Download Planetarium Activity 1 Learning to measure brightness and Limiting

Planetarium Activity 1
Learning to measure brightness and Limiting magnitude
February 14, 2008 2:25-5:25
Instructions: In this exercise you will determine the accepted names for the brighter stars in
several familiar constellations by distinguishing between degrees of brightness and using the
Greek alphabet. You will also be deriving a technique for determining the magnitude of stars and
limiting magnitude for any night.
Things to review before you come:
Constellations, naming conventions of stars in constellations, apparent magnitude, and
magnitude scale, Greek Letters
Task 1
Instructions
1. You will be shown five popular constellations (Ursa Major, Cassiopeia, Leo, Ursa Minor
and Orion) fix their position in the sky when the lights are off so that its approximated
location can be found as the lights brighten. Use dots to Sketch the constellations on your
worksheet and connect the stars with dash line.
2. As the lights are raised the first time, note the relative order in which stars in the
constellations disappear.
3. The second time the lights are raised, number the stars (on your worksheet) in the order
of their disappearance. This step will be repeated several times if you are unsure of
differences between stars of similar brightness.
4. Assign Greek Letters to the stars in each constellation in the order of their brightness. The
name of the Greek letter plus the name of the constellation is the name of each star.
Task 2
1. Determine the limiting magnitude on five clear nights; that is, determine the magnitude of
the faintest star visible. To do this, simply count the number of stars visible within the
Great Square of Pegasus (or an alternate constellation) and find the limiting magnitude
from the following table.
2. Record your results on the worksheet.
Number of Stars
Visible
1
2
3
4
5
6
7
8
Limiting Magnitude
4.4
4.6
4.7
4.8
5.1
5.3
5.4
5.5
Number of Stars
Visible
10
12
13
18
23
25
30
37
Limiting Magnitude
5.7
5.9
6.0
6.1
6.2
6.2
6.4
6.5
Name:
Planetarium Activity 1
Worksheet
Date:
Time
Questions for Task 1
1. Describe the rule used to name the brighter stars in the constellations. One constellation
is an exception to this rule. Described how the stars in these constellations are named.
2. The magnitude of Beta Leo is given in catalogues as 2.2. Using this as a guide, estimate
the magnitude of the other stars in Leo which are shown on your worksheet.
Identification Magnitude
1.
2.
3.
4.
5.
Identification
6.
7.
8.
9.
10.
Magnitude
3. Beta Pictoris has been known to contain objects around it. What can you determine about
the location and brightness of this star?
Table for Task 2
Night
1.
2.
3.
4.
5.
Date
No. of Stars
Limiting Magnitude