[AZ-Observing] Re: Comet 2012 - Lessons Learned - Reprocessed
- From: "David M. Douglass" <dmdouglass@xxxxxxxxxxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Wed, 16 Jan 2013 12:04:59 -0700
As I said in my original post, I was aware the automated gif was “not the best”…
The main problem I seem to be having here is stable star positions.
I have an inherent problem, taking the images at 2-min in Alt AZ. That would be
rotation.
So, each 2-min image has some minor rotation, and the 3 image stack has a
larger chunk of it.
So…. I established a 3-point, 3-star “alignment” triangulation, and then had a
“cropping mask” overlaid on that.
I really thought it would come out better. But I guess with cropping, and all,
it was not good enough.
What I needed was a “alignment and stacking” routine, without the “stacking”.
I found it !!! I have Nebulosity 3, and this can be done there. I had not
noticed it before.
They also have a sequence known as “Automatic Alignment – (non-stellar)”,
which is what I used. Wow !! What a difference.
I re-processed the 20 images, aligning them with Nebulosity. This, ironically,
also helped with the disparity in the “brightness-contrast” area. So…. Now the
stars are “locked”, and the presentation is much nicer.
I was also able to create a “stacked” version of all 20 frames, resulting in a
“displayed trail” of the travel path of the comet.
I decided to give ISON its own wage page. Both the new automated gif, and the
composite of the 20 frames, are shown here. I am much happier with this
presentation of the data.
http://www.az-douglass.net/astronomy/DMD-ISON.htm
David M. Douglass
dmdouglass@xxxxxxxxxxxxxxx (secondary)
david@xxxxxxxxxxxxxxx (main)
Cell (602) 908-9092
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