The EXTraS Public Data Archive is the repository of all results and products generated by the EXTraS project.

Should you use our archive for your research and publish results, please use the acknowledgement below:

This research has made use of data produced by the EXTraS project, funded by the European Union's Seventh Framework Programme under grant agreement no 607452

and cite the paper describing EXTraS:

De Luca et al., 2016, in Caraveo P., D’Avanzo P., Gehrels N., Tagliaferri G., eds, Proc. Sci., Vol. 233, Swift: 10 Years of Discovery. Springer International Publishing, Switzerland, p. 135


Data Access

The main data access page is here.

A powerful interface will allow you to search our catalogues with basic as well as advanced query and filtering options and to retrieve all or selected data products.

A visualization server will provide you with interactive display of archived data.

Full download of our catalogues (fits format and VOTables) is also possible.


Details on data analysis, together with a description of available products and results and information on their usability can be found by following the links listed below:

WP2  Short-term aperiodic variability
WP3  Pulsations
WP4  New, fast transients
WP5  Long-term variability
WP7  MWL characterisation (spectra) and classification


EXTraS is a collaborative project funded by the European Union's Seventh Framework Programme under grant agreement no 607452. The EXTraS consortium is coordinated by INAF (Italy) and involves Scuola Universitaria Superiore IUSS Pavia (Italy), Consiglio Nazionale delle Ricerche – Istituto di Matematica Applicata e Tecnologie Informatiche “E. Magenes” (CNR-IMATI, Italy); University of Leicester (UK); Max Planck Gesellschaft zur Foerderung der Wissenschaften – Max Planck Institut fuer extraterrestrische Physik (MPG-MPE, Germany); Friedrich-Alexander Universitat Erlangen-Nuremberg – Erlangen Center for Astroparticle Physics (ECAP, Germany).

Here is a list of our papers, publishing EXTraS results. Click here for a full list of publications, including talks and posters.

  • A. De Luca, R. Salvaterra, A. Belfiore, S. Carpano, D. D'Agostino, F. Haberl, G.L. Israel, D. Law-Green, G. Lisini, M. Marelli, G. Novara, A.M. Read, G. Rodriguez-Castillo, S.R. Rosen, D. Salvetti, A. Tiengo, G. Vianello, M.G. Watson, C. Delvaux, T. Dickens, P. Esposito, J. Greiner, H. Haemmerle, A. Kreikenbohm, S. Kreykenbohm, M. Oertel, D. Pizzocaro, J.P. Pye, S. Sandrelli, B. Stelzer, J. Wilms, and F. Zagaria (arXiv) :

    The EXTraS Project: Exploring the X-ray Transient and variable Sky

    Astronomy & Astrophysics, in press. Doi: 10.1051/0004-6361/202039783

  • S. Motta, M. Marelli, F. Pintore, P. Esposito, R. Salvaterra, A. De Luca, G.L. Israel, A. Tiengo, and G. Rodriguez (arXiv):

    The Slow Heartbeats of an Ultraluminous X-Ray Source in NGC 3621

    The Astrophysical Journal, 898, 174-184, 2020. Doi: 10.3847/1538-4357/ab9b81

  • G. Novara, P. Esposito, A. Tiengo, G. Vianello, R. Salvaterra, A. Belfiore, A. De Luca, et al. (arXiv):

    A supernova candidate at z=0.092 in XMM-Newton archival data

    The Astrophysical Journal, 898, 37-45, 2020. Doi: 10.3847/1538-4357/ab98f8

  • G. Rodriguez, G. L. Israel, A. Belfiore, et al. (arXiv):

    Discovery of a 2.8s pulsar in a 2 d-orbit high-mass X-ray binary powering the ultraluminous X-ray source ULX-7 in M51

