Especially during March 9-12, 1999 these pages will change rapidly. If you have questions or helpful suggestions you are welcome to email me: duncan@oddjob.uchicago.edu.

This Manual has three main sections:

Description of the Instrument (including sample spectra)

Observing

Data Reduction.

DESCRIPTION OF THE INSTRUMENT

Overview

Details of the optical design (will be linked to the WWW pages of designer Shu-i Wang)

Jump immediately to observations of:

• Flux (throughput) standard, the star HD84937
• Comparison (Th-Ar) lamp
• Solar spectrum

The "Observing" section is in two parts. The first describes the various windows you see on the screen and what they control.  The second gives some sample observing sequences.  Although there are half a dozen windows which present various information about the telescope and instrument, they are clear and straightforward, and you can expect to become an efficient observer within a few hours.  The few things I have found not intuitive or easy to get wrong are shown in red, to warn you.

Part I - Windows and what they control.

You or the telescope operator also need to specify where the data you take will be stored.  (Locally, at APO.  You can move it later.)  The default is a directory /export/images.  If you are observing more than one night, most people find it convenient to put each night's data in its own subdirectory, e.g. feb2, feb3, etc.  To do this, you will have to login to the MC in a telnet session and type e.g.:

• mkdir feb2
• chmod 777 feb2
• set imdir /export/images/feb2

Now start up REMARK (double click on its icon).  The first thing you will see is the "main" screen, which has two important panels which look like this:

These panels show you the status of the telescope and allow you to control the telescope. The upper part of the window shows RA and Dec, and a nice circular diagram which shows the entire sky, with a black dot indicating the position of the telescope.  When a new position is entered, a gray dot appears to indicate where in the sky the telescope will move to.  This is useful for e.g. determining the airmass of the next target you are thinking of moving to.

The lower part of the window, "OFFSET CONTROL," is used for guiding.  The offsets in X and Y are changed either with the mouse or keyboard. The units are in arc seconds. By using the mouse to click in appropriate quadrant of the Nudger, the telescope will offset in instrument coordinates by the amount set in the X and Y thumbwheels. Note that if you use the Nudger the signs are ignored because the quadrant you click on selects the direction. If you hit the 'offset' button, then the telescope will offset using the signs. Be sure to have the 'Rel(ative)' button selected so that each time you offset, the telescope will move relative to the current position. Great for guiding.

Go to the pull down menu called "Instruments," and select "Echelle." The following window will open at the top right of your screen:

Call this the Camera-Echelle Window. It is used to:

• Control exposure time
• Start exposures
• If necessary, STOP, PAUSE, or ABORT an exposure (the echelle can't respond during flushes or reads)
• Monitor an exposure's elapsed or remaining time and display in the digital indicator as well as the 'clock' pie chart (via a pie chart)
• Enter information which is stored in the COMMENTS keyword in image headers
• Control multiple exposures (useful for biases, flats, etc.)
• Select the type of exposure using the 'Function' popUpMenu (Normal, Bias, Dark).

You probably want to choose a root name under "Save Image As..." which indicates the the date of your observing run, e.g. "ech20299" for Feb. 2 in a Feb. 1999 run.  The root name stays the same until you change it, and the sequence number automatically increments, giving you a unique name for each exposure.  Most people save their data in FITS format, since the latest version of IRAF/SDAS (see "Data Reduction," below) works directly with fits files and eliminates the need to separately keep track of header and pixel files.

The current echelle system automatically identify flats or comparison exposures with keywords in the image header.
One warning: the RA and Dec stored with your data is what you type into the above window, not necessarily exactly where the telescope points.  (It is not read from encoders, for instance).  If you do some offsetting and/or searching, the position recorded with your data can be slightly off from the actual pointing.  The "OK" button closes the window. [This is not exactly true. We should check this with the current behavior of the telescope. The header should record an offset value from the reference position as well as the real RA/DEC of the current telescope position.]

Click the button "config" in the Camera-Echelle Window and the following will appear:

Call this the Echelle-Configuration Window.  It is used to:

• Change the flip mirror in front of the slit from Source (view the sky; flip mirror is out of the way), to Calibration (flip mirror is in, so it reflects down the slit whatever calibration is turned on).  You do this by making a the selection "Mirror" in the column Next Move, and then clicking MOVE.  Note that until you click MOVE, nothing changes.
• Monitor the configuration of the flip mirror and lamps, under the Current Status column.  Warning: The Current Status column, not the Next Move column, shows the actual configuration.  If, for some reason, the Current Status column does not change after you click "Move," something is wrong. (It takes a few seconds for motions to occur.)
• Turn off and on the various calibration sources, either the white (=flat-field=Qth) lamp or a  comparison emission lamp (Th-Ar).

The Guide Camera Window is used to:

• Specify the exposure time for integrations of the guider CCD camera
• Take an exposure which will be used as a bias frame for automatic subtraction. Click the 'Bias' button to take a bias exposure. If you do not want automatic subtraction, uncheck the 'Use Bias' button.
• Take a single exposure by clicking the "expose" button.
• Take continuous exposures  by clicking the "Autoexpose" button. The interval (in seconds) between exposures is set in the thumbwheel to the right of the "AutoExpose" button. This is used for guiding. It should be set to at least 5 seconds more than the exposure time although you won't break things if you don't do this.  Due to seeing fluctuations, most observers prefer to set an interval of about 10 seconds, to avoid chasing motions due to seeing.  Of course, if your target is faint enough, you may need even longer integration times than this.
• Set binning.  This is almost always left at 3,3 for the guide camera.
• Move an ND (neutral density) filter in front of the guide camera for bright sources. This control works the same as in the configuration window described above.
• Choose a subframe of the CCD for readout.  This is done for guiding, to get a faster response.  The entire frame 1536 x 1024 pixels, or 76.8" x 51.2" For acquiring objects, you probably want to use the entire field. To guide, click the box "Subframe." The square in the middle of the Guide Camera Window then gets a dashed-outline box, which you can move by dragging with the mouse (and resize by holding down the 'command' key on the keyboard and dragging a corner of the box with the mouse). The box determines which Subframe of the entire CCD gets read out. Note that a small black dot in the full frame display indicates the position and size of the slit (not shown in the example).