A Swift/XRT observation of Aql X-1 during its recent outburst (2006)
Wijnands, R.A.D., Maitra, D., Bailyn, C., Linares, M.
We report on an observation performed with the Swift/XRT of the neutron-star X-ray transient Aql X-1 which was recently found to start a new outburst as inferred from an increase in source luminosity...
Correction to ATEL 871: A Swift/XRT observation of Aql X-1 during its recent outburst (2006)
Wijnands, R.A.D., Maitra, D., Bailyn, C., Linares, M.
In ATEL #871 the fluxes were incorrectly quoted. All the fluxes should be multiplied by 1E-10 in order to obtain the correct values. The quoted luminosities are correct since the right fluxes were...
Wijnands, R.A.D., Kuulkers, E., Muno, M.P., Cackett, E.M., Maccarone, T.J., ...
On 8-9 September 2006, a series of 7 XMM-Newton observations were performed as part of our XMM-Newton/Chandra monitoring campaign of the 1.7 square degree region around Sgr A* (Wijnands et al. 2006,...
Kilohertz quasi-periodic oscillations in SAX J1808.4 3658 (2006)
I present a short overview of the behavior and properties of the two simultaneous kilohertz quasi-periodic oscillations (kHz QPOs) seen in the accreting millisecond X-ray pulsar SAX J1808.4 3658. I...
Very faint X-ray transients in our Galaxy (2006)
We present the first results of our X-ray monitoring campaign using the X-ray satellites XMM-Newton and Chandra on the 1.7 square degree region centered on Sgr A*. The purpose of this campaign is to...
Accretion-Driven Millisecond X-ray Pulsars (2006)
I present an overview of our current observational knowledge of the six known accretion-driven millisecond X-ray pulsars. A prominent place in this review is given to SAX J1808.4-3658; it was the...
Quasi-persistent neutron-star X-ray binaries in quiescence (2006)
We propose to observe the next (quasi-)persistent neutron-star low-mass X-ray binary that turns off and becomes quiescent. This will provide an excellent opportunity to study the effects of prolonged...
Monitoring Observations of the Galactic Center Region (2006)
We propose to continue our monitoring campaign using XMM-Newton and Chandra of the inner 1.2 square degree region centered on the Galactic Center. We will be able to detect transients in this region...
XMM-Newton observations of very faint X-ray transients (2006)
We propose 35 ksec observations during the outbursts of very-faint X-ray transients, which are newly identified enigmatic transients which are underluminous by orders of magnitude compared to the...
Accreting Millisecond Pulsars An Overview of Recent Developments (2006)
It has been nearly nine years since the first accreting millisecond pulsar was discovered. Since then six additional systems have been found. I will present a brief historical overview about the...
Igr J17464-2811 is Xmmu J174716.1-281048 (2006)
The position of the new fast X-ray transient IGR J17464-2811 (ATEL #970) is consistent with that of the transient XMMU J174716.1-281048 which was active during XMM-Newton observations of this region...
INTEGRAL discovery of two faint hard X-ray sources in the Galactic Bulge (2006)
Turler, M., Shaw, S.E., Kuulkers, E., Brandt, S., Courvoisier, T.J.L., Garau, A.D., ...
Analysis of INTEGRAL Galactic Bulge monitoring observations (ATel #438) taken between 16:51 and 20:33 UTC on 3 April 2006, reveals the presence of two new sources of hard X-rays. They both have a...
INTEGRAL detects hard X-ray emission from XTE J1817-330 (2006)
Shaw, S.E., Zurita, J., Kuulkers, E., Brandt, S., Chenevez, J., Courvoisier, T.J.L., ...
During the start of the third period of the INTEGRAL Galactic Bulge monitoring observations (Kuulkers et al 2005, ATel #438), the X-ray transient and black-hole candidate XTE J1817-330 (ATel #714)...
Further INTEGRAL observations of IGR J17497-2821 (2006)
Shaw, S.E., Soldi, S., Mowlavi, N., Kuulkers, E., Brandt, S., Chenevez, J., ...
