UNSWIRF Observing Procedure
Observing with UNSWIRF differs little from
the normal mode of observing with IRIS,
require a little more setting up. Here we outline the basic setup procedure,
and point out some traps for the unwary.
- If IRIS is already running, you may still wish to restart it,
particularly as a new data directory needs to be created each day.
Type exit, and answer y to Exit from
Observer also? (y/n).
- On an NCD Xterm, connect to aat40a, and
login as OBSERVER.
- At the 40a> prompt, enter system irisct,
followed by xon node, where node
is the name of the xterm you are working at (If IRIS is being
run on the 4th floor rather than on the telescope, then you
will also need to issue the commands ccdu_vac and
iris_vac to specify the CCD and motor controllers
to be used).
- To enable communication between UNSWIRF and the VAX, enter
DITS_NETSTART (This is in addition to the
dits_netstart command that needs to be issued from the Sun
workstation when establishing
communications with the UNSWIRF PC).
- To have the Unix server automatically create both FITS and IRAF
versions of the raw files, login to aatssf, and issue the (seemingly
redundant) command xhost aatssf. When the first image is taken,
a window will pop up showing the status of file creation (make sure both
"FITS" and "IRAF" are selected).
- To get the IRIS control system started, enter
rvicl ccdn , where n is the number of the CCD
controller given on the whiteboard on the telescope console. This will
bring up an IRIS control window labelled IRISCT.
Wait a couple of minutes until you see the
Iris: prompt in this window.
If attempts to initialise IRIS are met with MAJOR SYSTEMS
FAILURE, check that the telescope control computer is running
(Right Ascension display is updating), or else the XMEM
may need to be restarted.
Error messages that have scrolled past in the IRISCT window
can be recalled with the Prev Screen key.
- At the ICL> prompt (not the Iris: prompt in the
other window), enter
LOAD DISK$USER:[SLL.IRIS]DISPn (where n
is the number of the CCD controller given on the whiteboard on the
telescope console). This will give a more useful XMEM display, including
a greyscale lookup table with which any saturated pixels will appear red.
It may take some minutes before all the actions are completed.
- To define the extra software needed to control the FP in tandem with IRIS
and telescope offsetting, enter
LOAD DISK$DATA:[OBSRED.UNSWIRF]UNSW.ICL at the next
- In the IRISCT window, check the following:
- FLATT OUT (this should be set to FLATT BLANK
during the day to protect IRIS from inadvertent saturation).
- GRISM OPEN
- LENS WIDE, HAND OPEN3 for the wide-field
optics, or LENS INTERM followed by HAND 9MM
for the 0.25 arcsec pixels.
- SLIT OPEN
- WINDOW IRIS128 (equivalent to WINDOW ROCKWELL_128).
- If necessary, set Idle Mth to IRIS_IDLE1 by
typing IME 1 in the IRIS window, and set the idle time
with IT 1.5.
- Generally, use Observing Method 1 (ME 1) and Idle Method 1
(IME 1) for tests, and Observing Method 4
(ME 4) and Idle Method 2 (IME 2)
for actual observing. Setting the idle time to the same as that
used for a dark exposure is useful for looking for lines in real time,
but remember to set it back to 1.5 before observing, in order to
cut down on overheads.
- Commands can be sent manually to the FP by entering in the ICL window
the line obeyw aatssy##UNSWIRF SEND command,
where command could be beep (beep the UNSWIRF
terminal), "z 500", "slide out", or any of
the other UNSWIRF commands.
- It is a good idea to stow the FP under the slide cover during the
day (to minimise dust falling on it), which is accomplished with
the slide out command. To return the FP to the observing
position, do a slide in, followed by slide 150
(to better centre the etalon in the IRIS field).
Although individual exposures and FP settings can be commanded manually,
the repetitive nature of infrared observing makes it much more efficient
to set up a file specifying the parameters for each observation (object
name, FP spacing, telescope offset, etc.). This file can then be executed by
ICL, and the whole sequence of exposures repeated if necessary.
