Extracting cosmological 21cm emission from the radio foregrounds which dominate requires precision calibration, including sub-percent measurements of the complex instrument beam. 21cm cosmology experiments are typically driven to be compact transit interferometers with poor point-source sensitivity, and have found it difficult to constrain the beam shape to this precision with sky data alone. A technique that has been developed and demonstrated by multiple groups to address this is to transmit a calibrated radiofrequency signal from a drone into the telescope to measure the beam pattern. I will present ongoing improvements to drone calibration techniques performed by the Newburgh group at Yale University, including a new drone and digital noise source, and improvements to our data reduction and analysis pipeline from the past year. I will also present measurements of the complex beam pattern of a 3m dish acquired in the near-field and the methods and instrumentation used to recover the phase of the antenna under test. We will compute the far-field beam pattern of the 3m dish using a near-field to far-field transformation to demonstrate the feasibility of this technique that can be used to calibrate large diameter telescopes.
MSI and Astro seminars are held on Tuesdays at 3:30 pm on alternating weeks during the fall and winter semesters.
Astro Seminars: feature speakers who discuss topics in astronomy, astrophysics and cosmology. Seminars will be held in the R.E. Bell Conference Room (room 103) in the Rutherford Physics Building.
MSI Seminars: feature speakers who discuss topics in astrophysics, planetary science, atmospheric science and astrobiology. Most seminars are held in the MSI conference room at 3550 University. Some seminars are held in the R.E. Bell Conference Room (room 103) in the Rutherford Physics Building (to accommodate larger audiences).