radio astronomy: an informal talk presented to the society of physics students northern virginia...

Radio Astronomy:An Informal Talk

Presented to the

Society of Physics Students

Northern Virginia Community College

19 November

by

Prof. Harold Geller, GMU

What I’ll talk about

• Telescopes

• Electromagnetic waves

• Radioastronomy basics

• NRAO at Green Bank, West Virginia

• Small Radio Telescope at George Mason University

What does a telescope do?

• Collect electromagnetic waves– Collecting ability proportional to the square of

the diameter of the objective

• Resolve electromagnetic sources– Related to the atmosphere, wavelength and

curvature of the objective• Magnify surfaces of planets and the Moon

– Magnification only of Moon, Sun and planets

Looking Beyond the

Eyes

Optical Telescopes

Reflector

Refractor

Different Views of Sun

Sun in Hydrogen-alpha Sun in X-ray

Radio Astronomy

Basics

A Little More Detail

Jansky’s Original Radiotelescope

Grote Reber’s Telescope

170 foot Diameter Radio-

telescope at Green Bank,

WV

The 100-meter Green

Bank Telescope

Even Bigger than you Think

Jupiter in Radio

Saturn in Radio

3C296 Radio/Optical

Composite

A Vision for George Mason (based upon Univ. Indianapolis)

Small Radio Telescope Justification

• Radio science observations in the L-band – L-band lies in the 1400-1427 MHz region of

the electromagnetic spectrum– detection of what astronomers call the 21-cm

line of hydrogen• this is a portion of the hydrogen spectrum, in the

radio region of the electromagnetic spectrum, which is generated by the neutral hydrogen clouds in the interstellar medium

Small Radio Telescope Justification

• Observations in C-band, which is 4313-4338 MHz and 3788-3813 MHz– Radio science observations in the C-band allow

for the radio emission examination of the moon, which acts as a body at a temperature of 200 K.

– Students will be able to scan the moon, and detect the estimated 6000 joules of energy from the lunar surface.

GMU SRT Background

• Funding– National Science Foundation

• education portion of grant won by Dr. Rita Sambruna

• Order History– ordered first week of June 2002

• stated 12 week delivery time

– received 15 October 2002• damaged antenna

GMU SRT Background Part II

• Order History– boxes damaged– FedEx insurance inspector called and visited to

assess damage - refused claim– replacement parts to be shipped by vendor

• Base assembled on roof– 1 November 2002

• Remaining electronics and replacement antenna parts received 30 January 2003

Did You Say Fragile?

Picking Up the Pieces on the Roof

Whistle While You Work

Tolerance

Cleanup On The Roof

The Base Of SRT

Servo Motors Attachment

Servos with Ring Assembly

Dish/Receiver Assembly

Readying for Final Mechanical Assembly

From Mechanical to Electrical

Assembled and Ready to Test

Sample Data

Even Smaller - Radio Jove

Small Radio Science Demonstration Projects

• Undergraduate research– Steve Richardson

• web site built with some results from data acquired using U of Indianapolis

– http://physics.gmu.edu/~arichar6/radio/index.html

• prepared presentation for GMU “innovations” fair

• prepared presentation for CPAC meeting at Bucknell University

Really Smoothing

Playing With The Data

A Potpourri Of Color

Family Portrait (2001 conference)

Radio Astronomy Observatory at George Mason University

Looking To The Future

Future GMU Observatory

OnLine References

• http://www.aoc.nrao.edu/intro/image.index.html• http://www.aoc.nrao.edu/intro/faq.html• http://donald.phast.umass.edu/~fcrao/education/

report1.html• http://www.haystack.mit.edu/• http://www.jpl.nasa.gov/radioastronomy/• http://www.bambi.net/sara.html• http://radiojove.gsfc.nasa.gov/

Book References

• Radio Astronomy by John D. Kraus• An Introduction to Radio Astronomy by Bernard

Burke• The Amateur Radio Astronomer’s Handbook by

John Potter Shields• Radio Astronomy for the Amateur by David

Heiserman• Radio Astronomy (Above and Beyond) by Adele

Richardson

Many Thanks

• Rita Sambruna (GMU)

• Maria Dworzecka (GMU)

• Justin Brown (GMU)

• Dan Thomas (GMU)

• Kathy Santiago (NVCC)

• John Avellone

• Christopher Helm

• National Science Foundation (NSF)

• MIT Haystack Observatory