The Observatory is located on top of T.S. Painter Hall on 24th street. The dome can be seen on the top of the building from the street. Take the southwest stairway up to the 5th floor and then follow the signs. Unlock the doors and inside the room, immediately to your right are two light switches. Adjust the brightness of the lights with the white knob (turned completely clockwise for dimming).
A. Removing the dust cover
The dust cover is located on the front lens of the telescope. Be sure the RA is unlocked and the declination is unlocked. Using the wheel on the pier, move the telescope in RA so that the weight moves until it is very nearly level with the telescope. Lock the RA, unlock the declination and move the front of the telescope down far enough so that you can reach the dust cover (be sure not to touch the lens). Remove the dust cover.
B. The Clock Drive
Inside the glass door on the west side of the pier is the clock drive mechanism. This drive compensates for the Earth's rotation and tracks the star you wish to observe automatically. The telescope is driven by a weight which slowly falls inside the pier. To wind the clock drive, turn the crank in the clockwise direction until you meet some resistance. Don't go any farther. Before you start observing, always check to be sure that the drive is fully wound.
To turn the clock drive on, push the switch on top of the mechanism from left to right. REWIND THE CLOCK DRIVE EVERY HOUR.
The clock drive is turned off by pushing the switch from right to left.
C. Opening the Dome Slit
To open the dome slit, first pull on the cable to the left of the pulley. This will unlock the slit. Then pull on the rope to the right side of the pulley and open the slit completely. Remember to re-hook the rope after opening the slit.
D. Turning the Dome
The wheel in the northwest corner of the observatory is used to turn the dome slit to whatever section of the sky you want to observe. To avoid breaking the lights in the dome, hook the slit rope on the hook to the left of the slit. Sometimes the dome will not rotate when you turn the wheel. You can usually correct this by rocking the wheel back and forth a few times. If this is not successful, close up and contact the observatory director as soon as possibly.
A. Right Ascension controls
There are two shafts which run parallel to the telescope. The one that has two black knobs holds the right ascension controls. The inner black knob is the right ascension (RA) lock. In the dark, you can distinguish this knob by the grooves which are located along its edge like the serrations on a quarter. The outer knob is the RA slow motion, which you can use to center a star in the field of the 9-inch. The big wheel on the north side of the pier turns the telescope in RA only. When turning the telescope with this wheel you should be sure that the RA is unlocked and that the declination is locked.
B. Declination Controls
The inner knob on the other shaft is the declination lock. The edge of this knob is smooth so that you can distinguish it from the RA lock in the dark. The outer knob is the declination slow motion.
C. Moving the Telescope
It is strongly advised that when you are moving the telescope though any large angle, you move it in one coordinate at a time and have the other one locked. Be careful not to hit the pier or the ladder while moving the telescope.
The counterweights should never be allowed to get higher than the pier; this means they should never be allowed to get above horizontal. You can check that this never occurs by monitoring the hour angle circle- the counterweights will be horizontal (even with the pier) when the hour angle reads either 12 or 24 hours. Typically, you will find the counterweights are about to go above horizontal if you move the telescope from the east to the west (or vice versa) without raising the counterweights above the pier. In such an instance, move the telescope in declination to 90 degrees. Then, you may move the telescope in RA until the counterweights are on the other side of the pier (which should now be close to the desired RA) and reset the declination to the required value. If you fail to observe this precaution, you may damage the telescope by running it into the pier.
** Do not use force on any of the telescope controls. This can damage the telescope.
Do not over-tighten the RA or Dec knobs.
A. Setting the telescope
After you have opened up, you will be ready to observe. You must start by setting the right ascension circle. Just as any place on earth can be defined in terms of its latitude and longitude, the position of any astronomical object can be specified by its right ascension (celestial longitude) and its declination (celestial latitude).
The RA dial has to be set each night and whenever the clock drive has been shut off. The dial is located on the north side of the pier, just above eye level.
To set the RA dial, pick an object whose coordinates are known, set the telescope on that object and then set the dial so that it reads the correct RA for the objects at which the telescope is pointed. On the wall beside the blackboard is a list of four bright stars and their coordinates. At any time of the year, at least one of these stars will be in the evening sky.
Vega ---- Summer, Fall
Betelgeuse ---- Winter, Spring
Sirius ---- Winter, Spring
You should check the RA dial occasionally when you move to a new object.
Also, remember that since the declination circle does not need adjusting, it is possible to use it to help find bright stars and planets. Merely turn the telescope to the proper declination, then sweep in RA until the star is found.
You can now use the setting circles to find any object whose coordinates are known and which is bright enough to be seen through the telescope (assuming that the clock drive was on when you set the RA dial). For example, suppose you wish to look at Beta Cygni, a double star.
