The ESI GUI (Graphical User's Interface) controls all aspects of the instrument including the CCD. The main functions are:

• Set the "Observing Mode": Echellette, Low-D, or Imaging.
• Choose the CCD format (binning, windowing, no. of amplifiers, etc.).
• Focus the spectrograph.
• Turn calibration lamps on and off.
• Select the observation type ("ObsType" on the GUI): object, bias, dark, line, internal flat, dome flat, sky flat.
• Open or close the hatch cover.
• Select exposure times and initiate exposures.
• Select filters or slits.
• Bring up various informational and diagnostic panels.

All these tasks (and a few more) are handled through a single "Dashboard" GUI.

6.1. Starting the Software

In the OpenWindows desktop menu is a submenu called "ESI Control." In this submenu the first selection is "*** Start ESI software." Select this to start all of the various components of the software. This will start:

• The esicon control and status panel (Fig. 10)
  This can control some of the software pieces, but is in practice mainly used as a status display for the various software components shown under "Remote MUSIC Services." You should see blue lights to the left of each of these components. If you don't, consult your support scientist.

Fig. 10. The "esicon" control and status panel.

• Electrolog
  This is an electronic log facility that is customizable and automatic. It has some bugs in it, and in general observers find it more satisying to keep traditional paper logs. However, the electronic log can provide a useful backup to your paper log.
  
  
• Readout Complete notifier
  Similar to the audio notifiers used on LRIS, HIRES, and other Keck instruments, this allows you to select a sound to be played when an exposure ends and/or an image finishes reading out.
  
  
• Dashboard
  The ESI control and status GUI, described in detail below.

6.2. GUI top level

The Dashboard GUI itself is multilayered; Figure 11 shows the topmost level.

Fig. 10 The Dashboard GUI, shown in midexposure, with the next spectrograph setting ready to go. Note that the GUI is still evolving, so it may not be represented exactly by the figure.

• The menu bar and single-line status field at the top.
• Blocks representing the state of the instrument, including both motors and detector.
• A region below this which will contain the status of motor moves and CCD exposures and readouts. (With nothing happening, this region is generally blank.)
• Towards the left are eight important buttons with various functions.
• To the right of those is the exposure control area.
• Near the very bottom is a long "Exposure progress" bar.
• At the very bottom are a couple more buttons and, in the middle, a summary of the current exposure.
  
  

6.2.1. "Start Here!"

On starting the GUI you will usually have a yellow-background button 2/3 of the way from the top toward the bottom and towards the left side. This is the recommended starting place. Clicking on this button pops up a screen used to set general options for the night, like the data directory, default filename, and observer name. A directory is created auutomatically for you, on the data disk with the most space available and using the UT date of the night's observing (which before 2 p.m. HST is not the current UT date!). The observer name is set by default to your username (e.g. "esi1"); feel free to change this.

Also available is the "Initialize Instrument" button. Usually the instrument will have already been initialized, but this button allows you to return it to a known state. If you need to initialize the instrument click on this button. The process takes about 4-1/2 minutes.

Once you have viewed and dismissed this screen, the button will change to a neutral color and rename itself "User Config". Normally it will be in this latter state once you are observing; we have shown it above in its initial state just for demonstration purposes.

6.2.2. Instrument State

We will return to the menu bar, but of more immediate interest is the current state of the instrument. Rectangles are used to represent various motors/stages/functions, from the hatch (left) through the lamps, the triple wheel, the large optics stages (represented by "Observing Mode") and collimator focus to the CCD on the right.

The general philosophy of this GUI is that both actual values (the instrument's current state, shown by the text boxes on the top of the blocks) and desired values (what you plan to change the settings to, represented by the pull-down menus on the bottoms of the blocks) are shown. The Move button "commits" your desired values, moving motors and setting parameters until the actual matches the desired. Multiple desired values can be set and then committed all at once. No changes are made until the "MOVE" button is clicked. The motor moves all occur in parallel.

As mentioned, each major subassembly of the instrument is represented by a rectangle, through which a simplified "light beam" passes (blue in the figure above, red if the light is from an internal calibration lamp). In Figure 10, the light beam passes by the open hatch. This is the only block that stays down when it is "open," and stays up, blocking the blue beam representing starlight, when it is closed. Clicking on the arrow allows you to select the desired state.

The actual settings of the triple wheel show two Clear_I positions and the V filter, indicating the observer is currently taking a V image. The Observing Mode is "Imaging". The collimator focus is 50,800. "FCS OFF" in the middle of this block indicates that the open-loop flexure-compensation system if turned off. (Normally it is on all during observing.) The ObsType is "Object", meaning the software is expecting settings consistent with light from the sky, and the exposure time is 180 seconds. The CCD is set to read out in dual amp mode; note both "L" and "R" beneath the "Amps" label. The rightmost block gives the CCD detector temperature. If this drops too low it changes to a bright blue, and if too high to red.

