A Standard Field for Surveys?


This website hosts the responses to the following contribution that appeared in the Oct/Nov 2007 issue of the Standard Star Newsletter:

In the course of an email discussion among the members of the organizing committee of Commission \#45, the idea of a Standard Field for Surveys came up.  Its genesis was the Joint Discussion sponsored by that commission at the General Assembly in Prague on ``Exploiting Large Surveys for Galactic Astronomy''.  The large surveys that were the subject of that JD included SDSS/SEGUE,  Gaia, RAVE, 2MASS, Pan-STARRS, LSST, UKIDSS, JASMINE, etc.  And  surveys continue to proliferate.  While the goals of these surveys are all different, (for instance, SDSS focusses primarily on galaxies and quasars, while SDSS/SEGUE and Gaia concentrate on stars and Galactic
structure), all of these surveys are obtaining data on stars, and all are using those data to characterize stars in some way. Without exception, these surveys are analyzing those data using automated methods which vary from survey to survey.  It occurred to us that it would be very useful for all surveys, as far as it is possible and consistent
with their designs, to observe a certain carefully chosen standard field.  Such standard field observations would be valuable, as theywould allow direct comparisons between the surveys, enabling the detection of systematic differences.  Stars in this standard field could also be observed and analyzed with more traditional methods using ground-based telescopes, thus providing a link between tried and true methods, and the constantly evolving new techniques.  And while those consistency checks would be of great value, of even greater interest would be the science that would derive from observations of this standard field.  The standard field would be the most intensely studied patch of the sky in the history of astronomy, and the stars in that field would be observed in multiple wavelength bands from the X-rays to the far infrared, and we would have precise parallaxes, astrometry and radial velocities for those stars.  Multiple observations of the standard field by each survey would give information on variability and binary frequency.  A carefully chosen standard field would contain a wide variety of stellar types and stellar populations, and thus those observations would yield important and unique information for the fields of stellar astrophysics and evolution and Galactic structure and evolution.   

We are interested in the reactions of the ``standard star community'' to this idea.  If it is generally agreed that this is a good idea, it will then be necessary to decide on the size and the location of the field.  All ideas and reactions are welcome.  Send your thoughts to the editor of the Standard Star Newsletter.

(please send your responses to grayro@appstate.edu)

Responses:

From Ted von Hippel (Nov 27, 2007)

In response to

"We are interested in the reactions of the ``standard star community'' to this
idea. If it is generally agreed that this is a good idea, it will then be
necessary to decide on the size and the location of the field. All ideas and
reactions are welcome. Send your thoughts to the editor of the Standard Star
Newsletter."

I think this is a good idea.  In 20 years, I suspect that much of the
calibration will be higher precision and take less observing time, since we
will calibrate the entire sky.  This is now almost being done by photometric
surveys, and hopefully it won't be long before it can be done by
spectrophotometric surveys.  Until these surveys observe the entire sky,
however, it would be a major step forward to have an agreed-up
calibration region that all surveys should endeavor to do.

My simple suggestions is that this field be
1. equatorial,
2. have b > 10 deg since many types of surveys avoid the Galactic plane,
3. very low reddening, and
4. be modest in size (e.g. 10 sq deg) so as not to increase survey overhead
    substantially, but still be large enough to contain a variety of stellar
    types.

-Ted