Observing

Next Tuesday

• We’ll meet at the observatory even if it is cloudy– If the weather is really bad (a foot of snow or

something) I’ll send an email changing the meeting place, but otherwise…

Observatory location

Observatory Location

Telescopes

• Reflector– 24-inch (60-cm) mirror

• Refractor– 6 inch (15-cm) achromatic lens

24-inch

Ritchey-Chretien

• A special kind of cassegrain telescope

• Gives good wide field images (but our CCD field of view will be limited to 11 x 11 arcmin)

6-inch

What to observe?

A BL Lac Object

• BL Lac objects are one of the family of active galactic nuclei, a group which includes quasars and Seyfert galaxies, among others

Long term light curve

Makarian 421

Reading assignment

• Read the section on Makarian 421 on the AAVSO web page

• Check the web/library for further info on BL Lac objects

• Give me (at the next class) a one page writeup on what is believed to cause the brightness changes of BL Lac objects (be sure to express this in your own words)

Other possibilities

• Galaxies

Star Clusters

• M67

Gaseous Nebulae

• M42