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Posted by: moozoo Jul 29 2011, 02:25 AM

I'm no expert on this, so please ignore this if its not relevant. I had this idea and then went hunting for it on the internet and found this (which is pretty close to what I had in mind)

Would this be relevant for KBO detection?

http://iopscience.iop.org/1538-3881/130/4/1951
"This includes extending detection ranges to fainter magnitudes at the noise limit of the imagery and operating in dense cluttered star fields as encountered at low Galactic latitudes."

The basic idea as I understand it is to stack (add) images in all possible combinations based on expected movement of the targets and then look for them as round blobs. i.e. imagine if you already knew where and how the KBO was moving, you could then get the telescope to track it and do a long exposure of just the KBO (enhance its SNR?). Stars, which would be streaks would not add. I'm guessing they could also be suppressed by subtraction. i.e. move and stack 1-0,2-1,3-2,4-3 etc
I'd imagine you would need a lot of short exposures adding up to the same result as a long exposure but filtered on the expected movement of the target.

The paper mentions this is computationally intense, but they where talking about using a 2 Ghz Pentium 4. I'd imagine something a bit more powerful (GPGPU based?) could be throw at the problem today.

Posted by: NGC3314 Jul 29 2011, 07:09 PM

...snip...



I think this is essentially the approach taken by http://adsabs.harvard.edu/abs/1995ApJ...455..342C in an early Hubble search for smallish TNOs (although the details of statistics have proven controversial as to what exactly they detected). For computational and field-of-veiw reasons, they had to take fairly restricted orbital parameters to search, which might be relaxable now. I've wondered whether one could do something similar to search for Vulcanoids in SOHO data, since stability considerations restrict the ranges of semimajor axis, inclination , and eccentricity one would need to search.

Posted by: moozoo Aug 1 2011, 10:38 PM

Thank you, a very interesting paper. I found a detailed response to it http://iopscience.iop.org/1538-4357/490/1/L119/975466.text.html.

It seems to me that a simple test would have been to randomly re-order their 34 images, fully process it and then compare the results. Perhaps repeating that several times in order to check that the in-order images had different properties.

I was thinking of some thing more like video astronomy where there would be something like 340 images or even 3400 images taken over the same time period with a corresponding shorter exposure. The logic being that this might decrease the chances of noise randomly adding up to something (moving).
Anyway its great that this method is know about and has been tried before in some form.

Posted by: john_s Aug 2 2011, 04:21 PM

Yes, we'll be doing similar tricks with our automated object search (which we're running in parallel with the KBO Zoo search- we don't know yet which will be most effective). Our job for New Horizons is a bit simpler in that we know the rate of motion of the objects we're interested in- they have to be going at a particular speed and direction or New Horizons can't reach them! So we don't need to try a large number of rates to just find the accessible guys.

John