Gamma-ray Burst 040827

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Fri 27 Aug 04 13:47:40 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    1,   Sub_Num: 1
GRB_RA:         229.2437d {+15h 16m 58s} (J2000),
                229.3090d {+15h 17m 14s} (current),
                228.5427d {+15h 14m 10s} (1950)
GRB_DEC:        -16.1582d {-16d 09' 28"} (J2000),
                -16.1751d {-16d 10' 29"} (current),
                -15.9752d {-15d 58' 30"} (1950)
GRB_ERROR:      3.00 [arcmin, radius, statistical only]
GRB_INTEN:      7.13 [sigma]
GRB_TIME:       42671.19 SOD {11:51:11.19} UT
GRB_DATE:       13244 TJD;   240 DOY;   04/08/27
SC_RA:          240.48 [deg] (J2000)
SC_DEC:         -22.06 [deg] (J2000)
SUN_POSTN:      156.41d {+10h 25m 37s}   +9.84d {+09d 50' 39"}
SUN_DIST:        76.67 [deg]
MOON_POSTN:     302.51d {+20h 10m 02s}  -25.27d {-25d 15' 56"}
MOON_DIST:       68.29 [deg]
GAL_COORDS:     346.44, 34.15 [deg] galactic lon,lat of the burst
ECL_COORDS:     231.14,  1.95 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.

red DSS finding chart ps-file
GCN notice #2670
S. Mereghetti, D. Gotz (IASF, Milano), M.Beck, S.Shaw, P.Lubinski, J.Borkowski (ISDC) on behalf of the IBAS Localization Team report
A 40 s long GRB has been detected with the INTEGRAL Burst Alert System (IBAS) on Aug 27 at 11:50:48 UT. The GRB has been detected with IBIS/ISGRI in the 15-200 keV band but with a significance below the threshold for automatic delivery of the IBAS Alert Packets.
Its coordinates (J2000) are:
```
R.A.  15h 16m 37.7s
Dec. -16deg 09' 29''
```
with an uncertainty of 3 arcmin (90% c.l. radius)
This message can be cited.
GCN notice #2671
D. Gotz and S. Mereghetti (IASF-Milano) report:
the preliminary peak flux for GRB 040827 in the 20-200 keV band is 0.6 photons/cm2 s (6.E-8 erg/cm2 s).
This message can be cited.
GCN notice #2672
S. Mereghetti, D. Gotz (IASF, Milano), M.Beck, S.Shaw, P.Lubinski, J.Borkowski (ISDC) on behalf of the IBAS Localization Team report
From further analysis of GRB 040827 we derived an improved position at:
```
R.A.:  15h   16m  59.8s
Dec.  -16deg 08' 21''
```
with an uncertainty of 2.5 arcmin
Note that this updated position is consistent with the one in the IBAS Alert Packet, but due to an error is at about 5 arcmin form that reported in GCN 2670.
GCN notice #2673
XMM-Newton will observe GRB080427 field at location (RA=15h 16m 57.7s, DEC=-16d 09' 29'', J2000), starting at 18:07:56ss UT, on Aug 27, 2004, for an exposure of 54300 seconds.
GCN notice #2674
B. Monard (Bronberg Obs., bmonard@mweb.co.za) reports on behalf of the AAVSO International GRB network:
Observations of the INTEGRAL error circle for GRB040827 (Mereghetti et al., GCN 2670, 2671, 2672) were made with the Bronberg 0.30m telescope + unfiltered CCD. Twenty-five 13-second exposures with UT midpoint of 040827.701 (5.0hrs after the burst) were stacked, with a limiting magnitude of 20.0CR (based on USNO-A red magnitudes). No new object is seen in a 15x15arcmin region centered on the INTEGRAL coordinates down to approximately CR=19.5 when comparing against a DSS2-red image.
The AAVSO International GRB network is greatful for a generous grant from the Curry Foundation and to NASA for the financial support for the High Energy Workshops for Amateur Astronomers.
GCN notice #2676
V. Lipunov, A.Krylov, V.Kornilov, G.Borisov, D.Kuvshinov, A.Belinski, M.Kuznetsov, S.Potanin, G.Antipov, E.Gorbovskoy, N.Tyurina
Sternberg Astronomical Institute, Alexsandr Krylov Observatory, Moscow
At 5.9 h after INTEGRAL alert MASTER robotic telescope (GCN 2672 Refined position) had imaging the corresponding area of the sky under the large zenit distance and bad weather condition. The first image was started at 17h41m25s UT.
We have 25 unfiltered images of the error box (30s exposition, 40 x 50 arcmin, 200 mm camera).
