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IPHAS IDR released via AstroGrid

The IPHAS Initial Data Release is available at http://idr.iphas.org

Centre of the Rosette nebulae as imaged with IPHAS

The INT/WFC Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS)

The IPHAS consortium (http://www.iphas.org, a collaboration of over 50 astronomers, led from the UK, with partners in Europe, USA, Australia) announces the Initial Data Release (IDR) of the first comprehensive optical digital survey of the plane of the Galaxy. The IDR is described in a paper submitted to MNRAS, and is also available as astro-ph/0712.0389 (Gonzalez-Solares et al, 2007). Access is available via the web at http://idr.iphas.org/, or via the public IPHAS site, http://www.iphas.org/idr/

The IPHAS survey, nearing completion on the Isaac Newton Telescope in La Palma, will eventually be extended to cover the entire Galactic plane of our galaxy, covering Galactic latitudes within the band -5 < b < +5. This initial data release is of observations of the Northern Plane that cover 1600 sq deg, in two broadband filters, r and i, and narrow-band H-alpha. The median image resolution is 1.2 arcsec in this release, and the limiting r magnitudes are typically 20-21.

The catalogue generated from the survey, now being released, contains some 200 million unique objects. These data span a sky area of 1600 square degrees, and are made available with a photometric calibration constructed on a per observing run basis (pending a final global and uniform photometric calibration to be undertaken after survey completion, and not sooner than 2009).

Access to the data products has been implemented through use of standard Virtual Cbservatory publishing interfaces as provided by AstroGrid (http://www.astrogrid.org/). Simple traditional web access is provided to the main IPHAS photometric catalogue, in addition to a number of common catalogues (such as 2MASS) which are of immediate relevance. Access through the AstroGrid VO Desktop enables full integration with the wider range of data and services available through the Virtual Observatory. The IDR represents the largest dataset published primarily through VO interfaces to date, and as such heralds the future of survey data mining.

This immense resource, complementary to the building UKIDSS/GPS database, will foster studies that can be both comprehensive and subtle, of the stellar demographics of the optically-accessible Galactic Plane.

The narrowband H-alpha filter observations are aimed at picking out the fewer than one in a thousand stars that are in the least well-understood early and very late stages of their evolution. For this reason the products of this survey will push forward our understanding of stellar evolution.

In support of the latter aim, we also announce the availability of a catalogue of IPHAS candidate emission line stars that has been derived by applying the selection method of Witham et al (2007, MNRAS, 382, 1158) to the database as it stood at the beginning of 2007. The catalogue is described by Witham et al (2008, to appear in MNRAS; see astro-ph/0712.0988), and presently contains close on 5000 conservatively-selected, high-confidence candidates. The catalogue itself is available via AstroGrid and is already linked to the IDR site, and to the IPHAS public webpages.

Notes/acknowledgments:

The INT/WFC Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS) is an imaging survey being carried out in H-alpha, r' and i' filters, with the Wide Field Camera (WFC) on the 2.5-metre Isaac Newton Telescope (INT) to a depth of r'=20 (10sigma). The survey is aimed at revealing large scale structure in our local galaxy, and also the properties of key early and late populations making up the Milky Way. The IPHAS web page is at http://www.iphas.org.

The Virtual Observatory is an international initiative aimed at providing standard access to the worlds global data resources. All systems conform to agreed interoperability standards defined by the International Virtual Observatory Alliance (http://www.ivoa.net). A leading Virtual Observatory project is the UK's AstroGrid project (http://www.astrogrid.org). The IPHAS data release has been made possible by utilising AstroGrid technology - this IPHAS IDR access work being one supported through an open AstroGrid Tools Call programme (see http://www.astrogrid.org/calls).

The IPHAS survey to date has been carried out using the INT, operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

Contacts:

Dr Eduardo Gonzalez-Solares                IPHAS IDR Lead Scientist
Institute of Astronomy                     email: eglez@ast.cam.ac.uk
University of Cambridge                          
Madingley Road                                   
Cambridge, CB3 0HA, UK                           

Dr Nicholas A Walton                       AstroGrid Project Scientist
Institute of Astronomy                     email: naw@ast.cam.ac.uk
University of Cambridge                          
Madingley Road                                   
Cambridge, CB3 0HA, UK

Professor Janet Drew:                      IPHAS Principal Investigator
Centre for Astrophysics Research           email j.drew@herts.ac.uk
Science & Technology Research Institute    
University of Hertfordshire              
Hatfield, AL10 9AB

Dr Christian Knigge                        H-alpha Emission Line Source
School of Physics And Astronomy            Catalogue Lead Scientist
University of Southampton                  email: christian@astro.soton.ac.uk  
Southampton, SO17 1BJ, UK