Download AST-103L Fall 2001: Introduction to Starry Night In this exercise, you

AST-103L
Fall 2001: Introduction to Starry Night
In this exercise, you will learn some of the basics of the all-sky program Starry Night Pro that is
available on our lab computers. This is an extremely clever and useful program for amateur (and
some professional) astronomers. Later in the semester you will use this program to aid in some
of your observations and interpretations.
Objectives:
! Learn how to set up Starry Night for a particular night/observation
! Use Starry Night to take and analyze data
! Make finder’s charts
Equipment:
! Starry Night Pro (available on our lab computers)
! Lab notebook
! Calculator
Set-Up:
First, your instructor will give a quick demonstration of some of the features and capabilities
of Starry Night Pro. Then you will retire to the lab and complete these exercises using the
program. Record all pertinent information and details of observations in your lab notebook.
Clearly mark answers to discussion questions.
I. START-UP AND FAMILIARIZATION
When you first start up the Starry Night program, you should make sure the location is set
properly (Austin, TX, USA; N 30º17’, W 097º44’). The main control panel and date/time panel
should be open by default; open them if they are not. The date and time defaults to whatever the
computer thinks the current date and time are. Check these to make sure they are correct. Do not
forget to check if Daylight Savings adjustments are taken into account automatically or if you
must apply these corrections yourself.
Spend a few minutes just playing around with the menus and other settings like daylight
toggle on/off, horizon toggle on/off, search box, field of view, stars, planets, pointer tool vs.
compass tool, labels and information boxes on/off, update intervals, and other features. Also play
around with the date and time settings. Starry Night is capable of several thousand years of
precession and it is interesting to actually see what happens. When you are reasonably
comfortable with the basic functions, proceed to the next section.
II. BASIC EXERCISES
A. Set up on the current date at 7pm and face the western horizon (make sure the horizon is
turned on). It is probably best to use a larger field of view, approximately 100º or so. Use
the compass tool and measure the angular height of the Sun above the horizon. Record
the observation in your notebook. Using what you know about the rotation of the Earth,
at what time would you expect the Sun to set?
B. Set up on the current date at 9pm. Put the field of view on 100º and set the limiting
magnitude at +5 (this is the best we can hope to achieve with the naked eye here in
Austin with the city’s ambient light pollution). You may face any direction as long as the
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C.
D.
E.
F.
G.
Fall 2001: Introduction to Starry Night
horizon is turned on and you aren’t looking through it. Take a minute to slew around the
sky, noticing the numbers and types of objects that are visible. Now leave everything as it
is but change the limiting magnitude to +7 (can gain two magnitudes by using a good pair
of binoculars). View the same regions of the sky and take note of what you see. Repeat
again but with the limiting magnitude at +10 (this is usually possible even on a mediocre
night here in the city with a telescope like our 16-inch reflector and some standard
eyepieces).
Set up on the current date at midnight and locate Polaris. The field of view should be
wide (100º or so). Set an appropriate update interval and run the date/time up/down in
such a fashion that you can watch the motion of the sky over several hours. Describe
what you observe.
The ecliptic is especially important in astronomical observations. Turn on the ecliptic so
that it is projected onto your field of view. If you do not know what the ecliptic is, play
around with the program, turning things/objects on/off, etc. until you begin to see the
“catch.” If you already know what the ecliptic is, turn on the appropriate features and
convince yourself that you are correct. If you are, share your knowledge with someone
that doesn’t know, i.e. help your neighbor out.
Determine what constellation the Sun is in on your birthday this year. Does it matter what
time of day you check this? Where was the Sun on the day you were born? Does this
match your astrological (zodiacal) sign?
You want to observe M31 (the Andromeda Galaxy) tonight from here in Austin. The
instruments at your disposal are your eyes, binoculars, and the rooftop 16-inch reflector.
Assuming a 100º field of view for naked-eye observations, a 7º field for the binoculars,
an 0.5º field for the 16-inch, and appropriate limiting magnitudes, generate a finder’s
chart for each observation. [A finder’s chart is a map designed to locate a specific object
in a field. Astronomers take them to the telescopes to help them identify their objects so
they know they’re observing the right things.]
Now you want to look at the Great Nebula in Orion (it contains the famous Horsehead
Nebula) from here in Austin. You can observe any time, but you want the most
spectacular view, so you want to choose the optimal observing date and time. With the
same instruments and specs available as in Exercise F, decide what instrument(s) you
should use, when to observe, and generate the appropriate finding charts.
ANSWER THE FOLLOWING QUESTIONS IN YOUR LAB NOTEBOOK.
1. Are corrections for Daylight Savings Time applied automatically or manually?
2. In Exercise A, you predicted the time of today’s sunset. Your instructor will give you
the actual time of sunset. Compare this with your answer. How close did you get? If you
did not get the exact answer, speculate as to why this was the case.
3. In Exercise B, describe the changes in the sky, i.e. what do you notice about the
populations of objects visible in each instance?
4. In Exercise C, how does the sky change?
5. What is the ecliptic and why is it important?
6. Why does it not matter what time of the day/night you check to see what constellation
the Sun is in?
7. If the Sun was not in the constellation matching your zodiacal sign on the day of your
birth, why not? If it was, why might this be the case?
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Fall 2001: Introduction to Starry Night
8. Fasten your finder’s charts from Exercise F in your lab notebook. When and where
should I look for M31?
9. Based on what you did in Exercise G, when should you plan to view the Orion Nebula,
what instrument(s) should you use to look at it, and why did you choose these options?
Include the finder’s charts in your notebook.
III. INTERMEDIATE EXERCISE
If your instructor did not show you how to use Starry Night to generate an H-R diagram, get her
to do so now. Set up on the current date and time with a field of view of about 75º and a limiting
magnitude of +10. Locate the constellation Orion. Turn off the horizon and daylight as necessary
to view the “night” sky in that region. Generate the H-R diagram of that region.
ANSWER THE FOLLOWING QUESTIONS IN YOUR LAB NOTEBOOK.
10. When you actually observe them, the stars Rigel and Betelgeuse look about the same
size but Rigel looks blue and Betelgeuse looks red. Which star is hotter?
11. What kinds of stars are Rigel and Betelgeuse (i.e. white dwarfs, main sequence, etc.)?
12. Which is older?
13. What are the temperatures, B-V color indices, and absolute magnitudes of Rigel and
Betelgeuse?
14. If you have any knowledge of the spectral sequence and what an H-R diagram
illustrates, does the empirical data agree with what you might have expected just by
looking up in the sky? Comment on why or why not.
IV. WRAP-UP
You should now be able to complete similar tasks with little to no help (though you are always
encouraged to seek it when necessary). If you are hung-up on a particular function, ask a
neighbor or your instructor for assistance. Feel free to play around with the program and to come
and use it to aid not only in your observations for this class, but for independent observing. For
example, you might find it particularly useful for generating finder’s charts for objects that you’d
like to see, but may not be viewable during this semester. You can set up the program for the
optimal observation of that object, save and/or print out the chart, and then use it at the right
time.
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