RAT J1953+1859: a dwarf nova discovered through high amplitude QPOs in quiescence (2009)
Ramsay, Gavin, Hakala, Pasi, Barclay, Thomas, Wheatley, Peter, Marshall, George, Lehto, Harry, ...
We report the discovery of an accreting binary, RAT J1953+1859, made during the RApid Temporal Survey (RATS) on the Isaac Newton Telescope. It showed high amplitude (0.3 mag) quasi-periodic...
2XMMi J225036.9+573154 - a new eclipsing AM Her binary discovered using XMM-Newton (2009)
Ramsay, Gavin, Rosen, Simon, Hakala, Pasi, Barclay, Thomas
We report the discovery of an eclipsing polar, 2XMMi J225036.9+573154, using XMM-Newton. It was discovered by searching the light curves in the 2XMMi catalogue for objects showing X-ray variability....
The defining characteristics of Intermediate Polars - the case of three candidate systems (2008)
Ramsay, Gavin, Wheatley, Peter J., Norton, A. J., Hakala, Pasi, Baskill, Darren
Intermediate Polars (IPs) are a group of cataclysmic variables (CVs) which are thought to contain white dwarfs which have a magnetic field strength in the range ~0.1-10MG. A significant fraction of...
The Emission from Post-Shock Flows in mCVs (2007)
Mark Cropper Kinwah, Kinwah Wu, Gavin Ramsay
We re-examine the vertical structure of the post-shock flow in the accretion region of mCVs, and the X-ray emission as a function of height. We then predict X-ray light curves and phase-resolved...
Detection of the optical counterpart of the proposed double degenerate polar RX J1914+24 (2007)
Gavin Ramsay, Mark Cropper, Kinwah Wu, K. O. Mason, Pasi Hakala
We have detected the optical counterpart of the proposed double degenerate polar RX J1914+24. The I band light curve is modulated on the 9.5 min period seen in Xrays. There is no evidence for any...
Simultaneous EUV and Optical Observations of the Magnetic Cataclysmic Variable PQ Geminorum (2007)
Steve B. Howell, Martin M. Sirk, Gavin Ramsay, Stephen B. Potter, Simon R. Rosen
We present the results of simultaneous optical polarimetry and EUV spectroscopy and photometry of PQ Gem, a magnetic cataclysmic variable which shows observational properties of the strongly magnetic...
Continuum and Line emission from Post-shock Flows (2007)
Mark Cropper Kinwah, Kinwah Wu, Gavin Ramsay
. The post-shock flow in the accretion region of MCVs is considered to be a magnetically confined cooling flow. The X-ray spectrum from this hot plasma is emitted from a range of temperatures and...
Gavin Ramsay, S. B. Potter, Peter J. Wheatley
CP Tuc (AX J2315--592) shows a dip in X-rays which lasts for approximately half the binary orbit and is deeper in soft X-rays compared with hard X-rays. It has been proposed that this dip is due to...
RX J 1914.4+2456: the first double-degenerate polar? (2007)
K. O. Mason, S. B. Potter, Gavin Ramsay
RXJ1914.4+2456 exhibits a light curve with a strong modulation at 569 sec: this period is characteristic of the white dwarf spin period in intermediate polar (IP) systems. However the X-ray light...
Evidence for pole switching in the magnetic cataclysmic variable BY Camelopardalis (2007)
Paul A. Mason, Gavin Ramsay, Ivan Andronov, Sergey Kolesnikov, Nickolay Shakhovskoy, Elana Pavlenko
An analysis of X-ray and optical light curves of the magnetic cataclysmic variable (MCV) BY Cam is presented. This system is one of 3 MCVs in which the spin period of the white dwarf and the binary...
The new Intermediate Polar RX J1238--38: a system below the period gap ? (2007)
David Buckley Mark, Gavin Ramsay, Dayal T. Wickramasinghe
We present optical observations of the recently discovered ROSAT source, RX J1238-- 38, which is a new member of the Intermediate Polar class of asynchronous magnetic cataclysmic variables. Optical...
A comparison of white dwarf mass estimators using the Intermediate Polar XY Ari (2007)
Gavin Ramsay, Mark Cropper, Coel Hellier, Kinwah Wu
We determine the mass of the white dwarf in the eclipsing intermediate polar XY Ari following the method given in Cropper, Ramsay & Wu using a multi-temperature bremsstrahlung model. By fitting...