The new INTEGRAL source IGR J17497-2821 (ATel #885) has been clearly detected by IBIS/ISGRI (S/N=33, 20-60 keV) in the INTEGRAL Galactic bulge monitoring program (ATels #438, #874) on 2006, Sep 18,...
Miller, J.M., Raymond, J., Homan, J., Fabian, A.C., Steeghs, D., Wijnands, R.A.D., ...
We observed the bright phase of the 2003 outburst of the Galactic black hole candidate H1743-322 in X-rays simultaneously with Chandra and RXTE on four occasions. The Chandra HETGS spectra reveal...
The magnetic nature of disk accretion onto black holes (2006)
Miller, J.M., Raymond, J., Fabian, A.C., Steeghs, D., Homan, J., Reynolds, C., ...
Although disk accretion onto compact objects-white dwarfs, neutron stars and black holes-is central to much of high-energy astrophysics, the mechanisms that enable this process have remained...
Evidence for a Magnetically Driven Disk Wind in the Black Hole GRO J1655-40 (2006)
Miller, J.M., Raymond, J., Fabian, A.C., Reynolds, C., Steeghs, D., Homan, J., ...
We recently observed the Galactic black hole GRO J1655-40 in outburst on two occasions, using Chandra and RXTE. The Chandra/HETG spectra reveal over 90 absorption lines. The lines are blue-shifted,...
Chandra Constraints on the Column Density to XTE J1817-330 (2006)
Miller, J.M., Homan, J., Steeghs, D., Wijnands, R.A.D.
We observed the black hole candidate with Chandra for 50 ksec, starting on Feb 13 2006 at 02:04 UT. The HETGS was used to obtain a high resolution spectrum, which was read-out with the ACIS-S array....
A Pointed RXTE Observation of XTE J1817-330 (2006)
Miller, J.M., Homan, J., Steeghs, D., Torres, M.A.P., Wijnands, R.A.D.
We report on a pointed RXTE observation of XTE J1817-330, obtained on 2006-02-13 at 08:10:40 UT. After standard screening, the net good time for the PCA was 9.6 ksec, and the net good time for the...
A Long, Hard Look at the Low/Hard State in Accreting Black Holes (2006)
Miller, J.M., Homan, J., Steeghs, D., Rupen, M., Hunstead, R.W., Wijnands, R.A.D., ...
We present the first results of coordinated multiwavelength observations of the Galactic black hole GX 339-4 in a canonical low/hard state, obtained during its 2004 outburst. XMM-Newton observed the...
The INTEGRAL Galactic Bulge monitoring program (2006)
Kuulkers, E., Shaw, S.E., Brandt, S., Chenevez, J., Courvoisier, T.J.L., Ebisawa, K., ...
The Galactic Bulge region is a rich host of variable high-energy point sources. These sources include bright and relatively faint X-ray transients, X-ray bursters, persistent neutron star and...
Kuulkers, E., Shaw, S.E., Paizis, A., Gros, A., Chenevez, J., Sanchez-Fernandez, C., ...
We performed a re-analysis of all consolidated data of the INTEGRAL AO-3 Galactic Bulge monitoring program (ATel #438; Kuulkers et al. 2006, astro-ph/0603130), and detected a new source with...
INTEGRAL and RXTE monitoring of XTE J1817-330: evolving through a state change? (2006)
Kuulkers, E., Goldoni, P., Shaw, S.E., Brandt, S., Chenevez, J., Courvoisier, T.J.L., ...
INTEGRAL Galactic Bulge monitoring observations (ATel #438) indicate that the X-ray transient and black-hole candidate XTE J1817-330 (ATel #714) has increased in hard X-rays (20-60 keV) compared to...
Broadband INTEGRAL analysis of IGR J17497-2821 (2006)
Kuulkers, E., Chenevez, J., Shaw, S.E., Brandt, D., Courvoisier, T.J.L., Garau, A.D., ...
