The [[Observational astronomy/Supernova]] page has images of galaxies where a supernova has been observed recently. In this activity we will retrieve images taken before the supernova occured, and compare them to the new images.
[[Image:UGC14.jpg|thumb|300px|right|Supernova 2006sr in the galaxy UGC 14 on 2007-01-02]]
*Start Aladin and click on the '''Load...''' button. In the '''Server selector''' window click on '''DSS''' and select an image server. In the '''Target''' box enter the name of the galaxy which is '''UGC14''' and then choose '''POSS1_Red''' for the '''Survey'''. Click '''Submit'''.
*In the Aladin multiview window click on the icon labeled '''pixel'''. In the '''Pixel mapping''' popup window click on the '''Reverse''' button to change the image from a negative to a positive.
*To find out when this image was taken click on the icon labeled '''prop''' and look for '''Date-Obs:''' which indicates that the image was taken Aug. 11, 1953.
*Compare the image displayed in Aladin to the image shown at right. Click [[:Image:UGC14.jpg|here]] (or on the image) to see a larger version and to find out when it was taken (the '''Date''' is '''2007-01-02T23:03Z'''.) This supernova was first seen on Dec. 12, 2006, so it will not be visible in the earlier image displayed by Aladin. Do you see the supernova in the recent image? If you are unsure, click [[:Image:06srMU C200701022303.jpg|here]] to see another version of this image that is marked to show which star the supernova is.
*More images of this supernova can be found in [[:Category:Supernova Images]] or at the [http://www.rochesterastronomy.org/sn2006/sn2006sr.html Supernova 2006sr in UGC 14] webpage. Compare images taken on different dates to see if the supernova has changed brightness. The difference will be very subtle in images taken a week apart. It is more [[:Image:06srMU C200701262343.jpg|obvious]] after about a month.
Astronomers can gain an understanding of objects in the universe by studying them with a telescope. Observational astronomy is the process of collecting and analyzing data to learn about these objects. In this learning project a computer program will be used to view and study images taken with a telescope to learn basic concepts in astronomy.
Activities
A CCD (Charge-coupled device) imaging system is a type of digital camera that is very sensitive to the dim light from distant objects. The CCD camera is attached to a telescope and the images are stored on a computer where they can later be analyzed. Astronomical images are stored in a computer file format called FITS. These images can be opened and viewed by using computer software that understands this file format.
