Changes
/* Brief description of GIRAFFE */
== '''Current Status''' ==
GIRAFFE has been mothballed following the failure of its control software, a lack of source code to delve into to fix it and a current lack of staff resources for creating a modern control programme. The instrument was undergoing a series of upgrades to improve performance and provide a data reduction pipeline. This is now on hold, with other instrument projects taking priority.
== '''Brief description of GIRAFFE''' ==
2. A thin client system for data storage ''ltsp.suth.saao.ac.za''.
3. [[APD|A laptop running a LabView program to display the APD counts]], i.e. monitor the light intensity emerging from the fibre.
4. The Linux TCS PC for acquisition and autoguiding.
=='''Data storage''' ==
The PC on which QUARTZ should not be used for any other purpose. The same applies to the TCS. GIRAFFE data should be automatically transferred from the ''giraffe'' PC to the server, which is accessible from the thin client (the monitor to the left of APD counting laptop), where data reduction software, ds9, web browsers, etc. can be used.
You should check that your data is being transferred by logging into the thin client
Username: ccd74
Password: label on monitor
cd /data/74in/giraffe/data/image/yyyymmdd
Your files will be named ''annnmmmm.fits'', where ''nnn'' is your run number.
[[Indlulamithi|Data reduction Software for Giraffe]]
'''Even in bad weather, the cryostat must be filled during the night.''' The last filling for the night should not be done before midnight.
=='''Instrument setup& software startup'''==
The instrument is controlled by the QUARTZ software on giraffe PC.
'''2.1 Starting the software'''
1) Log on as ''ccd'' (usual password)
* Wait 2 minutes for it to finish initalising.
* Check that things are working, by reading out the CCD by selecting ''Read CCD'' from the ''CCD'' drop-down menu at the top right of the QUARTZ window. This will display information regarding the bias reading and the maximum CCD count.
* Select “Filter” → “Init” at start of run, and again before every filter change.
=='''Setting prism position & determining wavelength range'''==
1) Select Initialise the prisms: select “Init” → “Find reference” and wait for “Finding reference...” window to close
2) Select “Init” → “Define red” or “Define blue” depending on the prism you wish to use and enter prism position
4) Check and note down the prism position in the “Prism” status box at the bottom of the QUARTZ window.
5) Select “Filter” → “Init” at start of run, Take a fibre flat and again before every filter changean arc exposure (follow steps in Calibrations section).
6) By taking an On ltsp, run the data reduction software on the flat & arc (follow files to determine the orders present in the image and the wavelength range. '''If the calculated orders are far from those expected''', the prisms will need initialising. Repeat steps (1)-2 (6) until the expected orders are in Section the frame. When this happens, the correct prism position is usually achieved over 3initialisations, but it is important to move the prism after an initialisation, i.e. always follow steps (1) with step (3)(you can skip step (2) because you already defined your desired position); don't do step (1) twice in a row, or GIRAFFE will get quite upset. =='''Focus'''== '''Spectrograph focus''' You can check the resulting orders spectrograph focus on an arc image by clicking the "Gauss Fit" button left of centre below the image display, then clicking on arc lines across the image. The FWHM in X & Y are correct displayed in the information box (see section ideally, X=Y and is approximately constant across the field). Focus the camera by turning the knob on reductions softwarethe camera stage in increments of a quarter turn (duck under the cryostat filling pipe inside the Coude room and locate the silver knob with vernier scale on the camera stage) . Take an arc, measure the lines, move the focus and spectrograph iterate. '''Telescope focus''' If GIRAFFE has been used for the week before your run, you can probably assume that the telescope focus is good (see Section 5)about right. However, after an instrument change the focus might be quite far off. Good focus with GIRAFFE tends to fall in the range 1800-2100, depending on temperature. On the TCS, set the telescope focus to somewhere in this range. You can look in the scruffy A4 notebook stored in the "Log Books" section of the book shelf for a recent history of telescope focus values.