We further analysed the INTEGRAL JEM-X observations performed on UT 2006, Sep 18, 08:30-12:12 (ATel #886) of the new hard INTEGRAL source IGR J17497-2821 (ATel #885). We find average fluxes of 31 +/-...
Recent X-ray observations have detected a class of very faint X-ray transients in the Galaxy which probably reveal a previously unrecognized type of accretion on to neutron stars or black holes. We...
Swift J174540.2-290005.3: Detection of a faint transient near Sgr A* (2006)
Kennea, J.A., Wijnands, R.A.D., Burrows, D.N., Nousek, J., Gehrels, N.
Swift/XRT monitoring of the Galactic Center region has detected a faint transient source, Swift J174540.2-290005.3, close to Sgr A*. The source is detected in observations starting on Oct 20th, 2006,...
Swift J174540.2-290005: Updated position and erratum (2006)
Kennea, J.A., Wijnands, R.A.D., Burrows, D.N., Nousek, J., Gehrels, N.
Further observations with the Swift/XRT have allowed us to refine the position of the faint Galactic Center X-ray transient Swift J174540.2-290005 (ATEL #920). The new position is as follows: ...
Evolution of the X-Ray Jets from 4U 1755-33 (2006)
Kaaret, P., Corbel, S., Tomsick, J.A., Lazendic, J., Tzioumis, A.K., Butt, Y., ...
We report on new X-ray observations of the large-scale jets recently discovered in X-rays from the black hole candidate 4U 1755-33. Our observations in 2004 show that the jets found in 2001 are still...
XMM-Newton observations of the black hole X-ray transient XTE J1650-500 in quiescence (2006)
Homan, J., Wijnands, R.A.D., Kong, A., Miller, J.M., Rossi, S., Belloni, T., ...
We report the result of an XMM-Newton observation of the black hole X-ray transient XTE J1650-500 in quiescence. The source was not detected, and we set upper limits on the 0.5-10 keV luminosity of...
Rapid evolution of variability properties in XTE J1817-330 (2006)
Homan, J., Miller, J.M., Wijnands, R.A.D.
We observed the black hole candidate X-ray transient XTE J1817-330 five times with RXTE on February 24, between 06:03 UTC and 17:04 UTC. The unabsorbed 4-25 keV fluxes were close to 6.2e-10...
New XMM Observations of the Accreting Millisecond X-ray Pulsar SAX J1808.4-3658 in Quiescence (2006)
Heinke, C.O., Wijnands, R.A.D., Jonker, P.G., Taam, R.E.
We have performed a second observation of SAX J1808.4-3658 in quiescence (after the first in 2001, Campana et al. 2002). Reanalyzing both observations, our observation finds SAX J1808.4-3658 at a 30%...
Faint X-Ray Sources in the Globular Cluster Terzan 5 (2006)
Heinke, C.O., Wijnands, R.A.D., Cohn, H.N., Lugger, P.M., Grindlay, J.E., Pooley, D., ...
We report our analysis of a Chandra X-ray observation of the rich globular cluster Terzan 5, in which we detect 50 sources to a limiting 1.0-6 keV X-ray luminosity of 3¿031 ergs s-1 within the...
Precision Timing of an Accreting Millisecond Pulsar Over Seven Years (2006)
Hartman, J.M., Chakrabarty, D., Morgan, E.H., Watts, A.L., Klis, M. Van Der, Wijnands, R.A.D., ...
We present a comprehensive timing study of the 2.5 millisecond X-ray pulsar SAX 1808.4-3658. Using data from the Rossi X-ray Timing Explorer, we construct a phase-connected pulse timing solution for...
The LOFAR Transients Key Project (2006)
Fender, R.P., Stappers, B., Braun, R., Wise, M., Coenen, T., ...
LOFAR, the Low Frequency Array, is a new radio telescope under construction in the Netherlands, designed to operate between 30 and 240 MHz. The Transients Key Project is one of the four Key Science...
Three active neutron star X-ray transients: SAX J1747.0-2853, XTE J1739-285 and GRS 1747-312 (2006)
Chenevez, J., Shaw, S.E., Kuulkers, E., Brandt, S., Courvoisier, T.J.L., Ebisawa, K., ...
