**Log In**
To Log In to this CLEA Exercise:

    1)  Select "File"->"Log In..." from the main menu.  The login dialog
    will appear.

    2)  Enter the appropriate name(s) in the fields provided.

    3)  The laboratory table number may already be set.  If it is not,
    or is incorrect, enter the correct table number.

    4)  Press "OK".  The selections on the file menu that control the
    exercise will be activated, while the "Log In..." selection will be
    deactivated.  (You cannot return to the login dialog after you have
    completed it.)

The information entered on the login dialog is used to generate names
for data files, and will appear on data and printouts that are produced
by the exercise. If you have entered no information, a box will warn you
of this when you press "OK".  If you select "Cancel" on the warning box
you will return to the login dialog.  If you select "OK" on the warning
box, the program will continue.  In this case, generated data and files
will be identified as "NoLog".

**Access Telescope Window**
In order to make photometric measurements of stars, you must access the
telescope window.  Select "File"->"Run" from the main menu and the
telescope window will appear, showing the telescope control panel.
There may be some delay at this point as portions of the program are
initialized.  Do not attempt to press buttons or make menu selections
until the message informing you that you have control of a telescope has
appeared.

It is not necessary to access the telescope window in order to load and
process data that has been saved previously.  See Help topic "Load Data"
under "Data Operations" for details.

**Telescope Controls**
The following buttons are used to operate the telescope.  They are
located on the left side of the telescope control panel.

    "Dome" - Press this button to open and close the dome.  This is the
    only button that is enabled when the dome is closed.  The dome is
    closed when a telescope is first accessed, and closes automatically
    when the user elects to change telescopes. (See Help topic "Change
    Telescope").

    "Tracking" - This button turns on the sidereal tracking that enables
    the telescope to remain pointed at a particular spot on the sky as
    the Earth turns.  When tracking is off, the stars will drift through
    the telescope field.  Tracking is off when a telescope is first
    accessed.  The other telescope controls are enabled only when
    tracking is on.

    "Slew Rate" - This button sets the rate at which the telescope moves
    when a slew button (N,S,E,W) is pressed.  The rate doubles each time
    the slew rate button is pressed, up to a maximum rate of 16.  The
    rate resets to 1 if the slew rate button is pressed when the rate is
    16.

    Slew Buttons ("N","S","E","W") - The slew buttons are used to move
    the telescope to point to a particular spot (direction) in the sky.
    To move the telescope, press and hold the appropriate button.  The
    telescope will slew at a speed determined by the slew rate setting.
    Release the button to stop the slew.  For long slews, the button
    will stay down if you slide the cursor off of it before releasing
    the mouse button.  In this case, stop the slew by pressing and
    releasing the mouse button with the cursor over any slew button.

    If you slew some distance from the original field center, you may
    encounter delays as the sky display is updated, which may require
    loading a new field file.  These delays can be fairly lengthy on
    slower machines.  The wait cursor (hour glass) will be displayed
    during these pauses.  Do not attempt to press buttons or make menu
    selections if you see the hour glass cursor.

    "Change View" - The telescope has two magnifications (or field
    sizes) available.  The "Finder" field is 2 1/2 degrees on a side,
    and is used for locating particular stars and other objects.  The
    "Instrument" field is 15 arc minutes on a side, and is used to
    center the object in the photometer aperture, which appears in the
    center of the photometer field.  (The small square in the center
    of the finder field shows the relative size and location of the
    photometer field.)  The photometer is enabled for use only when
    the photometer field is displayed.

    There may be some delay as the view is changed on slower machines.
    Do not attempt to press buttons or make menu selections when the
    "Changing View" message is displayed and/or the wait cursor (hour
    glass) is visible.

    "Set Coordinates" - Pressing this button activates a dialog which
    allows the pointing coordinates for the telescope to be entered
    directly.  This is generally faster than using the slew buttons to
    move the telescope from object to object, unless the objects are
    very near each other in the sky.  Some fine adjustments with the
    slew buttons may be necessary to center the object in the
    photometer slit after setting the coordinates.

**Request Telescope Time**
Access to the larger telescopes may be restricted.  You may request time
on telescopes that are not currently available to you (the selections
are grayed).  To request time, select "Telescope"->"Request Time"->
(telescope selection) from the main menu.

