Extension of the u'g'r'i'z' Standard Star Network

Participants:
J. Allyn Smith
Douglas L Tucker,
Sahar S. Allam


Project Description:
The u'g'r'i'z' filter system was developed to support the specific 
goals of the SDSS and therefore, has limits on the calibrated color
range.  Further, it is limited in magnitude range by the requirement
to use the PT for sky monitoring.  The u'g'r'i'z' filter system is 
currently gaining wide acceptance in the astronomical community and is 
currently in use or planned for several future surveys and individual
research projects.  To this end, we have received numerous requests
from investigators over the past few years for redder and fainter
standard stars.  These could also be of potential use for the
proposed SDSS extension projects (specifically SEGUE).

We are re-analyzing the original USNO standard star data to extract
all the stars in each frame.  The goals are:
1) find an opposite color star in each (non-equatorial) primary field,
2) create secondary standards that are fainter for use with larger 
   telescopes,
3) create standard that are redder than the M0 cutoff of the current
   standard system, and
4) create a variable star catalog for these fields, though most should
   be known at our magnitude limit.

As many of these secondary standards will be unsaturated in the 2.5m,
this project provides a powerful means of more tightly tying the 2.5m
and USNO40 photometric systems together.  In addition, these new 
secondary standards will help create a seamless tie to the southern 
hemisphere standards being created by a separate project.