Apart from the active black-hole candidate X-ray transient XTE J1817-330 (ATel #714), three known neutron star X-ray transients have been found to be active in the INTEGRAL Galactic Bulge monitoring...
INTEGRAL detects SWIFT J174535.5-290135.6 (2006)
Chenevez, J., Sanchez-Fernandez, C., Kuulkers, E., Shaw, S.E., Brandt, S., Courvoisier, T.J.L., ...
We report on a detection of the new source SWIFT J174535.5-290135.6 (ATel #753) by the JEM-X monitor during INTEGRAL Galactic Bulge monitoring observations taken between 2006, 17 Feb 21:11 and 18 Feb...
XMM-Newton discovery of the X-ray transient XMMU J181227.8-181234 in the Galactic plane (2006)
Cackett, E.M., Wijnands, R.A.D., Remillard, R.
We report the discovery of an X-ray transient, observed in outburst with XMM-Newton on 2003 March 20, and with position (J2000, approximate positional error 2arcsec). No known source is present at...
Cooling of the quasi-persistent neutron star X-ray transients KS 1731-260 and MXB 1659-29 (2006)
Cackett, E.M., Wijnands, R.A.D., Linares, M., Miller, J.M., Homan, J., Lewin, W.H.G.
We present Chandra and XMM-Newton X-ray observations that monitor the neutron star cooling of the quasi-persistent neutron star X-ray transients KS 1731-260 and MXB 1659-29 for approximately 4 yr...
Cooling of Accretion Heated Neutron Star Transients (2006)
Cackett, E.M., Wijnands, R.A.D., Linares, M., Miller, J.M., Homan, J., Lewin, W.H.G.
Some neutron star X-ray transients (the quasi-persistent transients) spend an unusually long time in outburst, with outbursts lasting years to decades rather than the usual weeks to months. During...
A Chandra X-ray observation of the globular cluster Terzan 1 (2006)
Cackett, E.M., Wijnands, R.A.D., Heinke, C.O., Pooley, D., Lewin, W.H.G., Grindlay, J.E., ...
We present a ~19-ks Chandra Advanced CCD Imaging Spectrometer (ACIS)-S observation of the globular cluster Terzan 1. 14 sources are detected within 1.4arcmin of the cluster centre with two of these...
Discovery of twin kHz quasi-periodic oscillations (QPOs) in Cir X-1 (2006)
Boutloukos, S., Wijnands, R.A.D., Klis, M.V.D.
We report the discovery with the RXTE/PCA of twin kHz QPOs in the low mass X-ray binary Circinus X-1. Out of 497 observations in the RXTE Public data base, using standard FFT power spectral...
Discovery of Twin kHz QPOs in the Peculiar X-Ray Binary Circinus X-1 (2006)
Boutloukos, S., Klis, M. Van Der, Altamirano, D., Klein-Wolt, M., Wijnands, R.A.D., Jonker, P.G., ...
We report the discovery with the RXTE PCA of twin kHz QPOs in the peculiar X-ray binary Circinus X-1. Eleven cases of simultaneous double QPOs occurred, with significances of up to 6.3 and 5.5 sigma...
Altamirano, D., Wijnands, R.A.D., Klis, M. Van Der, Mendez, M.
We have studied the rapid X-ray time variability in 99 pointed observations with the Rossi X-ray timing Explorer Proportional Counter Array of the Low Luminosity Burster 1E 1724-3045 which is located...
Wijnands, R.A.D., Heinke, C.O., Pooley, D., Edmonds, P.D., Lewin, W.H.G., Grindlay, J.E., ...
We present a Chandra observation of the globular cluster Terzan 5 during times when the neutron star X-ray transient EXO 1745-248 located in this cluster was in its quiescent state. We detected the...
Relations Between Timing Features and Colors in Accreting Millisecond Pulsars (2005)
Straaten, S. Van, Klis, M. Van Der, Wijnands, R.A.D.
