CHIPASS 1.4 GHz radio continuum map

Paper

A New 1.4 GHz Radio Continuum Map of the Sky South of Declination +25°
Calabretta, M.R., Staveley-Smith, L., & Barnes, D.G. (2014), as published in Publications of the Astronomical Society of Australia (PASA) (© Astronomical Society of Australia, 2014).

Abstract

Archival data from the HI Parkes All-Sky Survey (HIPASS) and the HI Zone of Avoidance (HIZOA) survey have been carefully reprocessed into a new 1.4 GHz continuum map of the sky south of declination +25°. The wide sky coverage, high sensitivity of 40 mK (limited by confusion), resolution of 14.4 arcmin (compared to 51 arcmin for the Haslam et al. 408 MHz and 35 arcmin for the Reich et al. 1.4 GHz surveys), and low level of artefacts makes this map ideal for numerous studies, including: merging into interferometer maps to complete large-scale structures; decomposition of thermal and non-thermal emission components from Galactic and extragalactic sources; and comparison of emission regions with other frequencies.

Data products (FITS format)

	The extended source map in Galactic coordinates on a Hammer-Aitoff projection as seen above, with associated sensitivity map. This map is calibrated in mK full-beam brightness temperature as per Reich et al. ( 1982, 1986, & 2001).
	A subset of the above, the Galactic Plane map, in Galactic coordinates but on a plate carrée projection spanning +68° > ℓ > -180° with |b| < 10°, plus associated sensitivity map. This map is provided specifically for studies of the many complex sources in the Galactic Plane (see below).
	The extended source map in J2000 equatorial coordinates on a plate carrée projection, with associated sensitivity map. This is the most suitable map to use for blurring the HPBW, or regridding onto other coordinate systems and map projections.
	The compact source map in Galactic coordinates on a Hammer-Aitoff projection, with associated sensitivity map. This map, calibrated in Jy/beam, is best suited for measuring point source positions and flux densities.
	The CHIPASS map was converted to HEALPix format, and also regridded onto an HPX projection (and others), by Nils Odegard (NASA) and are provided on the Lambda web site.

Scroll right to see the full extent of this annotated subset of the CHIPASS Galactic Plane plate carrée map (above). Annotations for HII regions in red are from the catalogue of Paladini et al. (2003), and for supernova remnants in green from Dave Green's SNR catalogue.

kvis annotations for PKSCAT are also available to be used for the J2000 equatorial plate carrée map.

About these greyscale images

The images above were constructed using kvis and GIMP.

The all-sky image is a 3-cycle logarithmic greyscale in the range 22 mK to 22 K by which the map value exceeds 3.3 K, that being the map minimum. Thus the greyscale is divided equally between 3.322 K (black), 3.52 K (two-thirds grey), 5.5 K (one-third grey), and 25.3 K (white). This scale was designed to accentuate the faint wispy tendrils emanating from the Galactic Plane, as well as the weaker point sources in the background. (Specify the range as 3300 to 25300 in kvis with 3-cycle log(val-min) intensity scale, also bearing in mind that kvis mishandles coordinates for the Hammer-Aitoff projection – use SAOImage DS9 for that.)

The Galactic plane image is a 1-cycle logarithmic greyscale in the range 1.8 K to 18 K by which the map value exceeds 2 K. Thus, the image is black at 3.8 K and below, and white at 20 K and above, with the half-way point at about 6.2 K.

Saturated pixels in each image have been rendered white, which is correct in each greyscale as they are well beyond the white limit, thus indistinguishable from their unsaturated neighbours. An all-sky image is available in which the 300 saturated pixels are rendered black and so readily identifiable (they are, of course, blanked in the FITS images).