Voyager 1 Observations of the Interstellar Magnetic Field and the Transition from the Heliosheath

Voyager 1 (V1) has been observing interstellar magnetic fields for more than one year beginning approximate to 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 approximate to 2012/167 and approximate to 2011/276 with high inclinations (99 degrees +/- 10 degrees. and 89 degrees +/- 10 degrees, respectively). From 2013.0 to approximate to 2013.6, the difference between the azimuthal angle lambda of B from the Parker spiral angle at the latitude 34 degrees.6 of V1 was lambda - lambda(P) = 22 degrees +/- 3 degrees and the corresponding difference of the elevation angle delta was delta - delta(P) = 23 degrees +/- 8 degrees. 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 approximate to 2012.30 to approximate 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.