We have studied the aperiodic X-ray timing and color behavior of the accreting millisecond pulsars SAX J1808.4-3658, XTE J1751-305, XTE J0929-314, and XTE J1814-338 using large data sets obtained...
Wijnands, R.A.D., Homan, J., Heinke, C.O., Miller, J.M., Lewin, W.H.G.
We observed the accretion-driven millisecond X-ray pulsars XTE J0929-314 and XTE J1751-305 in their quiescent states using Chandra. From XTE J0929-314 we detected 22 source photons (in the energy...
Revealing the Focused Companion Wind in Cygnus X-1 with Chandra (2005)
Miller, J.M., Wojdowski, P., Schulz, N.S., Marshall, H.L., Fabian, A.C., Remillard, R.A., ...
We have analyzed a Chandra HETGS spectrum of the Galactic black hole Cygnus X-1, obtained at a source flux that is approximately twice that commonly observed in its persistent low-intensity,...
Cackett, E.M., Wijnands, R.A.D., Heinke, C.O., Edmonds, P.D., Lewin, W.H.G., Pooley, D., ...
The globular cluster NGC 6440 is known to harbor a bright neutron star X-ray transient. We observed the globular cluster with Chandra on two occasions when the bright transient was in its quiescent...
Kuulkers, E., Shaw, S., Paizis, A., Mowlavi, N., Courvoisier, T., Ebisawa, K., ...
The Galactic Bulge is a region rich in bright and variable high-energy X-ray and gamma-ray sources. From February 17, 2005 and onwards we will observe this region regularly, using the European...
INTEGRAL observes fading of GRO J1655-40 above 20 keV (2005)
Shaw, S., Kuulkers, E., Paizis, A., Mowlavi, N., Courvoisier, T., Ebisawa, K., ...
We have observed a decrease in the the hard X-ray flux (above 20 keV) from the black hole binary GRO J1655-40, of about a factor of two (in four days), using INTEGRAL. This object has been observed...
INTEGRAL monitoring of IGR J17098-3628 (2005)
Mowlavi, N., Kuulkers, E., Rodriguez, J., Shaw, S., Paizis, A., Courvoisier, T., ...
IGR J17098-3628 (ATEL #444) has been observed by INTEGRAL in the Galactic Bulge Monitoring program (ATEL #438). We detected the source with ISGRI in observations during 2005, March 26 00:00, April 2...
X-ray Binaries in Terzan 5 (2005)
Heinke, C.O., Wijnands, R.A.D., Grindlay, J.E., Cohn, H.N., Lugger, P.M., Edmonds, P.D., ...
Terzan 5 is a rich globular cluster located near the Galactic Center, containing a transient LMXB and a large number of millisecond pulsars. Two Chandra observations have identified the transient...
GRO J1655-40 enters a highly-variable, high-luminosity state (2005)
Homan, J., Miller, J.M., Wijnands, R.A.D., Lewin, W.H.G.
GRO J1655-40 enters a highly-variable, high-luminosity state Jeroen Homan (MIT), Jon M. Miller (CfA), Rudy Wijnands (U. of Amsterdam), and Walter H.G. Lewin (MIT) Recent RXTE observations of the...
SAX J1808.4-3658 is in Outburst Again (2005)
Markwardt, C.B., Swank, J., Wijnands, R.A.D.
RXTE PCA Bulge scans on May 31, 23h UTC, indicate that a source consistent with the position of SAX J1808.4-3658 has entered outburst. The previous outburst of J1808 was in October 2002, and this...
A Glance in the I-band to XMM J174457-2850.3 and GRS 1741.9-2853. (2005)
Laycock, S., Zhao, P., Torres, M.A.P., Wijnands, R.A.D., Steeghs, D., Grindlay, J., ...
Following the recent report of renewed activity in the Galactic Bulge X-ray transients GRS 1741.9-2853 and XMM J174457-2850.3 (ATEL #512), we used the IMACS imaging spectrograph mounted at the...
