Harvard Student CMB Lab

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The Harvard Student CMB Lab has been run in Harvard's Astronomy 191 course each year since 2011. Its goal is to replicate the Penzias and Wilson CMB discovery measurement using a simple antenna and radiometer, built from scratch by the students themselves, using mostly commercially available parts.

We have run various versions of this lab in Harvard's Advanced Undergraduate Astrophysics Lab course (Astronomy 191) with a start-to-finish time of roughly 6 weeks. Students begin by studying Penzias and Wilson's discovery paper and/or Wilson's published description of the original measurement. They are encouraged to identify the challenges of the measurement, define specifications for the required equipment, develop a proposal for building the apparatus, design the measurement program, make observations, analyze and report the results with a full a description of statistical and systematic uncertainties. Extensions to the lab have included building apparatus and making measurements at multiple frequencies: successfully student CMB detections have been made so far at 11 GHz, 19 GHz, 26 GHz, 36 GHz, and a plausible constraint set at 90 GHz. Students have built scanning versions of the telescopes to probe the isotropy of the background signal and to map the microwave sky, including galactic radio emission. We have also run a 1-day version of the lab in Harvard's Graduate Radio Astronomy course (Astronomy 218), using existing apparatus, coaching students through beam mapping and sky dip measurements, and having them focus on analysis and reporting of the results.

Original ideas for this student CMB measurement come from John Carlstrom, who created a student lab at the University of Chicago which uses an observatory-grade cryogenic HEMT-based radiometer for successful rooftop CMB skydip measurements, and from Edward Tong and Robert Kimberk at the Smithsonian Astrophysical Observatory who first suggested attempting this measurement using inexpensive room temperature satellite TV Low-Noise Blocks. Huge thanks goes to the students of Astronomy 191 who have developed the different working versions of this lab at Harvard, and much of the content on this site.

This website was created to share information about the Harvard Student CMB Lab with educators at other institutions, to encourage replicating the experiment in various forms and to share experiences teaching with it. If you are interested in replicating this experiment at your learning institution or would like more information, please see the contact link. To ensure each educator can choose what information to share with their students, site access is restricted to registered educators and we request that the unpublished information here (apparatus descriptions, sample datasets and solutions) not be reposted to public locations.