Imaging
Objectives
The students will use Browser Astronomy to take images of deep space objects in the southern sky.
Grade Level(s)
8-12
Vocabulary/Key Terms
Star
Telescope
Cluster
Galaxy
Constellation
A natural luminous body of gas visible in the sky especially at night
An optical instrument for viewing distant objects
Small group of stars
A large group of stars and matter found throughout the universe
One of 88 sectors into which astronomers have divided the sky—each named after its pattern
of stars—which contrasts with the traditional definition of a recognizable pattern of bright stars
Slew
To move a telescope’s focus rapidly from one location in the sky to another
Magnitude
A system used in astronomy to indicate the brightness of stars and other objects
Right Ascension One element of the astronomical coordinate system which can be thought of as longitude on
the earth projected onto the sky
Declination
One element of the astronomical coordinate system which can be thought of as latitude on
the earth projected onto the sky
Angular Size
A measure of how large the object actually appears to be to an observer, which is a function
of both actual size and distance away
Altitude
The angular distance from the observer's horizon measured directly up from the horizon
toward the zenith
Field of View
The angular extent of the observable sky
Materials
Computers with Internet access (one for each group of two to three students)
Computer with LCD projector
Telescope Imaging Plan instructions and data tables
Share the Skies Internet Telescope Observing Log
Stellarium planetarium software (open source program available at www.stellarium.org)
Images of the constellation Hercules, M13, or other constellation and star pairs
Procedure
Begin by showing students the image of the constellation Hercules. Ask the students what they know about this
constellation and the stars that are a part of it. Depending on the students’ ages and prior knowledge, you may get
responses about mythology, stars, galaxies, or telescopes. You may choose to tell the Greek myth of the constellation
below:
Hercules was the greatest hero in all mythology. He was the son of Jupiter, the ruler of the gods. When
Hercules was a baby (but a big one!), the goddess Juno sent two snakes into the crib. Hercules killed them both
with his bare hands, marking the beginning of his career as a hero.
Hercules married a princess named Megara (MEG ah rah). He served the king Eurystheus (U ris THEE us),
performing the twelve labors for which he is most famed. These included killing the poisonous monster Hydra
(HY drah), which could regenerate its own head, stealing the three-headed dog Cerberus (SUR bur us) from the
underworld, and killing a large dragon to obtain the golden apples of the Hesperides (hes PER ah DEEZ).
©Virginia Department of Education, 2008
The constellation Hercules shows him holding his club and with Cerberus, the three-headed dog. His foot rests
on the head of Draco (DRAY ko), the dragon. The constellation is huge—the fifth-largest in the sky—but rather
dim, which is an interesting parallel with Hercules himself. The hero was famous for his strength, but he was not
very bright.
Point out the “stars” visible with the naked eye within the constellation. Discuss briefly how telescopes have allowed us to
see more clearly into deep space; these “stars” are really different celestial objects such as clusters, galaxies, or nebula.
Show the image of M13, the globular cluster in Hercules.
Tell the students that you have reserved time on the Share the Skies Internet telescope located in Pingelly, Australia, so
that they may take images of celestial objects. Discuss the location of the telescope, the portion of the southern sky
available during the current season, the time differences, etc. Depending on the age and prior astronomy knowledge of
the students, you may choose to discuss right ascension, declination, zenith, field of view, camera settings, or other
astronomy topics.
Explain that each group of two to three students will be able to choose a target object and take several images of it for
study after creating a telescope imaging plan. Hand out and review the Telescope Imaging Plan.
This lesson should be spread over three or more class periods, depending on the number of students and computer
access. After introducing the topic, allow students to use the Web sites specified and the Stellarium software to research
and develop an imaging plan. Teachers should review the plans and assign imaging time in 15-30 minute increments,
staggered as students complete approved plans. Final images may be saved for further study or posted on the Share the
Skies blog.
Virginia Standards of Learning
Science
ES.1
The student will plan and conduct investigations in which
 technologies, including computers, are used to collect, analyze, and report data and to demonstrate concepts
and simulate experimental conditions;
 scales, diagrams, maps, charts, graphs, tables, and profiles are constructed and interpreted;
 variables are manipulated with repeated trials;
 and a scientific viewpoint is constructed and defended.
