LWS
Pre-Observing Checklist

The following routine is recommended to prepare for the night's observing.

Summary

Afternoon Procedure

Log in

  1. Log in.

    2. Log into the data-taking computer (haleiwa in Remote Ops I) using the account name and password provided by your Instrument Specialist (who will be listed on the telescope schedule). The following windows should appear on your leftmost screen:
  2. Start Netscape.
  3. Check instrument availability.
  4. Prepare logsheets.

Start up LWS

  1. Start up the LWS software.
  2. Execute the LWS startup script.
  3. Verify windows.

    4. You should now have the following windows on your display: Feel free to re-arrange these window to suit your personal taste; however, note that you can't drag windows from one screen to another.
  4. Disable DCS Simulation Mode.

    5. In the LWS Auxilliary window, type the following command to determine the status of the DCS simulator: 
    check_dcs_mode
    If you receive this response: 
    You are talking to the REAL DCS
    then the simulator is already disabled and you may proceed to the next step. If the response instead reads 
    You are talking to the DCS Simulator
    then turn off the simulator by typing the following command in the LWS Auxilliary window: 
    make_dcs_real
  5. Start data acquisition system.

    6. Begin taking data in order to enable use of the real-time data monitoring software:
    1. In the Xpose/LWS window, click on the Show... to display current values of various datataking parameters.
    2. Click on Set Mode to bring up the mode menu, and click on Video to acquire continuous data.
    3. A window will appear warning you that the chopper is not engaged. Click on Acquire w/o Chop to avoid starting the chopper.
    4. Verify that the box in the upper left of the Xpose/LWS window changes from "not acquiring" to "acquiring."

Configure QuickView software

QuickView is the real-time data monitoring and analysis system for LWS.
  1. Click Dynamic Display to enable real-time updates.
  2. Click Non-Accumulate to turn off accumulation.
  3. Click Raw DC Frame to display a single readout. Since the chip is not yet on, you should see a pattern of vertical stripes representing the output levels from the four amplifiers in the ADC chain.
  4. Click Chop Difference to display the difference between consecutive image pairs. This should be a pure noise frame, with some pattern noise possibly visible.

Turn on LWS

  1. Turn on detector temperature control. The detector must be maintained at a constant temperature of 8.5° K in order to obtain useful data. To run the heater:
  2. Home motors. Upon startup it can be wise to home the motors. To do so:
  3. Wait for detector to reach operating temperature. Monitor the detector temperature via the dettemp readout window on XLWS. The temperature should rise slowly until reaching the nominal operating temperature of 8.5° K. Once this temperature is reached, it is safe to continue to the next step and supply power to the detector.
  4. Power up dectector.

Check the background level

Measuring the flux received from the background of the mirrored sector wheel will help determine whether the detector is functioning properly.
  1. Configure LWS for imaging.

    2. Take the following actions in the XLWS window: This rotates a mirrored blade of the sector wheel into the beam and will cause the detector to look back into the dewar.
  2. Change QuickView display.
  3. Plot a line cut.

Take a series of darks.

  1. Prepare spectrograph.

    2. In the XLWS widget, click on the Dark aperture selector and then click Set to select the dark aperture.
  2. Take test exposure.
  3. Verify image writing.

    4. In the LWS Auxilliary window, type the command cdata to go to your data output directory and list recent files. There should now be at least one image there; check the time to verify that your last image was properly written to the disk.
  4. Take a series of darks.

    5. Inspect the first dark frame using QuickView. If okay, then take additional dark frames by typing the following command in the LWS Auxilliary window: 
    goi 10
    Substitute the desired number of exposures for 10.
  5. Repeat for other frametimes. Different observing modes require different detector frametimes, as described in the LWS Recommended Instrument Settings web page. It is advisable to take additional sequences of dark exposures for each detector frametime setting you plan to use.

Create and verify target lists

  1. Create, format, and install your target list (``starlist'') as described in Creating and Installing Starlists for SKY.
  2. Verify the formatting of your starlist using the SKY program as described in the Using SKY page.
  3. If the accuracy of your coordinates is suspect, use SKY to display the Digital Sky Survey image of your LWS field as described in the Using SKY page.

