[Kstars-devel] AuxData and QStrings in unnamed star objects

[James Bowlin]

On Fri June 5 2009, you wrote:
> For dynamically loaded stars, this is fairly easy. They all live on a
> Triangular Mesh of depth 8. So first, we can identify the "trixel" by
> a number (< 4 * 4^8, or something like that). Once the trixel is
> identified, the stars in the data file are placed in order in each
> trixel. Just having their "line number" within each trixel appended
> to the trixel number should produce a UID.

Unfortunately this won't work due to star duplication that was used to
solve the proper motion problem.  The same star can end up in more than
one trixel yet we want those same stars to use the same AuxInfo.  We 
need a UID that is associated with the star itself, not its location in 
our data file.

I suggest using an existing index such as the Henry Draper (HD) index.
If we have stars that are not in the index then we could use our own
made-up negative numbers for those stars (for example) in that same 
field.  The benefit of this scheme is that the one data field would 
serve two purposes. It would be used to index the AuxInfo hash and it 
would also provide the HD index (for stars that have it).

The downside of this scheme is that it would increase the size of the
star data file and thus slightly increase the time it takes to load
stars.  The only other thing I can think of is to hash on the J2000
RA and Dec of each star (assuming no two stars have the same RA and
Dec within the precision we currently store them in).

H'mm.  I wonder if we could squeeze one more field in without increasing
the size of the file by relaxing the restriction that each data field be
byte-aligned although this would certainly increase the complexity of 
reading in the star data.


-- 
Peace, James