If your request is granted:
    You will be informed of the number of uses you have been given (the
    number of stars you can measure with the restricted telescope).  You
    may then access the telescope in the normal manner (see Help topic
    "Access Telescopes"), but a tally will be kept of your uses, and you
    will be informed when you have used up your allotment.  You may then
    request more time if you wish.

If your request is not granted:
    You will be informed that you may reapply after a certain number of
    minutes.  Until that time has passed you will not be able to request
    time on that particular telescope.  When the time has elapsed a
    message will appear informing you that you may reapply.  You may do
    anything else you wish, including requesting and/or using other
    telescopes, while waiting to reapply.

**Access Telescopes**
To change telescopes, select "Telescope" from the main menu, and then
make your selection from the "Access" list that appears.  If a
particular selection is grayed, you must request and be awarded time on
that particular telescope in order to use it (see Help topic "Request
Telescope Time").

When you have selected a telescope to access, the dome on the current
telescope will close, and there will be a pause while the system
attempts to access the telescope you have selected.  If the selected
telescope is available, you will be given control.  Note that you must
again open the dome and turn on the tracking before you can proceed to
make photometric measurements with the new telescope.  If the telescope
you select is restricted and you have been granted a limited number of
uses, you will be informed of your remaining uses before the telescope
is accessed.

**Change Star Field**
The "Field..." selection on the main menu accesses a dialog from which
you can select other star fields (if your exercise involves multiple
fields).  Note that the field cannot be changed unless the dome is open
and the tracking drive is on.

There will be some delay as the new field is accessed.  Do not attempt
to press buttons or make menu selections when a "Wait" message is
displayed on the screen and/or the wait cursor (hour glass) has replaced
the normal (arrow) cursor.

**Access Photometer Window**
You can access the photometer window only when the instrument (15 arc
minute) field appears on the monitor.  After you have carefully centered
the object in the photometer aperture using the slew buttons, press the
"Take Reading" button and the photometer window will appear. The
photometer window has its own menu to control taking and saving
photometric data of the object in the slit.  Note that some selections
from the main menu remain available when the photometer window is
displayed.

**Set Filter**
To change the active filter, press the button labeled "Filter" on the
photometer control panel.  The color-coded indicator will cycle through
the available selections.  Note that you must take a sky reading with
each filter that you plan to use. (See Help topic "Take Sky Readings".)

**Set Integration Seconds**
Press the button labeled "Seconds" on the photometer control panel to
set the duration of each integration (the length of time that the photon
counts accumulate when a reading is taken).  The selections range from
0.1 second to 100 seconds by factors of 10.  (See Help topics "Set
Number of Integrations" and "Take Photometric Readings".)

**Set Number of Integrations**
Press the button labeled "Integrations" on the photometer control panel
to set the number of integrations that make up a complete reading.  The
selections range from 1 to 5.  (See Help topics "Set Integration
Seconds" and "Take Photometric Readings".)

**Take Sky Readings**
You must take a sky reading through each filter before you can measure
the brightness of stars through that filter.  One set of sky readings is
sufficient as long as you continue to use the same telescope.  If you
change telescopes you must take a new set of sky readings, even if you
are returning to a telescope you have used previously.  Take sky
readings as follows:

    1)  Change to the "Instrument" view and position the telescope so
    that there is no star in or immediately adjacent to the red aperture
    circle.

    2)  Press "Take Reading" to access the photometer controls.  If the
    telescope is properly positioned, the box labeled "Object" should
    say "Sky".

    3)  Set the filter to the desired color.  (If a sky reading has been
    taken with a particular filter, the box labeled "Mean Sky" will
    contain the mean sky counts per second for that filter.  Otherwise,
    the entry will indicate "NO SKY!".)
 
    4)  Set the integration time to 10 seconds and the number of
    integrations to 5.

    5)  Press "Start Count" and wait for the readings to appear.  You
    will see the raw counts as each integration is completed.  When the
    reading is complete the mean sky count in that color will appear in
    the box labeled "Mean Sky".

    6)  Repeat for each filter you will be using.

    7)  Select "Record Readings" from the menu to save the sky readings.
    (You may not need to do this if the program is set to automatically
    compute the stellar magnitudes for you.  If you are computing the
    magnitudes yourself from the photon counts you MUST record the sky
    readings.)

(See other Help topics under "Taking Data".)

**Take Photometric Readings**
You must take sky readings before you can take photometric measurements
of stars.  When you have completed the sky measurements, take
photometric readings of stars as follows:

    1)  Roughly center the star in the red square on the "Finder" view.
    Change to the "Instrument" view and accurately center the star in
    the red aperture circle.  (If the star has a nearby companion, be
    sure to keep the companion outside of the aperture circle.  In this
    case the star you are measuring may not be well centered.)

