Abstract
Voyager 1 (V1) has been observing interstellar magnetic fields for more than one year beginning ≈2012/209, when V1 crossed a current sheet, a "CS0" having the structure of a tangential discontinuity. The inclination of this current sheet is consistent with an interstellar magnetic field B draped on a blunt heliopause. Two other current sheets (sector boundaries) were observed at ≈2012/167 and ≈2011/276 with high inclinations (99° ± 10° and 89° ± 10°, respectively). From 2013.0 to ≈2013.6, the difference between the azimuthal angle λ of B from the Parker spiral angle at the latitude 346 of V1 was λ − λP = 22° ± 3° and the corresponding difference of the elevation angle δ was δ − δP = 23° ± 8°. During 2012, the deviation from the Parker spiral angle was somewhat smaller. The interstellar magnetic field has a "west to east polarity," opposite to the direction of planetary motions. The magnitude of B varied smoothly in the range 0.38–0.59 nT with an average B = 0.486 ± 0.045 after 2012/237.7. The transition from heliosheath to interstellar magnetic fields is related to a "two-step" increase in the cosmic ray intensity observed by V1 from ≈2012.30 to ≈2012.65. The first step increase began near the end of an unusual "away-polarity" sector, and it reached a plateau when V1 moved into a "toward-polarity" sector that ended at CS0. The second step increase began slowly after V1 crossed CS0, and it ended abruptly at 2012/237.728.
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