S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), N. Gehrels (GSFC),
S. T. Holland (CRESST/USRA/GSFC), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC)
(for the Swift-BAT team):
 
We report further analysis of three events from SGR 0501+4516
(triggers 321174, 321177, & 321252; GCN Circs. 8112
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 , 8113
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 , & 8115, repect;
and ATEL 1676).  We used data sets from T-2min to T+3min around each
of the 3 trigger times.  The BAT ground-calculated combined position is
RA, Dec = 75.264, 45.271 deg, which is 
   RA(J2000)  =  05h 01m 06.4s 
   Dec(J2000) = +45d 16' 17.1" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial codings were 67%, 100%, and 100%, respectively.
 
Trigger 312174:

The mask-weighted light curve shows a roughly triangular shaped peak
with the rise time slightly slower than the fall time.
T90 (15-350 keV) is 0.080 +- 0.014 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index -1.99 +- 0.01, 
and Epeak of 35.3 +- 2.0 keV (chi squared 65.4 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.5 +- 0.5 x 10^-8 erg/cm2
and the 1-sec peak flux measured from T-0.47 sec in the 15-150 keV band is
11.8 +- 1.0 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.43 +- 0.5 (chi squared 134 for 57 d.o.f.).
 
Trigger 312177:

The mask-weighted light curve shows a FRED peak with T_rise about 2 msec
and T_decay about 20 msec.  There is a small peak riding on the decay tail.
T90 (15-350 keV) is 0.072 +- 0.018 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.04 +- 0.49, 
and Epeak of 29.6 +- 3.3 keV (chi squared 69.3 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.7 +- 0.4 x 10^-8 erg/cm2
and the 1-sec peak flux measured from T-0.47 sec in the 15-150 keV band is
11.9 +- 0.8 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 3.39 +- 0.5 (chi squared 239 for 57 d.o.f.).

Trigger 312252:
 
The mask-weighted light curve shows two slightly overlapping triangular
shaped peaks.
T90 (15-350 keV) is 0.060 +- 0.014 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.0 to T+0.1 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.00 +- 1.35, 
and Epeak of 48.9 +- 10.5 keV (chi squared 54.4 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.4 +- 0.3 x 10^-8 erg/cm2
and the 1-sec peak flux measured from T-0.45 sec in the 15-150 keV band is
2.9 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.06 +- 0.25 (chi squared 64.5 for 57 d.o.f.).

All the quoted errors are at the 90% confidence level. 
 
We note that there were many spike-like pulsed events in the BAT data
around the time spanning these three events that were not sufficently strong
to yield successful triggers in the on-board processing.
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/321174/BA/
http://gcn.gsfc.nasa.gov/notices_s/321177/BA/
http://gcn.gsfc.nasa.gov/notices_s/321252/BA/

H. A. Krimm (CRESST/GSFC/USRA), D. M. Palmer (LANL), M. Perri (ASDC),
B. Preger (ASDC), M. Stamatikos (NASA/ORAU) and L. Vetere (PSU)
report on behalf of the Swift Team:

At 04:47:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a large flare from the newly-discovered SGR 0501+4516 
(GCN 8113
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 , Barthelmy et al.; trigger=321481).  Swift was pointed 
at the source at the time of the outburst. 
The BAT on-board calculated location is 
RA, Dec 75.270, +45.278 which is 
   RA(J2000) = 05h 01m 05s
   Dec(J2000) = +45d 16' 41"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single spike
of duration < 0.128 sec with a second smaller spike 0.5 sec later.  
The peak count rate was ~175000 counts/sec (15-350 keV), 
at ~0 sec after the trigger.  There is no obvious 'ringing'
at the SGR's rotation frequency following the burst, but this
may be found in further analysis. 

Because this was identified onboard as a known source,
it did not result in a GRB response with XRT and UVOT data
immediately available through TDRSS.  However, both instruments
were observing the source at the time of the flare, and will return
data through Malindi.

A. de Ugarte Postigo (ESO Santiago & IAA-CSIC Granada), A. J.
Castro-Tirado (IAA-CSIC Granada), J. M. Corral-Santana and J. Casares (IAC La
Laguna), J. Blomme (Katholieke Univ. Leuven), P. Kubánek, M. Jelínek and
J. Gorosabel (IAA-CSIC),
report:

"Following the discovery of the new soft gamma-ray repeater SGR 0501+4516
by SWIFT (Holland et al. GCNC 8112, Barthelmy et al. GCNC 8113), we have
observed the field starting on Aug 23 (since 01:45 UT) with different
telescopes/instruments on Spanish ground-based observatories: 0.6m
BOOTES-2 (Z-band), 1.2m Mercator Telescope (Ic-band) and 2.5m Isaac Newton
Telescope (r' & i' -bands). No optical counterpart within the reported
Swift XRT error box is detected on the first r'-band image obtained on Aug
23, 02:49 UT (high
airmass, limiting magnitude r'~21.5). We notice that some of the later
images overlap in time with the large gamma-ray flare reported by Krimm et
al. (GCN 8120
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 ) with null detection as a preliminary result once we have
inspected
by eye the whole BAT error box. Further analysis is on going".


This message can be quoted.

[GCN OPS NOTE(23aug08): Per author's request, "J. Corral" was replaced with
"J. M. Corral-Santana" in the author list.]

