Ring-averaged central velocity of the NH₃ (1,1) (black circles) and (2,2) lines (red circles) in the Guitar Core in L1287. The rings used were 1″ wide, and the error bars are the rms of the values inside each ring. The central dashed line is the best fit obtained for an infinite infall radius and a central mass of M_* = 2.1 M_⊙, and the horizontal dotted line is the best fit systemic velocity, V_sys = −18.67 km s⁻¹. The fits for central masses of 1.1 and 3.4 M_⊙ are also shown.