    The Astrophysical Journal, 895, 60-74, 2020. Doi: 10.3847/1538-4357/ab8a44

  • A. De Luca, B. Stelzer, A. J. Burgasser, D. Pizzocaro, P. Ranalli, S. Raetz, M. Marelli, G. Novara, C. Vignali, A. Belfiore, P. Esposito, P. Franzetti, M. Fumana, R. Gilli, R. Salvaterra, and A. Tiengo (arXiv):

    EXTraS discovery of an X-ray superflare from an L dwarf

    Astronomy & Astrophysics, 634, L13, 2020. Doi: 10.1051/0004-6361/201937163

  • D. Pizzocaro, B. Stelzer, E. Porretti, S. Raetz, G. Micela, A. Belfiore, M. Marelli, D. Salvetti, and A. De Luca (arXiv):

    Activity and rotation of the X-ray emitting Kepler stars

    Astronomy & Astrophysics, 628, A41, 2019. Doi: 10.1051/0004-6361/201731674

  • L. Sidoli, K. Postnov, A. Belfiore, M. Marelli, D. Salvetti, R. Salvaterra, A. De Luca, and P. Esposito (arXiv):

    Supergiant Fast X-ray Transients uncovered by the EXTraS project: flares reveal the development of magnetospheric instability in accreting neutron stars

    Monthly Notices of the Royal Astronomical Society, V. 487(1), p.420-434, 2019. Doi: 10.1093/mnras/stz1283

  • M. Marelli, D. De Martino, S. Mereghetti, A. De Luca, R. Salvaterra, L. Sidoli, G. Israel, and G. Rodriguez (arXiv):

    The First Orbital Period of a Very Bright and Fast Nova in M31: M31N 2013-01b

    The Astrophysical Journal, V. 866(2), 125, 2018. Doi:10.3847/1538-4357/aadc67

  • S. Mereghetti, A. De Luca, D. Salvetti, A. Belfiore, M. Marelli, A. Paizis, M. Rigoselli, R. Salvaterra, L. Sidoli, A. Tiengo (arXiv):

    EXTraS discovery of a peculiar flaring X-ray source in the Galactic globular cluster NGC 6540

    Astronomy & Astrophysics, V. 616 pp. A36, 2018. Doi: 10.1051/0004-6361/201833086

  • M. Marelli, D. Salvetti, F. Gastaldello, S. Ghizzardi, S. Molendi, A. De Luca, A. Moretti, M. Rossetti, A. Tiengo (arXiv):

    A Systematic Analysis of the XMM-Newton Background: I. Dataset and Extraction Procedures

    Experimental Astronomy, V. 44(3), pp.297-308, 2017. Doi: 10.1007/s10686-017-9542-5

  • D. Salvetti, M. Marelli, F. Gastaldello, S. Ghizzardi, S. Molendi, A. De Luca, A. Moretti, M. Rossetti, A. Tiengo (arXiv):

    A systematic analysis of the XMM-Newton background: II. Properties of the in-Field-Of-View excess component

    Experimental Astronomy, V. 44(3), pp.309-320, 2017. Doi: 10.1007/s10686-017-9539-0

  • S. Ghizzardi, M. Marelli, D. Salvetti, F. Gastaldello, S. Molendi, A. De Luca, A. Moretti, M. Rossetti, A. Tiengo (arXiv):

    A systematic analysis of the XMM-Newton background: III. Impact of the magnetospheric environment

    Experimental Astronomy, V. 44(3), pp.273-285, 2017. Doi: 10.1007/s10686-017-9554-1

  • F. Gastaldello, S. Ghizzardi, M. Marelli, D. Salvetti, S. Molendi, A. De Luca, A. Moretti, M. Rossetti, A. Tiengo (arXiv):

    A systematic analysis of the XMM-Newton background: IV. Origin of the unfocused and focused components

    Experimental Astronomy, V. 44(3), pp.321-336, 2017. Doi: 10.1007/s10686-017-9549-y

  • M. Marelli, A. Tiengo, A. De Luca, D. Salvetti, L. Saronni, L. Sidoli, A. Paizis, R. Salvaterra, A. Belfiore, G. Israel, F. Haberl, and D. D'Agostino (arXiv):

