Don McCarthy's Questions of the Week

Puzzle #1: Imagine you are sitting in a dark room, where you are handed a deck of 52 cards. Ten of those cards have been turned facing up; the rest are facing down. Your job is to separate the cards into two stacks, each containing the same number of cards facing up. Is it possible to do this?

Puzzle #2:

Don McCarthy's Questions of the Week

Puzzle #1: List a few reasons why astronomers prefer to observe objects at an "hour angle (HA)" within +/- 2. What angle does an HA=2correspond to from the "meridian"?

Puzzle #2:

Meeting Minutes and Preparation for Observing

• Dr. Yancy Shirley gave a presentation about observing star forming regions in the Milky Way. We will be working with Dr. Shirley on this radio observing project using the 12m radio telescope on Kitt Peak. If you missed the presentation, it can be downloaded here or here. If you would like to be a part of this project, email Amy at arobert @ email . arizona . edu.
• On April 17th, we will be going to Biosphere 2 to run astronomy activities for the public for their Earth Day celebration.
• We will be planning a trip to Flagstaff, AZ some time this spring to see the construction of the 4.2m Discovery Channel Telescope.
• We will not be meeting this week to talk to the Ouida Springer Elementary School Astronomy Club.
• Next week we will be forming committees for our projects to meet on a regular basis.
• The extrasolar planet project group will be meeting on Friday at 5pm in Steward Observatory room 204.
• We have received observing time on the 90" telescope on Kitt Peak on Saturday, February 27th. In preparation, we are working with Dr. Don McCarthy to learn some basics about observing at large telescopes. The next two meetings are mandatory for those planning on going on this trip. If you missed this week's meeting, please review these notes and come prepared to discuss the questions of the week posted below.
  

Don McCarthy's Questions of the Week

1. The focal ratio of the 21" Ray White Reflector is not published on Steward's Web site. How could you measure it?

2. The 61" telescope has a focal-ratio of f/13.5 and the ratio for 90" telescope is f/9. How do their plate scales compare?

3. Both the 61" and 90" telescopes also can be used at f/45 but neither telescope was built with this capability. Can you think of any reasons for wanting that focal ratio?