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Re: TASS - PSFs
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- Subject: Re: TASS - PSFs
- From: Michael Gutzwiller <firstname.lastname@example.org>
- Date: Wed, 27 Aug 1997 20:12:53 -0400
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> I have been focusing and adjusting the VCO. The best I can do is:
> Camera PSF
> V (Camera O) 3X9
> R (Camera 1) 5x7
> I (Camera 2) 7x7
> The PSF seems to stretch out much more than can be explained by the
> VCO setting. I can get numbers like 3x5 for V with the optimum VCO
> setting for V, but then the R and I numbers get much worse. I assume
> that the minimum area for all three is what I want to work for?? What
> say Mike?
Minimal area is correct. The smaller the area of the PSF the better the
separation from other stars and the better the statistics.
> The PSF above is what comes out of Star in the star list.
> How do these numbers compare with what the rest of you are seeing?
They arre comparable. I have had great difficulty getting the I
filtered PSFs to be smaller than 7x7 though I usually can get V to 5x5
at the same time. I don't seem to be seeing as much disparity in focal
length between the two as you are getting.
> It seems to me that I could attempt to improve the focal length for V by
> adding some glass. This would add two surfaces with the resultant light
> loss. It would also require a lot of fussing. I figure it is not worth
> BTW, now that I have three cameras all looking at the same spot, I can
> compare stars found. It is roughly what I would expect. The I camera
> finds more stars. The I filter has roughly twice the bandwidth of the
> V and R. But it also sees more background light. This is a tough game.
> With the sky background limit, twice the light only gets you Sqrt(2)
> more S/N. This holds true for larger diameter lenses. S/N goes up
> with the diameter, so it is just not worth the effort to go to more
> expensive lenses.
> Tom Droege