  We present new observations of the low-mass companion to HD 984 taken with
the Gemini Planet Imager as a part of the Gemini Planet Imager Exoplanet Survey
campaign. Images of HD 984 B were obtained in the J (1.12--1.3 micron) and H
(1.50--1.80 micron) bands. Combined with archival epochs from 2012 and 2014, we
fit the first orbit to the companion to find an 18 AU (70 year) orbit with a
68% confidence interval between 14 and 28 AU, an eccentricity of 0.18 with a
68% confidence interval between 0.05 and 0.47, and an inclination of 119
degrees with a 68% confidence interval between 114 degrees and 125 degrees. To
address considerable spectral covariance in both spectra, we present a method
of splitting the spectra into low and high frequencies to analyze the spectral
structure at different spatial frequencies with the proper spectral noise
correlation. Using the split spectra, we compare to known spectral types using
field brown dwarf and low-mass star spectra and find a best fit match of a
field gravity M6.5+/-1.5 spectral type with a corresponding temperature of
2730+120 K. Photometry of the companion yields a luminosity of log(L_bol/L_sun)
= -2.88+/-0.07 dex, using DUSTY models. Mass estimates, again from DUSTY
models, find an age-dependent mass of 34+/-1 to 95+/-4 M_Jup. These results are
consistent with previous measurements of the object.
