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Gemini Setup Checklist
Last update 5 April 2008
Topics:
Cooling Down Gemini
Vacuum Pump
Recharging Helium in Compressor
Mounting on Telescope
Computer Configuration
Software Startup
Telco
Warming Up Gemini
Labeled Instrument Photos
Cooling Down Gemini
Start at least 2 days before instrument goes on telescope,
preferably start 3 days before
Pertinent Instrument Photos: Gemini Front View,
Vacuum Guage,
Vacuum Pump,
Helium Compressor Front,
Cold Head,
Lakeshore Temperature Controller,
Helium Compressor Back
- Plug in and turn on Gemini power strip.
- Make sure motor drivers are turned OFF.
- Plug in pressure gauge (both coax and pinned connector, and power
outlet of course). If pressure less than 5e-2 torr, then do not need
to put on vacuum pump, but usually a good idea to pump on Gemni during
cooldown anyway.
- Put Gemini on vacuum pump. See Vacuum Pump below.
- Pump until at least down to 5e-2 torr (more vacuum is good - can't
over pump it)
- Shut down vacuum pump in opposite order of start up (you can stop pumping
at this point or pump during cooldown).
- Plug Helium Compressor (CCR) into 220V plug (make sure compressor power
switches are off before plugging in - they are often left on
because the dome crew just unplugs it at the end of the run).
- Connect CCR to Gemini
A. Electrical cable
B. Hoses: supply to supply, and return to return
- Recharge helium in CCR if necessary (e.g. if
static pressure of helium in CCR is below 250 psi).
- Start filling Gemini with LN2 (must be started by morning 2 days
before it goes on telescope)
- Set temperature to 28K on Lakeshore temperature controller. Top
LED display is temperature readout, bottom display is the temperature
setpoint. To set temperature, push the setpoint button and then the
arrow keys until you get to the desired temperature.
- Set heater power to low on Lakeshore temperature controller. Push
heater button until display shows low.
- Turn on power to CCR
A. Turn on Compressor
B. Turn on Cold Head
- Keep filling Gemini with LN2 for the next 48 hours according the
following schedule:
hours 1-2, fill every 20 to 30 minutes
hours 3-6, fill every 45 minutes to 1 hour
hours 7-12, fill every 2 to 3 hours
hours 12-24, fill every 4 to 6 hours
hours 25-48, fill every 6 hours
Note: every cooldown is different, fill more often if necessary
- Fill with LN2 every 8 to 12 hours while on telescope.
- Shut down vacuum pump in opposite order of start up if pump still
running (I usually stop pumping when the pressure gets down to at 4e-7
torr on the vacuum gauge).
- Disconnect vacuum gauge and coil wires out of the way (typically
they get carefully wrapped around the vacuum valve).
The plot below shows the approximate temperature of each chip as a function
of time when filling Gemini according to the schedule listed above. The
SBRC temperature is the temperature shown on the Lakeshore controller. The
NICMOS temperature is the temperature shown on channel 2 of the blue
temperature gauge. If Gemini cooldown is going significantly slower than
the plot indicates it should, even after filling more frequently, check to
be sure that the motor drivers are turned off. These can generate a great
deal of heat and prevent the instrument from reaching the desired temperature.
Vacuum Pump
We are now using the new (June 2002) turbo vacuum pump instead of the old
vacuum pump described in the brown text. The old directions will remain here
just in case the new pump is unavailable (e.g. broken so badly that there is
no hope of using it within the next 24 hours).
The turbo vacuum pump is very easy to use:
- Hook up vacuum pump hose to Gemini's vacuum valve.
- Make sure all valves are closed.
- Turn on vacuum pump (and also the vacuum gauge, if desired).
- When the green LED turns on, slowly open the turbo pump valve.
The green LED should turn off and the pump will go into roughing mode.
- When the green LED turns on again, slowly open Gemini's valve.
- Pump on Gemini until the vacuum is as least 1e-3 torr. I usually pump
until the vacuum is less than 5e-7 torr.
- Close Gemini valve.
- Close turbo pump valve.
- Turn off vacuum pump and carefully disconnect the vacuum hose.
(Please replace the nozzle that usually is attached to the Gemini
vacuum valve).
- I usually leave Gemini's vacuum gauge attached until just before mounting
on the telescope so that the pressure can be properly monitored as
long as possible.
Pertinent Instrument Photos: Vacuum Pump,
Vacuum Pump Inside
- Plug in.
- Make sure Multiplier is Off, Toggle switch is Off, and Gauge Selection
is on Pressure.
- Close Throttle Valve (cw).
- Open Pump Isolation Valve (ccw).
- Turn on Power Switch.
- Wait for quiet forepump (about 2 minutes).
- Turn on Diffusion Pump Switch.
- Wait 15 minutes wile pump heats to operating temperature.
- Slowly but completely open Throttle Valve (ccw).
Recharging Helium in Compressor
Pertinent Instrument Photos: Helium Compressor Front
- Get helium tank to compressor.
- Attach regulator (with copper fill line) to tank.
- Uncoil copper line until it will reach fill nozzle on back of
compressor (close to pressure gauge). Be careful when uncoiling
because the copper tube has kinks in it. Try not to bend them more
than necessary.
- Unscrew the nozzle cover on the compressor.
- This is the important part-there are four valves:
- The tank valve is on the top of the tank and opens CCW
- The regulator valve (labeled Increase/Decrease) is on the front of the regulator and opens CW
- The flow valve (labeled Open/Close to the left of the regulator valve) and opens CCW.
- The compressor valve is next to the nozzle and opens CCW.
- Make sure the tank valve is closed and the regulator valve is set
to zero psi.
- Open the flow valve.
- Open (CCW) the tank valve. One turn should open fully.
