Bright Gamma Ray Burst

Last night there was a particularly bright gamma ray burst (080319B) located in Bootes that was perfectly located for a number of observatories to go after. An camera called "Pi of the Sky" caught the burst and estimated the peak visual brightness at magnitude 5.7, an amazing level for an object that, when spectra were taken of the fading remnant, is nearly 7.7 billion light years away, at a redshift of 0.937. In one of those coincidences there were 4, count them, 4 GRBs yesterday.
See an animation of the burst from Chile here.

I have a link to the field in the local copy of SDSS here.

Pretty picture of the day

A dye laser points the way for the VLT towards the center of the galaxy.




Grab the huge versions of these at the ESO press page.
Seen via Astronomy Blog

The space-time bending of galaxy cluster CL0024

As mentioned a few posts ago, galaxy cluster CL0024 bends space-time in a particular manner which shows a unique signature from its dark matter distribution. The press release image used ghostly blue as the mapping choice. Perhaps a more interesting way is showing the distortion of graph paper behind the cluster, from the LSST site:



The original press image:

The dark matter ring

When you see this image in the popular media, be sure to realize it's a statistical map of the distribution of dark matter around a galaxy cluster _superimposed_ on an image of the cluster. It's not an image of dark matter. The actual image is this one:



By looking at the blue arcs in the image, astronomers can map how the massive galaxy cluster bends light from a more distant galaxy behind the cluster, and compare that distribution with what they see in the visible.

Here's a crop of the upper-left section of the cluster--you can see distorted images of a blue, star-forming, possibly spiral galaxy. The paper will probably have a reconstituted image of the lensed galaxy.


It's unfortunate that many people will see the blue image and think Hubble directly imaged some dark matter. The more important detail of the science was the ring shape and the proposed physics behind the shape from galaxy interactions.

More discussionn at Bad Astronomy