DAL sessions in Victoria

[Guy Rixon]

On Wed, 26 Apr 2006, Rob Seaman wrote:

> ...
> The complications for temporal searching are several.  First, you
> need to be able to search in a barycentric (or arbitrary) time
> system.  Second, you need to be able to search through some sort of
> evenly gridded comb filter in cadence - something like "return all
> images/spectra whose mid-exposure occurred near an even quarter-
> hour".  Third, you have to be able to specify "near" - "within a
> window of plus or minus one minute".  Fourth, you may need to be
> sensitive to some very creative observing modes and data structures.
> SONG also experimented with a multiple ramped exposure mode for
> acquiring a time sequence of spectra in a single exposure.  Makes me
> wonder further about searching for off-band data from dual exposure
> nod-and-shuffle observations from instruments such as MARS on Kitt
> Peak.  The second field is shifted both spatially and temporally
> (interleaved as with any chopping or beam switching mode).

Thinks me, that sort of think needs a full query language on the scale of
ADQL, not a little language like those inherent in the S**Ps. It's not the
sort of thing that you're going to express in an HTTP-get URI.

Unless...

> ISO 8601 provides (as a central design feature) a simple way to
> specify cadences on a wide range of timescales, i.e., so many seconds
> or tens of seconds, minutes, hours, days, (even weeks, I believe),
> months, years, centuries, etc.

Does this imply that a single ISO8601 argument can handle the selection for
your use-case above?

Guy Rixon 				        gtr at ast.cam.ac.uk
Institute of Astronomy   	                Tel: +44-1223-337542
Madingley Road, Cambridge, UK, CB3 0HA		Fax: +44-1223-337523