2019-2020 Science Planning Summaries
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2019-2020 USAP Field Season
Project Detail

Project Title


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A-115-M Research Location(s): Long Duration Balloon Facility


Event Number:

Program Manager:
Dr. Vladimir Papitashvili

ASC POC/Implementer:
John Rand / Jennifer Blum / Paul Sullivan / Chad Naughton

Principal Investigator(s)

Dr. Henric S. Krawczynski
Washington University
Department of Physics
St. Louis, Missouri


Supporting Stations: McMurdo Station
Research Locations: Long Duration Balloon Facility


X-Calibur is a balloon-borne X-ray polarimetry mission that will observe mass-accreting black holes and neutron stars in the 25-60 kiloelectronVolts (keV) energy range. X-Calibur measures the linear polarization degree and angle – two new observables relating to the uniformity and orientation of the electric field carried by X-rays. This new capability of polarimetry allows X-Calibur to obtain geometrical information about objects that are too far away and too small to be imaged. The 2018-19 balloon flight will be used to observe four to ten sources and to measure their energy-dependent, hard X-ray polarization properties. The sources will include the accreting neutron star and X-ray pulsar Vela-X1, and the results will constrain the location and physical mechanisms that accelerate particles in Vela-X1.

Field Season Overview

Activities this season will focus exclusively on recovering the balloon payload that was deployed last year and landed approximately 725 miles east-south-east of the South Pole. ASC personnel will lead the recovery efforts. No science personnel are scheduled to deploy.