Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~zoa/docs/zoa_gridzilla.txt Дата изменения: Fri Mar 17 19:26:10 2006 Дата индексирования: Tue Oct 2 05:24:51 2012 Кодировка: Поисковые слова: п п п п п п п п п п п п п п п п п п п п п п п п п п

Data Reduction for Zone of Avoidance (ZOA) survey with ALFA - Gridzilla

P. Henning, Original form July 2005, with 17 March 2006 update

The data reduction is very similar to that done for the AGES survey,
which has nice documentation at www.naic.edu/~ages

To grid the data, you'll use the sdfits files created by LiveData.
Log in as "zoa" (for password, check with Trish, Arun, Emmanuel, Barbara or
Chris). You should find the sdfits files in areas called, eg.

/share/zoa/zoa_a2004/20050710

This would contain the sdfits files for the Taurus project, a2004, for the
scans observed on 10 July 2005. For project a2055, the sdfits are at, eg.:

/share/zoa/zoa_a2055/basketweave_files/20050701

This area holds the sdfits for 1 July 2005 for a2055.

Check the data reduction logs for the locations of the sdfits files:
/share/zoa/zoa_a2055/a2055_reduction_log.txt
/share/zoa/zoa_a2004/a2004_reduction_log.txt
/share/zoa/zoa_a2056/a2056_reduction_log.txt

Set the search path to include the directories of all of the sdfits files
you want to grid.

Before running Gridzilla, create, or check that an area exists, to put
the cubes. Do remember to do this, because Gridzilla doesn't check
for a valid directory to put the cubes when it starts, so if the
area isn't there, Gridzilla will fail at the end, wasting a lot of
time. For instance, for the Taurus, a2004 project, we put them at:

/share/zoa/zoa_a2004/imfit

For the region around l=45, the basketweaving portion of the a2055
project, I put them at:

/share/zoa/zoa_a2055/basketweave_files/imfit

And for a2056, cubes go into

/share/zoa/zoa_a2056/imfit

We've been running Gridzilla on one of the cluster machines aoxcN,
where N = 1 to 4, depending on which is least busy. To start, type
"gridzilla".

Now, consult the webpage for AGES Gridzilla. We set everything the
same as for AGES documentation, except:

1. Set the FITS spectral type to Aips convention, FELO-xxx. AGES now
does this too, but hasn't updated their documentation as of yet. (Also,
the screenshot of gridzilla for ZOA/a2004 data reduction has this
wrong.)

2. Set the frequency range to 1333 - 1433 MHz.

3. We need to specify the centers and extents of our cubes. The reason
for this is that the basketweave observations are done over large areas
of the sky, and if we just made one cube for these regions, they'd be
enormous datasets to handle. So, for project a2055, I have divided the
observed rectangle into four regions:

Region 1: RA 18h 42m 05.25s, Dec 07d00'00"
Region 2: RA 18h 56m 27.75s, Dec 07d00'00"
Region 3: RA 19h 10m 50.25s, Dec 07d00'00"
Region 4: RA 19h 25m 12.75s, Dec 07d00'00"

The extent I've been using is 240 x 240 pixels, where each pixel is
1 arcmin. This maps the full Dec range, and gives some overlap in
RA. For bookkeeping, name the output files for the four different regions
r1842d07, r1856d07, r1910d07, r1925d07.

For project a2004, the area mapped is enormous, so I suggest dividing
it into 8 areas, 4 central RA's, and 2 Dec's:

RA 1: 3h 50m 27.7s
RA 2: 4h 15m 36.0s
RA 3: 4h 40m 44.4s
RA 4: 5h 05m 52.8s

Use these 4 RA's with higher and lower Dec's

higher Dec: 30d 22' 00"
lower Dec: 24s 22' 00"

Use 360 x 360 pixel extent, each pixel 1 arcmin. If these cubes are too
large, we can subdivide further.

When you do different cubes, name the output cubes uniquely, r0350d30,
r0415d30, r0440d30, r0505d30, r0350d24, r0415d24, r0440d24, r0505d24.

For project a2056, we are making cubes of 7 subregions of the whole
observed area, each with center Dec of 21d00'00", with RAs:

RA 1: 4h 56m 36s
RA 2: 5h 13m 42s
RA 3: 5h 30m 54s
RA 4: 5h 48m 00s
RA 5: 6h 05m 06s
RA 6: 6h 22m 18s
RA 7: 6h 39m 24s

We use sizes of 250 x 250 pixels, with each pixel 1 arcmin as for all
the rest.

As for the others, the cubes are uniquely named, for instance r0456d21,
r0513d21, etc.