These run files can be created in any directory on the VAX, provided it
has World readership permission. We suggest using the directory
DISK$DATA:[OBSRED.UNSWIRF], which can also be accessed from the
Sun network as /vaxdata/obsred/unswirf/. Use your favourite
editor on either the VAX or Sun to create a file like the example shown
! command name z TI CY PE RP dR dD
aatssy##UNSWIRF M83nuc_2.17_z720 720 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z720 720 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z770 770 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z770 770 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z780 780 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z780 780 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z790 790 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z790 790 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z800 800 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z800 800 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z810 810 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z810 810 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z820 820 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z820 820 120 1 8 1 0 300
aatssy##UNSWIRF M83nuc_2.17_z830 830 120 1 8 1 0 0
aatssy##UNSWIRF M83nuc_2.17_z830 830 120 1 8 1 0 300
The first line of this file is a comment line, indicated by the
! mark. The first entry on each line is a command to
the UNSWIRF controller
via the SparcStation aatssy. The next entry is the object
name you want inserted in the image header. The first number is the
etalon z spacing you desire for the line of interest at the object's
redshift (you can get this by using Galactic sources such as OMC-1 or
M17 as references, or the program /home/aatssy/unswirf/fpz).
The second number is the total integration time (120
seconds), consisting of 1 cycle (CY=1), multiple readouts separated by 8
seconds (PE=8), and no repeats (RP=1). Note that owing to a bug in the
ICL, requests for repeats in any line of this file other than the first
will be ignored. The last 2 numbers are offsets in RA and Dec in seconds
of arc (of polar axis rotation in the case of RA) from the telescope
position prior to the run file being executed. After the run file
has been executed, the telescope will return to this original position
(unless the run file was aborted for some reason, in which case you will
need to ask the night assistant to return the telescope to the original
coordinates, after which you type tidy (twice), followed
Although moving the telescope back and forth from object to sky position
(here 300" E) will incur greater overheads, we strongly recommend observing
this way, rather than doing all the object z settings, followed by all the
sky z settings. Repeat sequences should use (say) an offset of 300 arcsec W,
so that stars in the sky frames will not be repeated. Do not deliberately
"jitter" exposure sequences like this on the object if accurate intensities and
velocities are required, otherwise the fits generated with the
assistance of arc-line width maps will be invalid. Most of the bad
pixels and even the "holes" caused by stars in the sky frames can be
removed in the reduction, continuum-subtraction, and cube-fitting, or
if necessary, using imedit in IRAF.
The Perl script cube.pl can be used to generate these
run files semi-automatically. You will need to edit the following
When you are happy with the new parameters, save the file and execute it
with something like ./cube.pl > /vaxdata/obsred/unswirf/m83.dat
to generate the run file.
- $object, the object name and filter (only the most recent
definition of this parameter is used).
- $line_centre_z, the FP z corresponding to the expected
- $time, $cycles, $period, $repeat, the integration
- The first command should be a ∥ this computes
automatically the optimum x and y settings for plate parallelism as a function
of the chosen FP z.
- This is followed by a combination of:
&go for a single etalon setting and telescope offset;
&gonomove for a single etalon setting (no telescope offset;
&sequence for an etalon scan at fixed RA and Dec offset;
&seqarc for an arc line scan/flatfield sequence; and
&ossequence for an etalon scan alternating between
object and sky. Note that half of the number_of_images will
be at lower z than $line_centre_z, and half will be at larger z,
spaced delta_z apart.
- The die; command terminates the script at this point, ignoring
Before executing the file, check that the required narrow-band blocking
filter is in place, select Method 4 or Method 1, and if necessary, set
Period to some
value greater than zero, but less than the total integration time.
Having edited the file to your satisfaction, you can execute it
from the ICL> prompt with a command of the form
unsw m83.dat. Chances are, this will be greeted with an
error like Cannot open file; don't panic! Just press the
up-arrow key, and re-issue the command.
If this doesn't work, try deleting any Emacs backups of your file, as
these can confuse the VAX-SUN disk naming system. Next, check that the
file has world read and execute privilege: SET PROT=(W:RWED)
on the VAX, or chmod a+x /vaxdata/obsred/unswirf/m83.dat;
chmod a+r /vaxdata/obsred/unswirf/m83.dat
on the SUN. You may also want to try issuing the ICL command tidy
twice. Give the unsw m83.dat command again, and
keep trying: it should be accepted eventually!
The run file should now execute the desired sequence of observations,
but you will still need to keep a record of the exposure sequence. Should
the sequence crash for any reason, remember to issue the tidy
command twice in ICL before continuing.
With one of the 1% bandpass filters in place, ask the night assistant
to slew to a star of 4th magnitude or brighter. When roughly centered
on the array, switch to the smaller window (WINDOW IRIS25)
and allow the night assistant to run through the standard FOCOFF procedure.
In some cases, it may be necessary to override the auto-scaling of the
IDLE display, with (say) DISPLAY SCALE,IDLE_ER,20000,30000.
When focussing is completed (the focus does not change with the filter
used), return to the normal display with DISPLAY AUTO,IDLE_ER
and WINDOW IRIS128.