White Dwarf Masses in Magnetic CVs: Multi-temperature Fits to Ginga Data (2007)
One method of obtaining the mass of the white dwarf in magnetic CVs is through their hard X-ray spectra. However, previous mass estimates using this method give lower limits because the temperature...
Kinwah Wu, Gavin Ramsay, Aysegul Kocabiyik
Received: We have calculated the temperature and density structure of the hot postshock plasma in magnetically confined accretion flows, including the gravitational potential. This avoids the...
The X-ray spectrum of RX J1914.4+2456 revisited (2007)
It has been proposed that RX J1914.4+2456 is a stellar binary system with an orbital period of 9.5 mins. As such it shares many similar properties with RX J0806.3+1527 (5.4 mins). However, while the...
A search for electron cyclotron maser emission from compact binaries (2007)
Ramsay, Gavin, Brocksopp, Catherine, Wu, Kinwah, Slee, Bruce, Saxton, Curtis
Unipolar induction (UI) is a fundamental physical process, which occurs when a conducting body transverses a magnetic field. It has been suggested that UI is operating in RX J0806+15 and RX J1914+24,...
XMM-Newton observations of the eclipsing polar V2301 Oph (2007)
We present XMM-Newton observations of the eclipsing polar V2301 Oph which cover nearly 2.5 binary orbital cycles and 2 eclipses. This polar is believed to have the lowest magnetic field strength (7...
X-ray emissions from two-temperature accretion flows within a dipole magnetic funnel (2007)
Saxton, Curtis J., Wu, Kinwah, Canalle, Joao. B. G., Cropper, Mark, Ramsay, Gavin
We investigate the hydrodynamics of accretion channelled by a dipolar magnetic field (funnel flows). We consider situations in which the electrons and ions in the flow cannot maintain thermal...
XMM-Newton observations of AM CVn binaries: V396 Hya & SDSS J1240-01 (2006)
Ramsay, Gavin, Groot, Paul J., Marsh, Tom, Nelemans, Gijs, Steeghs, Danny, Hakala, Pasi
We present the results of XMM-Newton observations of two AM CVn systems - V396 Hya and SDSS J1240-01. Both systems are detected in X-rays and in the UV: neither shows coherent variability in their...
Ramsay, Gavin, Napiwotzki, Ralf, Hakala, Pasi, Lehto, Harry
The RApid Temporal Survey (RATS) is a survey to detect objects whose optical intensity varies on timescales of less than ~70 min. In our pilot dataset taken with the INT and the Wide Field Camera in...
XMM-Newton observations of the complex spin pulse of the intermediate polar PQ~Geminorum (2006)
Evans, P. A., Hellier, Coel, Ramsay, Gavin
The intermediate polar PQ Geminorum shows a complex pulsation, caused by a spinning white dwarf, which varies markedly with wavelength. We report XMM-Newton observations, including the soft and hard...
XMM-Newton and Chandra observations of the ultra-compact binary RX J1914+24 (2006)
Ramsay, Gavin, Cropper, Mark, Hakala, Pasi
The nature of the X-ray source RX J1914+24 has been the subject of much debate. It shows a prominent period of 569 sec in X-rays and the optical/infra-red: in most models this has been interpreted as...
Simmons, Bruce, Maheshwari, B. L. (Basant Lal), Ramsay, Gavin
The current water supply crisis has led to the development and utilisation of alternative water supply systems for irrigating urban playing fields. There is however little understanding of the social...
Simmons, Bruce, Maheshwari, B. L. (Basant Lal), Ramsay, Gavin
The current water supply crisis has led to the development and utilisation of alternative water supply systems for irrigating urban playing fields. There is however little understanding of the social...
Schwecke, Melanie, Simmons, Bruce, Maheshwari, B. L. (Basant Lal), Ramsay, Gavin
The current water supply crisis has led to the development and utilisation of alternative water supply systems for irrigating urban playing fields. There is however little understanding of the social...
Chandra observations of the globular cluster M54 (2005)
We have carried out a Chandra observation of the globular cluster M54. We detected 7 sources located within the half-mass radius of M54, at a flux limit of 1.5x10^-15 erg/s/cm in the 0.3-8 keV energy...
