2008-10-22

rule of thumb

Phil Marshall emailed me, asking about the original citation / derivation of the rule of thumb that a source detected in an image at some signal-to-noise ratio [s/n] can be centroided to an accuracy of about the FWHM divided by [s/n]. It was funny he asked, because we had discussed the very same issue only days earlier in responding to the referee for the faint-motion paper. Rix found King (1983), which probably is the first paper to discuss this (interested if anyone out there knows a more recent reference). Nowadays, the standard answer is the Cramer-Rao bound (Robert Lupton said this in response to a query from me), but that isn't quite the answer most people are looking for.

Posted by at
Labels: , , ,

1 comment:

  1. Anonymous28 October, 2008 18:35

    Here are some other/earlier references that I think are relevant. First here is very comprehensive reference for generic elliptical gaussians (Condon 1997, see Eq. 21):

    http://adsabs.harvard.edu/abs/1997PASP..109..166C

    And a much earlier comprehensive treatment of 1D gaussians (Kaper 1966, see Eq. 5.8):

    http://adsabs.harvard.edu/abs/1966BAN....18..465K

    Both of the above show the derivations that yield an error in the centroid of ~ FWHM/SNR.

    ReplyDelete

Subscribe to: Post Comments (Atom)