INTEGRAL observations of XTE J1818-245 (2005)
Shaw, S.E., Kuulkers, E., Turler, M., Mowlavi, N., Courvoisier, T., Markwardt, C., ...
The IBIS/ISGRI instrument aboard INTEGRAL has observed the transient black hole candidate XTE J1818-245 (ATel #578) during seven 1800 second exposures of the Galactic Bulge region between UTC...
INTEGRAL detects XTE J1739-285 (2005)
Bodghee, A., Mowlavi, N., Kuulkers, E., Wijnands, R.A.D., Shaw, S.E., Courvoisier, T., ...
The JEM-X telescope on board INTEGRAL detected the X-ray transient XTE J1739-285 while monitoring the Galactic Bulge in revolution 350. The source was detected in three successive pointings of 30...
Brightening of H1743-322 and the Rapid Burster (2005)
Kretschmar, P., Shaw, S.E., Kuulkers, E., Wijnands, R.A.D., Turler, M., Mowlavi, N., ...
Observations done on Aug 17 and 21, 2005 as part of the INTEGRAL Galactic Bulge monitoring campaign show further brightening of H1743-322 (ATel #575,#576) and an outburst of the rapid burster (4U...
Correction: Rapid Burster = MXB 1730-335 (2005)
Kretschmar, P., Shaw, S.E., Kuulkers, E., Wijnands, R.A.D., Turler, M., Mowlavi, N., ...
In ATel #593, the Rapid Burster was also labeled 4U 1730-335, an identifier found in the SIMBAD database. Walter H.G. Lewin has brought to our attention that this is a misnomer, since the Rapid...
GRO J1655-40 returning to the hard state (2005)
Homan, J., Miller, J.M., Wijnands, R.A.D., Lewin, W.H.G.
We have been monitoring the ongoing outburst of the black-hole X- ray transient GRO J1655-40 with more than 400 pointed RXTE observations since its start in mid February 2005 (ATel #414). During the...
INTEGRAL sees XTE J1739-285 change to hard state (2005)
Shaw, S.E., Kuulkers, E., Oosterbroek, T., Courvoisier, T.J.-L., Paizis, A., Ebisawa, K., ...
Continuing INTEGRAL Galactic Bulge Monitoring observations have detected the X-ray transient XTE J1739-285 above 20 keV. XTE J1739-285 was first detected by INTEGRAL during JEM-X observations on...
Chandra observations of enigmatic X-ray and radio transients (2005)
We propose a series of Chandra observations on two, newly identified, possibly related, classes of enigmatic X-ray and radio transients. The X-ray ones are underluminous by orders of magnitude vs....
Quasi-persistent neutron-star X-ray binaries in quiescence (2005)
We propose to observe the next (quasi-)persistent neutron-star low-mass X-ray binary that turns off and becomes quiescent. This will provide an excellent opportunity to study the effects of prolonged...
Type-I X-ray bursts from XTE J1739-285 (2005)
Brandt, S., Kuulkers, E., Bazzano, A., Courvoisier, T.J.-L., Domingo, A., Ebisawa, K., ...
During the Galactic Bulge Monitoring and Galactic Centre Scan observations performed with INTEGRAL, two X-ray flares coming from XTE J1739-285 were observed with the X-ray monitor JEM-X (3-25 keV)....
Swift Observation of SAX J1747.0-2853 (2005)
Kong, A.K.H., Wijnands, R.A.D., Homan, J.
Following the recent report of renewed activity of the neutron star X-ray transient SAX J1747.0-2853 (ATel #637, #638), we have obtained a Swift TOO observation of the field on 2005 October 25. The...
On the (hard) X-ray activity of SAX J1747.0-2853 as seen with INTEGRAL (2005)
Kuulkers, E., Kretschmar, P., Brandt, S., Wijnands, R.A.D., Courvoisier, T.J.-L., Ebisawa, K., ...
Following the report of the X-ray activity of the neutron star transient SAX J1747.0-2853 (ATels #637, #638, #641) we add that its current outburst was detected by INTEGRAL on Oct 10 and 12, 2005....