FASST meeting 2:30- ~3:45  6/20/2001

Notes from Megan Donahue
FASST website: http://corsair.stsci.edu:6699/fasst
FASST email list: fasst@stsci.edu

Attending: Rick White, Megan Donahue, Niall Gaffney, Mark Dickinson,
Myron Smith, Tim Kimball, Stefano Casertano, Ed Hopkins, Harry Ferguson
[If I've left you out, let me know - Megan]

Discussion of Science Cases
[FASST members: if you would like to be more articulate (or more accurate!) than I have been in my notes do not hesitate to contribute more complete descriptions. These minutes are extracted from my notes and memory. I have generally ascribed some contributions to individuals, but I did not take a full transcript; just a sense of the very interesting discussion. Thank you!]

I would gather multi-wavelength photometry for galaxies - as much as exists, to use to constraing galaxy evolution.

  1. What exists? Given: quality criteria, limiting mags, sky coverage, spatial resolution, overlapping bands.
  2. Uniform catalogs (create source lists of reasonable photometry, filter bandpass, unit conversions)

Starting with a catalog of (say) Veron-Cetty quasars, ask:

  1. Which has observations available in the radio, optical, X-ray?
  2. Define filters and required depths
  3. Ask how many have observations which satisfy criteria
  4. Request and get data

  5.  .... Clustering and colora analysis from images. Useful product: full images and "atlas" (cut-out) images = extracted regions.
Distilled to: find catalog, convert to appropriate formats, extract information, self-determined depths.

Density in stars as a function of galactic latitude  -> K-band counts,catalog, star-galaxy separation, common photometry.

We talked about HST data in particular. Some obvious product enhancements include: summed, stacked images, limiting magnitudes in the observation catalog, more/better image statistics (object counts, sky estimates, etc.) The first question is almost always: What is available? Some difficulty arises in where to go from there - the data are not always friendly.  Documentation, primer material should also accompany data. Data ideally is in a format and a calibration state as close to science-ready (prepared for analysis beyond calibration) as possible.

Another common theme is finding what tools are out there? What is available to overlay and align images and contour plots? What are the catalogs available and what are their characteristics? Which catalogs do I use for photometry/astrometry/morphology? What are the systematics inherent in the catalogs?

Megan noted three themes in the discussion:

There is also a need for the ancillaries to the science data: the documentation, the links to the literature and to the original astronomer(s) (email/homepage/telephone), the  software tools needed to create (a) the derived products and (b) analyze the data in hand. (There also is a need to be able to understand and use statistical analysis tools, cross correlation techniques, probabilities.)

It might not be too crazy to say that nearly all astronomy will use the NVO or something like it, to some extent: science builds upon the past, and can't be conducted very efficiently in isolation from it. So every project from the simplest to the most glorious multi-million dollar projects will use archival data. We can take the two suggested above, but be conscious of the needs general to both.

There are some science problems to be aware of:

FIND the data
GET the data
EXTRACT the catalogs and/or the desired scientific quantities (object number, object properties, sky values, final detection limits)

Next time (June 27):
Review other services: ADASS, ADCCC lists, 2MASS, etc. Seek out useful tools, useful features. Check website.

Next next time (July 4): No meeting.