N. Gehrels (NASA/GSFC), J. Mao (INAF-OAB), D. M. Palmer (LANL),
M. Perri (ASDC), B. Preger (ASDC), G. Stratta (ASDC) and
L. Vetere (PSU) report on behalf of the Swift Team:

At 11:27:35 UT, the Swift Burst Alert Telescope (BAT) triggered on
a large flare from the newly discovered SGR 0501+4516 (trigger=321551). 
Swift was already observing this source location due to a previous
trigger on this source. 
The BAT on-board calculated location is 
RA, Dec 75.265, +45.281 which is 
   RA(J2000) = 05h 01m 04s
   Dec(J2000) = +45d 16' 52"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a roughly 
flat-topped structure with a duration of about 0.256 sec. 
The peak count rate was ~300k counts/sec (15-350 keV), 
at ~0.2 sec after the trigger. 

The BAT burst response algorithm causes a TDRSS alert only
when a known source exceeds twice its previous fluence, so
additional large flares may have occurred since the 
previously-reported large flare at 4:47:48 UT.  Ground
processing of Malindi data will be required to report
on other activity by this source. 

[GCN OPS NOTE(25aug08): Per author's request, the end of the
second sentence was changed from "...due to its previous." to
"...due to a previous trigger on this source.".]

A.J. van der Horst (NASA/ORAU) and C. Kouveliotou (NASA/MSFC) report
on behalf of a large collaboration:

"We observed the position of the new SGR 0501+4516 (GCN 8112
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 , 8113
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 )
at 4.8 GHz with the Westerbork Synthesis Radio Telescope at August 23
03.66 UT to 09.49 UT.
We do not detect a radio source at the Swift XRT position (GCN 8112
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 ).
The three-sigma rms noise in the map around that position is 99 microJy
per beam. The formal flux measurement for a point source at that location
is 13 +/- 33 microJy.

We would like to thank the WSRT staff for promptly scheduling and
obtaining these observations."

N. R. Tanvir (U. Leicester), W. Varricatt (JACH) report on behalf of a
larger collaboration:

We observed the field of SGR 0501+4516 with UKIRT/UFTI about 2 hours
after the first BAT trigger (Holland et al. GCN 8112
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 ).  We clearly
detect a faint point source in the K-band image within the XRT error
circle, at a position, relative to 2MASS stars in the field, of:

 05:01:06.75 +45:16:34.0 (J2000)

with an uncertainty of about 0.5 arcsec.  The magnitude of the source
is K~18.6 (also calibrated to 2MASS) and there is tentative evidence of
variability at the 0.2 mag level between sub-exposures, supporting the
possibility that it is the nIR counterpart to the SGR.

Further analysis is ongoing.

T. V. Kryachko (Astrotel Observatory, KSU/AST), D. V. Denisenko (IKI) 
and B. L. Satovskiy (Astrotel) report:

We have observed the field of SGR 0501+4516 (Barthelmy et al., GCN 8113
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 ; 
ATel 1676) remotely with 30-cm Astrotel-Caucasus telescope from Aug. 23, 
21:08:46 UT to Aug. 24, 01:21:52 UT.  In total, forty-five 300-sec 
exposures were obtained.  The first image taken at large zenith distance 
(69 deg) and with the last-quarter Moon only 26 deg away serendipitously 
covered an interval of burst activity from SGR 0501+4516.  Four BAT 
triggers occurred during these five minutes (Palmer, ATel 1678).  No 
object was found in our image inside the XRT error box or at the 
position of possible UKIRT nIR counterpart (Tanvir and Varricatt, GCN 
8126
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 ) to the limiting magnitude of R=19.0.  Comparison with the next 
image did not show any significant brightening of the variable star 
mentioned in GCN 8114
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 .

The analysis of full data set is underway.  Future observations of the 
field with Astrotel-Caucasus are planned.

I observed the Swift XRT location of SGR 0501+4516 (Holland et al., GCN #8112
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 ;
Barthelmy et al., GCN #8113
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 ) in the R-band using the MDM 2.4m telescope
on the nights of Aug. 23 and 24 UT.  Preliminary flux calibration was
performed with Landolt standard stars.  In a sequence of 90 s exposures from
Aug. 24 09:55 UT to 11:49 UT, I find variability of the star noted by
Denisenko (GCN #8114
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 ) as variable between POSS epochs.  It began at R = 17.16,
remaining at plateau for the first hour, then declined monotonically to
R = 17.35 over the next hour.  Within a radius of 10" of the XRT position,
there is no new object that is not on the POSS to a limit of R = 23.0 in the
summed images from Aug. 24.

I also obtained a series of 10 s exposures that bracketed the time
of the large flare on Aug. 23 11:27:35 UT (Gehrels et al., GCN #8124
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 ),
but unfortunately did not include it.  No optical increase is seen
in the Denisenko star in an exposure beginning 16 s after the burst
to a limit of 0.05 magnitudes.  No new object appears in the vicinity
of the XRT position to a limit of R = 20.5 in this image.

S. R. Kulkarni and D. A. Frail report:
We undertook VLA observations of SGR 0501+4516 (GCN 8113
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 )
on 2008 August 24 (starting at 0928 UT, 30 min duration) and
2008 August 25 (starting at 1054 UT, 1 hour duration) in the
8-GHz and 1.4 GHz bands.