The unfiltered optical limit on sum is 17 m .
Possible optical transient inside error box:
```
alpha = 15 17 08
delta = -16 09 00
m = 15+-0.5
error =+-5"
```
Sum FITS image are available at http://observ.pereplet.ru/images/GRB040827/
This message may be cited.
GCN notice #2678
P. Rodriguez-Pascual and B. Juarez:
Quick-Look-Analysis of the XMM-Newton observation of the GRB040827 field based on 3ks exposures in the EPIC pn camera, shows the presence of a source within the error circle.
XMMU J151701.3-160828 (J2000):
R.A. = 15h 17m 01.3s Decl. = -16deg 08' 28''
with an estimated EPIC/pn count rate of 0.01 [counts/sec];
At this stage of reduction the position error is expected to be less than 10''.
GCN notice #2679
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), I. Khamitov, Z. Aslan (TUG), I. Bikmaev, N. Sakhibullin (KGU)
report:
The INTEGRAL error circle of GRB 040827 (GCN 2672) was observed by Russian-Turkish 1.5-m telescope (Bakyrlytepe, TUBITAK National Observatory, Turkey). We made 17x100s R band images, starting at 17:30UT, 5:40 after the burst. Due to bad seeing (2''), extremely large zenith distance (60--80 degrees), partially cloudy sky and very bright moon the combined image is only slightly deeper than DSS2. We detected no new objects as compared to DSS2 red plate.
We do not confirm optical transient reported by Lipunov et al. (GCN 2676).
There is also nothing at the position of XMM X-ray source (GCN 2678) down to the limit of our combined image, i.e. to approximately 20.5 mag. More exact limit will be obtained after when our image will be calibrated photometrically.
This message may be cited.
GCN notice #2680
E. Berger, Ian Thompson (Carnegie Observatories) and Wojtek Krzeminski (Las Campanas Observatory) report:
"We imaged the 2.5-arcmin error circle of GRB 040827 (GCN #2672) with the Swope 40-inch telescope at Las Campanas Observatory (LCO) from August 27.98 to 28.02 UT (12.2 hours after the burst) for a total of 40 minutes on source. Observations were taken in the I-band in good weather conditions and seeing of about 1.1 arcsec. We do not detected any strong sources within the 10-arcsec error circle of the XMM-Newton X-ray source (GCN #2678), but a weak source (~4-sigma) is detected about 4.7" from the center of the XMM error circle with I=21.8 mag (compared to USNO-B1) at:
```
        RA=   15:17:01.4
        DEC= -16:08:23.3   (J2000)
```
with an uncertainty of about 0.3" in each coordinate."
GCN notice #2681
M. Gladders and E. Berger (Carnegie Observatories) report:
"We imaged a portion of the 2.5-arcmin error circle of GRB 040827 (GCN #2672), centered on the XMM-Newton X-ray source (GCN #2678), with the PANIC instrument on the Magellan Baade 6.5-m Telescope. A total of 36 minutes were obtained in the Ks-band under good weather conditions with a seeing of about 0.55". Within the 10-arcsec XMM error circle we find two sources with a magnitude of Ks~19.8+/-0.2 mag (XMM-1) and Ks~19.4+/-0.15 mag (XMM-2) compared to 2MASS. The positions of the two source are (J2000):
```
        RA=  15:17:01.43
        DEC= -16:08:22.7        (XMM-1)
and
        RA=  15:17:01.35
        DEC= -16:08:28.6        (XMM-2)
```
Source XMM-1 coincides with the I-band source reported by Berger, Thompson and Krzeminski (GCN #2680), while source XMM-2 appears to be extended. We therefore conclude that XMM-1 is the likely optical/NIR afterglow of GRB 040827. A comparison of the Ks- and I-band magnitudes indicate a spectral index beta~-0.5 typical of GRB afterglows."
GCN notice #2682
N. Tanvir, R. Priddey and M. Hughes (U. Hertfordshire), A. Levan (U. Leicester), M. Swinbank (U. Durham) and J. Buckle (JAC) report on behalf of a larger collaboration:
We observed the XMM error box reported by Rodriguez-Pascual and Juarez (GCN circular 2678) with the UFTI instrument on UKIRT. Total exposure time was 40 minutes in the K[98] filter, begining at August 28.22 UT.
We identify the same two K band sources reported by Gladders and Berger (GCN Circular 2681) but our provisional photometry shows no indication yet of variability of either source in comparison to their reported magnitudes. Specifically we find K=19.72 for XMM-1 and K=19.36 for XMM-2, with an error of about 0.1 mag.
