Results from 2006 Jun 06

D2 plots      D3 plots      D2+D3 plots side by side      Colour coeff slopes (text)

Description

Date Sent:  	Tuesday, June 06, 2006 10:45 AM
From: 	        neill@uvic.ca 		
Subject: 	RE: SDSS 'dr5' color terms and zeropoints

    Here are the results from the latest D2 and D3 catalogs, provided by Mark.
    
    These are from our culled tertiary standards (i.e. our psf standards)
    and are compared against the pre-release sdss 'dr5' catalogs from the D2
    and D3 regions that we got from David Schlegel.
    
    As we suspected, the slope differences in g' do not go away.  There was
    some movement in the slopes, but nothing major.  Mark gave me
    zeropointed magnitudes, so the plots now have their y-axis ranges near
    zero and the slopes will appear inverted compared with previous plots I
    have sent.
    
    I'll send these results to David Schlegel later today.  If you have any
    comments, please let me know.
    
    -Don

Older version - from 2006 May 29

D2 plots         D3 plots

Description


       Subject:         RE: SDSS 'dr5' color terms and zeropoints
       Date:            Mon, 29 May 2006 14:58:58 -0700
       From:            Don Neill 


OK, here is an update, mostly minor.  I've included error estimates on
the slopes provided by a linear least-squares fit of the binned data.
The bins are indicated by the red filled circles (color-cut) and the
green (full set).  The error bars are the rms scatter in the bin.  If I
use the error in the mean of the bin, then I no longer get probable
linear fits, even though the errors go way down.

I've also included a plot of the coverage, since we were curious.  The
circles are definitely big enough, but there are gaps in D2.

In comparing the D2 and D3 slopes, you can see a batch of blue outliers
in the D3 points that are forcing slightly steeper slopes than D2, which
does not show those outliers.  A conservative approach would be to say
that the error on the slopes is the difference between the D2 and D3
values.  A bolder approach is to say that the D2 values are probably
more correct.  Check out the plots and see what you think.

The numbers and plots are attached.

Enjoy,

-Don