ES.3
The student will investigate and understand how to read and interpret maps, globes, models, charts, and
imagery.
ES.14
The student will investigate and understand the planets and other members of the solar system; the history and
contributions of the space program; and concepts related to the origin and evolution of the solar system, galaxy,
and universe. Key concepts include
 characteristics of the sun, planets, their moons, comets, meteors, and asteroids; and
 cosmology and the origin of stars and stellar systems (the Big Bang, the solar nebular theory, stellar
evolution, star systems, nebulae, constellations, and galaxies).
National Educational Technology Standards
NETS.1 Creativity and Innovation
Students demonstrate creative thinking, construct knowledge, and develop innovative products and processes
using technology. Students:
a. apply existing knowledge to generate new ideas, products, or processes.
c. use models and simulations to explore complex systems and issues.
d. identify trends and forecast possibilities.
©Virginia Department of Education, 2008
NETS.2 Communication and Collaboration
Students use digital media and environments to communicate and work collaboratively, including at a distance,
to support individual learning and contribute to the learning of others. Students:
a. interact, collaborate, and publish with peers, experts, or others employing a variety of digital environments
and media.
c. develop cultural understanding and global awareness by engaging with learners of other cultures.
NETS.3 Research and Information Fluency
Students apply digital tools to gather, evaluate, and use information. Students:
a. plan strategies to guide inquiry.
NETS.4 Critical Thinking, Problem Solving, and Decision Making
Students use critical thinking skills to plan and conduct research, manage projects, solve problems, and make
informed decisions using appropriate digital tools and resources. Students:
a. identify and define authentic problems and significant questions for investigation.
NETS.5 Digital Citizenship
Students understand human, cultural, and societal issues related to technology and practice legal and ethical
behavior. Students:
b. exhibit a positive attitude toward using technology that supports collaboration, learning, and productivity.
NETS.6 Technology Operations and Concepts
Students demonstrate a sound understanding of technology concepts, systems, and operations. Students:
a. understand and use technology systems.
d. transfer current knowledge to learning of new technologies.
©Virginia Department of Education, 2008
Telescope Imaging Plan
We have reserved access on the Share the Skies Internet telescope in Australia for the upcoming week. Each
group of three students will have the opportunity to pick a target object and take several images of the object
using the telescope. You may choose your object from one of the following sources:
Southern Deep Sky Objects
The Messier Catalog
The NGC/IC Project
http://ftp.seds.org/Messier/xtra/similar/albi-s.html
http://www.seds.org/Messier/Messier.html
http://www.ngcic.org
1) Begin by creating a list of ten objects you might be interested in observing in the Possible Observing
Targets table. You can use the deep sky objects listed on the southern sky map, the Web sites above, and
Stellarium to choose possible targets. Try to pick a variety of types of objects. Individual stars don’t make
good targets—they just look like tiny dots.
2) Determine the object’s catalog number(s), location, angular size or dimensions, apparent magnitude, and
visibility as well as its discoverer, if possible.
Could You Image It?
Your choice of objects is limited by (1) the location of the telescope—near Perth, Australia, (2) the time of night
we’ll be observing (they’re currently 12 hours ahead of us), and (3) the limitations of the telescope (its field of
view is 10’ x 15’; it won’t do well with objects fainter than about 11th magnitude).
Consider each limitation and write Y/N in the final column. The chosen objects must

Fit the field of view of our telescope (10’ x 15’). Note that if the angular size of the object is a
little bigger than the telescope’s field of view, you will probably still be able to get a good image. If
it is much larger or much, much smaller compared to the telescope’s field of view, you need to
pick a different object. Trying to image a 40’ object with this telescope is sort of like trying to take a
picture of someone’s face and ending up with a picture showing only their cheek.

Be brighter than 11th magnitude. Brighter is even better—10th & 11th magnitude objects are hard
to image if there is any haze or moisture in the atmosphere.

Be visible in the southern sky during the majority of our class time.
Develop Your Target List
In order to actually observe an object, we’ll also need to figure out the length of time we’ll be exposing the
telescope’s CCD camera to the light from the object.
1) Choose four of the objects that will be easily observable during class and write them in the Target List table.