We concur that XMM-2 appears extended.
This message may be cited.
GCN notice #2683
D.L. Kaplan (MIT) and E. Berger (Carnegie Observatories) report:
"We again imaged the position of the XMM-Newton X-ray source (GCN #2678), localized inside the error circle of GRB 040827 (GCN #2672), with the PANIC instrument on the Magellan Baade 6.5-m Telescope. A total of 36 minutes were obtained in the Ks-band on Aug. 28.97 UT with a seeing of about 1". A comparison to images obtained on the previous night by Gladders and Berger (GCN #2681) reveals that XMM-1 has not faded and remains steady at Ks~19.4 mag. XMM-2 appears fainter by about 0.5 mag, but this may be due to the poorer seeing conditions (1" compared to 0.55" on Aug. 28.02 UT) and the extended nature of this source. The lack of variability (see also GCN #2682) casts doubt on the identity of XMM-1 as the afterglow of GRB 040827. Further observations of XMM-2 in the NIR are encouraged."
GCN notice #2684
N. Tanvir, R. Priddey (U. Hertfordshire) A. Levan (U. Leicester), T. Geballe (Gemini) and T. Wold (JAC) report on behalf of a larger collaboration:
We have obtained a 2nd epoch of K band imaging at UKIRT, 40 minutes (again in ~0.6 arcsec seeing), starting at August 29.22 UT.
We confirm the findings of Kaplan and Berger (GCN Circular 2683), that XMM-2 has faded by between 0.4 and 0.5 magnitudes, but similarly caution that the photometry is quite sensitive to the chosen aperture size (2.2 arcsec diameter was used) since the source is somewhat extended.
XMM-2 is therefore likely to be the GRB afterglow (+ host), and the power-law decay slope a relatively shallow alpha~0.5, consistent with a fairly significant host contribution to the measured magnitudes.
XMM-1 has remained constant at about K~19.8
This message may be cited.
GCN notice #2685
Daniele Malesani, Paolo D'Avanzo, Andrea Melandri, Dino Fugazza, L. Angelo Antonelli, Stefano Covino, Gianpiero Tagliaferri, Sergio Campana, Guido Chincarini, on behalf of a larger collaboration, report:
We performed both NIR and optical observations of the field of GRB 040827 (Mereghetti et al., GCNs 2670, 2672) with the ESO-VLT. NIR observations were performed on Aug 27.96 and 28.96 (11 and 35 hrs after the GRB respectively).
We confirm the variability of source XMM2 (Gladders & Berger, GCN 2681; Kaplan & Berger, GCN 2683; Tanvir et al., GCN 2684), which fades by 0.7 +- 0.2 mag in the K filter. During both observations the seeing was similar (0.9" and 1.0"), therefore even if the source is extended (thus making photometry more tricky) this variability is a real effect. JHK colors of the object (on Aug 27) are consistent with a power law spectral shape, with a spectral index beta ~ 1.4. Note however that a significant contribution from the host may be present in our measurements.
Given the variability of XMM2 and its spatial coincidence with the X-ray source detected by XMM (Rodriguez-Pascual & Juarez, GCN 2678; see also http://xmm.vilspa.esa.es/external/xmm_news/items/grb040827/index.shtml for a refined position), we also conclude that XMM2 is likely the afterglow of GRB 040827 (Kaplan & Berger, GCN 2683; Tanvir et al., GCN 2684).
I-band observations were performed on Aug 28.99 and Aug 30.01. No significant variation is seen between the two epochs (at the ~0.2 mag level). The source has I ~ 22.6 in both nights. This suggests that the emission is dominated by the host galaxy at these epochs, therefore implying a very weak afterglow. Otherwise, the decay may have experienced a plateaux phase.
A spectrum taken with the VLT on Aug 30.00) shows a weak featureless continuum in the range 4600-8600 A. The lack of detection of any emission lines does not allow us to determine a redshift, but it can put some constraints on it. For example, the non-detection of [O III] 5006 A (usually prominent in GRB host galaxies spectra) would imply z > 0.7. The absence of Ly alpha emission also limits z < 2.7.
We acknowledge the big effort of the ESO observing staff at Paranal, in particular Chris Lidman, Elena Mason, Claudio Melo, Nancy Ageorges, Stephane Brillant and Andres Pino.
This message can be cited.
