July 27, 2011

This morning I downloaded more HST optical images.  I also got an email from Rupal telling how to tell if the optical image is off.  I have to find the coordinates of the guide star and compare them to a list of guide stars.  The problem is, with a search radius of 2.5 arcminutes, about 25 possible stars are given.  So I have to look through by hand for the closest star to the location I entered. 

Another problem rises when trying to align the optical and radio images.  The radio images have a resolution of about 2 arc seconds and the optical images have a resolution of about .1 arc seconds.  Not sure what that means? Here is a picture to show the difference.

The image on the left is optical and the image on the right is radio.  Both images are showing the same area and are the same scale.  That makes it difficult to use the radio image as a reference for the optical image, but I had to do that.  This is really an unfair example; most of the radio images are better in resolution, but still not as good as the optical images.