AIPS tut 1
•
The approach: to dip into and out of AIPS
several times, each time doing something
more complicated.
1. Starting AIPS and exiting.
2. Loading a FITS image and displaying it.
3. Calibration of a continuum observation (an
observation of a gravitationally lensed quasar by the
MERLIN array in the UK) via a runfile.
4. Some CLEANing.
•
See chapter 3 of the AIPS Cookbook:
–
•
ftp://ftp.aoc.nrao.edu/pub/software/aips/TEXT/PUBL
/COOK3.PS.gz
There are links to both the cookbook and the
AIPS home page off my web site.
NASSP Masters 5003F - Computational Astronomy - 2009
•
AIPS tut 1
Before you start AIPS, there are a few
things you will need to do.
1. Decide where you want to keep your FITS files.
Maybe make a special directory for them.
2. Do export MYAREA=<name of this directory>.
3. Decide where to keep ‘runfiles’ (AIPS scripts).
4. Do export RUNFIL=<name of this directory>.
5. Obtain a user ID from the AIPS administrator
(me). You will be given a decimal integer and
an extended hexadecimal (ehex) version of this
integer.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
– Change the names of your runfiles so they
end in .<your ehex ID>. Eg if your user ID
number is 10, the ehex version of this is
00A. Hence you should rename a runfile
MERLIN.XXX to MERLIN.00A.
•
You are now ready to start aips. In the
following steps I’ll show what you should
type in greenish, leftish boxes, and what
you see in response in pinkish, rightish
boxes. A ® character means the ‘enter’
key. Any text between <> means that
what you type there depends on
circumstances.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• At your normal Unix command line, type
aips notv®
• You will see something like:
You have a choice of 5 printers.
These are:
No. [ type ] Description
------------------------------------------------------------1. [
PS] n
2. [
PS] Spare
3. [
PS] Main
4. [
PS] n
5. [
PS] n
------------------------------------------------------------START_AIPS: Enter your choice, or the word QUIT [default is 3]:
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• Just choose the default (ie hit enter).
®
START_AIPS: Your initial AIPS printer is the Main
START_AIPS: - system name <some printer>, AIPS type PS
START_AIPS: User data area assignments:
(Using global default file <some file> for DADEVS.PL)
Disk 1 (1) is /home/aips/AIPS/DATA/LOCALHOST_1
Tape assignments:
Tape 1 is REMOTE
Tape 2 is REMOTE
START_AIPS: Starting TPMON daemons on LOCALHOST asynchronously...
Starting up 31DEC09 AIPS with normal priority
Begin the one true AIPS number 1 (release of 31DEC09) at priority = 0
AIPS 1: You are NOT assigned a TV device or server
AIPS 1: You are NOT assigned a graphics device or server
AIPS 1: Enter user ID number
?
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
<your ID integer>®
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
>
1:
1:
1:
1:
1:
1:
1:
1:
1:
31DEC09 AIPS:
Copyright (C) 1995-2009 Associated Universities, Inc.
AIPS comes with ABSOLUTELY NO WARRANTY;
for details, type HELP GNUGPL
This is free software, and you are welcome to redistribute it
under certain conditions; type EXPLAIN GNUGPL for details.
Previous session command-line history recovered.
TAB-key completions enabled, type HELP READLINE for details.
Recovered POPS environment from last exit
• At this point you have landed on the planet of
AIPS. You are within the AIPS private file system.
AIPS runs a shell called POPS which is similar in
many ways to Unix. Before we do anything
interesting, let’s get back to Unix, just to prove that
it’s possible to enter AIPS and live to tell the tale.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
kleenex®
AIPS 1: Begin check for any 'standard' scratch files
AIPS 1: Scratch files -- destroyed:
0 still active:
0
AIPS 1: User
2:
4 messages, oldest written 22-APR-2009 19:02:40
AIPS 1: Deleted
0 messages
AIPS 1: Saved POPS environment in area named 'LASTEXIT'
► ►
AIPS 1: Session command-line history saved.
AIPS 1: localhos 31DEC09 TST: Cpu=
0.0 Real=
9 IO=
2
<your unix prompt>$
• You are back in Unix.
• Now we are going to import an image file into
AIPS and display it.
• AIPS grudgingly concedes that it has to
communicate with files in the real world. So it will
read and write FITS files (although it writes bad
FITS which other programs can’t read).
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• There are two principal file types in AIPS –
lists of visibilities, and images. AIPS
denotes these by the letter codes UV and
MA respectively.
• Before going further, download the file
M82_DIRTY.FITS from my website and put
it into your previously selected AIPS data
directory. This is a FITS file, an image,
which is the product of previous AIPS
manipulations.
• Now do
aips®
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• You will get the same printer prompt as before;
just choose the default again.
• You’ll be prompted for your user ID same as
before, but before you can type it in, AIPS will
start up 3 more windows, and print a lot more
text at the prompt.
