DAL sessions in Victoria
gtr at ast.cam.ac.uk
Wed Apr 26 06:50:43 PDT 2006
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.
> 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
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