GCN notice #2688
P. Rodriguez-Pascual and R. Gonzalez-Riestra from the XMM-Newton SOC report:
Preliminary EPIC-pn images, light-curves and spectra from the XMM-Newton observation of the field of GRB 040827 are available at the home-page of the XMM-Newton Science Operations Centre:
http://xmm.vilspa.esa.es/external/xmm_news/items/grb040827/index.shtml
The XMM-EPIC exposure started less than 4.5 hours after the notification of the outburst was received (or roughly 6 hours after the IBAS detection). The light curve of the source reported in GCN 2678, XMMUJ151701.3-160828, is highly variable, decreasing from 0.07 to 0.02 counts/sec (0.2-7 keV) during the 54 ksec of the observation. The average observed flux in the 2-10 keV band is approximately 1E-13 erg cm-2 s-1
GCN notice #2689
A. Soderberg (Caltech) and D. Frail (NRAO) report on behalf of a larger Caltech/NRAO/Carnegie collaboration:
We observed the field of GRB 040827 (GCN 2670) with the Very Large Array on August 31.98 UT. We do not detect a radio counterpart to the X-ray/NIR afterglow candidate (GCNs 2678,2680) and place an upper limit of 70 microJy (2-sigma) at the position of the NIR transient.
One radio source is detected within the Integral error circle (GCN 2672), with flux density 240 +- 35 microJy at:
```
	RA: 15:16:56.77   Dec: -16:08:56.7 (J2000).
```
which is likely to be a pre-existing source, based on the observed number density of radio sources across the sky and the size of the Integral error circle."
GCN notice #2698
A. DeLuca & D. Gotz (IASF-Mi), S. Campana (OA Brera) on behalf of a larger collaboration report:
"We have analysed the data XMM-Newton observation of GRB 040827 (Gotz et al. GCN 2670). A preliminary account of these data has been given by Rodriguez-Pascual & Gonzalez-Riestra (GCN 2688).
The observation started on 2004-08-27 at 18:07:56.UT, lasting 54.3 ks. Thanks to quick-look data it was soon realised that an afterglow was present but it was more than 1arcmin off the camera boresight. Therefore, the telescope was re-pointed during the observation (causing problems in the generation of the ancillary file for spectral analysis).
The source intensity profile is consistent within errors with the instrumental PSF (possible earlier reports of an extended source might be due to the re-pointing of the satellite). Astrometry of the XMM-Newton/EPIC images was done by matching X-ray sources in the field to stars in the USNO-B1 catalogue. The refined position (J2000) for the X-ray afterglow (source XMMUJ151701.3-160828, GCN 2678) is: RA(2000) 15h 17m 01.39s, Dec(2000):-16d 08' 28.77''. The positional accuracy is at a level of 1.5'' (68% c.l.). This position is consistent with earlier reports (Rodriguez-Pascual & Gonzalez-Riestra GCN 2688, XMM-2) and with the position of the likely afterglow established based on optical-NIR data (Berger et al. GCN 2680; Gladders & Berger GCN 2681; Kaplan & Berger GCN 2683; Tanvir et al. GCN 2684; Malesani et al. GCN 2685).
We extracted spectra from the three EPIC cameras. We took the arf file from the same region of extraction of a different observation. A single absorbed power law model provides a good description of the data (chi2_red=1.2 with 187 degrees of freedom), however the column density (N_H=3.7_{-1.2}^{+4.2}x10^21 cm-2, errors at 90% c.l.) is much larger than the column density in this direction of the Galaxy (N_H=8x10^20 cm-2, Dickey & Lockman 1990, or N_H=5x10^20 cm-2 based on Schlegel et al. 1998 maps). Fixing the column density to N_H=8x10^20 cm-2 results in a unacceptable fit with chi2_red=3.0. We then include an absorption component at the redshift of the afterglow, keeping fixed the Galactic column density to N_H=8x10^20 cm-2. The new fit is good (chi2_red=1.0) providing a heavily absorbed afterglow with N_H=1.3_{-0.3}^{+0.6}x10^22 cm-2. The redshift is relatively well constrained to z=0.9_{-0.2}^{+0.9}. The power law photon index is Gamma=2.3+/-0.1 and the unabsorbed 0.5-10 keV flux is 3.4x10^{-13} erg cm-2 s-1.
The 0.2-10 keV pn light curve shows a clear decay in time. We excluded from this analysis the first 4 ks when the XMM-Newton pointing was not definitive. A power law decay with t^{-1.6+/-0.2} can account for the main decay."
This message can be cited.
GCN notice #2700
An Observation Data File (ODF) for the XMM-Newton observation of GRB 040827 with an improved attitude solution is available from the XMM-Newton Scientific Archive, or from http://xmm.vilspa.esa.es/external/xmm_sched/too/index.shtml

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Jochen Greiner, last update: 09-Sep-2004 [Disclaimer]