This is compiled from
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Preliminary Test Procedure for IRAF, IRAF Version V2.11, Jeannette Barnes, Central Computer Services, National Optical Astronomy Observatories, P.O. Box 26732, Tucson, AZ 85726, Revised September 23, 1997,
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A Beginner's Guide to Using IRAF, IRAF Version 2.10, Jeannette Barnes, Central Computer Services, August 1993.
The following pages describe a short test procedure that sites can execute to test some basic image functions within IRAF for a new installation. This process will help verify that everything is working correctly and also help the rst time user gain familiarity with the system. The commands you need to type and the expected terminal output are given below.
We will assume that you have started IRAF and are residing in an empty directory from which you wish to work.
All of the IRAF core packages are loaded when you log into IRAF. You
can list what packages are currently loaded by typing the word
package. The following should be displayed, but the packages may not
be listed in the same order:
cl> package
clpackage
language
system
lists
noao
nttools
utilities
proto
imutil
immatch
imgeom
imfit
imfilter
imcoords
images
New packages can be loaded by simply typing the packages name. Not the
change of the prompt. The last package loaded can be unloaded by
typing bye. Try the following. Note that in our example the top
level packages listed may be different than yours.
cl> digiphot
di> ?
apphot daophot photcal ptools
di> bye
cl> ?
dataio language noao plot softools utilities
images lists obsolete proto system
An IRAF image exists in the dev$ directory. Lets make a copy of this
image into the current working directory.
cl> imcopy dev$pix image.short
dev$pix -> image.short
Let's look at the header information for this image with imhead.
cl> imhead dev$pix long+
dev$pix[512,512][short]: m51 B 600s
No bad pixels, min=-1., max=19936.
Line storage mode, physdim [512,512], length of user area 1621 s.u.
Created Mon 23:54:13 31-Mar-1997, Last modified Sun 16:37:53 12-Mar-2006
Pixel file "HDR$pix.pix" [ok]
'KPNO-IRAF' /
'31-03-97' /
IRAF-MAX= 1.993600E4 / DATA MAX
IRAF-MIN= -1.000000E0 / DATA MIN
IRAF-BPX= 16 / DATA BITS/PIXEL
IRAFTYPE= 'SHORT ' / PIXEL TYPE
CCDPICNO= 53 / ORIGINAL CCD PICTURE NUMBER
ITIME = 600 / REQUESTED INTEGRATION TIME (SECS)
TTIME = 600 / TOTAL ELAPSED TIME (SECS)
OTIME = 600 / ACTUAL INTEGRATION TIME (SECS)
DATA-TYP= 'OBJECT (0)' / OBJECT,DARK,BIAS,ETC.
DATE-OBS= '05/04/87' / DATE DD/MM/YY
RA = '13:29:24.00' / RIGHT ASCENSION
DEC = '47:15:34.00' / DECLINATION
EPOCH = 0.00 / EPOCH OF RA AND DEC
ZD = '22:14:00.00' / ZENITH DISTANCE
UT = ' 9:27:27.00' / UNIVERSAL TIME
ST = '14:53:42.00' / SIDEREAL TIME
CAM-ID = 1 / CAMERA HEAD ID
CAM-TEMP= -106.22 / CAMERA TEMPERATURE, DEG C
DEW-TEMP= -180.95 / DEWAR TEMPRATURE, DEG C
F1POS = 2 / FILTER BOLT I POSITION
F2POS = 0 / FILTER BOLT II POSITION
TVFILT = 0 / TV FILTER
CMP-LAMP= 0 / COMPARISON LAMP
TILT-POS= 0 / TILT POSITION
BIAS-PIX= 0 /
BI-FLAG = 0 / BIAS SUBTRACT FLAG
BP-FLAG = 0 / BAD PIXEL FLAG
CR-FLAG = 0 / BAD PIXEL FLAG
DK-FLAG = 0 / DARK SUBTRACT FLAG
FR-FLAG = 0 / FRINGE FLAG
FR-SCALE= 0.00 / FRINGE SCALING PARAMETER
TRIM = 'Apr 22 14:11 Trim image section is [3:510,3:510]'
BT-FLAG = 'Apr 22 14:11 Overscan correction strip is [515:544,3:510]'
FF-FLAG = 'Apr 22 14:11 Flat field image is Flat1.imh with scale=183.9447'
CCDPROC = 'Apr 22 14:11 CCD processing done'
AIRMASS = 1.08015632629395 / AIRMASS
HISTORY 'KPNO-IRAF'
HISTORY '24-04-87'
HISTORY 'KPNO-IRAF' /
HISTORY '08-04-92' /
Note that the pixels are short integers (=16 bits).
Print the same, but without the user fields:
cl> imhead dev$pix l+ u-
dev$pix[512,512][short]: m51 B 600s
No bad pixels, min=-1., max=19936.
Line storage mode, physdim [512,512], length of user area 1621 s.u.