XMM-Newton observations of AM CVn binaries (2005)
Ramsay, Gavin, Hakala, Pasi, Marsh, Tom, Nelemans, Gijs, Steeghs, Danny, Cropper, Mark
We present the results of XMM-Newton observations of four AM CVn systems -- AM CVn, CR Boo, HP Lib and GP Com. Their light curves show very different characteristics. The X-ray light curves show no...
Bhardwaj, Anil, Branduardi-Raymont, Graziella, Elsner, Ronald F., Gladstone, G. Randall, Ramsay, Gavin, Rodriguez, Pedro, ...
During November 26-29, 2003 XMM-Newton observed soft (0.2-2 keV) X-ray emission from Jupiter for 69 hours. The low-latitude X-ray disk emission of Jupiter is observed to be almost uniform in...
Saxton, Curtis, Wu, Kinwah, Cropper, Mark, Ramsay, Gavin
We use a two-temperature hydrodynamical formulation to determine the temperature and density structures of the post-shock accretion flows in magnetic cataclysmic variables (mCVs) and calculate the...
Canalle, Joao B. G., Saxton, Curtis J., Wu, Kinwah, Cropper, Mark, Ramsay, Gavin
Field-channelled accretion flows occur in a variety of astrophysical objects, including T Tauri stars,magnetic cataclysmic variables and X-ray pulsars. We consider a curvilinear coordinate system and...
RApid Temporal Survey - RATS I: Overview and first results (2005)
We present the aim and first results of the RApid Temporal Survey (RATS) made using the Wide Field Camera on the Isaac Newton Telescope. Our initial survey covers 3 square degrees, reaches a depth of...
XMM-Newton observations of the ultra-compact binary RX J1914+24 (2004)
Ramsay, Gavin, Hakala, Pasi, Wu, Kinwah, Cropper, Mark, Mason, K. O., Cordova, F. A., ...
We present XMM-Newton observations of the 569 sec period system RX J1914+24 (V407 Vul). This period is believed to represent the binary orbital period making it an ultra-compact binary system. By...
Properties of serendipitous X-ray flares discovered in XMM-Newton observations (2004)
Trenholme, Duncan, Ramsay, Gavin, Foley, Carl
We present the results of a search of the XMM-Newton public data archive for stellar X-ray flares. We find eight flaring sources for which we identify 7 optical counterparts. Three of these sources...
XMM-Newton observations of the eclipsing polar EP Dra (2004)
Ramsay, Gavin, Bridge, C. M., Cropper, Mark, Mason, K. O., Cordova, F. A., Priedhorsky, W.
We present XMM-Newton observations of the eclipsing polar EP Dra which cover nearly 3 binary orbital cycles. The X-ray and UV data show evidence for a prominent dip before the eclipse which is due to...
Accretion stream mapping with genetically modified "fire-flies" (2004)
Bridge, C. M., Hakala, Pasi, Cropper, Mark, Ramsay, Gavin
We apply an eclipse mapping technique using `genetically modified fire-flies' to the eclipse light curves of HU Aqr and EP Dra. The technique makes as few assumptions as possible about the location...
XMM-Newton observations of the dwarf nova YZ Cnc in quiescence (2004)
Hakala, Pasi, Ramsay, Gavin, Wheatley, Peter, Harlaftis, Emilios, Papadimitriou, C.
We present results from the XMM observations of the dwarf nova YZ Cnc in a quiescent state. We have performed a detailed time series analysis of the resulting light curves. Unusually, we do not...
XMM-Newton observations of polars in low accretion states (2004)
Ramsay, Gavin, Cropper, Mark, Wu, Kinwah, Mason, Keith, Cordova, France, Priedhorsky, William
We have made a series of snap-shot observations of 37 polars using XMM-Newton. We found that 16 of these systems were in a low, or much reduced, accretion state. Of those, 6 were not detected in...
XMM-Newton EPIC & OM observations of Her X-1 over the 35 day beat period (2004)
Zane, Silvia, Ramsay, Gavin, Jimenez-Garate, Mario A., Herder, Jan Willem Den, Hailey, Charles J.
We present the results of a series of XMM-Newton EPIC and OM observations of Her X-1, spread over a wide range of the 35 day precession period. We confirm that the spin modulation of the neutron star...