- Standard Stars
For flux calibration, we recommend selecting one of the
spectroscopic standard stars in Appendix
1.2 of the IRIS
manual, at an airmass similar to that of your program object. A
single integration of 10 seconds (with 10 NDRs) on a 4th magnitude
star should suffice, but you should obtain two images with the star
displaced 15 arcsec either side of the field centre. It is also
suggested that you obtain images of the standard with all of the FP
settings used on your program object to assist in scaling and
The variations in sensitivity of IRIS + UNSWIRF are such that you
MUST obtain flatfields at each FP setting and with all the
blocking filters you used for program objects. Because of the way
the etalon may drift out of parallelism during the day, it is highly
recommended that you obtain all necessary flatfields as soon as the
night ends. WARNING: UNSWIRF observing is not for those
who like to go to bed before the Sun rises! Be kind to your night
assistant, and offer to close the mirror covers and switch on the
building lights for him when you have finished.
For flatfields, use the floodlamp on maximum brightness pointed at
the white patch, with all the mirror covers open. Integration times
of 20 seconds, with 2 second periods will give you of order 10000
counts above the background. You may want 3 flatfield images at each
setting to allow medianing, but one will probably suffice. A global
"dark" frame (lamp off) for each filter should suffice. Flatfield
sequences can be commanded by a run file; make sure there are no RA or Dec
offsets at the end of each line, since the telescope
tracking will be turned off. You will still need to command filter
changes yourself from the IRIS window.
- Arc Line Scans
Since most sources will be too weak for the cube-fitting routine to
treat line width as a free parameter, the best way to constrain it is
by assuming the line to be unresolved, and using high S/N observations of
an arc line to construct a map of line width over the etalon area. Use
cube.pl to take a series of 16 images spanning the arc line
centre, at intervals of 2 Z units. Use docube.cl and
unswspec.cl to examine the resulting cube, to make sure the peak can
be well determined over most of the image area. The following table gives
suggestions for appropriate arc lines and exposures to match most lines of
|1.64 ||Ar 1.6436 ||40/1/4/1 ||50 |
|1.65 ||Ar 1.6519 ||10/1/1/1 ||-48 |
|2.12 ||Kr 2.1165 ||40/1/4/1 ||-262, +813 |
|2.16 ||Ar 2.1534 ||60/1/6/1 ||-280 |
|2.21 ||Kr 2.1902 ||10/1/1/1 ||-320 |
|2.25 ||Kr 2.2485 ||60/1/6/1 ||200 |
|2.34 ||Kr 2.3340 ||40/1/4/1 ||92 |
- Observing Strategies
For astronomical objects, total integration times of 180 seconds per
etalon setting are sufficient to guarantee sky-limited backgrounds in all
filters, while still enabling a sequence of etalon settings on object and
sky to be completed before the sky background changes appreciably. The
whole sequence can then be repeated as often as required until the desired
signal-to-noise is achieved. Note that the velocity differences between
objects, even in our own Galaxy, can be significant (as much as 30 Z units),
and unless accounted for using /home/aatssy/unswirf/fpz, can cause
you to miss the line peak altogether.
- No Arc Lines Visible: Is the telescope power switched
on? (Main Power key to left of observing console). Has the
arc lamp fallen from the top of the slide? Has the CS100 gone out of
lock? (See below).
- XMEM / IRIS Crash: If the XMEM
should crash, i.e., the
XMEM monitor display does not update (try swapping between Idle Methods)
and/or the IRIS control window has crashed, then go over and press the
black button marked COLD START on the XMEM control rack.
After a minute or so, the words
AAO XMEM V4.3 should come up on the XMEM display monitor.
In the meantime, you will need to EXIT from the ICL
window, and answer Y to Exit from OBSERVER also?
Reissue the rvicl ccdn command, and then run through
the entire startup procedure again.
- UNSWIRF Communication problems: While the ICL script
is running, keep an eye on the (x,y,z) values returned by the UNSWIRF PC;
if you get a warning of a possible communications problem, you may need
to abort the sequence (use Ctrl-c twice).
Possible causes include the PC needing to be
rebooted, or (more likely) the /home disk of the Sun
controlling UNSWIRF is 100% full (ask the night assistant to fix this).
