With such a diverse assortment of users, the CFHT instrument control system had to be designed so that it could be quickly and easily mastered by visiting astronomers, yet provide the power and flexibility that the engineering staff demands. We believe the challenge of providing such an interface has been met through the development of the "Pegasus" operating environment. Visiting astronomers can intuitively navigate with relative ease through the system because the basic tools they need are provided with simple menus. Pointing with a mouse and selecting an option is much less demanding, especially at 14,000 feet, than trying to accomplish the same task from memory with a command line interface. Redeye, like all of the CFHT facility instruments, is operated through a Pegasus session, hence observers who are already familiar with running any of the facility instruments can quickly learn how to use Redeye. In fact, observers who are already familiar with FOCAM should find running Redeye to be a very similar task.

• Instrument status icon: displays instrument device status after a motion order has been given.
• Array status icon (see Figure 6.2): provides information about a running Redeye exposure.
• Files status icon: provides information about files on disk or being saved to tape.
• IQE status icon: provides information about the image quality.

Currently no "help" is available on-line (read this manual!). We are planning to implement on-line help in the near future though.

• EXPOSE: form used to initiate exposures.
• FILTERS: form used to control Redeye filter wheels
• CAF: form used to operate the computer aided focus
• MODES: form used to set up automatic display and TCS enabling
• IMAGE: form used to display images with the SAOimage/CFHTimage tool.
• GRAPH: form used to display image cuts.
• IQE: form used to compute image quality.
• FILES: form used to manage image files on disk and tape.
• SUGGESTIONS: form used to send suggestions for improvements or fixes to the system manager.
• NEWS: delivers the latest news on the Data Acquisition User Interface and the instrument.
• ALOHA: form used to exit the observing session.

These main menu options are described in detail in the remainder of this chapter.

• Exposure type: object/bias/flat/dark
• Exposure time in seconds
• Number of iterations
• Median processing: on/off
• Object name: will be written to the FITS header
• Observer: will be written to the FITS header
• Comment: will be written to the FITS header

Once the fields have been edited/selected, take the appropriate action with one of the 4 "control" buttons. A "Redeye status" icon will then appear (Figure 6.2) displaying the file name that has been automatically linked to the image being acquired. This name has the form of a number, representing the exposure number in the CFHT archive system, followed by a small letter: "o" for object, "f" for flat, "d" for dark, or "b" for bias. The extension ".fits" is added to indicate that the data on disk is stored in FITS format. The file name is a crucial parameter for locating data, either on the summit disks while observing, or on the CFHT archive system. The status icon also shows the sequence number of the exposure (if you are running a sequence), the status of the array controller ("expose" when the array is integrating, "readout" when the data is being read out) and a count-down timer indicating the remaining exposure time. Also, a set of 5 buttons appear on the bottom of the icon. They offer the following actions:

• Stop: will stop the exposure, read-out the array, and create a file with the appropriate name. You can do this at any time during an integration. This will of course shorten the exposure time, depending on the time remaining on the timer.
• Abort: will abort the exposure with no array read-out hence discard the data.
• Hold: will stop the exposure, but will not read out the array. You can later use "restart" to resume the exposure. Although the total integration time is not modified, the array dark current will keep accumulating while the exposure is on hold. The total dark time is therefore the exposure time plus the hold time. The field "DARKTIME" in the FITS header of the array file will indicate the exact hold time. Note that if a 2.0+ m filter is used, the camera is effectively integrating on the back of the warm shutter during a "hold", hence the background will rise rapidly.
• Break: will break a sequence, the exposure currently being taken will be lost, and no further images will be taken in the sequence.

The IMAGE form allows the user to display the image of his choice. After selecting or editing the fields, clicking "Accept" will start a new process call SAOimage with the following attributes:

• File name: image to be displayed. "current.fits" refers to the last image acquired, while "previous.fits" refers to the image acquired just before the last one.
• Contrast: "Linear" or "Equalized Histogram". "Linear" will display the image scaled linearly between a minimum and a maximum value computed automatically or entered manually (see "Level setting"). "Equalized Histogram" will compute the image histogram, and select the display scaling based on the histogram mode. It is usually best for seeing faint objects in an image.
• Level setting: "Automatic" will compute the min and max values in the image and adjust the greyscale to map the full range of intensities. "Manual" will take the min and max values entered by the user to map the greyscale.

Images are displayed with SAOimage, a display package originally created by Mike VanHilst at the S.A.O. It is a stand-alone image display package with associated built in functions. The CFHT version, "CFHTimage", has been modified to incorporate a few custom features primarily associated with MOS/SIS.

