APOD: Good Morning Leonid (2018 Nov 23)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: Good Morning Leonid (2018 Nov 23)

Post by APOD Robot » Fri Nov 23, 2018 5:05 am

Image Good Morning Leonid

Explanation: On November 17, just an hour before sunrise, this bright and colorful meteor flashed through clear predawn skies. Above a sea of clouds this striking autumn morning's moment was captured from Hochblauen, a prominent 1165 meter high summit in southern Germany's Black Forest. Shining through the twilight, Sirius as well as the familiar stars of Orion are recognizable near the southwestern horizon, and the meteor seems headed right for the hunter's belt and sword. Still, as part of the annual Leonid meteor shower, the meteor trail does point back to the shower's radiant. The constellation Leo is high above the horizon and off the top left of the frame.

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Re: APOD: Good Morning Leonid (2018 Nov 23)

Post by Boomer12k » Fri Nov 23, 2018 7:08 am

Awesome lookin'....

I have posted a shot of Mt. Fuji... with MARS seen to its upper left in the cafe...

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Re: APOD: Good Morning Leonid (2018 Nov 23)

Post by starsurfer » Fri Nov 23, 2018 2:06 pm

I love Black Forest gateaux.

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Re: APOD: Good Morning Leonid (2018 Nov 23)

Post by alter-ego » Fri Nov 23, 2018 5:08 pm

APOD Robot wrote:
Fri Nov 23, 2018 5:05 am
...
Still, as part of the annual Leonid meteor shower, the meteor trail does point back to the shower's radiant. The constellation Leo is high above the horizon and off the top left of the frame.
It is a very nice picture, but I'm curious why the great-circle extension of the meteor trail back to Leo ends up ~15° south of the radiant?
I'm assuming this is a single image so the radiant is correctly positioned, and because the trail is well defined with enough stars visible, the back-tracking error is small.
A pessimist is nothing more than an experienced optimist

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Re: APOD: Good Morning Leonid (2018 Nov 23)

Post by ta152h0 » Sat Nov 24, 2018 4:08 am

BOA MANHA !!!!
Wolf Kotenberg

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Chris Peterson
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Re: APOD: Good Morning Leonid (2018 Nov 23)

Post by Chris Peterson » Sat Nov 24, 2018 2:40 pm

alter-ego wrote:
Fri Nov 23, 2018 5:08 pm
APOD Robot wrote:
Fri Nov 23, 2018 5:05 am
...
Still, as part of the annual Leonid meteor shower, the meteor trail does point back to the shower's radiant. The constellation Leo is high above the horizon and off the top left of the frame.
It is a very nice picture, but I'm curious why the great-circle extension of the meteor trail back to Leo ends up ~15° south of the radiant?
I'm assuming this is a single image so the radiant is correctly positioned, and because the trail is well defined with enough stars visible, the back-tracking error is small.
How did you determine this error? As someone who writes software to identify radiants in images, I can say that geometrical projection effects require using a spline or some other complex curve to backtrack the path. As the FOV gets larger, it gets trickier to identify the radiant, especially visually.
Chris

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alter-ego
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Re: APOD: Good Morning Leonid (2018 Nov 23)

Post by alter-ego » Sun Nov 25, 2018 7:09 am

Chris Peterson wrote:
Sat Nov 24, 2018 2:40 pm
alter-ego wrote:
Fri Nov 23, 2018 5:08 pm
APOD Robot wrote:
Fri Nov 23, 2018 5:05 am
...
Still, as part of the annual Leonid meteor shower, the meteor trail does point back to the shower's radiant. The constellation Leo is high above the horizon and off the top left of the frame.
It is a very nice picture, but I'm curious why the great-circle extension of the meteor trail back to Leo ends up ~15° south of the radiant?
I'm assuming this is a single image so the radiant is correctly positioned, and because the trail is well defined with enough stars visible, the back-tracking error is small.
How did you determine this error? As someone who writes software to identify radiants in images, I can say that geometrical projection effects require using a spline or some other complex curve to backtrack the path. As the FOV gets larger, it gets trickier to identify the radiant, especially visually.
That's exactly right. Except for determining RA/Dec coordinates for a few points within the meteor trail, I made no attempt to graphically extrapolate the trail to the expected radiant position (~45°away) using this or any images. Also, I couldn't estimate a radiant position error with a single meteor. However, I did estimate an in-passing proximity error.

I assumed the accepted practice that meteor trails are ideally straight as viewed projected onto the celestial sphere (ignoring in-flight deviation), and I determined the nominal separation between the positions in the trail is ~12.5° (about 60% of the trail length). So over this test length I did not see any measureable curvature wrt the nearby stars which means the position coordinates have negligible inherent error from image distortion within the test-length range (also any in-flight deviation not a concern). I determined reasonable RA/Dec estimates for these few trail locations using stars <3° from the position of interest. Using pairs of points, I calculated the few great circles containing the trail and intersecting the Leonid radiant RA circle. Given a conservatively large point-position error = ±½°, the "best-fit" great circle intersects the Leonid radiant RA circle at Dec = 6°± ~1°. That puts the meteor effectively passing about 16° south of the nominal Leonid radiate at { RA = 10h 5m, Dec = 22°18' }. I base my estimated 1° uncertainty on point location accuracy. Coordinate error due to local image distortion is negligible. Regardless of what little distortion exists within the 12.5°x 3° image region, the 16° proximity error is well dominated by meteor direction.
A pessimist is nothing more than an experienced optimist