Maybe I have missed the point of Jeff's recent e-mail on DM Use Cases, but my "vision thing" for the astrometric columns in the LSST database is that all columns are filled for all stars as part of the Observatory processing. That is to say, we will solve for (position, proper motion, parallax, and astrometric wiggles) for all stars, and put the results (significant or not) into the DB. So I don't expect queries like "compute the parallax for all stars with g-r colors in the range of -0.5 to 2.0".
But then again, I am not sure (i.e., I haven't read the document) on how or where such processing will take place. The part of the pipeline that keeps up with the camera isn't the place to do this. Presumably that pipeline has a calibration model and produces the stream of detections. Some other task will have the responsibility of cycling through the entire DB and doing processing on the ensemble of measurements for all objects. The astrometric task seems similar to the photometric task of detecting variability and trying to characterize it in terms of known objects (eg. is this a Cepheid? an RR Lyr?, etc.) It would seem that a crawler (or whatever the correct word may be) that goes through the DB in an optimized manner would be far more efficient that having this done at the user query level since we know that obnoxious users (i.e., me) will make such a request. -Dave _______________________________________________ LSST-data mailing list [email protected] http://www.lsstmail.org/mailman/listinfo/lsst-data
