April 2, 1990
NOTE: This information is somewhat out of date.
Argus is controlled by a 486 PC with a Mouse and a VGA graphics screen. The user interface is generally menu driven although various important functions are controlled directly with the function keys. See the template and Appendix A to learn what the function keys do.
There are three ways to select an option from a menu:
The OBSERVING MODE is the principal operation mode and is always entered
when the program is run. When you enter, it asks if you want to reset Argus.
This does a home checkout for all positioners, the periscope, the comparison
lamp assembly and the TV camera. If Argus is at "home" as it should be, the
checkout will take less than a minute. Unless you are ABSOLUTELY sure that
Argus is in the "home" position when the program was last exited, you MUST
answer this question "yes".
Options:
A. Enable/Disable Autocenter [OBSOLETE]
Under certain conditions, Argus can "autocenter" on a field of stars by
taking a series of short exposures around the nominal positions. It then uses
a centering algorithm to determine the position with the greatest flux. All
positioners move simultaneously. The autocentering process takes about 2
minutes. Because of how the current CCDs are read out, this option is no
longer used.
Unless a maximum in the flux is detected within two arcseconds of the
nominal position of an object, the positioner will return to the initial
location for the exposure. This almost always prevents the autocentering
process from centering on the wrong object. It may be desired to manually
disable autocentering in one or more fibers, such as on a diffuse object.
This option goes to a menu in which this can be done. It must be done
manually for each field and is rarely used.
C. Comparison Lamp Operations
Argus has a comparison lamp assembly incorporated into the periscope arm.
The periscope moves to a position slightly beyond the center of the field
and illuminates a small circle in the center of the field with a known
light source. This is the Comparison Lamp Position of the periscope.
The light is brought in via an incoherent fiber bundle. Fibers may be
illuminated by bringing them all in the smallest possible circle in the
center of the field. This is called the Comparison Position of the
positioners. They may also be placed in a larger circle from which each
may be brought separately to the center of the field. This is called the
Standard Position for the positioners.
When the fibers are centered individually, the image profile is slightly
better. Comparison exposures taken with the positioners moved
individually to the center give significantly better exposures in the sky
fiber. In the Comparison Position, the sky fibers are located at the very
edge of the region illuminated by the comparison lamps.
There are four comparison lamps:
To use the lamps, a mirror must be moved into place; positions #1-4,
correspond to lamps 1-4. There is also a 5th position which increases the
intensity of the quartz lamp sufficiently to make it visible to the naked
eye in the spectrograph room. This is a useful diagnostic tool, of little
importance to the astronomer.
Comparison Lamp Operations deal with moving fibers and periscope to the
comparison positions and turning the lamps on and off. These functions
are done directly with the function keys. See the Keyboard template for
details.
Options:
F. Fibers to Comparison
Moves all the fibers to a small circle near the center of the field.
(Comparison Position)
H. Periscope to Home
Brings the periscope to "Home". This must be done before exposing
on the comparison lamps, to get the periscope out of the way.
K. Keypad
This is the standard Keypad Mode more completely described as an
option in the Observing Mode.
P. Periscope to Comparison
Puts the periscope arm in the Comparison Lamp Position which will
illuminate the center of the field with the light from the
comparison lamp assembly.
X. Standard Star Sequence
It is possible to take a standard exposure in which all the fibers
are positioned over the center of the field, one at a time, for the
same time interval.
This option can be used to take an exposure of a standard star or
of the comparison lamps. All the positioners are first moved to the
Standard Position, which is a circle surrounding the center of the
field.
If your exposure is of a standard star, you will need to center the
star and begin guiding before selecting this mode. It will take an
exposure with the periscope in the "home" position.
If your exposure is of a comparison lamp, it will move the periscope
into the comparison lamp position and then initiate the exposure.
It will move the mirror to a position where the comparison lamp does
not illuminate the field while the individual fibers are moving in
and out. Be sure you have turned on the correct comparison lamp and
placed the comparison mirror in the correct position before electing
this mode.
After this mode has been selected, the astronomer is given the
opportunity to select an appropriate time for exposure in each
fiber, each positioner is brought in turn to the center of the
field, held there for the designated interval and then retracted to
the Standard Position.
An exposure is then taken. This exposure must be long enough to
allow the positioners to be moved into place and removed (about 5
seconds/positioner) plus 24 times the exposure for each individual
fiber. Thus, a five second exposure per fiber takes about 180
seconds. In practice, it is easiest to initiate a long CCD exposure
and then terminate it when the standard sequence is finished rather
than calculate how long the comparison lamp sequence will take.
Options:
C. Center a Star
yMoves the periscope and a given fiber to the center and then
waits for you to place a standard star at the center of the
field.
E. Enable/Disable
Enables or disables fibers from being involved in the
comparison sequence. Default is with all enabled.
