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.
NEWS
IPHAS INITIAL DATA RELEASE (IDR) is nearly ready. All data taken up to the beginning of 2006 has been uploaded and the finishing touches are being put to an astrogrid interface constructed at IoA Cambridge by Nic Walton and Eduardo Gonzalez-Solares. After some documentation has been prepared and checked, the release will be announced. The data will be calibrated at the individual field level - a uniform calibration across the survey area will be developed when resources permit. One path to accessing the IDR starts from the Early IPHAS Data link.
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 also have a second nova progenitor in V2467 Cyg, which went
into outburst on 15 March 2007: see ATEL No. 1031. In both cases
it can be deduced using the IPHAS photometry that the progenitors were Hα emission line objects.
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. Publications arising from the IPHAS survey are being posted here.
This is the Princes Nebula, an IPHAS discovery made from the first season's
data. The detected nebulosity is about half an arcminute long in its longest
dimension and is located at RA 01 25 08, Dec +63 56 52 (2000). As a rare
example of a quadrupolar planetary nebula, it is now the subject of a paper
that has appeared in 'Astronomy and Astrophysics' (Mampaso et al 2006, see the
publications
page). Our informal name for the nebula arises from the use made of its discovery as a virtual wedding present from the IAC to the Prince of Spain, an astronomy enthusiast, on the occasion of his wedding in 2004.
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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