- Open the regular valve (CW) so that gas starts flowing (20 or 30 psi is
plenty for this stage).
- Let gas flow to clean out lines. You can loosely attach it to the
compressor nozzle so the nozzle is flushed out too. Flush for 30 seconds or
more.
- Tighten copper hose onto nozzle with gas still running.
- Open regulator valve (CW) until regulator gauge reads > 275 psi.
You may have to tighten the compressor nozzle fitting if it starts to
leak (hiss).
- Slowly open compressor valve (CCW) and watch compressor gauge until
needle gets to 250 psi (if compressor is running, then fill to 270-280 psi).
Do not over fill the helium compressor. If you put in too much helium,
you will have to bleed it off to get back down to 250 psi (or 270-280 psi if
compressor is running).
- Close compressor valve (CW), flow valve (CW), and tank valve (CW)
in that order.
- Disconnect at compressor nozzle and put on nozzle cover.
- Decrease regulator valve pressure (CCW) to zero psi.
- Open (CCW) flow valve to release pressure in the regulator.
- Close (CW) flow valve.
- Remove regulator from tank and replace cover over tank
valve. Note: You might want to leave the regulator on the tank in case
this has to be done again. I wouldn't bother until it gets close to
200 psi.
Mounting on Telescope
I. Mechanical
- Put triangle with Gemini mounting flange on TUB.
- Make sure TUB is rotated to 90.
- Mount Argon line lamp on inside south end of triangle. There are a few
screws that hold it in the proper position.
- Attach compressor mount to telescope base.
- Attach 19" rack to telescope base.
- Add platform extenders to forklift.
- Move Gemini and compressor from prep room to dome floor. You may
have to turn off the compressor and disconnect the hoses and electical
power from the cold head to get it through the door. Reconnect and
turn on CCR ASAP so Gemini doesn't warm up to much (no more than 10
minutes with the CCR off).
- Remove Gemini lens cover.
- Roll Gemini onto lift platform. Secure with angle iron bar and clamps (raise
platform a few inches so can attach clamps).
- Put CCR on orange hydraulic lift.
- Raise lift and hydraulic lift at same time.
- Align Gemini with bolt holes and raise slowly. Bolt to telescope.
- Release Gemini from trolley and lower trolley away.
- Attach blue temperature gauge to side of Gemini, facing downwards.
- Transfer CCR to lift from hydraulic lift.
- Raise and attach CCR bungy cable to shackle at end of steel beam.
- Tie CCR hoses with cord so that they are horizontal.
- Install CCD Power Supply crate in 19" rack on telescope.
II. Electronic
- Plug argon lamp into Spare1_110SSR outlet of line lamp controller..
- Plug Gemini power strip into the UPS (may need an extension cord).
- Thread gray PC-Transputer (PCT) cable through loop on TUB, eye-bolt
on telescope fork, behind telescope control console and through cable
entry hole to the 120" ROR.
- Connect PCT cable military connector to Transputer crate on Gemini
(labeled PC Link).
- Connect cables from CCD Power Supply to Gemini (six cables in black
braided cable wrap, labeled A-F at Gemini end, SBRC A-C and NICMOS D-F
at other end).
- Plug CCD Power Supply into Gemini power strip.
- Strain relieve all cables.
- Turn on instrument:
- CCD Power Supply
- Transputer Crate
- Motor Control Transputer
- Motor Drivers (only turn this on if software will be started
immediately!)
Computer Configuration
- Set up Gemini computer with its 2 monitors. Small monitor should be plugged into
video port 1, large monitor into video port 2. Plug in all components
to power strip on UPS.
- The serial port connects to Lantronix port 5. (This is necessary for telescope
dithering from Gemini software as well as getting RA, Dec, and HA from Telco for the
FITS Header.)
- Connect PCT cable to parallel port (other parallel port should
be taped over). (This is the main data connection between the instrument and PC.)
- Connect ethernet cat-5 cable to ethernet card.
- Turn on monitors and boot computer.
Software Startup
- Log into shard and start shane_serial program.
/usr/local/lick/etc/init.d/shane_serial start
- Turn on Motor Drivers if not already on.
- On Gemini PC start software by typing gemini /licktcs
Do Not Initialize Motors when starting software!
- Initialize the following motors from Engineering menu (Motor Init
function).
- SW Filter
- LW Filter
- FP Aperture Wheel
- Aux Aperture Wheel
- Dichroic
- Take test exposures: press CTRL-F4 to take test exposures in the
following modes.
- Observation setup: 1s exposure, CDS mode with Blank filter
in each channel. Should look like bias images on
http://mtham.ucolick.org/techdocs/instruments/gemini/gemini_testing.html
- Change to J and K' filters (A and B channels respectively) and
do 10s CDS exposures. Should look like the flat fields on
http://mtham.ucolick.org/techdocs/instruments/gemini/gemini_testing.html
- Test moving the telescope from Gemini software:
- Turn on telescope power
- Press CTRL-F1
- Enter 10 arcsec Dec move
- Watch telescope position to make sure telescope moved.
- If exiting the software or not using Gemini for more than an hour,
be sure to turn off Motor Drivers.
Telco - OLD! using POCO now (which uses shane_serial on shard)
- Start Telco_serial on shane if not already running
/usr/local/lick/etc/init.d/telco_serial start
- Start Telco menu program on shane
telcontrol cass
- Set Guide Matrix to default cass matrix (---+).
Warming Up Gemini
- Stop filling with LN2
- Turn off Motor Driver
- Turn off Motor Controller
- Turn off Transputers
- Turn off CCD Power Supply
- Turn off CCR
- Turn off Cold Head power
- Turn off Compressor power
- Set temperature on Lakeshore controller to 295K