- CS100 problems: The CS100 controller may occasionally
go out of lock (the arc line image will go from roughly uniform
illumination to an a semi-circular arc, the green Close Loop
light on the front of the CS100 will go off, and one of the parameters
x_overload, y_overload, z_overload in status
will be non-zero). If this happens, you will need to slew the telescope
back to the zenith (ask the night assistant to MARK the
present telescope position first), go into the Cass cage, flick the
switch below the Close Loop lamp down, cycle the CS100
on/off switch, depress briefly the Reset switch, then
push up the Close Loop switch. The green light should
come back on. If the etalon is still out of lock, check the seating
of the cables to the etalon, as well as to the back of the PC.
A suggested software list and directory structure is as follows:
- ICL scripts in /vaxdata/obsred/unswirf/:
- unsw.icl - the ICL script that commands
telescope offsets as well as etalon spacing changes.
- the UNSWIRF run files created by cube.pl, which are
then input to unsw.icl.
- Scripts in /opt/obsred/unswirf/ on aatssf:
- cube.pl - Perl script used for generating
UNSWIRF run files of astronomical sources and sky positions, or
for arc line scans and/or flatfield sequences (for which no telescope
offsets are required).
- dokeys - a shell script that outputs the
value of a specified keyword for a sequence of images.
- login.cl - the usual IRAF startup script,
specifying the directories in which the .imh and
.pix files are to be stored (be sure to check that the environment
variables home and imdir are appropriate for the
machine you are working on).
- loginuser.cl - a supplementary file that
defines a number of useful UNSWIRF-related cl scripts described below.
- sdf2iraf - a shell script that converts
a sequence of .sdf files directly to their IRAF
.imh and .pix equivalents. You will need
to set the environment variable IRAFDIR to point to
your IRAF home directory (e.g., setenv IRAFDIR
- IRAF reduction cl scripts in /opt/obsred/unswirf/iraf/scripts
- docube.cl - takes a series of arc-line scan
images, subtracts a single dark frame from each, and stacks them into a
cube, ready for processing in IRAF with unswslope.cl.
- doscube.cl - same as docube.cl
but allows one to use a matching sequence of sky frames, instead of a
single sky frame.
- unswcube.cl - procedure for fully processing
datacubes prior to fitting, i.e., sky-subtraction, flatfielding, rotation,
cleaning of bad pixels, register images, scale and subtract continuum.
- unswflat.cl - procedure to form a series
of dark-subtracted dome flats automatically from a sequence of lamp-on /
lamp-off images (if only one lamp-off image is available, then use
- unswlin.cl - procedure to "pre-process" all
raw UNSWIRF frames. Converts from ADU to e- by multiplying by 9.5, gets
the etalon Z value from the comment line (or header), and places it in
the keyword Z_ETALON.
- unswphot.cl - for photometry of standard
star images. Extracts the names, identities, and exposure times from
a sequence of images, subtracts images of the same etalon Z (but opposite
stellar offsets), flatfields the result, allows the user to mark the
positions of the positive and negative stellar images, then carries
out the photometry and calculates the sensitivities as a function of
- unswproc.cl - more basic version of
unswcube.cl. Sky-subtracts, flatfields, rotates,
and cleans, but does not stack images into a cube.
- unswspec.cl - allows the user to plot a
spectrum (intensity as a function of etalon Z, or cube plane number),
averaged over some region in x and y.
- unswblank.cl - executes MCBA's Lorentzian
fitting routine, then allows the user to interactively blank out pixels
in both the intensity and velocity maps which fail to both exceed an
intensity threshold and yield a sensible velocity.
- unswfit.e - Michael Ashley's IRAF task for
fitting Lorentzian instrumental profiles to each pixel of the datacube.
The width can be a free parameter, fixed as a constant, or set by the
width found from scans of an (unresolved) arc line of similar wavelength.
The file unswfit.par should also be present in this
- unswslope.cl - procedure for fitting
Lorentzian profiles to arc-line scans (using unswfit.e),
followed by fitting of a plane to the "velocity" map to assess the
- unswvel.cl - corrects the fitted velocity
map of an astronomical object for any residual curvature, as mapped by
the "velocity" image of a matching arc-line scan. Converts from etalon
Z to km s-1, but the absolute velocity scale is arbitrary;
an offset of 100 km s-1 is added to avoid velocity values
- unswdisp.cl - task for sequentially
displaying each plane of a cube at 5 second intervals ("movie mode").
- xset.cl - a procedure that informs IRAF
of the number of rows in your Xterm window. Useful to prevent help
screens scrolling off the top of the page. Execute at startup.
If any of these programs are missing, you can always find the latest
versions in /home/aatssy/unswirf/ (note that you need to be
logged in to aatssy in order to see this directory).
Return to the main UNSWIRF page.
Last modified: November 21, 1999.