1. Observing

2. 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…

3. Observatory location

4. Observatory Location

8. Telescopes Reflector –24-inch (60-cm) mirror Refractor –6 inch (15-cm) achromatic lens

9. 24-inch

10. 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)

11. 6-inch

12. What to observe?

13. A BL Lac Object

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

15. Long term light curve

16. Makarian 421

18. 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)

19. Other possibilities Galaxies

20. Star Clusters M67

21. Gaseous Nebulae M42