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Hi Karen, I want to analyse the time course of a supernova. That means the aperture on the first images are bright waning to the end. Now I'm facing the problem that when setting the T1 aperture in the first image, the program does not position T1 on the last images with the dimmer aperture but jumps to a nearby brighter star.
Karen
The quick answer here is that you apparently have the centroid option turned on in the Multi-Aperture set-up panel. Its function is to stay centered on the star, and it assumes the brightest flux is the star you want to measure. So, you'll need to turn that option off. However, the aperture will no long follow the best centering on the SN assuming your pointing and tracking are not perfect.
Ok, I do understand! Since I want to measure a variable star I assumed turning on the „Auto Variable Aperture from each image T1 radial profile“ is appropriate. What is this adjustment for?
You'll instead need to plate solve the images if they are not ready solved with WCS headers, then in multi-aperture set-up, make sure Use RA and Dec to place apertures is enabled. Then zoom in very close on the SN and carefully place you aperture centered on the target. With centroid off, you will not see a "+" in the center of the aperture.
The images were plate solved and aligned. However, I turned-on the „Fixed aperture“ function and then it worked. In the previous session, I conducted the measurements with 1min exposed lights. The SN is now so dim (18mag) that I took images exposed for 1h which makes the result more precise.
Another option without a plate-solution would be to align the image stack using a bright star. Then zoom in and carefully place your aperture centered on the SN (still with centroid turned off).
Ok thanks for telling me that option as well!
Hope this helps
Yes it did, thanks a lot, Gerhard
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