Re: Data sets over time

[Chris Albertson <chrisalbertson90278@yahoo.com>]

Tom,

I assume all your data is in a "database".  The database would
have pointers the FITS file each point came from and the
parameters of that FITS file.  Getting a list of the files that 
"saw" a given point of the sky can be done with a single SQL
statement  The SQL querry would ask for the set of images that
intersect the study region in both space and time.  

The current database only provides point and
click access to remote users and no button for ths kind of
querry but someone
with ability to type in direct SQL could extract the information
you need in a minute or so.  With more effort a new button could
placed in the interface.

Of course all the database will
be able to tell you is the filesnames ofthe FITS images.  I assume
you have some way to physically locate the associated CD.

The next question is why would you want FITS image data of the sky
when you can have the reduced photometry?  Are you working on an
improved reduction pipeline?

For those who don't know what is SQL and what it can do, here is the
60 second summary:

SQL was invented by mathematicians, not by computer programmers.
SQL does NOT say HOW to perform an operation, it only specifies
the result.  Basically you define a set and some constraints on
that set that will pproducethe desired subset. 
An example SQL statment transliterates like this:
  "Give me the subset of  ( a, d, f(y))
   such that a > d and f(y) < g(a,b)
SQL is worth learning.  The above is MUCH easier then writting
a program to compute the result with loops and if statments.


--- tom <tdroege2@earthlink.net> wrote:

> Robert,
> 
> One more thing.  It is one of my projects to make just such data
> sets.  I will 
> need some software, possibly trivial for you but not so for me.  The
> software 
> needed would read disks full of images and look at the fits headers. 
> Then it 
> would load the fits images in such a way that one could select the
> type of 
> data set you desire. 
> 
> It is always a big project to go through even one camera.  However,
> if it were 
> all set up I could just load disks when prompted and could get
> through my 
> stash in a couple of weeks.  
> 
> The three telescope systems cover different areas of the sky.  TOM1
> covers -6 
> to +18, TOM2 +18 to +50, TOM3 +50 to +90.  I could set up enough
> storage on 
> one computer and load the disks from one camera, about 700 or so.  
> 
> TOM1 does overlap ASAS, don't know where OGLE is pointing.
> 
> Tom 
> 
> On Wednesday 15 September 2004 07:28 am, you wrote:
> > Tom,
> >
> > How difficult would it be for you to put together one
> > or a few CDs (more than a few CDs I could not handle
> > currently) of a specific region of sky on an extended
> > time basis?  I.e. months (years?) of observations of
> > just a single (or a few) frames with approx. the same
> > position?
> >
> > Also, for general analysis purposes it might be
> > interesting to be able to construct such a
> > time referenced data set with several points
> > of view.  I can think of perhaps 6 though I'm
> > not sure you can capture them all.
> > a) Directly towards the galactic center;
> > b) Directly away from the galactic center;
> > c) Directly forward of the sun's orbit around
> >    the galactic center;
> > d) Directly aft of the sun's orbit around the
> >    galactic center;
> > e) A view above the galactic bulge;
> > f) A view below the galactic bulge.
> >
> > In particular, (e/f) may overlap with the OGLE III
> > observations (though it is taking pictures from Chile
> > and it isn't clear to me how much overlap may be available).
> >
> > This might feedback into the question as to whether
> > the pipeline analysis needs to be adjusted by general
> > background (star density, dust density, etc.).
> >
> > Thanks,
> > Robert
> 
> 


=====
Chris Albertson
  Home:   310-376-1029  chrisalbertson90278@yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson@aero.org
  KG6OMK


		
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