Step 5 -
Overlay the HSC on an HLA image using Astroview, and then also using the Interactive Display. WE STRONGLY URGE USERS TO ALWAYS LOOK AT THE HSC OVERLAYED ON A HUBBLE IMAGE IN ORDER TO CHECK FOR ARTICFACTS !
First, click on the Toggle Overlay Image
). This will bring up the image in AstroView. While you will not be able to change the contrast of the image, unlike the HLA Interactive Display, it does have the advantage of allowing you to select different subsets of the data using the selection Filters on the left.
Now click on the cutout image itself (green
). This will bring up the HLA Interactive Display.
Click advanced contrast controls
, Apply astrometric
, Require NumImages > 20
, and then the HSC
) to overlay the HSC on this particular image.
small a value of NumImages
(e.g., > 0) can result in the inclusion of residual
Determining the best value for NumImages is oftern one of the most important decisions you will have when using the HSC.
Click on the nearest HSC object to the center (yellow
) to reveal the HSC summary form information for MatchID = 22214697. Scroll to reveal the other information for this object.
The object has 28 detections with a mean A_F606W
= 25.599 +/-0.022 (using 11 repeat measurements) , W3_F606W = 25.579 (no value of sigma since no repeat measurements). These are the same as what we found in Step 3.
The Concentration Index (CI; difference in magnitude between
0.05 and 0.15 arcsec radius measurement) has a value CI =
1.093, which is typical for a star on the ACS.