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