Twisted accretion curtains in the intermediate polar FO Aquarii (2003)
Evans, P. A., Hellier, Coel, Ramsay, Gavin, Cropper, Mark
We report on a ~37-ks XMM-Newton observation of the intermediate polar FO Aquarii, presenting X-ray and UV data from the EPIC and OM cameras. We find that the system has changed from its previously...
We revisit the XMM-Newton observations of the dwarf nova OY Car taken in July 2000 which occured shortly after an outburst. Ramsay et al (2001a) found a prominent energy dependent modulation at a...
The energy balance in polars revisited (2003)
In the EXOSAT and ROSAT eras a significant number of polars were found to show a soft/hard X-ray ratio much greater than that expected from the standard accretion shock model. This was known as the...
XMM-Newton observations of three short period polars: V347 Pav, GG Leo and EU UMa (2003)
Ramsay, Gavin, Cropper, Mark, Mason, K. O., Cordova, F. A., Priedhorsky, W.
We present phase-resolved XMM_Newton data of three short period polars: V347 Pav, GG Leo and EU UMa. All three systems show one dominant accretion region which is seen for approximately half of the...
Spin up in RX J0806+15 - the shortest period binary (2003)
Hakala, Pasi, Ramsay, Gavin, Wu, Kinwah, Hjalmarsdotter, Linnea, Jarvinen, Silva, Jarvinen, Arto, ...
RX J0806+15 has recently been identified as the binary system with the shortest known orbital period. We present a series of observations of RX J0806+15 including new optical observations taken one...
Multi-epoch spectroscopy and XMM-Newton observations of RX J2115-58 (2003)
Cropper, Mark, Ramsay, Gavin, Marsh, Tom
We present phase resolved optical spectroscopy and X-ray light curves of the asynchronous polar RX J2115-58 as they change on the beat period.
Stream eclipse mapping with 'fire-flies' (2003)
Bridge, C. M., Hakala, Pasi, Cropper, Mark, Ramsay, Gavin
We apply a new method of eclipse mapping to the light curves of eclipsing polars. The technique aims to locate the bright emission associated with the accretion stream, using a technique that makes...
Ultra-Short Period Double-Degenerate Binaries (2003)
Cropper, Mark, Ramsay, Gavin, Wu, Kinwah, Hakala, Pasi
We review the current observational status of the ROSAT sources RX J1914.4+2456 and RX J0806.3+1527, and the evidence that these are ultra-short period (
A search for X-ray variability in the open cluster NGC 2516 (2003)
Ramsay, Gavin, Harra, Louise, Kay, Hilary
We present the results of a search for X-ray variability in the galactic open cluster NGC 2516. This cluster has been observed on 8 occasions using XMM-Newton making it an excellent target for such a...
Accretion Flow Along a Dipolar Field: Application to Intermediate Polars (2003)
Canalle, J. B. G., Wu, Kinwah, Cropper, Mark, Ramsay, Gavin, Saxton, Curtis
A hydrodynamic formulation for accretion flow channeled by a dipolar magnetic field is constructed using a curvi-linear coordinate system natural to the field structure. We solve the hydrodynamic...
The XMM-Newton-MSSL survey of Polars (2003)
The XMM-Newton-MSSL survey of polars is a snapshot survey of nearly 40 polars. We present the initial results, with an emphasis on the energy balance in these systems and the number of systems which...
Variability of the Accretion Stream in the Eclipsing Polar EP Dra (2003)
Bridge, C. M., Cropper, Mark, Ramsay, Gavin, Reynolds, A. P., Perryman, M. A. C.
We present the first high time resolution light curves for six eclipses of the magnetic cataclysmic variable EP Dra, taken using the superconducting tunnel junction imager S-Cam2. The system shows a...
XMM-Newton observations of the polars EV UMa, RX J1002-19 and RX J1007-20 (2002)
We present XMM-Newton data of three strongly magnetic cataclysmic variables (polars) EV UMa, RX J1002-19 and RX J1007-20. These include the polar with the shortest orbital period (EV UMa) and the...
X-ray spectroscopy of Eta Carinae with XMM-Newton (2002)
Leutenegger, Maurice A., Kahn, Steven M., Ramsay, Gavin
We present XMM-Newton observations of the luminous star Eta Carinae, including a high resolution soft X-ray spectrum of the surrounding nebula obtained with the Reflection Grating Spectrometer. The...
