Three_C Getting Started Run the program called three_c by typing three_c and Enter. You will first of all be asked whether you have run planner for the current date. The procedure is different here than with the 18-inch system. There the nightly data are stored under different files by using the calendar date as the file name. Here data are always stored to the same files. Since different nightly coordinates will be computed for the stars, different catalogs will be used from night to night, and basic calendar information depends on the night, it is important that you know that planner has been run. A "yes" response allows you to proceed, while a "no" will terminate the three_c program. After a "yes" response the program asks for the initials of the user. Start and stop times for the observing run will be stored on an observing log along with the user ID at the end of the run. Three_c now reads the nitefile and starfile files that planner has created and then displays Reset Time 1. Read the Most Accurate Clock 2. Set the clock manually Selecting option 1 (either by placing the highlight bar on this option and pressing Enter or by pressing 1) directs three_c to reset the computer clock using the Heath Most Accurate Clock. The procedure for reading the MAC takes a minimum of one second, so be patient. Selecting option 2 brings up the additional screen Enter hour : ** Enter minute : ** Enter second : ** Press ESC to abort Press ENTER to set, After filling in the entries and pressing Enter after each entry, a small overlay window informs you to press Enter to set the time. Now you have arrived at the main menu of three_c. The tracking motor should now be operating on the telescope. The visual cue that it is tracking is the YM-25! = displayed in the upper left hand corner of the screen with the Y blinking and changing color. The character is the ASCII character code 13 (CR) and the is the ASCII character code 10 (LF). A pop down window will appear such as Stars Now Up Lambda Sgr W Ser V356 Sgr 161242 S 171624 S RZ Oph 184790 S ß Lyrae 196395 S V1507 Cyg This is a selection set box. The cursor will be on the first entry (Lambda Sgr in this case). Use the HOME and END keys to select the star you wish and press ENTER. The list contains all objects from your catalog that are presently in the sky at altitudes greater than 20° sorted in order of set time. Only the first ten stars meeting these conditions are displayed, but the window scrolls if there are more than ten stars to list. After you have made your selection, several windows will change as explained below. The telescope will be moving from the HOME position (refer to the definition of HOME above) to the selected star, the filter wheels will be turning to the first filter, the dome will be rotating, and the offset stages will be moving to positions appropriate for the comparison star and sky positions.