Rick,

great effort to image such a small and fast object.

Stefan


"Rick Johnson" schrieb im Newsbeitrag
...

2014 KH39 is a 22 meter in diameter asteroid that passed by a bit
further from the moon on June 3, 2014. I learned of it the morning
before its passage. I'd just taken my system down for its annual spring
cleaning. I pull the scope and clean all optics in it and the CCD
camera. The gears for the drive gears is removed and replaced with
fresh as this is recommended by Software Bisque for their Paramount ME.
I also recharge the desiccant in the camera. Then everything is put
back together and the scope remounted. This invariably messes up
pointing enough that a new Tpoint map needs to be made for accurate
tracking without guiding. This takes several hours. I didn't have time
and catch the asteroid. So I'd pretty well given up catching it and the
day was cloudy anyway. In fact it rained when we reinstalled the scope.
That's hard to do with the roof closed but we managed it.

Suddenly it cleared but the scope was likely pointing too poorly to find
it. The moon was out so I told it to find the moon and was astounded
that it put the moon's center right in the center of the CCD. Somehow
we put it back almost exactly as it was before. I'd never come close to
doing that. I tried other areas of the the sky. it was off some in the
area of where the asteroid would be when I first could catch it but
close enough to put it on the chip. But I track without guiding. That
pointing error was enough to make that task unlikely to succeed. Also
clouds were returning.

About 1 a.m. they cleared and I tried for the asteroid. It was moving
at 2" of arc per 1 second of time. Being further away than the moon and
only 22 yards across (best estimate) it would be dim. I took a 10
second image hoping to see a 20" trail but nothing. A plate solve told
me where it was to be and I centered on that position and tried again.
Nothing. I recentered it as it was moving fast but this time activated
tracking on the asteroid's "offset". This takes into account the
asteroids motion. Now the stars would be 20 second streaks and the
asteroid a point -- if my Tpoint map was good enough. It was. The
asteroid was right where it was predicted to be and a rather good point
of light.

I made a series of 40 one minute frames. The clouds had returned so on
some frames I got nothing but blank sky. Others had a dim image of the
asteroid. Also, since the Tpoint map wasn't accurate or the computed
offset rates incorrect it was drifting west against the stars. That
meant it was tracking on the RA axis a bit fast. I don't know the
source of the error. The drift didn't hurt the animation however. The
variable clouds sure did. For this animation I picked the best series
of 20 frames. This avoided all totally clouded out frames but on a
couple the asteroid fades to near invisibility.

On the third frame a piece of orbiting junk photo bombs my image. I
didn't clone it out. About midway through a fuzzy streak passes by to
the left of the asteroid. It is the galaxy CGCG 221-016 which is
estimated to be 230 million light-years distant. The asteroid was 4
light seconds away. If I did the math right that puts the galaxy 3
quadrillion times further from us than the asteroid. I measure the
galaxy to be about 57,000 light-years across. Again, if my math is
right the galaxy is 24,500,000,000,000,000,000 times larger. I think
that's 24.5 quintillion in the American system.

By the way while this asteroid is thought to be 22 meters across the
Chelyabinsk, Russia meteor was thought to be about 20 meters across so
it is only slightly larger than that window busting rock.

The frames were taken binned 3x3. Windows Movie Maker has slightly
resized it but the scale is still very close to 1.5" per pixel. Lousy
seeing from an incoming cold front didn't help the image quality.

14" LX200R @ f/10, L=20x1', STL-11000XM, Paramount ME

http://www.prairieastronomyclub.org/...s/2014KH39.wmv

Besides the movie link above I've attached a single frame from the
movie. It was one of the best and least bothered by seeing. It is at
exactly 1.5" per pixel.

Rick
--
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