XMM-Newton EPIC observations of Her X-1 (2002)
Ramsay, Gavin, Zane, Silvia, Jimenez-Garate, Mario, Herder, Jan-Willem Den, Hailey, C.
We present spin-resolved X-ray data of the neutron star binary Her X-1 taken using the EPIC detectors on XMM-Newton. The data were taken at three distinct epochs through the 35 day precession period....
STJ Observations of the Eclipsing Polar HU Aqr (2002)
Bridge, C. M., Cropper, Mark, Ramsay, Gavin, Perryman, M. A. C., Favata, F., ...
We apply an eclipse mapping technique to observations of the eclipsing magnetic cataclysmic variable HU Aqr. The observations were made with the S-Cam2 Superconducting Tunnel Junction detector at the...
First X-ray observations of the polar CE Gru (2002)
We report the detection of the polar CE Gru in X-rays for the first time. We find evidence for a dip seen in the hard X-ray light curve which we attribute to the accretion stream obscuring the...
XMM-Newton observations of the asynchronous polar BY Cam (2002)
We report observations of the asynchronous polar BY Cam made using XMM-Newton. We find evidence for two accretion regions which have significantly different spectra. In both regions we find evidence...
Pandel, Dirk, Cordova, France A., Shirey, Robert E., Ramsay, Gavin, Cropper, Mark, Mason, Keith O., ...
XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables, DP Leo and WW Hor, continuously for three orbital cycles each. Both systems were in an intermediate state of accretion....
Indirect imaging of the accretion stream in eclipsing polars IV: V895 Cen (2001)
Salvi, Nikita, Ramsay, Gavin, Cropper, Mark, Buckley, D. A. H., Stobie, R. S.
We present spectroscopic and high speed photometric data of the eclipsing polar V895 Cen. We find that the eclipsed component is consistent with it being the accretion regions on the white dwarf....
An electrically powered binary star? (2001)
Wu, Kinwah, Cropper, Mark, Ramsay, Gavin, Sekiguchi, Kazuhiro
We propose a model for stellar binary systems consisting of a magnetic and a non-magnetic white-dwarf pair which is powered principally by electrical energy. In our model the luminosity is caused by...
Ionisation Structure in Accretion Shocks with a Composite Cooling Function (2001)
Wu, Kinwah, Cropper, Mark, Ramsay, Gavin
We have investigated the ionisation structure of the post-shock regions of magnetic cataclysmic variables using an analytic density and temperature structure model in which effects due to...
First XMM-Newton observations of an isolated neutron star: RXJ0720.4-3125 (2000)
Paerels, Frits, Motch, Christian, Haberl, Frank, Zavlin, Vyacheslav E., Zane, Silvia, Ramsay, Gavin, ...
We present the high resolution spectrum of the isolated neutron star RXJ0720.4-3125, obtained with the Reflection Grating Spectrometer on XMM-Newton, complemented with the broad band spectrum...
Cropper, Mark, Zane, Silvia, Ramsay, Gavin, Haberl, Frank, Motch, Christian
We model the spin pulse intensity and hardness ratio profiles of the isolated neutron star RXJ0720.4--3125 using XMM-Newton data. The observed variation is approximately sinusoidal with a...
First XMM-Newton observations of a cataclysmic variable II: the X-ray spectrum of OY Car (2000)
Ramsay, Gavin, Cordova, France, Cottam, Jean, Mason, Keith, Much, Rudi, Osborne, Julian, ...
We present XMM-Newton X-ray spectra of the disc accreting cataclysmic variable OY Car, which were obtained during the performance verification phase of the mission. These data were taken 4 days after...
First XMM-Newton observations of a Cataclysmic Variable I: Timing studies of OY Car (2000)
Ramsay, Gavin, Poole, Tracey, Mason, Keith, Cordova, France, Priedhorsky, William, Breeveld, Alice, ...
We present XMM-Newton observations of the eclipsing, disc accreting, cataclysmic variable OY Car which were obtained as part of the performance verification phase of the mission. The star was...
Simultaneous optical polarimetry and X-ray data of the near synchronous polar RX J2115-5840 (2000)
Ramsay, Gavin, Potter, Stephen, Cropper, Mark, Buckley, David A. H., Harrop-Allin, M. K.