Several different areas are evident in the SAOimage window. First, a large display area, which is where the image is exhibited with the best resolution. Two small display areas are also used in the upper right corner of the window. The small display on the left represents the full image in the memory buffer. If a green box is in this display, this represents which part of the entire image is being seen on the large display area (under pan/zoom). The small display on the right is a zoomed portion of the image around the cursor. Changing the position of the cursor in the large display area changes the magnified view in this small window. A menu bar above the large display area is available for controlling the program. A greyscale is presented at the bottom of the window. The greyscale coding will change according to any modification of the look up table. A set of cursor coordinates in the upper left window area is listed above the large display area. When SAOimage is opened from "IMAGE", the coordinate display (i.e., X, Y position and intensity value) will update as you move the cursor around the large display area.

Other useful features in SAOimage include:

• New: display a new image.
• Track: the small zoom window is updated as the cursor is moved in the large display area. This is set automatically when SAOimage is opened from "IMAGE" in Pegasus.
• Coord: coordinate display is updated as the cursor is moved in the large display area. This is set automatically when SAOimage is opened from "IMAGE".
• Print: send image displayed to the laser printer. This typically takes ~ 30 sec for a Redeye image on the summit Sparc printer.
• Quit: quit and kill the SAOimage process.

• Cutting Along: X axis to cut along an array row, Y axis to cut along an array column.
• Cut # (1-2-3): up to three different cuts can be displayed simultaneously on the grapher display. Clicking on the box below "Cut #" enables or disables the corresponding cut. For each cut you have the following options:
• File Name: the name of the file to be cut.
• Position of Cut: the row or column number of the cut.
• Width to Average: the number of rows or columns to be average into the cut.
• Subtraction Position: grapher will subtract the columns/rows identified by the subtraction position/width from the main cut defined above. This is quite useful for a quick sky subtraction from a raw frame.

GRAPHER is an interactive plotting program. The actual plot window opens after "Accept" is selected in the GRAPH form. It provides the following possibilities (see Figure 6.9):

• Plots: pop-up menu (press the left mouse button, and keep pressing while you browse through the menu) allows reconfiguration of each plot, including file name, cut location, and subtraction.
• Options: pop-up menu permits modification of the line type, computes statistics on the graph, or adds labels.
• Print: pop-up menu controlling print of the displayed graph to the summit or Waimea printers.
• Zoom: pop-up menu controlling a zoom factor from ¼ to 4.
• Show plot: by clicking on the appropriate boxes, enables or disables the display of the 4 possible overlaid plots.
• Scaling adjustment: the program automatically adjusts the X and Y scales by clicking in the "X scale" and "Y scale" boxes.
• Pan: by either clicking or dragging the black horizontal bar at the bottom of the window, it is possible to pan across the plot.

Values computed: This area of the form is used to select the desired computed values, using a list of check-boxes.

Background from: This list is used to define the background for FWHM computations. Values can be generated as the mean of the entire edge of the selected area, which is normal for images. For spectroscopic data, the use of the first and last X (or Y) values may give a better approximation of the actual background. Selection is via a radio button.

Other options: The FWHM values are usually computed based on the maximum pixel's X and Y coordinates. If the entire area selected is useful for the calculations, the "Collapse for FWHM/PWHM" may be selected. This may be useful for spectroscopic data.

IQE output: After the "Accept" button is pressed, the computed statistics are presented in a pop-up window, as text. After viewing the results, press the "Quit" button that appears across the bottom of the this output window.

• List FITS files: list the file names (default actions).
• List FITS Headers: list the selected files' FITS headers.
• Write FITS files to tape: write the selected FITS files to magnetic tape.
• Remove FITS files: remove the selected FITS files from disk.

The actual FITS files can be selected through several techniques using the FILES form. Specifically:

• One file: perform the selected action on only one file after entering the file name in the field reserved for it.
• All Files (default): performs the selected action on all the files in the directory.
• Already On Tape: performs the selected action only on files which have been saved to tape.
• Not On Tape: performs the selected action only on files which have not been saved to tape. If "All files", "Already On Tape", or "Not On Tape" have been selected, one can narrow down file selection further by selecting one or both of the following:
• File Type Override: performs the selected action only on the files with the file type of "o" for object, "f" for flat, "b" for bias, or "d" for dark.
• Range Override: performs the selected action only for the files with exposure numbers falling in the range entered in the two dedicated fields.

After selecting the desired files and action, pressing the "Accept" button will execute the desired action. As each file is processed, it is listed in a pop-up window. When the last file has been handled, a message is displayed confirming this fact and the pop-up window can be closed with the "Quit" button. As files are listed in this pop-up window, those that have been saved to tape will be surrounded by parentheses. It is suggested that the "List Files" action be used to verify that the files desired have in fact been selected and then bring the FILES form up again to perform any action.