Jack Replinger Summer REU 2005 University of Wisconsin-Madison
In order for the Observational Cosmology Lab to gain experience with intereferometry as well as providing creating various educational outreach opportunities, the junior members of the ObsCosLab began a project to build three Small Radio Telescopes (SRTs) to map the nuetral Hydrogen of the Milky Way.
Neutral Hydrogen consists of one proton and one electron. When the spins of the particles are aligned the atom has a slightly higher energy than when the spins are opposite. When an electron in the lowest orbital changes from spin aligned to misaligned the energy of the atom decreases by a small energy E. In order to conserve energy, the a photon must be emitted with frequency f=E/h=1420MHz, corresponding to a wavelenght of 21cm. Our radio telescopes are designed to be sensitive to a small band of frequencies centered at 1420MHz.
We obtained the basic design for our SRTs from the Haystack Observatory at the Massachusetts Insitute of Technology. Our procedure consisted of ordering parts; designing and soldering the electronics boards; and assembling the the antennas, mounts, feedhorns, and motors. The 8.5ft diameter dishes and feedhorns were ordered from Skyvision, the base was ordered from Patriot Antenna Systems, and the az/el motor was ordered from Alfa Radio Ltd.. As many of the parts for the Digital Reciever Board and the Ground Control board are now obselete we found appropriate replacements. The boards were designed by UW-Madison Senior Instrument Technician Don Michalski, printed by Advanced Circuits with parts soldered by the junior members as well as Allison Noble (Undergraduate at the University of Wisconsin-Madison), with soldering instruction provided by UW-Madison Electrical Technician Sam Gabelt. The majority of the electronic components were ordered from Mini-Circuits, Digi-Key, and Newark InOne. I desgined a custom made up of two aluminum sheets that attach the antenna to the motor and support counterwaits, the designs are pictured below.
In addition to working on the Small Radio Telescopes, I had the opportunity to create outreach tutorials on CMB Polarization and Interferometry, which are essential to understanding the ObsCosLab's Project: The Millimeterwave Bolometric Interferometer (MBI). The tutorial are powerpoints and may be viewed with Internet Explorer or downloaded and viewed using Powerpoint.
please direct comments or questions to jrep@rice.edu
Thanks to everyone who made this summer a great experience, including: the NSF, the University of Wisconsin-Madison, Professor Timbie and the ObsCosLab, Christina Cheek, Kristen Jones, the AstroREUers, and Ed Mierkiewicz ... also my friends from the SERF, the Rose, the Profits, and Black Elephant.
"And it's just a box of rain, I don't know who put it there / Believe it if you need it or leave it if you dare / And it's just a box of rain, or a ribbon for your hair / Such a long, long time to be gone and a short time to be there" - Garcia/Hunter/Lesh