Created Mon 23:54:13 31-Mar-1997, Last modified Sun 16:37:53 12-Mar-2006
Pixel file "HDR$pix.pix" [ok]
'KPNO-IRAF' /
'31-03-97' /
Check the parameter settings for imhead:
cl> lpar imhead
images = image names
(imlist = "*.imh,*.fits,*.pl,*.qp,*.hhh") default image names
(longheader = no) print header in multi-line format
(userfields = yes) print the user fields (instrument parameters)
(mode = "ql")
It would be useful to generate two more copies of this image but with
different pixel types - one with 32-bit floating point pixels (called
reals) and one with 64-bit double precision floating point pixels
(called double). Note that IRAF also supports other pixel data types -
32-bit integers called long, 16-bit unsigned integers called
ushort, and complex numbers. Execute the following:
cl> imarith image.short / 1 image.real pixtype=r
cl> imarith image.short / 1 image.dbl pixtype=d
cl> imhead image.*
image.dbl.fits[512,512][double]: m51 B 600s
image.real.fits[512,512][real]: m51 B 600s
image.short.fits[512,512][short]: m51 B 600s
Let's execute a couple of more tasks that will exercise some image operators. Typing
cl> minmax image.dbl,image.real,image.short
image.dbl [77,4] -1. [348,189] 19936.
image.real [77,4] -1. [348,189] 19936.
image.short [77,4] -1. [348,189] 19936.
Now display a table with pixel values.
cl> listpix image.short[300:305,200:205] formats="%4s %4s" | table
1. 1. 145. 4. 2. 141. 1. 4. 149. 4. 5. 144.
2. 1. 143. 5. 2. 132. 2. 4. 149. 5. 5. 145.
3. 1. 141. 6. 2. 130. 3. 4. 146. 6. 5. 144.
4. 1. 142. 1. 3. 162. 4. 4. 143. 1. 6. 138.
5. 1. 135. 2. 3. 145. 5. 4. 145. 2. 6. 139.
6. 1. 138. 3. 3. 146. 6. 4. 140. 3. 6. 145.
1. 2. 147. 4. 3. 144. 1. 5. 144. 4. 6. 141.
2. 2. 147. 5. 3. 135. 2. 5. 145. 5. 6. 141.
3. 2. 145. 6. 3. 141. 3. 5. 133. 6. 6. 149.
Now let's test the use of image sections. Type and observe the following terminal interactions:
cl> imcopy image.real[200:300,200:300] image.sect
image.real[200:300,200:300] -> image.sect
cl> imhead image.sect
image.sect[101,101][real]: m51 B 600s
At this time, let's modify a couple of image titles.
cl> hedit image.real title "m51 real" verify=no
image.real,i_title: "m51 B 600s" -> "m51 real"
image.real updated
cl> hedit image.dbl title "m51 double" verify=no
image.dbl,i_title: "m51 B 600s" -> "m51 double"
image.dbl updated
We can verify the new title with the imheader task.
cl> imhead image*
image.dbl.fits[512,512][double]: m51 double
image.real.fits[512,512][real]: m51 real
image.sect.fits[101,101][real]: m51 B 600s
image.short.fits[512,512][short]: m51 B 600s
Now let's check some plotting options. Type
cl> plot
cl> pcol image.short 256 >G image.short.meta
cl> !ls image.short.meta
image.short.meta
cl> del image.short.meta
The redirected output graphics file should have the md5 sum
0806e05ccea335a1ad4962282905c830 on 64 bit. Unfortunately, this is
machine dependent, so on 32 bit, the md5 sum is
32e139a609d9d50c8f108d0023820c11.
Let's make a contour plot of the section image. We do it as IRAF graphics.
cl> plot
cl> contour image.sect >G image.sect.meta
Image will be block averaged by 1 in x and 1 in y
cl> !ls image.sect.meta
image.sect.meta
cl> del image.sect.meta
Unfortunately, the file contains local information and therefore the content can't be strictly compared.
Graphics output can be stored in files. These files are called
"metacode" files. Graphics metacode files can be generated by the task
itself, by the user by redirecting the graphics output to a metacode
file on the command line with the >G syntax, or by writing the plot
directly to a metacode file with the :.write option in interactive
graphics mode.
A metacode file is distributed with your IRAF system and we will use it to demonstrate these tasks.
cl> plot
cl> gkidir dev$vdm.gki
METAFILE 'dev$vdm.gki':
[1] (3517 words) The SINC Function
[2] (2855 words) The SINC Function
[3] (5701 words) .2
[4] (2525 words) Line 250 of dev$pix[200:300,*]
[5] (7637 words) Log Scaling
[6] (97781 words) NOAO/IRAF V2.3 tody@lyra Fri 23:30:27 08-Aug-86
[7] (2501 words) The Sinc Function
[8] (11719 words) Line 250 of dev$pix[200:300,*]
In the workstation environment the user displays an image into a frame buffer and then uses the display server, either IMTOOL or SAOimage, for panning, zooming, blinking, changing the lookup tables (greyscale and color), and so on. These functions will be done differently depending on the server you are using.