– The 3 extra windows are a Tek server, a Message
server and a ‘TV’.
• Just click back to focus on your original window,
and enter your user ID then ®. Don’t worry that
the ? prompt has got buried in extra output.
• AIPS will give the same messages as before,
ending with its POPS > prompt.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• Now we’re going to run a task.
– AIPS talks about tasks but also things which it
calls verbs. The difference is minor:
• A task usually takes a while to run. Thus it is run in
a ‘forked’ process, in the background, with output
to the message server. You can type another
command at the prompt in the mean time.
• A verb is a quick-running task. There is no fork for
these, you have to wait until the verb is finished
before entering further commands.
• The task we’re going to run is called
FITLD. It is one of several AIPS tasks for
importing FITS data (typical AIPS overkill).
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• FITLD also has a lot of parameters to cover all
kinds of special cases. Most of these can be left at
default values.
• (One source of confusion in AIPS is that
parameters which have the same name in 2 or
more different tasks remember their values from
task to task.
– The AIPS people claim this is a feature but I think it is a
trap for the unwary.)
• AIPS is case insensitive (except for Unix file
names).
• You can use unambiguous shortening of
parameter names. Eg indi instead of indisk.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• So, at the AIPS prompt, type
task ‘fitld’
inp®
• The inp requests a list of the FITLD
parameters. There are pages of them. See
next slide for the first page!
– Note that the exact number of lines on the
page depends on the size of your terminal
window. It may be more or less than I have
shown here.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
#
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
FITLD: Task to store an image or UV data from a FITS tape
Adverbs
Values
Comments
---------------------------------------------------------------INTAPE
1
Input tape drive # (0 => 1)
NFILES
0
# of files to advance on tape
DATAIN
*all ' '
Disk file name
OUTNAME
' '
File name (name)
OUTCLASS
' '
File name (class)
OUTSEQ
0
File name (seq. #)
0 => highest unique number
=> matching (on VLBA)
-1 => FITS tape value
OUTDISK
1
Disk drive # (0 => any)
OPTYPE
' '
Type of data to load,
' ' => all types
'UV' => UV data
'IM' => images
NCOUNT
0
Number of files to load.
DOTABLE
1
True (1.0) means load tables
for images.
DOUVCOMP
1
>0 => compressed data (FITS)
DOCONCAT
-1
>0 -> if VLBA or uv table,
append data to existing
files, or if no appropriate
files exist create a new file
and append all data to that
** press RETURN for more, enter Q or next line to quit print **
NASSP Masters 5003F - Computational Astronomy - 2009
•
•
•
•
AIPS tut 1
Don’t worry that it talks about tapes – FITLD
can read either from a disk or a tape – and
is pretty clever about working out which it
has to deal with.
Try continued carriage returns until you run
out of pages and get back to the > prompt.
Now press the up-arrow key. You’ll get the
inp back (same as Unix). Now press
carriage return to list the params all over
again.
But test the early exit capability with
q®
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• To get FITLD to load the file you want, you only
have to set 3 of the parameters. Do
datain ‘MYAREA:M82_DIRTY.FITS’
outname ‘M82’
outclass ‘IIM001’®
• Note that AIPS reads the value of your MYAREA
envar. It’s possible to type in the full Unix
pathname but this parameter only accepts a string
of maximum length 48 characters – ie really short.
• If you have a file name with some lower case
characters, leave off the final ‘ otherwise AIPS will
convert whatever you type to upper case.
• Do a final inp to check all params are set properly.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• Now do
go®
• In the MSGserver window (NOT the main
window!) you should see:
MSGserver: Starting AIPS task logging, Inet domain
hostna> task #: Message
---------------------------------------localh> FITLD1: Task FITLD (release of 31DEC09) begins
localh> FITLD1: Create FITLD
.TEMP .
1 (MA) on disk 1 cno
1
localh> FITLD1: RENAM M82
.IIM001.
1 (MA) ON DISK 1 CNO
1
localh> FITLD1: Image=M82
(MA)
Filename=M82
.IIM001.
1
localh> FITLD1: Telescope=MERLIN2
Receiver=
localh> FITLD1: Observer=
User #=
3
localh> FITLD1: Observ. date=31-MAY-2007
Map date=25-SEP-2008
localh> FITLD1: Minimum=-2.68784468E-03
Maximum= 1.42841954E-02 JY/BEAM
localh> FITLD1: ---------------------------------------------------------------localh> FITLD1: Type
Pixels
Coord value
at Pixel
Coord incr
Rotat
localh> FITLD1: RA---SIN
512
09 55 50.704
256.00
-0.015000
0.00
localh> FITLD1: DEC--SIN
512
69 40 43.591
257.00
0.015000
0.00
localh> FITLD1: FREQ
1
4.5460000E+09
1.00 1.4500000E+07
0.00
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
localh>
localh>
localh>
localh>
localh>
localh>
localh>
localh>
localh>
localh>
localh>
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FITLD1:
FREQ
1
4.5460000E+09
1.00 1.4500000E+07
0.00
STOKES
1
1.0000000E+00
1.00 1.0000000E+00
0.00
---------------------------------------------------------------Coordinate equinox 2000.00
Map type=DIRTY
Number of iterations=
0
Conv size= 0.05000 X 0.05000
Position angle=
0.00
Rest freq
0.000
Vel type: OPTICAL wrt YOU
Alt ref. value 0.00000E+00 wrt pixel
1.00
Maximum version number of extension files of type HI is
1
Appears to have ended successfully
localhos 31DEC09 TST: Cpu=
0.1 Real=
0 IO=
1
• Now do
mcat®
• This lists the image files you have in AIPS.
