# phase_HalleyMarcus¶

sbpy.activity.dust.phase_HalleyMarcus(phase)[source]

Halley-Marcus composite dust phase function.

Uses interpolate for spline interpolation, otherwise uses linear interpolation from interp.

Parameters
phaseQuantity, Angle

Phase angle.

Returns
Phifloat, ndarray

Notes

The Halley-Marcus phase function was first used by Schleicher and Bair (2011), but only described in detail by Schleicher and Marcus (May 2010) online at:

http://asteroid.lowell.edu/comet/dustphase.html

“To distinguish this curve from others, we designate this as the HM phase function, for the sources of the two components: Halley and Marcus, where the Halley curve for smaller phase angles comes from our previous work (Schleicher et al. 1998) while Joe Marcus has fit a Henyey-Greenstein function to a variety of mid- and large-phase angle data sets (Marcus 2007); see here for details. Note that we do not consider our composite curve to be a definitive result, but rather appropriate for performing first-order adjustments to dust measurements for changing phase angle.”

References

Schleicher & Bair 2011, AJ 141, 177. Schleicher, Millis, & Birch 1998, Icarus 132, 397-417. Marcus 2007, International Comets Quarterly 29, 39-66.

Examples

>>> from sbpy.activity import phase_HalleyMarcus
>>> import astropy.units as u
>>> phase_HalleyMarcus(0 * u.deg)                 # doctest: +FLOAT_CMP
1.0
>>> phase_HalleyMarcus(15 * u.deg)                # doctest: +FLOAT_CMP
5.8720e-01