Re: Tale of a Tile

["Tom Droege" <droege@snapmail.us>]

It would appear that always measuring a star in the same position in the
frame will reduce the scatter by a factor of 5.  I will leave it to the
experts as to whether this improves the accuract but I think not.

If I run with fixed sky tiles, then we will want to keep the tiles
separate forever.  This means that a star measured on one edge of a tile
will have to always be considered a different star from when it is
measured on the other edge of a tile. Well, it's the same star, but users
of the data will be urged to only look at the data from one tile at a
time.

This means that we don't want to have to look in the .fits header to sort
out all the images from a tile.  Well, I don't think we do.

This also means that we will want to put ra,dec into the .cal file names. 
My plan is to have .cal files associated with a tile in the sky.  Else we
lose the scatter improvement for the stars that appear in two tiles.

I plan to run the pipeline on data from only one tile at a time.

OK, folks, it is ugly but it looks nicer.  I expect a grand uproar.  But
we will only find the best scheme if we discuss it.  The critics of the
data do not like to see the "real" scatter.  They like much better to have
the real scatter hidden.  I agree.  For the purpose of studying variable
stars, the fixed position in a tile is better, and no worse in accuracy. 
So why not measure that way?

Tom Droege

Tom Droege

>
> Hi Tom,
>
> I have mixed emotions about changing the filenaming convention.
> On balance, however, it is true that more people will search for
> frames by sky position than by any other value. So, I support this
> change. On thing I would request is leading zeroes so that filenames
> can be parsed by string position.
>
> Cheers,
> Doug
>
> On Mon, 2005-04-04 at 18:17, Tom Droege wrote:
>> As you all know, I have been planning on taking fixed tiles from now on.
>> In order to ease moving sorce data around, I am thinking of adding ra
>> and
>> dec the file name as:
>>
>> hir_23456789_112_+16.fits
>>
>> This puts the date/time taken as well as the ra and dec of the tile in
>> the
>> name.
>>
>> Any comments or better suggestions?
>>
>> You all sure have been quiet.  This should stir you up.
>>
>> Tom Droege
>
>
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