Introduction to AIPS

31 Pages·2007·0.55 MB·English

by  Walter Alef

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http://www.aoc.nrao.edu/aips/
Some AIPS History I
Design began in 1979 in Charlottesville for the VLA
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Design criteria of the software
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– Transportable (space and time)
– Software needs to be general and flexible
– Interactive
– Efficient with computer resources
– User friendly and powerful
– Multiple interactive users and batch-like usage
– Well documented, uniformity in coding standards
Some AIPS History II
Designed initially on Modcomp computers with
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floating point array processor and special television
display
Next DEC VAX 11/780 with AP and TV
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FORTRAN66 (std. not well defined ! → portability)
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Early AIPS ran on Modcomps, VAXes, UNIX, IBM, Cray
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People involved: Eric Greisen, Bill Cotton, and others
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At present 1 to 2 people support AIPS
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Is now FORTRAN77 + system dependent routines in C
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Some (Bourne) shell scripts and PERL (installation)
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Structure of AIPS I
FITS development influenced AIPS data structures
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– AIPS header binary representation of the FITS
header
– Disk structure:
Header file
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Image or UV-data file
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Extension files (tables, plot files, history)
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AIPS main program: aips
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– User interaction, input from RUN files (text)
– POPS command interpreter
● TASKS (large number of) started by aips
FITS
Flexible Image Transport System
http://en.wikipedia.org/wiki/FITS
http://fits.gsfc.nasa.gov/
Multi-dimensional arrays: 1D spectra, 2D
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images, 3D+ data cubes
Tables containing rows and columns of
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information
Header keywords provide descriptive
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information about the data (human readable)
(80 character fixed-length strings)
AIPS structure II
Communication via the aips program
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– Language is POPS
– Interactive or via text file
Define values of ADVERBS
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– Adverbs are in common to all tasks !
Use VERBS (built into aips)
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Execute TASKS asynchronously/synchronously
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– Task parameters (adverbs) defined in “Help file”
– Note: tasks can be created or modified without modification
of aips
W
ER C GRE EN
4 S
I . I
AIPS
SymbolTable
AdverbValues
AIPSC
User
``Checker''
Terminal
POPSLanguage
FullPOPSLanguage
Interpret/compile
Verylittleapplications
Disk Causeexecution
text
Files
ApplicationVerbRoutines
disk
TVandTEK SAVE
... ... SUBMIT
GO disk
Verbs
GET
AIPSB
SymbolTable
disk
AdverbValues
TV,Graphics
Devices
Data
tapes disk
Imagecatalog POPSLanguage
Disks
Interpret/compile
Causeexecution
Poolofseparate``task'' programs
ApplicationVerbRoutines
. . . .
FITLD CALIB IMAGR FITAB
SAVE
... ...
GO xxxxxx xxxxx
GET

Fi gure 1. Block diagr am of AIPS from a user point of view. Various communications
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paths are sho n a ong the ain interactive progra , AIPS, the batch progra AIPSB,
and the collection of separate tasks.
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characters ay be found in reisen (2000). t its peak, develop ent and
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support of I S reached about 7 full-ti e e ployees for a short period;
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3{4 as ore typical, and the current nu ber is bet een 1 and 2 for the
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co bination of develop ent and user support.
A P
2. Structure of I S
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AIPS was begun at about the same time as FITS was designed see
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reisen (2002) in this volu e and as the rst syste profoundly af-
fected by FITS concepts. The internal header format of AIPS is a binary
representation of a FITS header and the disk structure consists of a header
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le, an i age or uv-data le, and \extension" les hich are ostly tables,
plot les, and history les. It is now written in ANSI-standard Fortran
W
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77 ith so e syste -dependent and - indo s routines ritten in SI-
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C C w
standard . ertain syste functions are perfor ed by scripts (no ostly
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ourne-shell I scripts) and recently so e have been recoded and ex-
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tended using erl, particularly the installation script.