Re: Zeropoint problem found (maybe)

From: Vitaliy Fadeyev (VAFadeyev@lbl.gov)
Date: Mon Apr 05 2004 - 18:55:59 PDT

  • Next message: Greg Aldering: "Re: Zeropoint problem found (maybe)"

    Rob,

    according to Greg, it looks like the zeropoints in the Z-band news
    are all constant, and defined to be around 32.32, with a note
    that they are from the header.

    For candidate 76 field, I get the zeropoint (translated from GOODs
    AB zeropoint with -0.56 correction to the Vega, and relative aperture
    photometry) of 32.39 +- 0.10.

    vitaliy

    "Robert A. Knop Jr." wrote:

    > 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 - 18:56:19 PDT