Zeropoint problem found (maybe)

From: Robert A. Knop Jr. (robert.a.knop@vanderbilt.edu)
Date: Mon Apr 05 2004 - 18:34:09 PDT

  • Next message: Saul Perlmutter: "Good news on one of the photo-z's: 076 (aka Zamorano) is an Elliptical at z = 1.61 according to Mobasher!"

    I've only tested one case, in Z-band, but what I found was that my
    aperture correction was ~0.6 magnitudes *too big*. This would tend to
    make our candidates 0.6 magnitudes *too bright*.

    As such, we can "fix" our Z-band magnitudes by *adding* 0.6mag to them.
    I think this brings us nicely in line with what Adam et al. have.

    (The reason we were closer last week was that I was using a bigger-- too
    big for efficiency purposes-- aperture, and with bigger apertures,
    errors in aperture corrections aren't as noticable.)

    I still haven't exactly tracked down this aperture correction error in
    the code, nor have I checked this in I-band, but this is what it looked
    like was happening.

    I apologize for the horrendous screw-up.

    -Rob 

    -- 
--Prof. Robert Knop
  Department of Physics & Astronomy, Vanderbilt University
  robert.a.knop@vanderbilt.edu

    This archive was generated by hypermail 2.1.4 : Mon Apr 05 2004 - 18:34:29 PDT