View Full Version : Earth "grazer" 2008AF3

2008-Jan-15, 09:04 PM
I wanted to get this guy as he passed by at closest approach on the 13th. But it was snowing. Last night about 11 UT it finally cleared enough for me to get it. One problem. Orbital elements I'd gotten earlier in the evening were already wrong. I checked again with the Minor Planet Center and new ones were up. These worked. But it was moving so fast just trying to intercept this guy wasn't easy. I had to work ahead of it and let it come to me. Here's 10 minutes tracked on the asteroid. It's the dot in the center. Image scale is 1.5" per pixel. This guy was moving nearly .6 seconds of arc per second of time. North is up, west to the right in this image. It was in the middle of Bootes when taken. It will be in Serpens Caput by the time it rises late tonight. It was about 435,000 miles away when this was taken, still rather close. It came within about 230,000 miles, a bit under .0025 AU.

14" LX200R, 10 minutes, STL-11000XM, Paramount ME


2008-Jan-15, 11:20 PM
That pic seems technically remarkable to me! Its awesome!


2008-Jan-16, 02:26 AM
Well done Rick!


2008-Jan-16, 05:15 AM
Great work finding this one Rick.

Kind regards

2008-Jan-16, 07:30 AM
I should add that it is thought to be about 19 meters across. If someone told me when I first got into this hobby in the early 50's that technology would come far enough an amateur could photograph a 19 meter asteroid at over 400,000 miles and track it while doing so I'd have thought them nuts. For 50 years before I got into the hobby it had changed little as to technology. Boy has that changed!


2008-Jan-16, 10:47 AM
Nice Work Rick!


2008-Jan-17, 02:40 AM
You should be really proud Rick, It's very amazing of it's size and capture. Nicely done and clear skies.

2008-Jan-18, 10:50 AM
I am impressed.

2008-Jan-18, 10:43 PM
Thanks all.

Finding it wasn't hard once I had good orbital elements but seeing it was. It was predicted at 17.8 magnitude which is easy for a slow moving asteroid in the main belt but not one speeding by at less than a half million miles away. It was on any one pixel for less than a second when tracking at sideral rate so didn't show. It was only after I programmed in the offsets in both axes that it showed up. Centering it turned off the asteroid tracking and turning that back on took time, moving it well off center by the time I could do so. I finally estimated where it would be one minute later, centered that, started the offset tracking rates and started recording. It worked.

Now if we get another one I'll know what to do. Also my brain doesn't function at anywhere near full capacity at 5 a.m. which didn't help. I did forget to turn on PEC so there's some wobble to the star tracks. Fortunately, even without PEC activated the tracking error is not much greater than my seeing.


2008-Jan-30, 05:09 PM
Great picture!

2008-Jun-30, 10:57 PM
It really is.

2008-Jul-01, 04:14 PM


2008-Jul-01, 09:33 PM
wow! Rick.

clear skies