Sunspot 2470 and an airplane – December 20, 2015

A brief Sunday imaging session with the Sun…

Knowing that a rather large sunspot was transiting our star, I’ve packed my 8 inch Newtonian and went together with my wife to a nearby observing location. Despite the Sun being low above the horizon (only 20 degrees), the seeing conditions were actually quite good (4-5/10).

The following shots were acquired with this stuff: 8inch F/5 homemade Newtonian (SkyWatcher optics), Baader Astrosolar full-aperture filter, ASI 120MM-S camera with Baader Red filter. The full-disk image was acquired with the Canon 550D camera; 25 frames at ISO 1000 and 1/4000s exposure were combined.

First shot, showing the full disk, and the relative size of sunspot AR2470:

SunDec20, 2015.jpg

Now, the result of the session, with 1200 frames selected from 20000, in both grayscale and artificial colors. Note also the apparent size of the Earth at the same scale with the sunspot:

AR2470BW.jpg

AR2470COL.jpg

Now, a combined image:

AR2470Dec20.jpg

And now for the big “WOOOOWWWW” of the session: a fantastically perfect transit of an airplane just in my field of view. This is very rare for me; it’s actually only the second time I’ve ever seen an airplane transiting the Sun directly in by camera’s field of view.

Following is a short animation showing the pass, animation which is set to 20fps; the original acquisition was done at 70fps. Note the bow shock near the sunspot, arriving just before the tip of the airplane!!!

G.gif

A 10 second video of the transit can be seen here:

https://youtu.be/6H9lQ0p5fwk

A short sequence showing the effect onto the sunspot’s shape in individual frames:

Bowshock.jpg

Two frames from the above video, processed with some colors; note that the solar granulation is also visible:

PlaneA.jpg

PlaneB.jpg

And a long mosaic, showing the entire airplane and part of the contrail. This was hard to assemble, since the field of view was small compared to the plane:

Plane.jpg

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