    2)  Press "Take Reading" to access the photometer controls.  The box
    labeled "Object" may contain some identification of the star you are
    measuring.  It should not say "Sky".

    3)  Set the filter to the desired color.  (If the "Mean Sky" box
    indicates "NO SKY!" you cannot take a measurement in that color.
    Return to the telescope controls, move the star out of the red
    aperture circle, then return to the photometer controls ("Take
    Reading") and read the sky.)
 
    4)  Set the desired integration time and number of integrations.
    (Some trial & error may be required here - see Step 5 below.)

    5)  Press "Start Count" and wait for the readings to appear.  You
    will see the raw counts as each integration is completed.  When the
    reading is complete, the mean counts per second, signal to noise
    ratio, and computed magnitude will appear in the labeled boxes. For
    greatest accuracy, your readings should be reflect signal to noise
    ratios of 100 or more.  If you get a S/N of less than this, you
    should increase the integration time, number of integrations, or
    both, and take a new reading (don't record the old one).  (If your
    S/N is REALLY low, you may need to use a larger telescope to get
    accurate photometry.)  If your S/N is very high (> ~500), you may
    want to decrease your integration time and/or number of integrations
    on future stars of about the same magnitude to save time.

    6)  Repeat readings for each filter you are using.  Note that most
    stars appear fainter in the blue (B), and fainter yet in the
    ultraviolet (U), than in the visual (V).  This is due to the
    combined effects of stellar temperature and interstellar reddening.
    You may have to increase the integration time and number of
    integrations - always check the signal to noise ratio.

    7)  Select "Record Readings" from the menu to save the photometric
    readings.  IF YOU RETURN TO THE MAIN DISPLAY WITHOUT RECORDING THE
    READINGS YOU WILL LOOSE THEM AND HAVE TO REPEAT THE MEASUREMENTS!

(See other Help topics under "Taking Data".)


**Record Readings**
To record photometric measurements you have taken, select "Record
Readings" from the Photometer Window menu.  A dialog box will appear
with information about the object and telescope, and the readings you
have taken.  You may enter any notes or comments you want to record in
the box labeled "Remarks".  Press "OK" to record all the data.

Normally, you should not record the data for each color (filter) as you
take it.  Wait until you have measured the star (or sky) in all desired
colors. (Each time you record data you create a separate record, even if
the record contains data for only one color.  You might need to do this
only if you require very accurate timing for variability studies.)  Note
that the records are time-tagged with the Julian date to 6 decimal
places (about 0.1 second). This is the time the last measurement you
took (regardless of the filter) was completed.

    NOTE:  Recording your readings in this manner saves them internally
    for additional processing, but does NOT write them to a file.  To
    do that, you must return to the main display and select "File"->
    "Data"->"Save" from the main menu.  (See Help topics under "Data
    Operations".)

**Return to Telescope Window**
You should complete your photometric measurements of the star in all
required colors (filters) and record your measurements before returning
to the telescope window.  Select "Ok" to close the "Record Readings"
dialog (if you have not already done so), then select "Return" from the
photometer menu.  You will be warned and given a chance to cancel the
return if you have not recorded all the data you have taken.  When you
return to the telescope window your recorded data for the star you have
been working with is placed in a list in memory, but is not saved to a
file. (See Help topics under "Data Operations".)

**Load Data**
You can load a file of data that was previously created and saved using
this program.  This feature allows you to:

    o   Accumulate data over several sessions as part of a project.  You
        can delay computing and/or plotting the final results until all
        stars have been measured.

    o   Recover from a system crash, at least to the point at which data
        was last saved.

    o   Use a spreadsheet program or other means to calculate results
        and plot graphs.

To load a file, select "File"->"Data"->"Load" from the main menu, then
locate or enter the file name on the "File Open" dialog, and press "OK".
Before you attempt this you should be aware of the following:

    o   When a file is loaded, it replaces any data currently present.
        You will be warned to save first if you attempt to load over
        existing data.

    o   Any data generated after a file load is added to the loaded
        data in memory.  You will have to save it to keep the complete
        set.
 
    o   The format of the file to be loaded must be same as written
        (comma delimited text), except that string fields need not be
        enclosed in double quotes (").

