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Physics

Telescope Operations FAQ

Q: Why has the telescope stopped responding to the commands from the computer?

A: A common reason this may have occurred is due to the telescope’s mirror system. The scope has a primary mirror and a secondary mirror to reflect light to the eyepiece. These mirrors rest inside the telescope, and there is no adhesive that binds the mirrors to the tubing. Therefore, the mirrors can fall out if the telescope tilts too far down. When the telescope passes a certain vertical threshold – usually a few degrees above the horizon of the dome – the machine triggers a failsafe. To fix this, one must use the hand paddle to reposition the scope back to a more vertical state. Once done, the telescope will most likely respond to the computer once again.

Q: I accidentally clicked Telescope Control twice! What do I do?

A: When this happens, the telescope gets very confused. Telescope Control is the brain of the operation – it knows where the telescope is in relation its last position before being shut off (which is why we always reset the scope to zenith before turning of TC). Therefore, if you click TC twice, the computer has trouble finding the telescope. To remedy the situation, turn the “Auto Dome” switch off and reset the rest of the switches. Then, position the scope with the hand paddle to zenith as best as possible and reset the system. Remember to sync the scope before observing.

Q: The dome won’t stop spinning! What do I do?

A: First of all, don’t panic – it happens. To counter this, use the hand paddle to move the dome to home position, and once there, flip the two dome switches on the computer. Reset the telescope control system and restart the computer if necessary. A common cause of this is a misstep in the set-up phase of observing. If you do not flip the “Motor Driver Chassis” switch before turning on Telescope Control, the dome will spin. Make sure that is ALWAYS the first switch you flip when setting up.

Q: Why do I see a big bright ring when I look into the eyepiece?

A: You are out of focus! When you see a ring in the eyepiece, it means that you have gone too far out of focus in either direction. To fix this, manually adjust the focus using the hand paddle until the object is clear. One trick is to view a familiar object – Jupiter, the Moon, etc. – and fix the focus on that point rather than an unknown object.

Q: The object I slewed to is nowhere to be found in the telescope field of view…

A: Once the telescope is set up, you have to sync the scope to the Sky’s atlas. Point it at a known object in the sky such a familiar star or a planet, and center the object in the eyepiece. To sync: go to telescope in the Sky6, then choose sync, and then choose the last option on the menu. Depending on how long you observe, you may need to periodically check the telescope to make sure it is still aligned.

Q: The dome moved on its own without command from the hand paddle or computer…

A: This is normal. The telescope will track an object as it moves across the night sky, and the dome is linked with the telescope. Once the telescope reaches the edge of the opening of the dome, the dome will adjust. In simple terms, the telescope always wants to be as close to centered in the dome opening as it can.

Q: Why won’t the dome hatch (lower portion) open?

A: There are a few reasons this may have occurred. First, check to see that the upper shutter has moved past the roller limit switches, and also make sure that the switch for the hatch is in the right direction. If these do not fix the problem, the dome mechanics may not be working, or the system could be frozen if the weather has been cold for a while (common in the winter). If you think one of these may be the case, email Steve Attinasi, the Natural Science Shop instructor with a message detailing the problem.

Q: When I use the CCD, my images have big streaks of white in them…

A: This is referred to as “bleeding”, and it is often a result of over exposure in an image. Decrease exposure time and try again.

Q: How do I focus the CCD?

A: To focus the CCD, use Telescope Control. Go to telescope and then miscellaneous. The optimal focal number for the CCD is 3003.