No source was detected in the first epoch in the 8-GHz band
(75 microJy rms), consistent with the lack of detection
by WSRT (GCN 8125
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 )  on 2008 August 23 (03.66 to 09.49 UT).

A very strong source is seen in the second epoch:
	3 +/- 0.1 mJy (8.46 GHz)
        14 +/- 0.8 mJy (1.43 GHz)
The spectral index is -1 between these two frequencies.

One may conclude that SGR 0501+4516 is waking up from
hibernation. Radio observations at other frequencies are
strongly encouraged (to constrain the spectrum). Searches
for radio pulsations can be expected to be highly productive.
Finally, should the source remain radio bright, proper motion
measurements via VLBI become feasible.

K. Hurley and D. Gotz, on behalf of the INTEGRAL AO-6 SGR ToO team, report:

We have triggered an approved INTEGRAL ToO observation of SGR0501+4516.
The planned observing times during revolution 717 will be:

Start time              Duration (s)  
2008-08-27 00:46:16.0   105624  
2008-08-28 07:47:52.0    32274  
2008-08-28 17:39:00.0    44010  
2008-08-29 06:50:02.0    23472  

SPI will not be operating during these observations, due
to annealing.

We encourage simultaneous observations at all wavelengths.

Any last-minute schedule changes will be posted at

http://integral.esac.esa.int/isocweb/schedule.html?action=intro

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin,
D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov
and T. Cline, on behalf of the Konus-Wind team report:


On August 23-25 Konus-Wind detected in triggered mode four bursts from
new SGR 0501+4516 (Holland et al. GCN 8112
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 , Barthelmy et al. GCN 8113
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 ).

First two of these bursts were localized by Swift (Palmer et al. ATel #1678).
The others had the same estimated ecliptic latitude, temporal structure
and spectral parameters and so we can with great degree of probability
attribute them to the new SGR.

The burst lightcurves vary from a single pulse with a duration of less
than 50 ms to more complex structure lasting for ~500ms.
The spectra of the bursts demonstrate a pronounced spectral evolution
and are well fitted (in the 20-200 keV range) by the power law with
exponential cutoff. The bursts energetics in this range is summarized
in the table below. The high values of the peak fluxes, comparable
to ones for the strongest recurrent bursts from the other known SGRs
may imply the lower distance to the source.

--------------------------------------------------------------------
Date     UT               Fluence       Peak flux (2ms)
                           erg/cm2       erg/cm2/s
--------------------------------------------------------------------
080823a  04:47:46.194(*)  --            --
080823b  11:27:32.652     4x10-6        7x10-5
080824   01:17:55.316     2.5x10-5      2x10-4
080825   04:48:27.445     3.3x10-6      1.6x10-4
--------------------------------------------------------------------
(*) data are incomplete at this time

The Konus-Wind light curves are available at Ioffe website:
http://www.ioffe.ru/LEA/SGRs/080823_T41252/
http://www.ioffe.ru/LEA/SGRs/080824_T04675/
http://www.ioffe.ru/LEA/SGRs/080825_T17307/

J. Hessels (Univ. of Amsterdam), N. Rea (Univ. of Amsterdam), S. Ransom
(NRAO), B. Stappers (Univ. of Manchester), & collaborators

On 2008 August 23 14:53 (UT) we observed the recently discovered Soft
Gamma-Ray Repeater SGR J0501+4516 (GCN 8112
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 , 8113
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 ) with the Green Bank
Telescope (GBT) for about 1 hour, using the Pulsar Spigot at 2 GHz.

Folding the data at the X-ray rotational period of 5.769s (ATEL 1677)
revealed no radio pulsations over a wide range of trial dispersion measures
(DMs).  We place an upper limit of 40microJy on a putative radio pulsar at
this epoch, consistent with synthesis upper limits on the radio counterpart
from earlier that day (GCN 8125
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 ).  We have also searched a large range of
DMs for individual bright pulses and bursts. No obvious radio bursts were
found down to a time resolution of 3ms and a maximum DM of 1000 pc/cm^3.
Note that during our observation Swift-BAT observed a large burst (on 2008
August 23 14:56:26 UT; ATEL 1678) for which no obvious radio counterpart was
detected.  We are continuing to analyze these data to search for fainter
signals.

Westerbork observations are planned starting on 2008 August 26 03:00 (UT) to
search for pulsations from the recently reported VLA radio counterpart (GCN
8130
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 ).  A GBT ToO monitoring program to search for radio pulsations has been
requested.  We would like to thank the GBT schedulers for their prompt
attention to our request for observations.

Kazuhisa Mitsuda on behalf of Suzaku team report:

A Suzaku ToO observation of the newly discovered SGR 0501+4516
(Barthelmy et al. 2008, GCN Circular, 8113) has started at 00:05:00
on August 26 2008 (UT). It will continue until 08:25:00
on 27 August 2008 (UT). All the Suzaku narrow field instruments
(XIS and HXD: 0.2-600 keV energy range) are on during the observation.

Further follow-up observations at other wavelengths are encouraged.

