WORKING WITH MUSICOS
The MUSICOS instrument is a fiberfed echelle spectrograph,
used on the INT. Fibers are attached under the IDS slit and
led through the polar axis to the spectrograph, located in
the temperature controlled room next to the observing floor
Start up TCS and UltraDAS the usual way:
The observing system windows popping up will be exactly the same as if
you were using IDS; No information what-so-ever will inform you that
MUSICOS is in use. The TCS configuration will also be that of IDS, i.e.
station cass, instrument IDS, agselect cass
- Ensure that lpss14 is up running with the correct MUSICOS configuration file
- On lpx22 open up a telnet window and connect to lpas2
- Login to lpas2 as int_login (password available in the control room)
- Select from menu "start" (infodisp + user interface pops up, original
window continues to be active as the telescope d-task
- Login to lpss13 as intobs
- SYS>obssys - select the appropriate MUSICOS configuration from the menu
The Cass TV will be looking at a dekker hole, typically of diameter 5", under
which the fiberhead will be located.
Take extreme care when filling the cryostat as it is poorly mounted on
the MUSICOS bench. If you accidently move it, chances are that you will need to
align the CCD again. A procedure you do NOT want to do!
The rotator position should under no circumstances be moved during
the night. First, it serves no purpose as the circular fiberhead
transmits no spatial information. Second, the fibers could be wrapped up
as the rotator goes around and in worst case break! So:
Do not move the rotator !, leave it at a fixed position, typically rot sky 0
Focussing the telescope is a bit trickier than you might think.
This is because the TV is focussed on the fiberhead, while MUSICOS
aqcuisition is done on the dekker plates. Because of the distance between
the dekker and the fiberhead (yet an unknown distance) the TV is actually
out of focus. You can do the first rough focussing on the TV, but to
find the real focus a set of focus images have to be taken. The throughput
at the detector will then determine what focus position is best.
Only with good seeing you can actually see the difference.
As the focus offset should be a fixed value, we should be able to
determine the focus offset once and for all.
10/08/00: Telescope focus on fiber: 14.65mm
As the telescope is focussed on the fiberhead, and the fiber is sitting
below the slit, the autoguider focus needs to be adjusted. This has to
be done manually on the first MUSICOS night, normally with the aid of the
dutytech. The procedure is as follows:
- Autoguide on a star (open loop), close to zenith, with the telescope
focussed as described above. The a/g star will appear as a dougnut, far
out of focus
- Go to the telescope, remove the plate below the rotator to access the
- A big knob will be visible next to the unit. This controls the focus
- Turn knob until best a/g focus is obtained. You might want to use the
walkie-talkies to communicate with the controlroom
- Put the plate back on again
Proceed as normal with a 1/7 star calibrate
No special cautions to take. Proceed as usual: Center
object on dekker, GSS to find guidestar, close guideloop.
The quick and dirty way:
The gold colored plate on which the cryostat is mounted can be moved using three
screws; Two in front and one in back. Adjusting these screws allows you to
Only apply small adjustments at a time, as the mount suffers from certain amount
- Align spatially (moving orders left/right on CCD) by using the two front screws
only: loosen one screw x turns, fasten the plate again using the other screw
- Focussing by loosen back (or front) screws and moving plate to fixed position
again by fasten the front (or back) screws.