Lupus I Observations from the 2010 Flight of the Balloon-borne Large
  Aperture Submillimeter Telescope for Polarimetry
  The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry
(BLASTPol) was created by adding polarimetric capability to the BLAST
experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's
1.8 m primary and its Herschel/SPIRE heritage focal plane that allows
simultaneous observation at 250, 350, and 500 {\mu}m. We flew BLASTPol in 2010
and again in 2012. Both were long duration Antarctic flights. Here we present
polarimetry of the nearby filamentary dark cloud Lupus I obtained during the
2010 flight. Despite limitations imposed by the effects of a damaged optical
component, we were able to clearly detect submillimeter polarization on degree
scales. We compare the resulting BLASTPol magnetic field map with a similar map
made via optical polarimetry (The optical data were published in 1998 by J.
Rizzo and collaborators.). The two maps partially overlap and are reasonably
consistent with one another. We compare these magnetic field maps to the
orientations of filaments in Lupus I, and we find that the dominant filament in
the cloud is approximately perpendicular to the large-scale field, while
secondary filaments appear to run parallel to the magnetic fields in their
vicinities. This is similar to what is observed in Serpens South via near-IR
polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura
and Z. Li.