=='''Calibrations'''==
'''3.1 Camera Flats'''
Taking camera flats involves interacting with the components on the bench in the Coude room. '''Please be extremely careful not to touch anything except the flatfield screen and the lamp'''.
7) After readout, check the information box on the bottom left – if saturated pixels are reported, reduce the exposure time. Flats with saturated pixels cannot be used. If satisfied, save to disk.
8) Check image is transferred to the thin client ''ltsp.suth:/data/74in/giraffe/data/image/yyyymmdd'', and check header info to ensure it is your file (not an old file with the same name). If data is not found on ltsp, check ''/data/image/yyyymmdd'' on the giraffe PC, and call IT (**113) to set up image transfer to ltsp.
9) Expose and save 10 camera flats.
'''3.2 Fibre Flats'''
At the start of an observation, take ~7 fibre flats as follows:
'''3.3 Arcs'''
At the start of an observation, take 2 arc exposures as follows:
== '''Observing''' ==
'''4Acquiring a target''' Before attempting this, you should read about using the [[APD|APD]]. The shabby A4 notebook stored on the bookshelf contains previous "red marker" positions on which to locate a target with the guide mirror in beam. '''Current latest red marker coordinates:''' (218,50) on 23/01/2015. Note that this position shifts slightly after each instrument change, and when pointing far from zenith. To acquire a target: 1 ) On the TCS, with guide mirror in beam, place a red marker on the acquisition image in the previously recorded position (e.g. 218,50). 2) Point the telescope to the target and centre it on the red marker. 3) On QUARTZ "Control" panel, click "APD" to turn on the avalanche photodiode. 4) On TCS, move guide mirror out of beam, and "Go To" XY-slide position (590, -12900) to view the fibre. Target Set acquisition camera exposure time ~2s. 5) On "Piet's Old Laptop", run the APD plotter by clicking on the white arrow and wait for the counts to stabilise. 6) With the hand paddle switched to "Guide" speed, adjust the telescope pointing to centre the star on the fibre. You should see an illuminated disc on the acquisition image, which is the reflection of the star from the small mirror inside the GIRAFFE head (although after an instrument change you may not see this yet). The technique to centring the star is to make small movements of the telescope and use the rising/falling APD counts and brightening/dimming acquisition image to help you centre the star on the fibre. As the star becomes better centred, the APD counts will increase, and a bright disc will appear on the acquisition camera image. 7) Set up a guide star, as per the TCS manual, start target exposureswith QUARTZ, and keep an eye on the APD counts to ensure that the target isn't drifting off the fibre over time. '''Exposing on a target'''
1) Select “ND Pos 1” and “Mir Pos 1” in the QUARTZ “Control” panel
2) Type “*target_name” in the text box at the bottom left (e.g. *TPyx)
3) Click the “Expose” button in the “Control” panel on the right of the QUARTZ window and enter the exposure time.
4) After each object exposure, take Take an arcat the beginning and end of observing a target, and at ~20 minute intervals on that target. == '''Troubleshooting & avoiding trouble''' == * Do not touch the ''giraffe'' PC while it is busy with a procedure - especially during readout - as QUARTZ is likely to crash.* If QUARTZ crashes, and complains of a Merlin/transputer error, you will need to go to the Coude room, duck under the coolant pipe, locate the blue Merlin transputer on the shelf below the optical bench and press the ~central red button. Then restart QUARTZ.* If the orders do not match the requested prism position, initialise the prism with "Find ref" and move to the requested prism position again. You may have to repeat this a couple of times for the prism/camera to reach the requested position. == '''Instrument shutdown''' == * Ensure that the APD and all lamps are switched off.* Ensure that the fibre flat filter (silver knob on telescope) is out of beam, or you may forget it the following night.* Leave the QUARTZ software running (the technicians need to check the temperature of the detector during the day).* Stop the APD count plotting software and shutdown the windows laptop.* If the cryostat was last filled before midnight, please fill it before you leave.* Shutdown the telescope using the printed recipe, stuck to the shelf above the TCS.
