Water and Methanol Maser Activities in the NGC 2024 FIR 6 Region
  The NGC 2024 FIR 6 region was observed in the water maser line at 22 GHz and
the methanol class I maser lines at 44, 95, and 133 GHz. The water maser
spectra displayed several velocity components and month-scale time
variabilities. Most of the velocity components may be associated with FIR 6n,
while one component was associated with FIR 4. A typical life time of the
water-maser velocity-components is about 8 months. The components showed
velocity fluctuations with a typical drift rate of about 0.01 km/s/day. The
methanol class I masers were detected toward FIR 6. The methanol emission is
confined within a narrow range around the systemic velocity of the FIR 6 cloud
core. The methanol masers suggest the existence of shocks driven by either the
expanding H II region of FIR 6c or the outflow of FIR 6n.
