2 What Every Observer Should Know
2.1 Observing Conditions
2.1.1 Obtaining the best seeing!
The telescope may only be used when the observing conditions are favorable (Section 2.1.2). A checklist of the normal START-UP procedure is given in Appendix A.
The best seeing is obtained when the dome air is continuously flushed with the ambient air, and sources of heat are minimized. Make sure that the louvres and garage door are fully open and that the passageway doors are closed. You are also advised to park the vehicles by the 1.3 m building and to keep the air-conditioning or heating in the 2.4 m living area at reasonable levels.
The 2.4-m primary mirror is cooled (Chapter 10) to reduce the effect of "mirror" seeing. When the mirror is warmer than the ambient air, tube currents can deteriorate the seeing, adding 0.4" for every 1°C. Ideally, the mirror should be at the same temperature as the ambient air, but when this condition cannot be met it is best to have the mirror slightly cooler than ambient.
It is important to leave the mirror covers closed until you are ready to observe because the ambient air will be warmer than the mirror.
2.1.2 Limits on Observing Conditions.
You should stop observing whenever any ONE of the following conditions are met:
The relative humidity is measured inside the dome, near the eastern declination bearing. It is displayed on the air-conditioning control computer located in the computer room. Use this to determine if conditions are suitable to open the mirror covers.
The optics are aluminized every two years. Please do not spoil the performance of the telescope for everyone by obtaining data under conditions that might risk damage to the mirror surfaces.
A checklist of the normal SHUTDOWN procedure is given in Appendix B.
2.2 Weather Conditions
2.2.1 Weather radio
The National Weather Service forecast for the greater Tucson area can be obtained on the "weather radio", which is kept on the window sill in the lounge. This is updated approximately every 2 hours. A similar forecast from Phoenix is available by switching the frequency knob located under the unit.
A good, but not always up-to-date, means of monitoring the weather forecast is on the web. The MDM Weather Information web page is a good set of local, mostly reliable links.
2.2.2 MDM Weather Monitor
The instantaneous weather conditions on the south-west ridge are read by the MDM weather station which is located outside the 2.4m and the monitor is located just outside the computer room on the west wall. The following parameters are available:
2.2.3 What to do during bad storms
Kitt Peak is very susceptible to bad lightning storms, especially between July and September, and this has caused considerable damage to equipment in the past. If a lightning storm occurs close enough that it appears to be a possible threat:
The lightning shutdown procedure is also posted prominently in the control room. During lightning season make sure that you understand how to carry out the procedure in advance of the occasion for implementing it.
Heavy snow can fall during the winter months. Please make sure that the dome louvres are fully closed. Carefully check the dome for ice before opening the shutters . When lots of ice builds up on the power lines they often break (!) and power at the observatory switches over to an emergency generator.
2.3 Emergency Conditions
2.3.1 Telephone help
To summon help in case of a fire or medical emergency dial 8777, which rings a variety of numbers at Kitt Peak sequentially. If no one answers after a while, dial 8721, which patches to the hand-held radios that are carried by most of the mountain staff. Remember to dial # to disconnect from the radios before hanging up.
If the telephones are not working (no lights active) then use the backup cell phone located it the 2.4m lounge.
2.3.2 Emergency Radio
A Motorola portable radio is available in either telescope control room to call Kitt Peak in case of an emergency. Kitt Peak is on Frequency 1. Full instructions are given on the control room wall, near the radio. Please read them in advance if you are not familiar with the radio.
2.3.3 Emergency Generator and the UPS
When the commercial power fails an emergency generator automatically switches in. Please note that each dome has its own generator; the 2.4-m unit is located to the north of the building, just by the roadside (photo). If commercial power is lost both generators should be running!
All the critical equipment (telescope, computers, instruments, telephones) are kept on an Uninterruptable Power Supply (UPS). When power is lost the equipment on this supply (orange outlets in the control/computer room) is not affected. The emergency generator should start within 10 seconds.
This generator provides power to the UPS and some additional circuits. The television and other circuits in the lounge are not on the generator supply.
When commercial power is restored it will automatically switch back and the generator will stop. So under normal circumstances you don't need to do anything. But what happens if the generator fails to start?
If the generator fails to start the UPS will run for approximately 45 minutes on its batteries. You should check that the generator is running and that the generator power has switched over. To check this, see if the fluorescent lights in the 2.4 m workshop area are working. If not, the UPS is being powered by its batteries and you need to take action.
Figure 2-1 shows the front panel of the generator. Check that the toggle switch is set to REMOTE. If it is not then set it to RUN. The generator should now start; wait 15 seconds and then put the switch back to REMOTE.
If the generator stalls:
If the unit stalls again the engine may be overloaded:
If the generator is running but the fluorescent lights in the 2.4 m
workshop area are still out, then the generator power failed to
transfer. The transfer switch is located in the utility room off the
lounge. The red "emergency" light should be active when the generator
is running. If not, call for assistance.
Report all problems with the generator (even ones you eventually
fixed yourself) in a Trouble Report.
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Updated: 2006-12-01 (rab/mdm)