Soft Gamma Repeater SGR 0501+4516: GBM Detection of multiple bursts 

C. Kouveliotou (NASA/MSFC), P.N. Bhat (UAH), E. Bissaldi (MPE), M.S.
Briggs (UAH), V. Connaughton (UAH), R. Diehl (MPE), G.J. Fishman
(NASA/MSFC), L. Gibby (NASA/MSFC), J. Greiner (MPE), A.S. Hoover (LANL),
A.J. van der Horst (NASA/ORAU), R.M. Kippen (LANL), G.G. Lichti (MPE),
C.A. Meegan (NASA/MSFC), S. McBreen (MPE), W.S. Paciesas (UAH), R.D.
Preece (UAH), H. Steinle (MPE), A. von Kienlin (MPE), M.S. Wallace
(LANL), and C.A. Wilson-Hodge (NASA/MSFC)report: 

The GLAST Burst Monitor has thus far triggered on 23 bursts from SGR
0501+5416, newly discovered with Swift (Holland et al. 2008, GCN Circ.
8112
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 , Barthelmy et al. 2008, GCN 8113
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  and GCN 8119
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 ). Additional
un-triggered bursts have been detected in the data; a complete census is
underway. The first GBM trigger was on 2008, August 22 (von Kienlin et
al. 2008, GCN 8122
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 ). The GBM team will issue future individual GCN
Circulars only for exceptionally bright SGR events. 

The GBM triggered-event rate has peaked at 14 events on 2008 August 23
and seems to be slowing down with only 2 on 2008, August 26.  We have so
far identified five events in common with Swift and three with
Konus-Wind. The event intensities range from weak to very bright; their
durations range between ~50 - 500 msec. Event spectra are on the average
best fit with a power law with an exponential cutoff and peak energies ~
40-50 keV. Taking into account the source location at the Galactic
anti-center, we assume a distance between 2-5 kpc, which corresponds to
a range of burst luminosities ~10^37 - 10^40 ergs.

G. J. Fishman (MSFC), S. McBreen (MPE), M. S. Briggs (UAH), C.
Kouveliotou (MSFC), A. von Kienlin (MPE), A. J. van der Horst
(MSFC/ORAU), P. N. Bhat (UAH), C. A. Meegan (MSFC), report for the Fermi
GBM team:


A recent GCN Circ. (Kouveliotou, et al., GCN 8138
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 ) summarizes
observations of SGR 0501+4516,as seen with the Fermi GBM (formerly GLAST
Burst Monitor). Below, we report on three exceptionally large events
from this data set observed on 24 and 25 August 2008.  Peak fluxes are
over a time interval of 64 ms and fluences for the durations listed;
both are for the energy range 20 to 200 keV. All event spectra were best
fit with a power law and an exponential cutoff; their spectral
parameters are also given below.

These large events may have observable ionospheric disturbances
associated with them.


----------------------------------------------------------------------

 Date      UT      Fluence    Peak flux  Index  E(peak)  Duration

                  (erg/cm2)  (erg/cm2-s)        (keV)     (ms)

080824*  1:17:57   2.2E-5      1.6E-4     0.21    50      448

080825*  4:48:29   2.7E-6      3.6E-5     0.14    39      192

080825   9:37:44   9.9E-7      1.0E-5     0.32    38      320

   * - reported by S. Golenetskii from Konus-Wind data (GCN 8132
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 )

-----------------------------------------------------------------------

V. Mangano (INAF-IASF PA), J. Kennea (PSU), M. Perri (ASDC),
G. Cusumano (INAF-IASF PA), D. N. Burrows (PSU),
N. Gehrels (GSFC), D. Palmer (LANL), S. Barthelmy (GSFC)
report on behalf of the Swift Team:

Swift XRT observed SGR 0501+4516 from 2008-08-22 12:43:36 s UT to
2008-08-24 01:35:43 s UT in Photon Counting (PC) mode and from
2008-08-26 05:14:58 s UT to 2008-08-27 02:31:59 s UT in Windowed Timing
(WT) mode for a total of about 38 ks exposure in PC and 30 ks in WT.
We performed the barycentric correction of photon arrival times and
a search for coherent pulsations over the full data set in the
0.2-10 keV band with epoch folding search techniques.
We had a highly significant detection at the period

P = 5.7620697 +/- 0.0000015 s

The quoted error is at the 90% confidence level and have been
calculated following the method described in
Cusumano, Massaro & Mineo, 2003, A&A, 402, 647.
The reference epoch is at 2008-08-22 12:42:08.278 s (Terrestrial time)
corresponding to the beginning of the PC observation.
This value is at < 2 sigma from the RXTE measure of 5.769 � 0.004 s
(Gogus et al. 2008, ATEL #1677).

The folded light curve shows a perfectly sinusoidal profile with a  
pulsed fraction of 17% (calculated as the half the difference between
the maximum and minimum count rates).

Further analysis to look for possible period evolution is ongoing.

We observed the field of the newly discovered SGR 0501+4516 (GCN 8112
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 , 8113
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 )
with the Giant Metrewave Radio Telescope at a central frequency of 618 MHz
between 03 to 08 UT on 25 August 2008. We do not detect a radio source at the
position of the SGR. The rms noise reached in the map is around 0.11 mJy per
beam. We place an upper limit to the flux at the target position of around 0.7
mJy at the 3 sigma level, due to nearby bright sources.

We thank the staff of GMRT who made this observation possible. GMRT is run by
the National Centre for Radio Astrophysics (NCRA) of the Tata Institute of
Fundamental Research (TIFR).