Coordinate with the OA

Observing Assistants cutomarily arrive at the summit (or HQ, if remote controlling) around 5:30pm. Once s/he arrives, you can do the following:
  1. Greet the OA.

    2. Check whether your PictureTel link is muted, as indicated by a mute symbol labeled NEAR on the TV. If muted, press MUTE on the PictureTel control to un-mute. Introduce yourself to the OA and alert them to any special needs that you will have.
  2. Wait for the OA to get settled.

    3. Setting up computers and bringing up all of the telescope control systems requires some time, and things go wrong much more often than we would prefer. Please be patient while the OA prepares the telescope for operation.
  3. Inform the OA about your starlist.

    4. Now would be a good time to let the OA know where your starlist is, so s/he can verify access to it.

Get dinner

You're tired and hungry and there's a long night ahead. Better get out the folder labeled Restaurant Dining Guide and select one of our fine local eateries to provide you with sustenance.

Evening Procedure

Start guider eavesdropping

Guider eavesdropping allows you to monitor the image from the guide camera in real time. To start eavesdropping:
  1. Log into pupukea (the single-headed workstation in between haleiwa and onomea) using your numbered LWS account.
  2. If you have already started any graphical programs on pupukea (e.g., Netscape, Xmet, FACSUM) you must quit them before starting the guider eavesdropping program. This is necessary in order for the guider display to obtain the needed colors from the colormap.
  3. Select the Guider Eavesdropping option from the OpenWindows menu.
  4. Select the Eavesdrop (default) item from this menu. The guider display and accompanying tkrose window will appear shortly. Once the display is active, you may continue to the next step and can re-start other software which you killed.

Start FACSUM

The ``Facilities Summary'' or FACSUM window is a real-time display of the telescope status. To run FACSUM:
  1. On pupukea, select the DCS Status option from the OpenWindows menu.
  2. Select the FACSUM Display item from the DCS Status menu. The FACSUM window will appear shortly.
  3. Click and drag left mouse on one of the window corners to expand the window to fill the screen.

Start Xmet

Xmet is a meteorological display showing current summit conditions. To run it:
  1. On pupukea, select the DCS Status option from the OpenWindows menu.
  2. Select the Meteorological Display item from this menu. The Xmet window will appear shortly.

Check mid-IR conditions

The ``tau'' statistic tracks the amount of airborne water vapor above Mauna Kea and is a good indicator of current conditions in the mid-IR because atmospheric transparency at these wavelengths is determined by the atmospheric water vapor density. Click here to check the current value of tau, and multiply the resulting value by 20 to estimate the amount of precipitable water vapor (in mm). Note that tau values below 0.05 (i.e., less than 1 mm of precipitable water vapor) indicate acceptable conditions for observing at 20 µm.

Home sector wheel

 Ensure that the sector wheel is out of the beam. In the Sector area (at the upper right of the XLWS window), click on SET to get a pop selection window then click HOME/OPEN and SET. Wait for the move to complete.

Open ZnSe Window

If observing conditions permit (i.e., primary mirror temp minus dewpoint is at least 10°C), open the ZnSe window to reduce the background flux. To do this, find the ZnSe window controls on the XLWS gui. Click on OPEN and then SET.

Wait for dome to open

The Observing Assistant (OA) is not permitted to open the dome until after sunset. Please be patient while the shutter opens and the OA checks the initial telescope pointing.

Verify coning status

Remind the OA to check that "coning" is enabled on the secondary mirror. This option repositions the secondary to account for LWS being off axis. Failure to set coning would degrade your image qaulity.

Select a focus star

After preparing the telescope, the OA will ask you what object you would first like to observe. Customarily, the first thing to do is to focus the telescope. To do so, first select a star from the IRTF standards list (in starlist file /kroot/starlists/000_IRTF) which lies near to the position of your first science target, then tell the OA the name of the star you want to focus on, and the name of the starlist file. The OA will first acquire one or more faint stars near the target to check telescope pointing, then will acquire your focus star in the guider and point LWS to the target.

Initialize chopper

Acquire the focus star

Focus the telescope for LWS

The Xfocus program is used to focus the telescope:

Acquire first science target

Now that you are in the right area, have all software set up, and have focused the telescope, you are ready to begin observations. You may now proceed to the observing checklists.

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Last modified: Fri Jul 19 16:55:39 HST 2002