Re: Neo Search and satellite imaging

From: Greg Roberts via Seesat-l <>
Date: Tue, 04 Nov 2014 15:32:47 +0200
I am no expert in NEO and the only time I have seen them is when a real 
close fly-by is announced and I might then stir myself and have a look. 
I do not think the orbits are near circular - I suspect they can go up 
to very large eccentricities , the only requirement is that somewhere 
along the way their orbit comes close to the earth at some stage. If you 
are really interested then I guess there should be plenty of information 
on the internet.

Obviously a near earth object can pass pretty close to the earth - in 
fact even pass between the geostationary belt and the earth so it should 
be possible to detect such by accident ( although probably already known 
to the NEO hunters). As far as I know I have never seen one by  accident.

Generally the exposures I use are too short to show asteroids and neo's 
- usually only a few seconds and at most a minute (rarely). I also have 
never  knowingly seen an asteroid by accident but then I do not look for 
them. As Ian explained APEX provides a list of unidentified objects - I 
basically ignore it. Asteroids move very slowly and generally one needs 
to take two exposures separated by (say) 20 minutes at least and then 
"blink" them to detect their motion. NEO's can move much faster and I 
guess could be confused with a moving high altitude satellite but I have 
not knowingly seen one.

Normally my exposures are too short to deduce an accurate light curve 
for a near geostationary object.

I measure all tracks that I can identify by doing a reasonably quick 
scan of the image visually and then match up with satellites were 
possible. If no match then report it as an unknown - provided that I got 
at least two images. One image is not reliable enough because the 
satellite may be variable, obstructed by a star trail etc etc.

I am sure someone will correct me if anything Ive said above is 
incorrect or incomplete.


On 2014-11-04 02:56 PM, Björn Gimle wrote:
> Excuse my ignorance about NEOs, but I wonder:
> Are NEOs only near-circular, near-ecliptic (near-equatorial!!) and 
> posigrade (ie usually slow)?
> And are other asteroids of no interest in these images ?
> Are exposure times so long that most satellites show light curves 
> "impossible" for NEOs ?
> If not, how can you rule out a track as being a satellite (not a fast 
> passer at lunar distance etc.) without measuring it ?
> If you do measure them without analysing, why not post them (with a 
> suitable fixed heading) to SeeSat-L for amateur analysis ?
> /Björn
> 2014-11-04 11:13 GMT+01:00 Greg Roberts via Seesat-l 
> < <>>:
>     Actually Marco APEX is also used for minor planet processing - I
>     think Ian Roberts has done this
>     It is one aspect of APEX that I have not investigated since I am
>     not particularly interested in
>     asteroids etc.....
>     ...
>     I was thinking along the line that you have the images loaded in
>     Astrometrica (astrometric software for asteroids) any way to
>     measure the asteroids. In principle, if you already loaded the
>     image in Astrometrica measuring the trail then is a matter of
>     clicking one end, clicking the other end, and you are done. I do
>     have self-written software to convert measurements in MPC format
>     to IOD format.
> -- 
> ----------------------------------------
> Björn Gimle, COSPAR 5919
> 59.2617 N, 18.6169 E, 51 m
> Phone: +46 (0)8 571 43 312
> Mobile: +46 (0) 704 385 486

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