MEASURING the SKY - An Introduction to Digital Astronomy 2000-2001                                                                     Side 1 of 2

Name_____________________  Period _____                               

by Rick Kang, Public Ed./Outreach Coordinator
         Friends of Pine Mountain Observatory

The sky is a huge place filled with many objects that we are just starting to understand.  Due to modern digital imaging technology, you can join the professionals in the mission of exploration!

GOALS: by the end of our session you will be able to:
a. Operate a CCD Camera & explain how the camera works.
b. Measure digital data & draw conclusions about space.

1. Good news and bad news about gathering data from deep space:   Data comes to us in the form of ________________.    There are lots of photons because there are lots of ___________, which are ______.  But, due to the large distances, the photons _____  ______, making what we look at appear very _______.

2. Gathering data: two methods to collect photons:
a. _______________ gather photons over a large area.
       The mirror or objective lens gathers and __________ light.
b. Cameras gather photons over a __________  _____  _________.

3. Take some images with our Charge Coupled Device (CCD) Camera.  
These digital images can be ___________.

The CCD Chip is a grid of _________ - ___________ cells.
Within each cell, __________ are knocked loose by incoming __________.  Then the electrons are _____________.
Therefore, you can accurately measure the _____________ and ___________  of each tiny box within the silicon grid.
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MEASURING the SKY - An Introduction to Digital Astronomy   2000-2001                                                                        Side 2 of 2

4. What can we measure about the sky?

a. How are objects distributed across the sky?
       Can we easily count them?: _____   _____   _____   _____ 
    What do our results indicate? We live in a _____________.

b. Do some objects move relative to other objects?
     We need to ____________  ______  __________.
     An object that "jumps" position in a short period
         of time must be much _________ than the other
         objects.  This object could be an ____________,
         and is within our ___________ ____________.

c. What else may be "hiding" out there?
       More distant objects will probably appear ________.
       To view these objects, we should set our camera
         to gather photons for a ___________ period of time.
       With increased exposure time, we begin to view
         other ____________ way in back of the foreground
         stars of our own Milky Way galaxy.

       By measuring the brightness of a star or galaxy
       (photon count, after correcting for "noise" from the
       instrument and from the sky), we can start to figure 
       out the _______________, _____________, ___________,
       _________, __________, __________, and ____________ of
       an object far, far away! 

Check out the Hubble Deep Field image on the Internet, to see the farthest any human has yet seen into deep space!

We live in a really big Universe!