Before doing anything involving image display the environment variable
stdimage must be set to the correct frame buffer size for the display
servers (as described in the dev$graphcap file under the section
"STDIMAGE devices") or to the correct image display device. The task
GDEVICES is helpful for determining this information for the display
servers.
cl> show stdimage
imt512
cl> set stdimage=imt800
cl> set stdimage=iism70v
The DISPLAY task is the main task used for displaying images, but
cannot be tested here. Running DISPLAY without an image server will
result in a failure.
IRAF has support for three coordinate systems. The "logical" coordinate system is defined by pixel coordinates relative to the current image or image section.
cl> listpix dev$wpix[16:20,5:6] wcs=logical
1. 1. 41.
2. 1. 38.
3. 1. 41.
4. 1. 42.
5. 1. 40.
1. 2. 38.
2. 2. 38.
3. 2. 38.
4. 2. 39.
5. 2. 38.
The "physical" coordinate system is also in pixel coordinates but relative to the original or parent image.
cl> listpix dev$wpix[16:20,5:6] wcs=physical
16. 5. 41.
17. 5. 38.
18. 5. 41.
19. 5. 42.
20. 5. 40.
16. 6. 38.
17. 6. 38.
18. 6. 38.
19. 6. 39.
20. 6. 38.
The "world" coordinates can be in any general world coordinate system such as right ascension and declination or wavelength.
cl> listpix dev$wpix[16:20,5:6] wcs=world format="%H %h"
13:28:05.1 47:24:01.4 41.
13:28:05.1 47:24:01.4 38.
13:28:05.0 47:24:01.4 41.
13:28:04.9 47:24:01.4 42.
13:28:04.8 47:24:01.4 40.
13:28:05.1 47:24:02.1 38.
13:28:05.1 47:24:02.2 38.
13:28:05.0 47:24:02.2 38.
13:28:04.9 47:24:02.2 39.
13:28:04.8 47:24:02.2 38.
Templates are character strings including some metacharacters. Templates can be used as input to IRAF tasks; those file names matching the template are used as input.
The following are a few examples of the more commonly used file templates.
cl> dir *.fits
image.dbl.fits image.real.fits image.sect.fits image.short.fits
The @file (pronounced "at file") can be used for handling large lists
of images for input and output. The @file is a text file containing a
list of images. The easiest way to generate an @file is with the FILES
or SECTIONS task. This is often the preferred input/output to tasks
rather than using templates directly. Since the @file is a text file
it can also be edited.
cl> files *.fits > inlist
cl> imstat @inlist
# IMAGE NPIX MEAN STDDEV MIN MAX
image.dbl.fits 262144 108.3 131.3 -1. 19936.
image.real.fits 262144 108.3 131.3 -1. 19936.
image.sect.fits 10201 363.9 346. 108. 7734.
image.short.fits 262144 108.3 131.3 -1. 19936.
You can also use the // operator:
cl> imarith @inlist * 2 @inlist//.2
cl> imstat @inlist//.2
# IMAGE NPIX MEAN STDDEV MIN MAX
image.dbl.2.fits 262144 216.6 262.6 -2. 39872.
image.real.2.fits 262144 216.6 262.6 -2. 39872.
image.sect.2.fits 10201 727.8 692. 216. 15468.
image.short.2.fits 262144 216.1 250. -26476. 29280.
cl> imdelete image.*.2.fits
A common extension can be specified as well in the list with the new
image opening code (set use_vo = yes; see
#235):
cl> imstat @inlist[0]
# IMAGE NPIX MEAN STDDEV MIN MAX
image.dbl.fits[0] 262144 108.3 131.3 -1. 19936.
image.real.fits[0] 262144 108.3 131.3 -1. 19936.
image.sect.fits[0] 10201 363.9 346. 108. 7734.
image.short.fits[0] 262144 108.3 131.3 -1. 19936.
The CL has a built-in calculator capability. Some variables that may be used are defined in the parameter file for the CL which includes the booleans b1, b2, and b3; the integer variables, i, j, and k; the real variables, x, y, and z; and the string variables, s1, s2, and s3. There are a variety of built-in functions that are also available including sin, cos, abs, exp, log, log10, max, min, sqrt, and tan.
For more complex examples see the document An Introductory User's Guide to IRAF Scripts, mentioned in §9.1.
cl> i=1;j=2;x=5;=i+x**j
26.
cl> =x
5.
cl> =sqrt(x/10)
0.70710678118655
cl> =(sin(0.5)**2+cos(0.5)**2)
1.
Hopefully all went well to this point. Let's clean things up a bit.
cl> dir
image.dbl.fits image.sect.fits inlist
image.real.fits image.short.fits
cl> imdelete image.*
cl> dir
inlist
Remember that if you want to delete any images you just use the task
imdelete. The task delete will delete your text files. If the
wrong task is used to delete images a warning message is printed and
no images are deleted.
If discrepancies occur during any of these steps, please look at the examples closely. It might be advisable to backtrack a few steps and verify things again. If the discrepancies are repeatable there could indeed be a problem. Please document the discrepancy and feel free to contact us if some advice or help is needed.