P.A. Evans and J.P. Osborne (U. Leicester) report on behalf of the
Swift-XRT team:

Using 9.1 ks of XRT Photon Counting mode data and 35 UVOT images, we find 
an astrometrically corrected X-ray position for SGR 0501+4516 (using the 
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 
catalogue): RA, Dec = 75.27834, +45.27649 which is equivalent to:

RA (J2000):   05h 01m 6.80s
Dec (J2000):  +45d 16' 35.4"

with an uncertainty of 1.4 arcsec (radius, 90% confidence). This 
position is consistent with the possible infra-red counterpart (Tanvir &
Varricatt, GCN Circ. 8126
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 ).

The position enhancement process is described by Goad et al. (2007, A&A,
476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current
algorithm is an extension of this method.

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

B. M. Gaensler (U. Sydney) and S. Chatterjee (U. Sydney) report:

We note that the newly identified magnetar SGR 0501+4516 
(GCN 8113
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 ) is in close proximity to the Galactic supernova 
remnant (SNR) HB9 = G160.9+2.6.

Specifically, the location of the SGR as determined by Swift XRT
(GCN 8112
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 ; GCN 8148
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 ) is just outside the south-eastern rim of HB9.
A 1.4 GHz radio image of the SNR taken from the Canadian Galactic
Plane Survey, and showing the position of the SGR, is available at:

http://www.physics.usyd.edu.au/~bmg/fig_sgr_snr.gif

The angular separation from the SNR's centre is approximately 
80 arcmin, corresponding to a projected space velocity of 
1700-4300 km/s for a distance to the SNR of 1.5 kpc and an age of
8000-20000 years (Leahy & Aschenbach, 1995, A&A, 293, 853).

The SGR's location outside the rim of a SNR and its high inferred
space velocity are similar properties to those inferred for other
SGRs. While there is as yet insufficient information to judge the
validity of a physical association between SGR 0501+4516 and SNR HB9, 
we note that this anti-centre region is relatively devoid of SNRs
and other evidence for massive star formation: there are only two
other catalogued SNRs within 15 degrees of this position.  A search
for other neutron stars associated with HB9 (Kaplan et al., 2006,
ApJS, 163, 344) did not detect any candidates.

This is a duplicate of ATEL #1683 (which should be cited instead of  
this GCN) copied to GCN as a courtesy to the gamma-ray burst community.

David Palmer (LANL) on behalf of the Swift Team, reports:

SGR 0501+4516 (ATEL #1675, #1676, #1677, #1678, #1682) has declined in  
activity. There have been no reported bursts in 43 hours, compared to  
the previous period with 56 bursts in 87 hours and a largest gap of 8  
hours.

Due to the unpredictable nature of these objects, this does not  
necessarily imply that it has returned to a multi-year (or even multi- 
day) quiescent stage.

As of the latest available Swift-BAT data, 2008-08-27 22:40 UT, the  
most recent reported burst from the SGR was detected by Konus-Wind on  
2008-08-26 at 03:16:15 (Konus-Wind team, private communication).  The  
most recent BAT detection was about 8 hours earlier.

The current list of BAT bursts, plus the reported Konus Wind bursts  
(from GCN #8132
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 ), follows.  As in ATEL #1676, which this expands, the  
bursts with more than 2000 counts in the BAT are marked with a '*'.


Trigger time (UTC) Trigger (ms) Notes

2008-08-22 12:41:59      64 *
2008-08-22 13:09:04     256
2008-08-22 13:12:53      16 *
2008-08-22 13:20:30           during slew
2008-08-22 14:17:55     256
2008-08-22 14:34:26      32
2008-08-22 17:29:30      64
2008-08-22 22:24:20      32
2008-08-22 22:36:53      32
2008-08-22 22:53:51      16
2008-08-23 00:28:13      32
2008-08-23 02:11:39         * during slew, 13k BAT counts
2008-08-23 04:47:49      16 * 35k BAT counts, seen by Konus-Wind
2008-08-23 06:31:37      16
2008-08-23 07:01:12           during slew, wrong time in ATEL #1678
2008-08-23 08:30:04      16 *
2008-08-23 08:34:57      32
2008-08-23 11:07:38      16
2008-08-23 11:27:35      16 * 90k BAT counts, seen by Konus-Wind
2008-08-23 14:27:37      64
2008-08-23 14:56:26      64 *
2008-08-23 16:31:22      16
2008-08-23 17:35:14      32 * 17k BAT counts
2008-08-23 17:35:15     128
2008-08-23 17:59:01       8
2008-08-23 19:08:10     128
2008-08-23 20:49:10     256
2008-08-23 20:53:29      16
2008-08-23 21:09:20      32
2008-08-23 21:11:17      64
2008-08-23 21:11:20      16
2008-08-23 21:13:40      64
2008-08-23 22:37:55       8
2008-08-24 00:05:30     128
2008-08-24 00:19:47       8 *
2008-08-24 01:17:55           Seen by Konus-Wind, not by BAT
2008-08-24 01:53:07      32
2008-08-24 02:02:47      32
2008-08-24 02:04:36      32
2008-08-24 06:56:53      32
2008-08-24 08:18:27      32
2008-08-24 08:23:39      16 * double peak
2008-08-24 08:23:39      32
2008-08-24 10:17:37     128
2008-08-24 18:19:38     128
2008-08-24 19:52:53      64 *
2008-08-24 22:30:12      16
2008-08-25 00:46:28      32
2008-08-25 03:19:18      32
2008-08-25 04:48:27           Seen by Konus-Wind, not by BAT
2008-08-25 10:22:03      16
2008-08-25 11:55:32      32
2008-08-25 19:24:09      32
2008-08-26 03:16:15           Seen by Konus-Wind, not by BAT

This GCN may not be cited.  Please cite ATEL #1683 instead.

