ASN_TAB
Name of the association table produced as part of the science dataset.
This table provides the information regarding the observation and how
exposures and products were associated. The MEM_TYPE column in this
table corresponds to the ASN_MTYPE keyword discussed below.
ASN_STAT
Complete/Incomplete- Indicates whether or not the association had orphan exposures. This affects whether the observation log files are archived individually or in one multi-extension FITS file. The observation log files
will normally only be combined if the ASN_STAT indicates COMPLETE.
ASN_PROD
T/F- Was the observation an association?
PRODNAMn
Rootnames of each association product. Within an association there can be
multiple products. There exists only one association product for STIS, but NICMOS may have one association product for the target and up to 8 background products. Only one observation log file is created for the target and
any background associations. The multiple extensions in the observation log files will contain pointing data for the background product and the target products. The order of the exposures (extensions) in the observation log file will follow the order given in the rootname_asn.fits table, which is one of the calibrated science products, and whose name
is given in the ASN_TAB keyword.
ASN_MTYP
Role of the particular exposure in the association.
An example at this point will probably be immensely useful. The idea of
all this discussion of course is to relate a given observation log's extention to the correct exposure. Below is an observation's asn table, showing a spiral dither chop, n48o06020_asn.fits.
cl> tedit n48O06020_asn.fits
Label ___MEMNAME____ ___MEMTYPE____ MEMPRSNT
1 N48O06G9Q EXP-TARG yes
2 N48O06GAQ EXP-TARG yes
3 N48O06GBQ EXP-BCK1 yes
4 N48O06GCQ EXP-BCK1 yes
5 N48O06GDQ EXP-TARG yes
6 N48O06GEQ EXP-TARG yes
7 N48O06GGQ EXP-BCK1 yes
8 N48O06GHQ EXP-BCK1 yes
9 N48O06GIQ EXP-TARG yes
10 N48O06GJQ EXP-TARG yes
11 N48O06GKQ EXP-BCK1 yes
12 N48O06GLQ EXP-BCK1 yes
13 N48O06G20 PROD-TARG yes
14 N48O06G21 PROD-BCK1 yes
The ASN table tells us the association contains 12 exposures, 6 on target and 6 on sky, grouped into 2 association products (N48O06G20, target and N48O06G21, background), and the rootnames and role of each exposure in the association.
Now looking at our n48O06020_jif.fits image:
cl> catfits n48O06020_JIF.fits
0 n48o06020_jif N48O06020_JIF.FITS 32
1 IMAGE jit 1 64x64 32
2 IMAGE jit 2 64x64 32
3 IMAGE jit 3 64x64 32
4 IMAGE jit 4 64x64 32
5 IMAGE jit 5 64x64 32
6 IMAGE jit 6 64x64 32
7 IMAGE jit 7 64x64 32
8 IMAGE jit 8 64x64 32
9 IMAGE jit 9 64x64 32
10 IMAGE jit 10 64x64 32
11 IMAGE jit 11 64x64 32
12 IMAGE jit 12 64x64 32
...we see that the jitter file has 12 extensions (plus the zeroeth group only
containing header parameters). These 12 extensions correspond to the 6 exposures
for both the target and background association products. Looking at the association
keywords in the header, we see...
ASN_ID = 'N48O06020' /unique identifier assigned to association
ASN_TAB = 'n48o06020_asn.fits' /name of the association table
ASN_STAT= 'COMPLETE' /status of association (COMPLETE/INCOMPLETE)
ASN_PROD= T /product created (T/F)
PRODNAM0= 'N48O06020' /rootname of the zeroth association product
PRODNAM1= 'N48O06021' /rootname of first association product
PRODNAM2= ' ' /rootname of second association product
PRODNAM3= ' ' /rootname of third association product
PRODNAM4= ' ' /rootname of fourth association product
PRODNAM5= ' ' /rootname of fifth association product
PRODNAM6= ' ' /rootname of sixth association product
PRODNAM7= ' ' /rootname of seventh association product
PRODNAM8= ' ' /rootname of eighth association product
PRODNAM9= ' ' /rootname of ninth association product
This block tells us that the jif and jit files have extensions with data covering
these association products, and that they correspond to the listing of exposures
in the table whose name is given in the ANS_TAB keyword, in this case n48o06020_asn.fits.
Looking at the ASN_MTYP and EXPNAME keywords for each extension of the n48o06020_jif.fits file,
we see...
n48o06020_jif.fits[1], ASN_MTYP = EXP-TARG EXPNAME = N48O06G9J
n48o06020_jif.fits[2], ASN_MTYP = EXP-TARG EXPNAME = N48O06GAJ
n48o06020_jif.fits[3], ASN_MTYP = EXP-BCK1 EXPNAME = N48O06GBJ
n48o06020_jif.fits[4], ASN_MTYP = EXP-BCK1 EXPNAME = N48O06GCJ
n48o06020_jif.fits[5], ASN_MTYP = EXP-TARG EXPNAME = N48O06GDJ
n48o06020_jif.fits[6], ASN_MTYP = EXP-TARG EXPNAME = N48O06GEJ
n48o06020_jif.fits[7], ASN_MTYP = EXP-BCK1 EXPNAME = N48O06GGJ
n48o06020_jif.fits[8], ASN_MTYP = EXP-BCK1 EXPNAME = N48O06GHJ
n48o06020_jif.fits[9], ASN_MTYP = EXP-TARG EXPNAME = N48O06GIJ
n48o06020_jif.fits[10],ASN_MTYP = EXP-TARG EXPNAME = N48O06GJJ
n48o06020_jif.fits[11],ASN_MTYP = EXP-BCK1 EXPNAME = N48O06GKJ
n48o06020_jif.fits[12],ASN_MTYP = EXP-BCK1 EXPNAME = N48O06GLJ
This information will reflect what is seen in the _asn table, and gives positive
identification of each extension in the jitter file, relating it to the individual exposures, in associations or otherwise.