(See other Help topics under "Data Operations.)

**Review Data**
To review data you have already generated or loaded, select "File"->
"Data"->"Review..." from the main menu.  A list entitled "Review
Photometric Data" will appear, from which you can use the mouse to
select individual records.  Once you have selected a record, you may
either edit it (press "Edit") or delete it (press "Delete").  If you
select "Edit", the "Photometric Data" dialog will appear.  This is the
same dialog that appears during the data-taking process.

When you have finished editing a record, press "OK" to return to the
"Review Photometric Data" list.  When you have finished reviewing all
records, press "Done" to close the "Review Photometric Data" list.

A list of the data in each record appears on the "Review Measurements"
display.  Fields shown (separated by vertical bars) include the
following: the object ID, the time tag (Julian Date minus 2,450,000.0),
the U, B, and V values, the data type (1=mean counts, 2=computed
magnitudes), the telescope (1=16", 2=1M, 3=4M), and the remarks field.

**Save Data**
To save all of your current data to a file, select "File"->"Data"->
"Save..." from the main menu.  The software creates a file name for the
saved data, and asks you to verify or change it.  (If part of your data
originated from an existing file that you loaded, the name of that file
is used for the save file.  If no previous file exists, the program
generates a file name from the first login name and the qualifier
".csv".)  If the file name you verify or provide already exists, you are
given the option of overwriting the existing file or providing a
different file name.

Saved data can be reloaded at a later time (see Help topic "Load Data"),
and can be analyzed and modified off-line, either with a text editor or
a spreadsheet program (see topic "Use Spreadsheet Program"), as long as
the original format is preserved.

The saved data is written in text form, one record per line, with commas
separating the values (comma delimited text).  String fields (in this
case, the ID and Remarks fields) and any empty fields are enclosed in
double quotes ("). This format can be read and parsed into individual
columns by most spreadsheet programs.  (But not all can write it back in
the same format - see "Use Spreadsheet Program").  Header information
and column titles are also written in this file as string fields and
will appear on a resulting spreadsheet.

You should save your data often, as a protection against system crashes.
You MUST save your data before you can print it (see Help topic "Print
Data").

**Print Data**
To print the exercise data, select "File"->"Data"->"Print" from the main
menu.  All records currently in memory are printed, along with
identifying header information and column labels.  Printing is
accomplished via Windows, employing the Windows Print Manager if so
specified in the Windows setup.  Output is directed to the default
printer, also specified in the Windows setup.

NOTE: To avoid any possiblity of data loss, the software will execute
the print only if the current data has been saved (see Help topic "Save
Data").  As an alternative, saved data can be read into a spreadsheet
program and printed from there (see Help topic "Use Spreadsheet
Program").

**Use Spreadsheet Program**
Computation of magnitudes (if required) and colors, as well as preparing
color-magnitude and color-color diagrams, may be facilitated by making
use of a spreadsheet program.  If a spreadsheet program is available for
your use, the "SpreadSheet" selection on the "File" menu will be dark
black.  (If this entry is grey, no spreadsheet program is available.)
The following outlines the steps to follow in using a spreadsheet:

    o   Take and record photometric measurements for all required stars.

    o   Save your data to a file ("File"->"Data"->"Save").  You will
        need to make note of the file name.

    o   Access the spreadsheet ("File"->"SpreadSheet").

    o   Load your data file into the spreadsheet (choose file type
        "Text" - qualifier .CSV).  Your instructor will assist you with
        this and other spreadsheet activities.

    o   If you are working with mean count data, use the spreadsheet to
        compute magnitudes.  You will need to utilize the sky counts,
        the telescope factors, and the measurements of standard stars
        (stars with known magnitudes and colors).

    o   Use the spreadsheet to compute the color indices B-V and U-B, in
        columns.

    o   Use the spreadsheet program to generate required plots, such as
        V vs B-V and perhaps U-B vs B-V.  You may have some difficulty
        getting the graphs to adhere to the astronomical convention of
        magnitude or color index values increasing downward along the
        Y-axis.  With some plotting packages the only solution is to
        plot the negative of the correct value.

    o   Print your completed graphs.  In some older spreadsheet programs
        this may require saving the graph and running a second program
        to print it.

    o   If so instructed, write the completed spreadsheet back out as a
        comma delimited file (in Excel, choose "File"->"Save As..." type
        CSV).

    o   Exit the spreadsheet (in Excel, choose "File"->"Exit").


