Observing at Drexel

This page describes technical details about using the telescopes at Drexel. Included below are "How To" guides for the telescopes and camera.

Telescopes

Celestron NextStar 5 inch Schmidt-Cassegrain

Meade 8 inch Schmidt-Cassegrain

Meade LX200 16 inch Schmidt-Cassegrain

The big boy lives inside the dome and is, quite obviously, NOT portable.

Telescope Dome

The dome that encloses the Meade 16 inch telescope is located on the roof of Curtis Hall. Go all the way to the 4th floor at the back end of Curtis and keep going up the stairs, past the rifle range.

Three lights are controlled from inside the dome: (1) An outside light for the deck, which is also controlled from a switch on the wall inside the door to Curtis (turn OFF!), (2) a regular white light inside the dome (OFF during observing), and (3) a red observing light (this can be ON while observing). There is also a very small red flashlight to use while observing. Get used to working in the dark. It takes about 30 minutes for your eyes to become dark-adapted and you restart the clock every time to turn on the lights again.

Controls for opening/closing the slit are on the wall of the dome. Be careful opening the slit - if you open it too far, it may become jammed! It "coasts" a bit after you stop running the motor, so stop before it's fully open. The pull handle is only to be used (gently) for observing objects near the zenith. One person pulls the handle to release the latch while the other carefully toggles the slit motor. When closing the dome, gently lower the upper part of the slit until it re-latches on the extension.

Rotate the dome using the motor control on the wall. As the dome rotates, the power cord swings across the dome. WATCH IT and do not allow the cord to catch on anything (the telescope, the finder scope, you).

Eyepieces

Selection of an eyepiece determines the magnification (equal to the ratio of telescope to eyepiece focal lengths) and field of view for visual observing. We have eyepieces ranging from 6.4mm to 40mm, yielding magnifications from 635 to 100, respectively, on the 16inch (quiz: what's the range on the other telescopes?). 26mm is a reasonable choice for starting out.

The eyepieces are expensive and relatively delicate, because they have several optical elements and their glass is soft. Please be gentle with them. No juggling.

CCD Camera

The camera is a SBIG (Santa Barbara Instruments Group) ST-9XE. The imaging chip is a 512 X 512 array of 20 micron pixels. On the 16 inch telescope (160 inch focal length at f/10), each pixel subtends 1 arcsecond (quiz: how large are those same pixels on the 8 inch or 5 inch telescope?), so the field of view is 8.7 arcminutes.

There are two "nosepieces" for the camera, 1.25 inch and 2.0 inch. On the 5 inch and 8 inch, the camera connects to the telescope with the 1.25 inch nosepiece by sliding into the eyepiece tube, held in by only a thumbscrew. On the 16 inch, use the 2.0inch nosepiece on the camera, and secure the camera into the backend of the microfocuser using two thumbscrews. Be very careful not to drop the camera!

Don't drop the camera or leave it on the bus unless you have a few kilobucks you'd like to part with.

Observatory Laptop

The camera is controlled by a Macbook laptop via a USB connection. Images are stored to the laptop for later upload to your machine for analysis. We are currently using the Equinox Image control software.

Set Up and Shut Down Procedures for the Joseph Lynch Observatory

See the open/close procedure document.

Using Autostar on the 16 inch

See the user's manual for the 16 inch.

Safety

Carefully read the procedures for safe telescope operation.

How to Find and Focus on an Object

How to Take a CCD Image

Binoculars

Back to the Physics 232 home page

Last update: 20 September 2007