You would proceed as follows:
1. Look up Beta Cygni's coordinates (19h 27m, +27d 45').
2. Unlock the RA and move the telescope until it reads 19h 27m.
3. Relock the RA
4. Unlock the declination and move it until it reads 27 degrees 45'.
5. Lock the declination. The star should be in the view finder.
A book which lists many interesting objects and their coordinates is Norton's Sky Atlas, a copy of which is kept in the observatory.
B. Locating the Star in the View Finder
Move the telescope over all large angles in one coordinate at a time, with the other coordinate locked, until the telescope is pointing approximately toward the object. You may then unlock both at once and align the telescope with the star and center it in the telescope.
C. Selecting an Eyepiece
The Erfle eyepiece affords a wide field of view and should be used first, so that you can center the star in the nine inch. Once this is done, you may wish to use a high power eyepiece. These may be obtained from the cabinet in the west part of the observatory. First, unscrew the Erfle from the telescope. Then screw the eyepiece mounted in the adapter into place. The power of each eyepiece is listed on a chart above the eyepiece cabinet. Also, for more easily accessible viewing, the diagonal can be inserted into the adapter first. The image of the object is focused with one of the two black focusing knobs located above the eyepiece of the nine-inch. The bronze knob is the focusing lock, and should be unlocked before you attempt to focus the star in. When the star is in focus (i.e., appears least diffuse), you may relock the focus. Camera adapters for prime focus pictures are also available in the cabinet.
A box is located on the north side of the pier contains the switched for the lights on the RA circle, the declination circle, and the hour angle circle. Throw the toggle switch to the right and push the appropriate buttons.
The following procedures MUST be followed in closing the observatory. FAILURE TO DO SO MAY RESULT IN LOSS OF OBSERVING PRIVILEGES.
1. Replace the dust cover on the telescope. Use a procedure similar to the one used in removing it.
2. Turn the telescope lights off by throwing the toggle switch to the left.
3. TURN THE CLOCK DRIVE OFF AND REWIND FULLY. This step is of extreme importance.
4. CLOSE THE SLIT AND LOCK IT. Turn the dome until the slit is facing the E (that way the slit can be seen from the astronomy dept. to check whether it's open or closed). The wheel should then be over the door. Make sure the rope is on the hook.
5. Put the Erfle eyepiece on the telescope.
6. Point the telescope towards Polaris (declination = 90 degrees)
7. Lock the declination.
8. Unlock the RA and move the telescope until the counterweights are aligned with the north side of the pier. They should be pointing straight down. LEAVE THE RA UNLOCKED.
9. Clean the room.
10. Sign the log book.
11. Turn off the lights and lock the door. Be sure to check that the door is locked before leaving.
This close up procedure is listed in the observatory. Read this list through to be sure that you will have done everything correctly before you leave.
Finally, here are some closing reminders on what not to do when using the telescope. These remarks are also found above the eyepiece cabinet in the observatory.
1. Don't attempt to fix the telescope if anything goes wrong; if you need help, get it from the observatory director or from a graduate student in the astronomy department.
2. Don't try to move the telescope in a direction when that direction's lock is engaged. This is one of the most common ways to damage the telescope.
3. Don't allow the counterweights above the main body of the telescope.
4. Don't turn the RA and declination knobs until you're blue in the face; once they're unlocked, they're unlocked, you need not turn them anymore.
5. Handle the eyepieces carefully; don't drop them or get fingerprints on them.
6. Don't touch or attempt to clean any of the lenses' surfaces, especially the main telescope lens.
The sign-up sheet is in RLM 15.220. Sign up for the telescope several days in advance so as to be fairly certain of observing on the night desired.
You may sign up for any period except for those which are marked PUBLIC NIGHT. There are generally three periods for observing on any given night:
A: 8 - 11 pm
B: 11 - 2 am
C: 2 - 6am
When signing up for a certain period, write down your name and phone number on the sign-up sheet. Do not sign up for more than two observing periods in a week.
The procedure outlined here is for students using the standard set of keys. These will be known as "standard observers". Non-standard key sets are those used by special arrangement with the department. Holders of non-standard sets will identify their status by writing "own keys" on the sign-up sheet, and therefore are to be excluded from the key transfer procedure. In what follows, the "observer" will only refer to students using the standard key set.
The "first observer" is responsible for picking up the keys to the observatory. The keys may be obtained in RLM 15.220 before 4pm on the day you are scheduled to observe. The "first observer" is the first person to observe on an evening or a weekend that uses the standard key set. This does not include other (non-standard) observers or the observatory director, who has a personal set. Do not depend on the observatory director to let you in on the public nights. The "first observer" should pick up the keys even if it is cloudy, or even if he won't observe so that he can pass on the keys to the next observer. The keys are transferred from one observer to the next one. It is strongly recommended that each observer make arrangements with the next observer to transfer the keys. The last observer on a week night, or at the end of a weekend, must return the keys to RLM 15.220 by noon the following day. Key transfer is totally the responsibility of the observers.