    Discovery of periodic dips in the brightest hard X-ray source of M31 with EXTraS

    The Astrophysical Journal Letters, V. 851(2), L27, 2017.Doi: 10.3847/2041-8213/aa9b2e

  • G.L. Israel, A. Belfiore, L. Stella, P. Esposito, P. Casella, A. De Luca, M. Marelli, A.Papitto, M. Perri, S. Puccetti, G. A. Rodriguez Castillo, D. Salvetti, A. Tiengo, L. Zampieri, D. D'Agostino, J. Greiner, F. Haberl, G. Novara, R. Salvaterra, R. Turolla, M. Watson, J. Wilms, and A. Wolter (arXiv):

    An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907

    ScienceV. 355(6327), pp 817-819, 2017. Doi: 10.1126/science.aai8635

  • G.L. Israel, A. Papitto, P. Esposito, L. Stella, L. Zampieri, A. Belfiore, G. A. Rodriguez Castillo, A. De Luca, A. Tiengo, F. Haberl, J. Greiner, R. Salvaterra, S. Sandrelli, and G. Lisini (arxiv

    Discovery of a 0.42-s pulsar in the ultraluminous X-ray source NGC 7793 P13 

    Monthly Notices of the Royal Astronomical Society, V. 466, pp.  L48, 2017. Doi: 10.1093/mnrasl/slw218

  • F. Haberl, G. L. Israel, G. A. Rodriguez Castillo, G. Vasilopoulos, C. Delvaux, A. De Luca, S. Carpano, P. Esposito, G. Novara, R. Salvaterra, A. Tiengo, D. D'Agostino, and A. Udalski (arXiv)

    EXTraS discovery of two pulsators in the direction of the LMC: a Be/X-ray binary pulsar in the LMC and a candidate double-degenerate polar in the foreground

    Astronomy & Astrophysics, V. 598, pp. A69, 2017. Doi: 10.1051/0004-6361/201629744

  • P. Esposito, G. L. Israel, A. Belfiore, G. Novara, L. Sidoli, G. A. Rodriguez Castillo, A. De Luca, A. Tiengo, F. Haberl, R. Salvaterra, A. M. Read, D. Salvetti, S. Sandrelli, M. Marelli, J. Wilms, and D. D'Agostino (arXiv) :

    EXTraS discovery of an 1.2-s X-ray pulsar in M 31

    Monthly Notices of the Royal Astronomical Society, V. 457(1), pp. L5-L9, 2016. Doi: 10.1093/mnrasl/slv194

  • D. Pizzocaro, B. Stelzer, R. Paladini, A. Tiengo, G. Lisini, G. Novara, G. Vianello, A. Belfiore, M. Marelli, D. Salvetti, I. Pillitteri, S. Sciortino, D. D'Agostino, F. Haberl, M. Watson, J. Wilms, R. Salvaterra, and A. De Luca (arXiv) :

    Results from DROXO IV. EXTraS discovery of an X-ray flare from the Class I protostar candidate ISO-Oph 85

    Astronomy and Astrophysics, V. 587, pp. A36, 2016. Doi: 10.1051/0004-6361/201526562

Click here for a PDF version

Monday, November 21

  • 8:15 - 9:00 : Registration
  • 9:00 - 9:20 : A. De Luca - The EXTraS Project
  • 9:20 - 9:50 : C. Argiroffi - Low-mass Stars (I)
  • 9:50 - 10:10 : D. Pizzocaro - Activity and rotation of the X-ray emitting Kepler stars
  • 10:10 - 10:30 : R. Nordon - Variability of a stellar corona on a time scale of days