If you don’t have four that are observable during class, you’ll need to go back and pick a few more before
moving on.
2) Copy the type of object, magnitude, and angular size for each from the previous table. Find each object’s
right ascension and declination using your Web resources.
©Virginia Department of Education, 2008
3) The best time to observe the object will be when it is closest to the zenith. If your object is within 15° of the
horizon, you will probably have trouble observing it. When the object is close to the horizon, you have to look
through more of Earth’s atmosphere—meaning you get more distortion from atmospheric turbulence. Use
Stellarium or your Web resources to record the altitude of each object at roughly the middle of the class
period.
4) The perfect exposure time for an object would show the full range of its structure to the best of the
telescope’s ability. It is determined by a HUGE variety of factors, including the diameter of
the telescope, its focal length, and the nature of the CCD camera in use. To detect the
faintest parts of the object, you want the exposure time to be long. However, if you make the
exposure time too long, you’ll saturate the detector—meaning that you’ve reached the
detection capability of the CCD camera and extra light detections spill into neighboring
regions of the camera. It will look like the star at the center of the picture shown. If the
weather is hazy, you’ll need to increase these exposure times.
5) The apparent visual magnitude of the object will determine the
best exposure time, within the constraints of the telescope we’re
using. You’ll be starting off with your estimated best exposure
time and trying out a variety of times to determine the actual best
value. To determine the best starting exposure time, use the table
and interpolate a good starting exposure time.
Apparent Visual
Magnitude
4
6
8
10
11
12
Starting Exposure
Time
1
5
10
30
70
200
With your group members, discuss the target objects. Consider the following in your discussion:
Which object has the highest altitude (will have the least atmospheric interference)?
Which object is the brightest (will yield the clearest picture)?
Which object do you find the most interesting?
Determine which object you will attempt to image first, and explain your reasoning on your sheet. If there is
enough time in class, you may have the opportunity to observe additional objects.
©Virginia Department of Education, 2008
Possible Observing Targets
Names_______________________________________________________________________________
Catalog #
Object Name
Type of Object
Discovered by?
Angular
Size
©Virginia Department of Education, 2008
Magnitude
Observable
in the
Australian
sky during
our class?
Could you
image it
with the
STS
telescope?
Target List
Object
Type of Object
Angular Size
Magnitude
Right
Ascension
Declination
Altitude
Starting
Exposure
Time
We will try to image _____________________________________________________________ first because
________________________________________________________________________________________
________________________________________________________________________________________
_______________________________________________________________________________________.
©Virginia Department of Education, 2008
Share the Skies Internet Telescope
Observing Log
Names _________________________________________________________________________________________
Date ____________________
Time _____________________
1) Begin by recording basic information about the telescope and its location.
Type of telescope: ____________________________________ Camera: _____________________________________
Location: ___________________________________________________ Local Time: ___________________________
2) Check and record the weather conditions.
Moon Phase: ________________________________
Humidity: ____________________
Is the Moon currently up? ______________
Dew Point: ______°F ______°C
Temperature: ______°F ______°C
The Cloud Sensor currently indicates it is ______________________________________________________________.
The weather over the last few hours has been __________________________________________________________.
3) Next, use the telescope to image your object with the starting exposure time you determined on your planning
sheet. Record the name of the object, magnitude, and the exposure time you used in the table below.
4) When the image is done, view the JPG. Save the file—be sure to save it in the Astronomy file in the folder for your
class period. When you save the file, you should give it a name like this:
YourFirstNames_ObjectName_ExposureTime.jpg. For example, if Bob and Anna took a 30 second exposure of the
Sombrero Galaxy, it would be named: BobAnna_SombreroGalaxy_30.jpg.
5) Write your initial reactions to the image in the table below.
6) Explore taking additional images of the same object but increasing or decreasing the exposure time. Be sure that
the change you’ve made is meaningful—i.e., if you took a 30-second exposure and want the image to be brighter,
you should increase the exposure time to 45 seconds (not to 31). Be careful not to saturate the detector when you’re
looking at bright objects. Repeat this until you have at least three different images of the object at different exposure
times and you’re happy with at least one of the images.
Object Name
Magnitude
Exposure Time
©Virginia Department of Education, 2008
What are your first impressions of the image?