metagalactic radiation field, healpix

I wasted much of the day building IDL routines to make pretty pictures from healpix maps. This was a waste both because there are better programmers than me, and better languages than IDL.

Over lunch, Schiminovich and I discussed our project of estimating the intensity of the ionizing radiation impinging on the Milky Way from extragalactic sources, and the contribution from different kinds of sources. We discussed the issue that most of the ionizing radiation comes from significant redshift; this is both because quasars are more abundant and luminous at higher redshift, and because galaxies tend to be self-shielding. Hopefully we can refine our understanding of the radiation with GALEX.


  1. Hi Hogg,
    Can u give me some idea of how to convert a fits image in ra,dec to healpix?.
    Thank you.!

  2. Anonymous: I don't think there are any good tools, but send an email to Doug Finkbeiner, who I think has done something. The code I refer to here (above) just visualizes the healpix map; it doesn't reproject it to anything more useful.

  3. Hi.
    I am trying to convert the co-ordinates (given in RA and DEC) of known LAT GRBs into positions on my HEALPix map. My pixel numbers are usually given by inputting theta and phi angles, along with Nside. Is there a simple way of me plotting these GRBs on my HEALPix maps? Thanks.