  • 10:30 - 11:00 : coffee break & poster viewing

  • 11:00 - 11:30 : A. Pollock - Exploring the dynamics of collisionless X-ray plasmas in single and binary hot stars (I)
  • 11:30 - 11:50 : N. Webb - Variable X-ray sources in the 3XMM catalogue
  • 11:50 - 12:10 : A. Read - Long-term variability of X-ray sources
  • 12:10 - 12:40 : G. Ramsay - Cataclysmic Variables - probes of accretion physics (I)
  • 12:40 - 13:00 : J.-U. Ness - Short-period X-ray oscillations in super-soft novae and persistent super-soft sources

  • 13:00 - 14:20 : lunch break & poster viewing

  • 14:20 - 14:50 : R. Turolla - The Neutron Star Zoo: Magnetars and other Wild Creatures (I)
  • 14:50 - 15:10 : S. Mereghetti - X-ray variability in rotation-powered radio pulsars: the extraordinary case of PSR B0943+10
  • 15:10 - 15:40 : E. Kuulkers - Variable phenomena in low-mass X-ray binaries (I)
  • 15:40 - 16:00 : R. Wijnands - Neutron stars accreting at extremely low accretion rates
  • 16:00 - 16:20 : F. Bernardini - Events leading up to the 2015 June Outburst of V404 Cyg

  • 16:20 - 16:50 : coffee break & poster viewing

  • 16:50 - 17:10 : M. Lewis - Monitoring the Optical Sky for Transients
  • 17:10 - 17:30 : M. Del Santo - Planetary tidal disruption events: the case of IGR J17361-4441 in NGC 6388
  • 17:30 - 17:50 : L. Amati - Understanding and exploiting Gamma-Ray Bursts through their X-ray prompt emission

  • 18:30 - 19:30 : R. Turolla - Buchi neri nella nostra galassia (Public lecture in Italian)

Tuesday, November 22

  • 9:00 - 9:30 : M. Coe - The family of HMXBs in the Magellanic Clouds (I)
  • 9:30 - 9:50 : F. Haberl - EXTraS discovery of two pulsators in the direction of the LMC
  • 9:50 - 10:10 : J. Vadakkumthani - Transient X-ray Sources in the Magellanic-type Galaxy NGC 4449
  • 10:10 - 10:30 : A. Belfiore - EXTraS discovery of an 1.2-s X-ray pulsar in M31

  • 10:30 - 11:00 : coffee break & poster viewing

  • 11:00 - 11:30 : L. Zampieri - Perspectives on Ultraluminous X-ray sources after the EXTraS discovery of two new pulsars (I)
  • 11:30 - 11:50 : G. Israel - An EXTraS view of the rising class of ULX pulsars
  • 11:50 - 12:10 : A. Mushtukov - Highly magnetized neutron stars at extreme mass accretion rates
  • 12:10 - 12:40 : I. McHardy - X-ray variability in AGN (I)
  • 12:40 - 13:00 : J. Mayers - XCS - It's not Just about Cluster

  • 13:00 - 14:30 : lunch break & poster viewing

  • 14:30 - 15:00 : S. Campana - SN shock break-out events and peculiar GRBs (I)
  • 15:00 - 15:20 : D. Goetz - Catching X-ray transients with SVOM
  • 15:20 - 15:40 : G. Novara - EXTraS discovery of a distant supernova shock break-out candidate
  • 15:40 - 16:10 : M. Branchesi - New perspectives for the transient sky with gravitational wave observations (I)
  • 16:10 - 16:30 : P. Evans - Multimessenger astronomy and the vital role of EXTraS

  • 16:30 - 17:00 : coffee break & poster viewing

  • 17:00 - 17:10 : N. Schartel - The XMM-Newton mission and EXTraS
  • 17:10 - 17:30 : M. Watson - Concluding remarks

  • 20:00 -  : social dinner at Peo restaurant

Wednesday, November 23

  • 9:00 - 9:35 : Characterization of aperiodic variability
  • 9:35 - 10:00 : Search for pulsations
  • 10:00 - 10:25 : Search for new, faint transients
  • 10:25 - 10:50 : Characterization of long-term variability

  • 10:50 - 11:10 : coffee break

  • 11:10 - 11:35 : Screening of results
  • 11:35 - 12:00 : MWL characterization and phenomenological classification
  • 12:00 - 12:25 : EXTraS public archive and tools
  • 12:25 - 12:50 : EXTraS Science portal

  • 12:50 - 13:30 : inspection of products/tools - questions & answers

It is a very busy time for our team. Less than five months are left, before the EXTraS project will officially end. The final version of all results and products will be released to the community in late December, this year.