We present simultaneous optical polarimetry and X-ray data of the near synchronous polar RX J2115-5840. We model the polarisation data using the Stokes imaging technique of Potter et al. We find that...
Determining the mass of the accreting white dwarf in magnetic CVs using data (1999)
We have extracted spectra of 20 magnetic Cataclysmic Variables (mCVs) from the RXTE archive and fitted them using the X-ray continuum method of Cropper et al to determine the mass of the accreting...
Detection of the optical counterpart of the proposed double degenerate polar RX J1914+24 (1999)
Ramsay, Gavin, Cropper, Mark, Wu, Kinwah, Mason, Keith, Hakala, Pasi
We have detected the optical counterpart of the proposed double degenerate polar RX J1914+24. The I band light curve is modulated on the 9.5 min period seen in X-rays. There is no evidence for any...
The Emission from Post-Shock Flows in mCVs (1999)
Cropper, Mark, Wu, Kinwah, Ramsay, Gavin
We re-examine the vertical structure of the post-shock flow in the accretion region of mCVs, and the X-ray emission as a function of height. We then predict X-ray light curves and phase-resolved...
Cropper, Mark, Wu, Kinwah, Ramsay, Gavin, Kocabiyik, Aysegul
We have calculated the temperature and density structure of the hot postshock plasma in magnetically confined accretion flows, including the gravitational potential. This avoids the inconsistency of...
Ramsay, Gavin, Potter, Stephen, Buckley, David, Wheatley, Peter
CP Tuc (AX J2315--592) shows a dip in X-rays which lasts for approximately half the binary orbit and is deeper in soft X-rays compared with hard X-rays. It has been proposed that this dip is due to...
Determining the mass of the accreting white dwarf in magnetic CVs using RXTE data (1999)
We have extracted spectra of 20 magnetic Cataclysmic Variables (mCVs) from the RXTE archive and fitted them using the X-ray continuum method of Cropper et al to determine the mass of the accreting...
RX J2115--5840: confirmation of a new near-synchronous polar (1998)
Ramsay, Gavin, Buckley, David A. H., Cropper, Mark, Harrop-Allin, M. K.
Following the suggestion of Schwope et al that the magnetic cataclysmic variable RX J2115-5840 maybe a near-synchronous polar, we obtained optical polarimetry of this system over a 2 week period....
The optical counterpart of the double degenerate polar RX J1914+24 (1998)
Ramsay, Gavin, Cropper, Mark, Mason, Keith, Hakala, Pasi
Cropper et al 1998 presented X-ray observations of RX J1914+24 and claimed that the most likely interpretation of their data was that of a double degenerate Polar. Here we show the preliminary...
Continuum and line emission from post-shockc flows (1998)
Cropper, Mark, Wu, Kinwah, Ramsay, Gavin
The post-shock flow in the accretion region of MCVs is considered to be a magnetically confined cooling flow. The X-ray spectrum from this hot plasma is emitted from a range of temperatures and...
RX J2115-5840: confirmation of a new near-synchronous polar (1998)
Ramsay, Gavin, Buckley, David, Cropper, Mark, Harrop-Allin, M Kate
Schwope et al (1997) suggested that the newly discovered Polar RX J2115-5840 is a near-synchronous system. We have obtained circular polarisation observations of RX J2115-5840 which show that the...
Spooner, David M., McLean, Karen, Ramsay, Gavin, Waugh, Robbie, Bryan, Glenn J.
The cultivated potato, Solanum tuberosum, ultimately traces its origin to Andean and Chilean landraces developed by pre-Colombian cultivators. These Andean landraces exhibit tremendous morphological...
Spooner, David M., McLean, Karen, Ramsay, Gavin, Waugh, Robbie, Bryan, Glenn J.
The cultivated potato, Solanum tuberosum, ultimately traces its origin to Andean and Chilean landraces developed by pre-Colombian cultivators. These Andean landraces exhibit tremendous morphological...
A Report Prepared for the Queensland Commercial Fishermen's Organisation
Ramsay, Gavin, Tisdell, Clem, Harrison, Steve, Pullar, David, Sun, Samantha, Tibbetts, Ian
Environmental Economics and Policy,