K. Keypad
Same as the Keypad Option in the Observing Mode
S. Standard Position
Moves positioners to the Standard Position preparatory to
taking a Standard Exposure.
T. Take Exposure
Initiates the Standard Exposure Sequence. Asks if you wish to
make a standard star exposure or to do the standard exposure
of the comparison lamps.
D. Diagnostics
These are special functions built into Argus for testing the system. They
should not be used except under special circumstances. Ask Observer
Support if you feel you need to use the Diagnostics.
H. Home Position Motion
This returns Argus to its "home" position. Argus also can move the fibers
to "home" and/or verify that they are there.
Going "home" with verification takes from 30 seconds to 2 minutes,
depending on the position Argus is in.
A home checkout should always be performed in the event Argus seems to be
lost.
I. Interactive Assignments
This option permits taking a Object File, which is a list of objects with
their right ascensions and declinations and making Assignment Files which
assign positioners to a set of objects. The format is described in the
file AFORMAT.TXT.
On selecting the Interactive Assignments option, a display similar to that
shown in the Keypad mode is shown. There are several options: One selects an
(O)bject File and a (R)eference Object. All objects in the Object File which
are in the field will be shown with the Reference Object placed in the center.
The field can be (Z)oomed in or out. Zooms of greater than one can be helpful
in crowded fields. Zooms of less than one can be of aid in selecting field
centers with object lists which cover a field larger than Argus. Beware of
zooms less than one! They are untested and there is no guarantee that they do
what you think they do, although they may.
Moving the cursor with the mouse, one can assign objects to positioners
interactively with the left mouse button. The system will determine if
positions are possible and advises in the event of collisions. Objects can be
re-assigned interactively.
If one wishes to be sure and include a high priority object, the (W)here
is object option will identify it.
After having made assignments, the assignment file can be (S)tored and the
objects in this assignment file will disappear from the field.
K. KEYPAD MODE
This mode can be entered directly from most other modes. It gives a
graphics display of the Argus and allows you to move positioners and the
periscope manually. In the keypad mode, there is a menu of the options
which are performed by the various keys on the keypad. Some of these
options are slower on the simulator than in Argus itself. This was done
on the simulator because it reduces memory needs for the simulating
computer and makes the simulator run on more machines.
The circle at the top of the field is the area completely or partially
vignetted by the TV camera pick-off mirror. The active fiber is a
different color from the rest.
The fibers are seen around the field with their pivot point shown at the
back.
The periscope is seen as a small box which can roam anywhere in the field.
Its "home" position is in the center of the field at the bottom.
When the periscope is at the "comparison" position, the periscope box will
be seen just below the bottom of the area blocked by the pick-off mirror.
S. STAR OPERATIONS
The normal mode of using Argus is to read in a list of objects from an
Object File and a set of assignments from an Assignment File. Then, the
positioners are moved to their positions and the telescope to the nominal
center of the field.
Going into the keypad mode, the periscope is sent to whichever probe is
closest to the center. The target for this probe is then moved to the
center of the field by moving the telescope. A guide star is selected in
the main TV camera field and the telescope's autoguider is turned on.
Now, the astronomer checks as many of the objects as desired with the
periscope, does an autocenter to tweak them all up and begins his or her
exposure.
"Star Operations" perform these functions.
Options:
B. Blind Offset
Blind Offset is used when it is desired to locate an object as
accurately as possible without autocentering. One begins by
positioning the positioners on reference objects and autocentering
on them. This position is defined as the "reference position".
Blind Offset can then jump to a new set of positions assuming the
positions of the reference and target objects are what the Object
File said they were. This allows very accurate location of objects
when relative coordinates are precisely known.
To use the Blind Offset mode, center on your reference objects, tell the
Blind offset that these are the reference positions, call a new set of
assignments and do a blind offset. You can do as many as you like from the
same set of references.
F. Assignments from file
This enters a new set of fiber-positioner assignments from an
assignment file.
G. Get Positions and Move
This uses a set of prerecorded absolute positions recorded by option
"R" to return to a previously known position.
K. Keypad Mode
See keypad mode description under the main menu
M. Move to Objects
Move to the objects identified by the currently active object and
assignment files.
R. Record Present Positions
Record the present absolute positions in order to be able to return
using option "G".
S. Get Stars from File
This enters an Object File into the computer.
T. Assignments from Terminal
Permits making or modifying an assignment file manually. Seldom
used.
T. TERMINATE PROGRAM
Leaves the Argus program. You will be asked if you wish to reset Argus
before leaving. The normal answer is "yes".
APPENDIX A: Function Keys
Be sure you have a copy of the function key template. It is reasonably
self-explanatory.
Note that the status of lamps and lamp selection mirror is clearly shown
on the main Argus menu screen.
The following is a summary of what the keys do.
Those which are not listed are not used.
OBSERVING MODE