Download Astron. J., 111

Astronomy 1020-H
Stellar Astronomy
Spring_2016
Day-4
Apollo-1 crew
STS-51-L Crew
Course Announcements
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Smartworks Chapter 1: Grades will be downloaded
sometime this weekend.
SW-2 … hop to it.
1st set of Dark Sky observing nights:
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Tues. Feb. 2 & Mon. Feb. 8 – 7:30pm at the observatory.
Tues. Feb. 9 is the weather backup if both are cancelled.
SDSS Site, telescope, camera
drawing, and coverage area.
SDSS Filters
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The SDSS filter system:
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Defined in Fukugita et al. 1996, Astron. J., 111, 1748
Magnitudes: u, g, r, i, z:
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Defined by Smith et al. 2002, Astron. J., 123, 2121
The SDSS-I spectrograph
Some SDSS figures
The First Lab
 In the first lab, you will explore the SDSS-DR7 data base (feel
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free to use DR-12 if you want – just let us know this) to see
what a variety of celestial objects (stars, galaxies) look like;
what solar system objects look like (asteroids); and what other
things look like (meteors, airplanes, “ghosts” – these are
caused by internal reflections from bright objects).
There are some comets in the data base, but the major planets
were avoided (too bright).
You will look for examples using the guide and give us
information about them (position, type, brightness).
There are about 400,000,000 objects in the data base, so you
will probably all have different answers.
The purpose of this lab is to have fun and explore.
The First Lab
 An example from the lab sheet:
 “A star with 15 < g < 18” – this means “look for a star whose
g-band magnitude (brightness) is between 15 and 18.
 “A very red star with r - z > 1.5” – this means “find a red star
whose color (r minus z) is greater than 1.5”
 In the next 3 slides, don’t let the “math” bother you, want
won’t have to determine any of this. It is shown if some you
have an interest to investigate further.
Brightness = Magnitude
 F2 
m2  m1  2.5 log  
 F1 
Note that this compares two stars. If a “zero point” is defined, then
m  2.5 log F  C
where C is the zero point offset
Color = Magnitude Difference
m  short  m long  color
• Where the two magnitudes are of the same object at two
different wavelengths ().
• By definition a color is the (shorter – longer) value.
• That is “bluer” – “redder”
Celestial Coordinates - Equatorial
 (Right Ascention) is
the angle around from
the Vernal Equinox.
Think LONGITUDE.
d (Declination) is the
angle above (+) or below
(-) the celestial equator.
Think LATITUDE.
Types of Objects - Galaxies
Types of Objects - Stars
Types of Objects - Airplane
DES image 505034 on 20151221,
Observers: Smith & Balbinot
First Activity
4 X 6 Card
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Name, major, year.
Astronomy experience (if any).
Why you’re taking the class.
What you hope to get out of the class.
What scientist, living or dead, would you most like to
meet?
Patterns
• We use patterns in our daily lives.
• Sunrise, sunset, moon rise, rainy season …
• Passage of time is important to humans.
• We can use the stars to help.
• There are 88 constellations in the modern sky.
• Semi-rectangular, recognized by the IAU.
• Northern : Latinized Greek-mythology names:
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Orion, Cygnus, Leo, Ursa Major, Canis Major
Southern : Latin names:
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Telescopium, Sextans, Pyxsis
Use the Big Dipper in the northern sky
as a way to find other groups of stars
Use Summer Triangle to find
constellations during evenings
Use Winter Triangle to find
constellations during evenings
Star Charts