N. Rea (U. Amsterdam), G.L. Israel, S. Mereghetti, A. Tiengo, P. 
Esposito (INAF), D. Gotz (CEA-Saclay) on behalf of a larger collaboration


We have triggered a ToO monitoring observation of SGR 0501+4516 with 
XMM-Newton. The planned observing windows are:

Start(UT)              Duration [s]

2008-08-29 06:48       26000
2008-08-31 09:45       22000
2008-09-02 09:45       22000
2008-09-06 13:20       27500


Simultaneous observations at all wavelengths are encouraged.

We are grateful to the XMM-Newton planning team for the efficiency in 
scheduling these observations, and to Norbert Schartel for approving our 
trigger.

D. A. Frail and S. R. Kulkarni report:

We have re-analyzed the VLA data taken at the VLA on 2008 August 24
and 25. We were unable to confirm the detection reported early by
Kulkarni & Frail (GCN 8130
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 ). The radio source seen in the second epoch
appears to be spurious, an artifact of the observing method, missed in
the initial data reduction.

Combining all data from August 24 and 25, the final limits on the flux
density at the position of the SGR are:

    43 +/- 400 uJy  (1.43 GHz)
   -12 +/- 23  uJy  (8.46 GHz)

Joseph D. Gelfand (NYU / NSF), Gregory Taylor (UNM), Chryssa Kouveliotou 
(NASA/MSFC), Bryan Gaensler (U. Sydney), and Alexander J. van der Horst 
(NASA/ORAU) report:

A VLA observation of SGR 0501+4516 (GCN 8113
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 ) on 2008 August 27 between 0846 UT 
and 1215 UT did not detect a radio source at the position reported in GCN 8148
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at any of the four observed frequencies.  The five sigma upper-limits on the 
radio emission during this period are:
 		   1.4 GHz	< 1 mJy    (rms = 0.2 mJy)
 		   4.8 GHz	<0.15 mJy  (rms = 30 uJy)
 		   8.5 GHz      < 0.2 mJy  (rms = 40 uJy)
 		   22 GHz       < 1.5 mJy  (rms = 0.3 mJy)

We would like to thank NRAO for promptly scheduling these VLA observations.

N. Rea (U. Amsterdam), E. Rol (U. Leicester), P.A. Curran (U.
Amsterdam), I. Skillen (Isaac Newton Group), D.M. Russell (U.
Amsterdam), G.L. Israel (INAF) on behalf of a larger collaboration


On 2008 August 25 we observed the new Soft Gamma-ray Repeater SGR
0501+4516 with LIRIS, the near-infrared imager on the William Herschel
Telescope (WHT) in La Palma. The observations were performed in the Ks
band with a total exposure time of 1.8 hours.

We clearly detect one object within the refined XRT error circle (GCN 
8148
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 ), at the position:

05:01:06.74  +45:16:34.1 (J2000)

with an uncertainty of 0.25 arcseconds (with respect to 2MASS 
astrometry). This is consistent with being the UKIRT suggested nIR 
counterpart (GCN 8126
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 ). We find the object at a magnitude of 19.2+/-0.2 
(with respect to 2MASS calibration), slightly fainter than the UKIRT 
detection. We plan to take further observations from WHT in a few days 
to confirm this very tentative nIR variability.

We wish to thank Chris Benn and Rene Rutten for promptly approving our 
Target of Opportunity request.

T. Fatkhullin (SAO-RAS Nizhnij Arkhyz), A. de Ugarte Postigo (ESO 
Santiago), A. J. Castro-Tirado, J. Gorosabel and M. Jelínek (IAA-CSIC 
Granada), V. Sokolov (SAO-RAS), S. Guziy (Nikolaev State Univ.), A. 
Pozanenko (IKI-RAS Moscow), E. Sonbas (Cukurova Univ.) and D. 
Pérez-Ramírez (U. Leicester), on behalf of a larger collaboration, report:

"Continuing with our monitoring campaign of the field of the SGR 
0501+4516 (Holland et al. GCNC 8112, Barthelmy et al. GCNC 8113) we have 
used the 6.0m BTA telescope (equipped with SCORPIO) at the Special 
Astrophysical Observatory (SAO, Russia). A combination of exposures 
adding a total of 1530s in the I-band obtained at a mean epoch of August 
25.18468 UT shows a low S/N source consistent with the NIR object 
reported by Tanvir and Varrycatt (GCN 8126
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 ), with a magnitude of I = 
23.3 ± 0.4. Taking into account the nIR magnitude reported by Rea et al. 
at about the same epoch (GCNC 8159), we derive an apparent color index 
(I-Ks) = 4.1 ± 0.6, uncorrected for Galactic extinction in the line of 
sight to the source. Further observations are planned."

This message can be quoted.