AIPS 1: Catalog on disk 1
AIPS 1: Cat Usid Mapname
AIPS 1:
1
3 M82
>
Class
Seq Pt
Last access
Stat
.IIM001.
1 MA 22-APR-2009 19:23:59
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• Explanation of the various fields:
– Cat: each file that AIPS stores has a unique
catalog integer. As we’ll see in a minute, this
can be a convenient way to grab a particular
file.
– Usid: should be your user ID integer. You can
only see those files corresponding to that ID.
– Mapname: should be what you supplied to the
outname parameter of FITLD.
– Class: should be what you supplied to the
outclass parameter of FITLD. Note that all
class names are 6 characters between two
dots.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
– Seq: each file with a given combination of
name and class has a unique sequence
integer. Note that AIPS policy is never to
throw anything away. If you modify a file, you
usually won’t overwrite the old file: it will just
store it with an incremented sequence
number.
– Pt: either MA for image or UV for visibilities.
– Last access: obvious.
– Stat: if a task is busy in the background
reading from or writing to a file, this ‘busy’
state will be indicated by the status.
• Note that ucat will list UV files and pcat will
list everything.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• AIPS lets you look at the ‘header’ (in a pseudofitsy kind of sense):
imhead®
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
AIPS
>
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
1:
Image=M82
(MA)
Filename=M82
.IIM001.
1
Telescope=MERLIN2
Receiver=
Observer=
User #=
3
Observ. date=31-MAY-2007
Map date=25-SEP-2008
Minimum=-2.68784468E-03
Maximum= 1.42841954E-02 JY/BEAM
---------------------------------------------------------------Type
Pixels
Coord value
at Pixel
Coord incr
Rotat
RA---SIN
512
09 55 50.704
256.00
-0.015000
0.00
DEC--SIN
512
69 40 43.591
257.00
0.015000
0.00
FREQ
1
4.5460000E+09
1.00 1.4500000E+07
0.00
STOKES
1
1.0000000E+00
1.00 1.0000000E+00
0.00
---------------------------------------------------------------Coordinate equinox 2000.00
Map type=DIRTY
Number of iterations=
0
Conv size= 0.05000 X 0.05000
Position angle=
0.00
Rest freq
0.000
Vel type: OPTICAL wrt YOU
Alt ref. value 0.00000E+00 wrt pixel
1.00
Maximum version number of extension files of type HI is
1
Keyword = 'PARANGLE' value = 5.211561E+01
Keyword = 'ZENANGLE' value = 4.789422E+01
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• Now the fun begins. Do
getn 1
tvall®
• Note: getn 1 grabs the file with cat no 1.
AIPS
AIPS
AIPS
AIPS
1:
1:
1:
1:
Hit
Hit
Hit
Hit
button
button
button
button
A
B
C
D
to
to
to
to
enhance B/W or color alternately
increment zoom & set zoom center
decrement zoom & set zoom center
exit
• Note that you don’t get the AIPS > cursor
back. The TV is in control now.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• The TV window should light up and display
what is in the image.
• You should see what looks like a single
point source centred in a fairly cruddy
field. Comments:
– The field is cruddy because it is a dirty image.
– The point source is actually a supernova
remnant which may have gone off as recently
as 1980. Observations spaced a few years
apart show it expanding rapidly.
• You’ll also note that the cursor becomes a
purple cross when it crosses the TV.
NASSP Masters 5003F - Computational Astronomy - 2009
AIPS tut 1
• Click in the TV window to capture focus on it. Then press
keyboard key b a couple of times. The display should zoom
in.
• Now click with left mouse button somewhere in the image:
the image should recentre to where you clicked.
• Press key a then drag the mouse over the image. You
should be able to change the contrast and brightness.
• Pressing a again gives you a false-colour map, with the
same mouse drag capability.
• There's lots more you can do with the TV. See the Cookbook
chapter 6.4. But for now we'll get out of the TV and then
AIPS. Press the d key to get out of ‘TV mode'. This should
get you back your AIPS > cursor. Then kleenex out to unix.
– All the windows disappear eventually although it can take a few
seconds.
NASSP Masters 5003F - Computational Astronomy - 2009