Astronomy Picture of the Day – 16 Jul 06

“The center of our Galaxy is a busy place. In visible light, much of the Galactic Center is obscured by opaque dust. In infrared light, however, dust glows more and obscures less, allowing nearly one million stars to be recorded in the above photograph. The Galactic Center itself appears on the right and is located about 30,000 light years away towards the constellation of Sagittarius. The Galactic Plane of our Milky Way Galaxy, the plane in which the Sun orbits, is identifiable by the dark diagonal dust lane. The absorbing dust grains are created in the atmospheres of cool red-giant stars and grow in molecular clouds. The region directly surrounding the Galactic Center glows brightly in radio and high-energy radiation, and is thought to house a large black hole.”

[taken from http://antwrp.gsfc.nasa.gov/apod/ap060716.html]

REU Summer 2006: KSU SRT Project

Ashley K. Wheeler

Mentor: Dr. Tim Bolton

Outline

• Why radio astronomy?– What is radio astronomy?– Versus optical astronomy?

• How are radio waves emitted?

• Basic Schematic• Resolution• Summary, pre-REU

Outline, cont.

• REU– Software– Sweeps/ Waveforms– Aliasing

• What is it?• Why is it a problem?

– Data Comparison– Baselines and Averaging– Possible Sources

Outline, cont.

• What’s next?– Software– Mounting

• For More Information

Why radio astronomy?

• What is radio astronomy?

• Versus optical astronomy?

[figure borrowed from http://www.disp.duke.edu/~dbrady/ece371/notes/l2/spectrum.html]

How are radio waves emitted?

• Black bodies

• Ionized gas clouds

• Change in energy states and masers

• Electron plus magnetic field (non-thermal)

• Moving magnetic field (non-thermal)

Basic Schematic

Resolution

• = 1.03/D = 1.03(c/)/D

• 0.02575 radians, or about 1.5 degrees

Summary, pre-REU

Sat finders and tees

REU

• CNVTWFM

• Moved the dish outside

• 1st sweep – Jun 20th, 2006

REU, cont. 1345 FFT

-120

-110

-100

-90

-80

-70

-60

-50

-400.00E+00 5.00E+08 1.00E+09 1.50E+09 2.00E+09 2.50E+09

Hz

dB

1345 Signal

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.00E+00 5.00E-08 1.00E-07 1.50E-07 2.00E-07 2.50E-07 3.00E-07 3.50E-07 4.00E-07

seconds

Vo

lts

REU, cont.

Aliasing

REU, cont.

Data comparison

Jul 20 Sup

-75

-70

-65

-60

-55

-50

9.50E+08 1.05E+09 1.15E+09 1.25E+09 1.35E+09 1.45E+09 1.55E+09 1.65E+09 1.75E+09

Hz

dB

m

noon

one

two

three

four

five

six

seven

eight

25 Jul Sup

-75

-70

-65

-60

-55

-50

9.50E+08 1.05E+09 1.15E+09 1.25E+09 1.35E+09 1.45E+09 1.55E+09 1.65E+09 1.75E+09

Hz

dBm

noon

one

two

three

four

five

six

seven

eight

REU, cont.

Baselines and averaging

Jul 20 Std Dev/ data pt

0

0.5

1

1.5

2

2.5

9.50E+08 1.05E+09 1.15E+09 1.25E+09 1.35E+09 1.45E+09 1.55E+09 1.65E+09 1.75E+09

Hz

dB

m

Jul 25 Std Dev/ data pt

0

0.5

1

1.5

2

2.5

9.50E+08 1.05E+09 1.15E+09 1.25E+09 1.35E+09 1.45E+09 1.55E+09 1.65E+09 1.75E+09

Hz

dBm

REU, cont.

• Manhattan, KS 39.179642 -> dec. of +39o 10’ 46.7112”

• RA = (our time of day) + (5 hrs)

Name/ Type RA Dec. S 5 GHz (Jy)

4C 39.23/ Quasar 08:24:55.483 865 +39 16 41.90430 0.99

?/ Quasar 10:23:11.565 623 +39 48 15.385 39 0.87

NGC 1023/ Galaxy

02:40:48.5 +39 05 27

Next, cont.

• Signal processing software

• Mounting?

For More Information

• The Astronomical Almanac

• www.radio.uindy.edu

• www.nrao.edu/epo/amateur

• www.wikipedia.org

• www.bambi.net