Celestial Coordinates

1
Celestial Coordinates

• Physical Astronomy
• Professor Lee Carkner
• Lecture 1

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Basic Information

• Professor Lee Carkner
• Office Hours MWF 230-330pm
• Office Science 208
• You will need
• An Introduction to Modern Astrophysics by
  Cengel and Boles, Second Edition (2007)
• Calculator
• Pencil and Paper
• Bring all to class each day

3
How the Class Works

• Read the material before class
• Do the homework and turn in at the start of class
• Go to web page and download lecture notes
• http//helios.augustana.edu/lc/ph330
• Web outline also gives readings and homework
• Fill in blank areas of notes during class
• Do the in-class activities
• Give 2 presentations
• One on a stellar object and one on an
  extra-galactic object (see sheet)
• Take the 2 exams and final

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Grading

• Two exams -- 40 (20 each)
• In Class Activities -- 15
• Can drop (or miss) three
• Homework -- 20
• Can drop (or miss) three
• Homework due at the start of class
• Can be handed in late for reduced credit, but not
  after the start of the next class
• Two class presentations 10 (5 each)
• Final Exam (Partially Comprehensive) 20

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Celestial Sphere

• Zenith overhead
• Meridian line running from north to south
  passing through zenith
• Horizon system
• Altitude (h) --
• Azimuth (A) --
• Only useful in one place at one time

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Equatorial Coordinates

• Declination (DEC or d)
• Measured in (degreesarcminutesarcseconds)
• Right Ascension (RA or a)
• measured in (hoursminutesseconds)
• 1 hour 15 degrees

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Motions of the Sky

• Once per day due to daily motion
• Objects move along DEC lines

8
The Sun

• Due to tilt of Earths axis, path of sun changes
  throughout year
• Can use RA of Sun to figure out when it will be
  dark

9
Motion in the Sky

• We generally can only find two kinds of motion
  (or distance)
• Transverse (in the plane of the sky)
• Radial (along the line of sight)
• Suppose we observe a star move a transverse
  distance q in the sky
• If the star is a distance r away, the actual
  distance it moves in the sky is
• Where D and r are in the same linear units and q
  is in radians

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Distance on the Celestial Sphere

• Note that circles of constant d vary in size
• (Dq)2 (Da cos d)2 (Dd)2

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Ancient Astronomy

• Instruments
• Concepts
• Results
• Calendars
• Distances to Sun and Moon

12
Copernican Revolution (1600AD)

• Instruments
• Telescope
• Concepts
• Laws of motion
• Results
• Heliocentric model

13
Birth of Astrophysics (1800s)

• Instruments
• Spectrograph
• Concepts
• Theory of radiation
• Results
• Stellar distances and compositions

14
Modern Astrophysics (1900s)

• Instruments
• Sky survey telescopes
• Concepts
• Results
• Expansion of universe

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21st Century Astrophysics

• Instruments
• Digital data handling and networking
• Concepts
• General Relativity
• Results
• Dark energy

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Next Time

• Read 1.3, 3.1, 3.2, 3.6
• Homework 1.8, 1.10, 3.3, 3.15a, 3.15b
• Download and print out lecture notes