A huge load of work has been already successfully completed, searching for, and characterising all temporal-domain information in XMM/EPIC data.

At INAF/IASF in Milan, we focused on aperiodic variability. Light curves were extracted for almost all (>95%) sources listed in the XMM serendipitous source catalog, with both uniform time bins and with the Bayesian block approach. FFT spectra have also been produced. A set of more than 50 parameters have been computed, to characterise different aspects of each source variability, on time scales ranging from a fraction of a second to ~1 day.

At INAF/OA Roma, we have been systematically searching for pulsations on the largest possible sample of sources (about 80% of the objects in the XMM serendipitous source catalog). An FFT-based search technique was used, taking into account the effects of any aperiodic variability possibly superimposed to the periodic signal. Upper limits to the pulsed fraction have been computed for all sources which do not show any significant periodicity.

At IUSS Pavia, our team analysed all EPIC data with a brand new approach, based on the Bayesian block algorithm, to search for new, faint transients - sources that rose above the detection threshold for a short time. More than 2,000 candidate transients have been detected on time scales ranging from tens of seconds to ~1 hr. Such sources are typically missed by the source detection run as a part of the standard XMM data processing, and thus are not included in the XMM serendipitous source catalog.

At the University of Leicester, long-term variability has been studied. For all sources located in sky regions observed more than once, we collated flux measurements from the XMM serendipitous source catalogue, as well as from a improved and enlarged version of the XMM slew survey catalogue. This was completed, in case of non-detection at a specific epoch, by upper limits computed from the related EPIC data. Test and characterisation of variability were performed on the resulting long-term light curves, displaying the behaviour of sources on time scales ranging from ~days to ~a decade.

To ensure the highest possible quality of EXTraS products for the community, a careful screening, both using automatic algorithms and by direct visual inspection, is being carried out at MPE in Garching.

All time-domain results, coupled to X-ray spectral information as well as to multi-wavelength archival data, are being used by our team at ECAP (Bamberg) to perform phenomenological classification of the sources, the first ever tried on a sample of hundreds of thousands of soft X-ray sources.

All EXTraS products are being ingested in the LEDAS high-energy data archive at Leicester, where user-friendly visualisation tools for users are also being developed.

For further details on our recent work, you can have a look at a series of posters presented at the last XMM Workshop in ESAC.

The scientific information included in our output is indeed huge. We are publishing a small sample of selected results. See e.g. our detection of a flare from a very early protostar (Pizzocaro et al.2016), and the discovery of the first pulsating, accreting neutron star in the Andromeda galaxy (Esposito et al. 2016) — more to come! We trust that the EXTraS catalogue, describing variability over a range of more than nine orders of magnitude in time scale, for hundreds of thousands of X-ray sources spanning six orders of magnitude in flux, will be a very useful resource in almost all fields of astrophysics.

In this perspective, we are glad to invite you in Italy to participate in a scientific workshop devoted to variability in the X-ray sky. We will meet in Pavia, from November 21 to 23, to discuss about X-ray time-domain studies of all kind of astrophysical sources, from nearby stars to extragalactic, rare transient events. EXTraS products will also be presented with detail in a dedicated hands-on session. See you in Pavia!


The paper describing the EXTraS project is in press in Astronomy & Astrophysics. We give details on the algorithms that... 
A new EXTraS paper, "Supergiant Fast X-ray Transients uncovered by the EXTraS project: flares reveal the development of... 
During a EXTraS workshop, highschool students discover a mysterious X-ray flare. The discovery led to a publication on the...