A. de Ugarte Postigo (ESO, Santiago), A. J. Castro-Tirado, J. Gorosabel
(IAA-CSIC, Granada), M. Morales-Calder�n and N. Hu�lamo (LAEFF-INTA,
Madrid), on behalf of a larger collaboration, report:

We have observed the field of SGR 0501+4516 (Holland et al. GCNC 8112,
Barthelmy et al. GCNC 8113) using the 4.2m WHT (equipped with LIRIS) on
Aug. 29.245 UT. A short integration in the K-band does not show any source
at the position of the proposed NIR counterpart (Tanvir et al. GCNC 8126)
down to a 3-sigma limiting magnitude of K~19.5. This is consistent with
the flux decline observed by Rea et al. on Aug 25 (GCNC 8159) and would
correspond with the decline in high energy activity reported by Palmer
(GCN 8150
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 , ATEL #1683). This implies that the source reported in the NIR
by Tanvir et al. and in the optical by Fatkhullin et al. (GCNC 8160) is
most likely the counterpart for SGR 0501+4516 at these wavelengths.

This message can be quoted.

K. Hurley and D. Gotz, on behalf of the INTEGRAL AO-6 SGR
collaboration, report:

INTEGRAL carried out a ToO observation of SGR 0501+4516 from
2008-08-27T00:46 to 2008-08-29T13:36 (GCN 8131
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 ).  A very preliminary
analysis of the data indicates that IBIS/ISGRI detected the quiescent
X-ray emission at the 2 mCrab level between 20 and 40 keV.  At least
four bursts were detected, at

2008-08-27T16:25:14 
2008-08-27T22:25:57
2008-08-28T03:32:28
2008-08-28T20:59:42

Data analysis is ongoing.

We would like to thank the INTEGRAL project for their support
and particularly Dominique Eckert and Volker Beckmann for the
quick-look analysis.

E. Rol, N. Tanvir (U. of Leicester), N. Rea (U. of Amsterdam),
K. Wiersema (U. of Leicester), I. Skillen (ING) and P. A. Curran (U. of
Amsterdam) report for a larger collaboration:

We observed the candidate counterpart to SGR 0501+4516 with LIRIS at
WHT, Roque the Los Muchachos and NIRI at Gemini-North, Mauna Kea,
around August 31, 3 UT and September 1, 14 UT, respectively. On both
epochs, we measure a magnitude of K = 19.1 +/- 0.1, consistent with
the magnitude previously reported in GCN 8159
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  (magnitudes calibrated
to 2MASS).  This is in contrast to the upper limit given in GCN 8162
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 ,
though our observations do not preclude a sudden decrease and
subsequent rise to the previous flux level. Our observations, however,
indicate a relatively stable nIR counterpart candidate over this time
interval.

N. Rea (U. Amsterdam), S. Mereghetti (INAF-IASF, Milan), G.L Israel 
(INAF-OAR), P. Esposito, A. Tiengo (INAF-IASF, Milan), S. Zane (UCL-MSSL) 
report on behalf of a larger collaboration:


XMM-Newton observed the new Soft Gamma-ray Repeater SGR 0501+4516
(Holland et al., GCN 8112
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 ; Barthelmy et al., GCN 8113
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 )
for ~49ks on 2008 August 23rd starting at 01:04:00 (UT).
Preliminary results show that the source flux is enhanced in
the soft X-ray range with respect to the possible quiescent
ROSAT counterpart (Kennea et al., Atel 1675).

The source persistent EPIC-PN spectrum is well fitted (in the 1-10keV
energy range; reduced chi2 = 1.02) by an absorbed blackbody plus a
power-law with Nh = 0.89(2) x 1022 cm-2, kT = 0.69(5) keV and photon
index Gamma= 2.76(6). The absorbed 1-10keV flux is 3.96x10-11
erg/s/cm2.

We measure a spin period of 5.762069(5)s (consistent with the
RXTE and Swift-XRT determinations: Gogus et al., Atel 1677; Mangano et 
al., Atel 1682), with a fundamental component pulsed fraction of 40(1)%
(pulsed fraction defined as the background-corrected semi-amplitude of
the best fitting sine component, and in the whole EPIC-PN energy band).

Several short X-ray bursts have been detected in this observation,
the brightest ones also observed by Swift BAT (Palmer et al., Atel 1678).

A detailed analysis of this and the subsequent observations of our
XMM-Newton monitoring program (Rea et al., GCN 8152
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 ) is in progress.
Note that we postponed the last observation of our monitoring (September 
6th, see GCN 8152
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 ), and will promptly diffuse a new date encouraging 
multiwavelegth follow-ups.

We thank Norbert Schartel and the XMM-Newton team for carrying out this
ToO observation.

[GCN OPS NOTE(10sep08): Per author's request, in the Subject-line,
the "0105" was changed to "0501".]

SGR 0501+4516: Spin Down Rate and Inferred Dipole Magnetic Field

Peter M. Woods (Dynetics), Ersin Gogus (Sabanci University), Chryssa
Kouveliotou (NASA/MSFC), report on behalf of a larger collaboration:

We continued monitoring the new Soft Gamma Repeater SGR 0501+4516
(Barthelmy et al. 2008, GCN # 8113, Palmer et al. 2008, ATel # 1678)
using our SGR ToO Program with RXTE. We acquired a total exposure of 40
ks in 13 RXTE pointings performed over a time span of ~7.5 days. The
time spacing between each pointing ranged between 0.1 - 0.9 d. We detect
numerous (between 1 to 50) short bursts in observations before 2008
August 28. We clearly detect the 5.76 s pulsations reported by Gogus et
al. 2008 (ATel # 1677) in the 2-10 keV PCA data. We employed a quadratic
spline fit to phase residuals and measured the spin period, P =
5.762067(2) s and the spin-down rate, Pdot = 1.5(5) x 10^-11 s/s. Note
that our spin period measurement is consistent with that reported by
Mangano et al. (2008, ATel # 1682). Assuming that the neutron star slows
down via magnetic dipole radiation, we infer a dipole magnetic field of
B = 3 x 10^14 G, confirming the new SGR as a new magnetar candidate.

