IPHAS: The INT/WFC Photometric Hα Survey of the Northern Galactic Plane
IPHAS is a survey of the Northern Galactic Plane being carried out, in Hα, r and i filters, with the Wide Field Camera (WFC) on the 2.5-metre Isaac Newton Telescope (INT). This will be followed in the next few years by a survey of the southern Galactic Plane on the VLT Survey Telescope (VST) using OmegaCam, once it is commissioned. Together, these surveys provide a springboard to a quantitative revolution in our understanding of the extreme phases of stellar evolution. The previous generation of Hα surveys of the Galaxy, conducted over 30 years ago, begin to be incomplete even at mV=12 - the new generation extends this limit down to red magnitudes fainter than 20.
Publications arising from the IPHAS survey are being posted here.
NEWS
IPHAS INITIAL DATA RELEASE IDR is ready. All data taken up to the beginning of 2006 have been uploaded and can be accessed via AstroGrid and via a cone-search tool and image thumbnail server (constructed at IoA Cambridge by Nic Walton and Eduardo Gonzalez-Solares, see Gonzalez-Solares et al 2008). The presently-released data are calibrated at the individual field level - a uniform calibration across the survey area will be developed when resources permit. The IDR can be accessed here (Early IPHAS data).
NOVA PROGENITORS On 2 April 2006 a nova outburst was reported in Cygnus (IAUC No. 8697. This has
been named V2362 Cygnus, and it reached a peak magnitude of 8 on 6 April 2006.
IPHAS observations of this object were obtained on 3 August 2004, and were found to include a (rare) pre-outburst detection at r' = 20.30(+/-0.05). See ATEL No. 795. We have since identified further nova progenitors (including e.g. V2467 Cyg, which went
into outburst on 15 March 2007: see ATEL No. 1031.).
CATALOGUE OF EMISSION LINE OBJECTS A preliminary catalogue listing photometry for nearly 5000 objects has been published. Please see Witham et al (2008) for details.
IPHAS imaging
This is a false-colour composite constructed from the IPHAS images of a
pair of overlapping fields in the Cygnus-X region of the northern Galactic
Plane. The colour scheme is red for Hα, blue for the Sloan r band, and
green for Sloan i. As this is a significantly reddened region, as well as
nebulous, there are many stars coming up strongly in the i band -- showing
here as a background of green stars. The data were obtained in October 2003.
N is up and E to the left. (Image prepared by Mike and Jonathan Irwin)
Some fine image mosaics constructed from IPHAS observations are in our image gallery.
IPHAS point sources
The final database is looking set to contain photometry on over 300 million
Galactic Plane objects (cf. SDSS DR5 at ~200 million and the 2MASS point source catalogue, with 490 million).
Among these, the important object classes that IPHAS data pick out:
- compact planetary and symbiotic nebulae; rapidly evolving post-AGB stars
- luminous blue variables (P Cygni and η Car like objects)
- Be stars of all types (including young Herbig stars, and B[e] supergiants)
- dMe stars; clusters of T Tau stars
- a range of interacting binary stars (symbiotics, `supersoft' compact binaries, WD/NS/BH accreting binaries generally)
- H-rich white dwarfs
- large numbers of near main sequence A stars
- M giants
Because of the selection for ionized stars and their nebulae, this survey will increase the stock of known OB associations, and other
clusters. It also provides the basis for an empirical mapping of the distribution of interstellar dust in the Galactic Plane. So, as well as stimulating a better understanding of stellar evolution, this survey has a role to play in the quest to clarify the Galaxy's structure.
This figure is a schematic representation of the (r'-Hα, r'-i') colour-colour plane that IPHAS data define. The points plotted on it are the IPHAS colours of
already known objects falling into the object classes specified in the key.
The main locus, occupied
by the great majority of normal stars, is located in between the synthetic tracks drawn in black, corresponding to unreddened (left) and reddened (E(B-V) = 4, right)
main sequences. The dotted tracks crossing these are the unreddened and E(B-V)=4 giant-star sequences.
The figure is from Corradi et al 2008. A discussion of the properties of the properties of the colour-colour plane, IPHAS survey methodology and sample data, have been presented by Drew et al 2005. (See also the publications page).
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