6.2.3. Changing Settings

The second line of text is actually a set of menus, from which the user can select the next instrument setting. Simply click the menu and choose from the listof names provided. In this case the observer has chosen an Echellette mode setting, with the 0.75 arcsec slit. Any time a desired setting differs from the actual setting, the desired button lights up yellow. If any of the stages differ, the Move button also lights up yellow. To actually move the stages you must click on the Move button. In the figure above the Move button's text is actually greyed out, indicating that you cannot move the stages during an exposure. Once readout starts or is complete the Move button becomes active again.

The CCD is handled in a separate but similar fashion. This is to allow you to change certain CCD parameters before readout begins, such as the windowing, the number of amps, and the exposure time. When changes are requested for such CCD-related parameters, the "UpdateCCD" button turns yellow, and must be clicked in order to actually set the parameters. In particular, the Object name can be changed at any time before readout. Type into the "Object" text field and it will turn yellow, indicating a requested but unfulfilled change. In this field only, simply moving the mouse out of the box sets the object name. Note that you can change the object name at any time up to the capture of the FITS header; at this point in the exposure cycle the entry box becomes inactive and does not revert to normal function until the header capture is complete. By then it's too late to change the OBJECT keyword for that image.

To adjust the exposure during readout you can change the time in the "desired" part of the CCD block. Remember to hit "UpdateCCD" or the small button labeled "ETime" which will appear below the exposure time box if you change the value.

The "Observing Mode" box actually represents two stages: the slide containing the echelle grating and the low-D mirror, and the slide containing the moveable prism and the imaging mirror. Since each of the three modes requires specific settings of these slides, it makes sense to group both of them into one block.

Some changes will affect blocks other than the one you selected. The most common case is when you select "Echellette" observing mode. This also selects "Decker" for the middle wheel. Note also that selecting ObsType of "Object" will select an open hatch (although of course it will not move the hatch unless the "Move" button is hit).

When motors are moving, the rectangles representing those stages will drop out of their normal position, and will not regain their normal alignment until the move is complete. A "MOVING" status is also shown below the block. The CCD again behaves slightly differently; it will change colors during the erase, expose, and readout parts of an exposure, with the corresponding text appearing below the CCD block. (Note the bright green color of the block and the word "EXPOSING" beneath it.) The progress of the exposure is shown not only by the box labeled "Time Remaining" but also by the progress bar near the very bottom. In this figure the exposure is a little more than halfway done.

6.2.4. Initiating an Exposure

When you are satisfied with your instrument setup, you can start an exposure by pressing the Expose button. The rectangle that represents the CCD will change visually as the exposure progresses, and status messages ("Erasing," "Exposing," and "Reading out") appear below it. The full CCD takes 12 seconds to erase and 39 seconds to read out in dual-amp mode. At the bottom of the GUI, a wide exposure progress meter shows the "percent complete" of the current exposure. A bold indicator in the exposure control area show seconds remaining.

6.2.5. Setting the CCD

From the top-level GUI the only CCD parameters you can change are the exposure time, the ObsType, the object name, and the readout window. The ObsType is an important button, not just to add FITS keywords to the header to make data reduction easier, but also to control the shutter and some of the logic in the GUI. You must select an ObsType of "Dark" to take a dark frame!! When you do, the background of the "Expose" button turns black as a visual reminder that the shutter will not be opening.

As some measure of protection against forgetfulness, the GUI has some rudimentary knowledge about what seems to make sense and what does not. For example, if you have a "Dark" selected yet the hatch is open or an internal lamp is on, a pop-up will warn you that this seems to be inconsistent. Note that in no circumstance does the GUI prevent you from doing anything! But perhaps you meant to take a lamp or object exposure and forgot to select the new ObsType. Or perhaps you meant to take a dark but forgot to close the hatch or turn off the lamps. The pop-up allows you to identify mistakes like this early in an exposure, so that if necessary you can abort the exposure, fix the problem, and start a new exposure with little lost time.

6.3. GUI lower levels

Double-clicking any of the blocks representing stages or functions brings up a "details" panel, which allows access to more detailed information and control. An example is the "CCD Control Panel", obtained by double-clicking the CCD block. Shown below, it is this panel which lets you change CCD binning, number of amplifiers, and windowing, among other things. There are two main sections to this panel. On the right are the current settings for a number of CCD and readout parameters, including the data directory, filename prefix, and disk-write flag. (These latter three are also available through the "User Config" button on the top-level GUI.) Buttons on the right and bottom reveal menus that let you change the CCD gain, readout speed, number of amplifiers, and whether or not you save non-image pixels. As throughout most of the GUI, if you change one of the "desired" settings there is a button (labeled "Go" on this panel) which you need to click to initiate the changes.

On the left of the CCD Control Panel is a sort of "workspace" where you can type in binning and/or/ windowing parameters. The labels provide a brief explanation of the parameters; this is meant to be more user-friendly than typing in the five window parameters on the right hand side (second parameter from the top). When changes are made to the left side of the panel the "Set" button lights up and is used to commit the changes. The changes will then show up on the right-hand side.