Joseph D. Gelfand (NYU / NSF), Gregory Taylor (UNM), Chryssa Kouveliotou 
(NASA/MSFC), Bryan Gaensler (U. Sydney), and Alexander J. van der Horst 
(NASA/ORAU) report:

A VLA observation of SGR 0501+4516 (GCN 8113
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 ) on 2008 August 31 between 
1109 UT and 1358 UT did not detect a radio source at the position reported 
in GCN 8148
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  at 4.8 GHz, the only frequency used during this observation. 
The resultant five sigma upper-limit on the radio emission during this 
period is < 0.1 mJy (rms = 20 uJy).  We would like to thank NRAO for 
promptly scheduling these VLA observations.

E. O. Ofek (Caltech), M. Kiewe and I. Arcavi (Weizmann Institute)
report on behalf of a larger collaboration:

On 2008 Sep 02.509 we obtained 7x120s i-band images of the region of SGR
0501+4516 with the Large Format Camera, mounted on the Hale 5m telescope.
At the position of the near-IR/visible light counterpart of SGR 0501+4516
(Rea et al. GCN 8159
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 ; Fatkhullin et al. GCN 8160
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 ; de Ugarte Postigo et al.
GCN 8162
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 ; Rol et al. GCN 8164
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 ) we marginally detected a source.
Using a POSS-II I-band magnitude of a nearby star to calibrate
the image, we find that this source has i(AB)=23.5+/-0.4 mag.
This measurement is consistent with the one reported by
Fatkhullin et al. (GCN 8160
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 ), who detected an I=23.3+/-0.4 source
at this position, on 2008 Aug 25.

Y.E. Nakagawa (RIKEN), K. Yamaoka, A. Yoshida (AGU),
T. Enoto, K. Nakazawa (U. Tokyo), K. Makishima (U. Tokyo/RIKEN),
N. Rea (U. Amsterdam), P. Esposito (INAF/IASF),
T. Sakamoto (GSFC/UMBC), and K. Hurley (U.C. Berkeley),
on behalf of the Suzaku SGR ToO team, report:

We report on a Suzaku ToO observation of the new soft gamma-ray
repeater SGR 0501+4516 (Holland et al. GCN #8112
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 , Barthelmy et al.
GCN #8113
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 ), started on 2008-08-26 00:05 UT, for an exposure time of
about 43 ksec (Mitsuda et al. GCN #8136
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 ). A bright point source was
clearly detected in the XIS CCDs at a position consistent with that of
SGR 0501+4516 (Evans et al. GCN #8148
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 ).

From a preliminary analysis of the XIS data, the 1-10 keV persistent
emission spectrum is well fit by a black body with a temperature of 
0.7 keV, plus a power-law with a photon index of 2.9, absorbed by a 
hydrogen column density of 1.0x10^22 cm^-2. The absorbed 1-10 keV flux 
was (3.7+/-0.1)x10^-11 erg/cm^2/s. The XIS data confirm the source
pulsations at a period of P = 5.762 +/- 0.001 s, consistent with the
periodicity derived by the RXTE/PCA (Gogus et al. GCN #8118
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 ),
Swift/XRT (Mangano et al. GCN #8146
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 ), and XMM-Newton (Rea et al. Atel
#1688; Israel et al. Atel #1692)

At least 16 short bursts were detected during the observation.
The largest burst was observed on 2008-08-26 03:16:16 by all Suzaku's
instruments including Suzaku-WAM, up to an energy of ~200 keV. The HXD 
spectral analysis of the persistent and burst emission is in progress.

We would like to thank the Suzaku managers and the operation team
for approving and carrying out the ToO observation.

V. Rumyantsev,  S. Artemenko (CrAO), A. Pozanenko (IKI), A. J. Castro-Tirado
(IAA-CSIC Granada),  report on behalf of larger GRB follow-up collaboration:

We observed the field of   SGR 0501+4516 (Holland et al. GCN 8112
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 , Barthelmy
et al. GCN 8113
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 ), in I band on August   26-28 with Shajn telescope of  CrAO.
The observation epochs are 2008-08-26T23:17:51 -- 2008-08-27T00:05:51 and
2008-08-27T23:27:32 -- 2008-08-28T00:31:32. We do not detect NIR/optical
counterpart of SGR 0501+4516 (Tanvir et al, GCN 8126
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 , Rea et al, GCN 8159
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 ,
Fatkhullin et al, GCN 8160
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 ) in the first epoch, while in the second epoch
(Aug. 27.9993) one may suggest a presence of counterpart. Upper limits of
combined images are following:

Mean epoch,   Exposure, UL (3sigma)

Aug. 26.9874  60x34     22.8
Aug. 27.9993  60x60     23.6