SkyView Blog

SkyView gets the underlying data for the FIRST data from the MAST archive. They have recently changed how they provide the data a little. The data used to be gzip-compressed but is now uncompressed. There’s a little bit of extra data too — coverage is extended over an additional 22 square degrees. The change shouldn’t affect many users of the Web page. Most of the FIRST data is already cached here at SkyView. It can cause problems for SkyView-in-a-Jar users since the current jar is trying to access the URLs using the old names.

We’ll be putting out an updated jar in the next couple of days. 99% of what we need to do is to just get rid of the .gz suffixes in the FIRST survey description which is very easy, but we also need to index the new files which will take a little longer.

The bug that caused the incorrect values of FITS CRVAL keywords for fixed projections (described in the previous post) has been fixed.

SkyView is currently putting incorrect values in the FITS CRVAL keywords of the fixed projections. The CRVAL keywords should be the center of the projection which in fixed projections is not necessarily the center of the image. For CAR, SFL and AIT projections the fixed center is 0,0 while it is 0,90 for the TOAST projection. SkyView is currently giving the center of the image — so that all-sky images, for which these projections are often used, are fine.

The image data themselves are unaffected.

We’ll be installing a patch shortly.