Note also the "QuickFrame" button in the workspace area. This allows easy access to two of the most common windowing choices: full-frame and an imaging window for the facility filters. The button is also available on the top-level GUI, on the far right side to the right of the "Object" text field.

The subpanels for motors contain mostly diagnostic information. They do generally show the named positions and a bar representing the current setting. This bar will move when a change to that stage is made. The lamps panel is accessed somewhat differently, by clicking the small icon representing the lamps and selecting the menu item "Panel". The buttons on this panel are immediate on/off switches; there is no "Move" or "Go" button. If, on the other hand, you select a lamp by selecting one of the other menu items, the "Move" button on the GUI lights up and you must hit it to effect the change.

Double-clicking the "Focus" block brings up a panel which shows the three collimator motors, but also has a button labeled "Set FC Mode" which can turn on or off the open-loop flexure compensation correction. If you see "*FCS OFF*" in the middle of the top-level Focus block, double-click the block to bring up the subpanel and click on "Set FC Mode". Then click "on" to start the flexure compensation. Note that the FCS requires knowledge of the telescope's elevation and the rotator position angle. These are generally not available until around 4 p.m. (HST) in the afternoon, when the swing techs start up the telescope software for the night. Another useful diagnostic of the FCS state is found in the detail panel, by looking at the three sets of keywords on the right side. The top three (the "FLX" keywords) should be within a few hundred of (0, -3000, 0). If they are exactly (0, -3000, 0) then the FCS is not working properly, or the telescope has not been initialized yet. The next set ("USR") should always be zero. The bottom set ("OFF") should be between -4 and +4 when operating properly. (They can deviate from this during telescope slews.) If the telescope is not slewing and these numbers are in the hundreds, then the FCS compensations are not getting all the way down to the collimator; seek out your Instrument Scientist for help.

6.4. Other Buttons

The button labelled "Tricorder" brings up a subpanel which shows environmental telemetry from ESI's sensors. This is generally used only for engineering. The "Help" button brings up a brief description of how the GUI works. "User Config" lets you turn on or off disk writing, select a new data directory, filename prefix, frame number, or observer name, initialize the instrument, and set audible alerts (keyboard bells) for taking exposures. In the lower left you can choose whether to block motor moves only during an exposure (allowing them to start immediately on the start of readout), or during both the exposure and the readout.

"TV Guider" brings up the control panel for the acquisition/guide camera. Here you can select different TV filters and focus settings, turn power on or off, and home (initialize) the two TV stages. This may become important during the night if there is a problem with the guider which requires power-cycling. The OAs have access to similar features on their ESI panel. One thing to note is that, at least currently, when you insert a filter into the TV beam, it does not automatically change the focus. There are setup files for setting to a different TV filter, but you probably want to leave this up to the OA. (The OA also needs to know when you are changing TV filters during observing so that they can pause guiding if necessary. Currently the TV filter wheel contains a neutral density filter, and BVRI filters.

The "Clear Desired" button, as its name implies, sets all of the "desired" settings to the actual settings, so that there is no requested changes pending. Use this when you have gotten the desired settings into a confused state and want to start over. "Previous Config." resets to the last settings. This can be useful for changing back and forth between one setup and another. "Move" has already been described and "STOP" is used to immediately halt all motor moves.

In the CCD control region, "StopExp" brings up a subpanel which allows you to immediately abort an exposure (throwing the data away), or stop an exposure, and read it out. It also has a button which lets you close the subpanel without doing anything; the exposure will continue as if you had not clicked the StopExp button. UpdateCCD has been described, as has "Expose". Note that once an exposure has started, the "Expose" button changes to read "Pause". This will allow you to pause the exposure countdown and close the shutter. If you do so, the button changes to read "Resume". Or, if you feel that you should read the CCD out, you can at that point select "StopExp" and "Stop exposure...". Remember that even though the shutter is closed and the exposure paused, the detector is still collecting ion hits! The "QuickFrame" button has been described elsewhere.

6.5. User Setups

It is possible to save configuration as "setups" which can be called by name. There are some standard predefined setups already in place for ESI. These can be accessed via the "Load..." button in the upper right of the GUI. As an example, selecting "Bimage" will load a set of desired values for the imaging mode: the "Clear_I", "B", and "Clear_I" for the upper, middle, and lower wheels respectively, the correct collimator focus value for the B filter, and the default imaging window for the readout.

To make your own named setup file, configure the instrument and CCD as you wish, then click the "Save..." button. Both facility and user setups should be stored in the "setups/" subdirectory on your home disk on kanaha.

Note that a powerful way to use setup files is to read in the files you will expect to use during the night. Then, click on the "Load..." button and then the "Configurations" option. This will bring up a window that contains a summary of all of the loaded setups. To change to a particular setup with a single click, just press the "Move" button at the top of that column on the window. Motors will start moving to the desired configuration immediately. If you choose you can instead click the "Load" button, which will merely load the desired settings. A pop up window reminds you to click the "Move" button on the main GUI window to apply the settings.