You are here

Kevin Jardine's blog

Lynds bright nebulae

Submitted by Kevin Jardine on 17 February, 2010 - 17:51

I've added the Lynds bright nebulae as an optional overlay to the false colour version of Douglas Finkbeiner's all sky hydrogen-alpha map in the Milky Way Explorer.

At some point soon, I'll add some commentary on the Lynds bright nebulae catalog. In short, it's a large catalog (1125 objects) covering the same area of sky as the BFS and Sharpless catalogs but in more detail. This sounds more interesting than it actually is, because in many cases the Lynds nebulae are just parts of nebulae already in the Sharpless catalog. However, it also contains designations for fainter and smaller nebulae not in the Sharpless catalog, so is useful in some cases.

NASA composite galactic centre image

Submitted by Kevin Jardine on 15 November, 2009 - 16:39

NASA released a new galactic centre image on 10 November that was supposedly constructed from three previous galactic centre images from Hubble, Spitzer and Chandra. I've now put it into the Milky Way Explorer and you can view it here.

Some of the mysteries around a few of the objects in this image have been discussed on the APOD discussion site. At least one of these objects does not appear on any of the three original images so it is a mystery where it came from.

Gamma ray data

Submitted by Kevin Jardine on 10 November, 2009 - 10:00

Gregory Dobler, Douglas Finkbeiner and colleagues have released a set of all-sky gamma ray images based upon the Fermi Large Area Telescope data release back in August. I've put a colour composite of three of these images in the Milky Way Explorer.

Normally I work with the full FITS format data released by astronomers, but in this case, the FITS files use the fairly obscure HEALPix projection which unfortunately is not yet supported by a number of key software tools. For example, Aladin hangs when I try to read these FITS files. So for the moment, I've used the black and white jpeg images also supplied to create the colour composite.

I experimented with a number of data combinations, and ended up using the smoothed versions (with no point sources removed) for these energy ranges: 0.5 to 1 GeV (red), 2 to 5 GeV (green) and 10 to 20 GeV (blue). Higher energy levels up to 300 GeV are available, but the higher energy gamma rays are not particularly constrained to the galactic plane. According to my reading of the accompanying paper, it appears that these higher energy photons are mostly from relatively local objects (within a few thousand parsecs).

The Fermi data is not very high resolution, but nevertheless, it is interesting to see major gamma ray concentrations in the directions of Orion, the Taurus and Ophiuchus dark cloud complexes, and the Large Magellanic Cloud.

BFS overlay

Submitted by Kevin Jardine on 27 September, 2009 - 14:20

I've added a BFS overlay map as the BFS catalog corrects the position errors in the Sharpless catalog. The nebula overlays are described here.


Subscribe to RSS - Kevin Jardine's blog