[AZ-Observing] Re: Sunrise On Rupes Recta
- From: Tom Polakis <tpolakis@xxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Thu, 13 Jan 2011 11:41:39 -0500
Chris,
(Disclaimer: technical stuff follows; ignore as you see fit)
The four images are pasted in as layers in Photoshop CS4, and then manually
aligned by "blinking" the layers, and shifting them with the arrow keys. Of
course the moon is not following a sidereal track, so the layers also had to be
rotated, despite pretty decent polar alignment.
Since I chose single-point alignment in the interest of getting to bed by
midnight, only the crater Birt is properly aligned properly while the rest of
the frame moves around between images thanks to poor seeing. The right way to
do this is to align on multiple points, and the software deforms the image as
needed, but that takes some serious CPU time.
It took a couple images to realize that nothing was going wrong with my mount's
tracking. The moon moves about half its diameter every 30 minutes of time, so
it was initially a surprise to come outside and learn that the Straight Wall
had moved so far out of the frame. Note to self: set the tracking rate to
lunar for this sort of work.
Tom
---- Chris Schur <comets133@xxxxxxxxx> wrote:
> Tom, thats a great movie. What software do you use to combine the images?
> Clear Skies,
>
> Chris
>
> Schur's Web Portal: http://www.schursastrophotography.com
>
> --- On Wed, 1/12/11, Tom Polakis <tpolakis@xxxxxxx> wrote:
>
>
> From: Tom Polakis <tpolakis@xxxxxxx>
> Subject: [AZ-Observing] Sunrise On Rupes Recta
> To: AZ-Observing@xxxxxxxxxxxxx, evac@xxxxxxxxxxxxxx
> Date: Wednesday, January 12, 2011, 11:47 PM
>
>
> The moon is librated enough tonight to show the Straight Wall at First
> Quarter. Typically it turns up at about 8 or 9 days after New Moon. I began
> at 9:10 p.m., and recorded four images at half hour interval to create this
> time-lapse animation. The shadow of the wall of the crater Birt diminishes
> quite a bit during the 1 1/2 hours of the sequence. Sunlight begins to
> illuminate the western rim of the crater Nicollet near the bottom of the
> frame.
>
> http://www.pbase.com/polakis/image/131789333
>
> And now... excuses. The seeing was horrible during that 4:40 image, so
> that's as sharp as that frame is going to get. Later, the transparency began
> to go as the moon was sinking, making evening out the brightness and contrast
> a challenge. Not appearing in this film is a 6:10UT image that was ruined by
> cirrus and the associated really bad seeing.
>
> Tom
>
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