SSP-4 Control and Data
Hopkins Phoenix Observatory
The SSP-4 can be used manually without
needing to be connected to a computer. Connecting to a computer has
its advantages, however. The computer software allows finer control
of the SSP-4 settings, automatic data acquisition and expanded dynamic
range (1 to 9,999 on the SSP-4 as opposed to over 1 to 64,000 with
Installing and Loading
The installation program is called setup_sssp4dataq.exe. This can
be downloaded from the Optec web site. Once loaded, click on the icon
(see Figure 1) to install the program. The program appears to require
at least Windows 95.
Program Installation Icon
Once the program has been installed make
a shortcut of the application program and put on the desktop. The
application program is called SSP4DATAA.exe (see Figure 2).
Application Program Icon
Using the Program
The SSP-4 Manual has a section on using the software, but it is very
misleading. The manual has information about a much lower level of
communicating with the SSP-4. The above program is much easier to
use and more intuitive.
Clicking on the Application Program Icon
(See Figure 2) will load the program and display the window seen in
Initial Program Display
First, if you wish accurate dates and times for the readings, make
sure the computer's internal clock is set for the correct date and
time. Next, click on the program Setup to display the program Setup
drop-down menu as seen in Figure 4.
Program Setup Menu
From the Setup menu:
Use this to set the program for your local time zone. This will allow
the program to report Universal Time for the data acquisition.
Most likely you will use Com 1.
The Messages: window should indicate the computer and SSP-4 are communicating
with a Connected message. This must be seen before proceeding. Until
the computer has successfully communicated with the SSP-4 the rest
cannot be done.
Unless the ambient temperature is warm, you should enter -40. The
temperature of the detector will be seen in the Temperature: window.
The display will be red as it cools down to the set temperature value.
If -40 cannot obtained due to too warm an ambient temperature, try
a setting of -35. Once the temperature has reached the set value the
number will turn green and the green light on the SSP-4 will illuminate.
Set up Filters
This allows you to arrange the order of and edit the Filter drop-down
menu. Normally nothing needs be done here.
Data that has been acquired can be saved as a text file. You can open
a data file that already exists or create a new one. Once created
data can be saved to it during the current session and new data added
in a future session. Note: This is not intuitive. To save data you
must have a data file open or have created a new one. Then you must
Save it and then Clear Data for the data to be put into the Data File.
Open Data File
To save the data select the Open Data File from the File drop-down
menu (see Figure 5). Select a current data file or create a new one.
Once the data file has been selected or a new one create any acquired
data can be saved.
You can clear the data from the computer display. This will save the
data to the data file.
This will quit the program.
Program File Menu
Once the program has been setup and is communicating with the SSP-4
the data acquisition settings can be set (See Figure 6). In Figure
6 all the data acquisition settings drop-down menus are displayed
for simplicity. In real life only one menu at a time can be displayed.
Data Acquisition Settings
the program runs through and displays the data from one set of readings,
you can then select a new Object or Filter. You can also change other
settings, but it is suggested for a given program star, comparison
star, and sky readings, the Gain, Integration and Interval not be
Whatever is selected here will be displayed with each set of data.
It is unclear as to just what the purpose and meaning of this selection
Select the object being measured for this set of data. Typically the
comparison star is measure first in both filters, the sky around the
comparison star in both filters, Next this is repeated for the program
star, then the comparison star again. Three sets of these are then
created with the program star bracketed in each set by the comparison
star readings. Make sure the Object is set correctly for what is being
Normally select either the J or H filter, depending on which filter
on the SSP-4 is being used.
While the Manual indicates you can type in values for gain, that seems
to not work and you must select one of the three values from the menu.
It is recommended to experiment a bit and use the highest gain for
all measurements that does not exceed a count of around 64,000.
The Integration time must be considered too and should also be held
constant. The display on the SSP-4 can only go to 9,999. Above that
the display will indicate an over range. However, the program can
display up to around a count of 64,000. While it is possible to switch
gains between different objects, it is recommended for highest accuracy
to keep the gain constant for all measurements during a session for
a given set of program data. At HPO we performed some gain linearity
measurements and determined the gain is constant to a few tenths of
one percent when switching gains. Unless there is a specific reason
to switch gains, keeping the gain constant will produce the best accuracy.
This is the gate time for the counter. Again it is indicted in the
manual you can make this whatever you wish, but in trying it appears
you can only use one of the three selections in the menu. Unless there
is a specific reason not to, it is recommended to use a 10 second
integration time for all measurements. This will smooth out fluctuations
caused by the scintillation of the star light.
You can select the number of measurements made for a given set of
reading. Typically 3 or 4 measurements are used.
This is a bit confusing, but selecting a trial count will display
the results in the messages window and not in the Main Data Window.
This can be useful in determining what gain and integration time to
use. However, it may be just as easy and provide a record if it is
displayed in the Main Data Window. Selecting slow (no idea why this
is called "Slow") will set the program for normal data acquisition
and display in the Main Data Window.
Once the settings are complete and the object is centered in the reticle,
the flip mirror is flipped out of the way and the start button selected.
The start will change to wait. Do not try to change any setting while
the wait is displayed. Doing so can produce strange results. After
all the readings have been taken they will be displayed as one line
of data in the Main Data Window along with the date and time and settings
used. By clicking the Notes button you can add comments for that line
of data. A new line of data will be shown at the top with the last
line moved down. If more lines of data are shown than can be displayed
the older data will be moved out of the window at the bottom. While
there are scroll bars for the window, they are non-functional. While
the data out of the window cannot be seen, it is still there and will
be saved to the text file.
Don't worry about getting the data listed perfectly. You can always
edit the text file after (in case there are bad readings or you forgot
to indicate a filter or setting change).
Sample Text File
DATA RAW OUTPUT DATA FROM SSP4 DATA ACQUISITION PROGRAM
UT DATE= 04/01/2005 TELESCOPE= C-8 OBSERVER= JLH CONDITIONS= Clear
MO-DY-YEAR UT CAT   OBJECT   F -----COUNTS------   INT
03-31-2005 12:46:41 VARIABLE H 04446 04425 04295 3 10 100   Test
03-31-2005 12:48:10 VARIABLE J 03200 03259 03238 3 10 100
03-31-2005 12:49:26 SKY      J 02426 02418 02425 3 10
04-01-2005 02:50:38 SKY      H 02423 02417 02399 3 10
04-01-2005 02:55:10 COMP     H 02654 02658 02654 3 10 100
04-01-2005 02:56:41 COMP     J 02511 02463 02414 3 10 100
04-01-2005 03:03:28 SKY      H 02151 02133 02169 3 10
04-01-2005 03:04:19 SKY      J 02061 02082 02085 3 10