New Maser Emission from Nonmetastable Ammonia in NGC 7538. II. Green
  Bank Telescope Observations Including Water Masers
  We present new maser emission from ^{14}NH_3 (9,6) in NGC 7538. Our
observations include the known spectral features near v_LSR = -60 km/s and -57
km/s and several more features extending to -46 km/s. In three epochs of
observation spanning two months we do not detect any variability in the ammonia
masers, in contrast to the >10-fold variability observed in other ^{14}NH_3
(9,6) masers in the Galaxy over comparable timescales. We also present
observations of water masers in all three epochs for which emission is observed
over the velocity range -105 km/s < v_LSR < -4 km/s, including the highest
velocity water emission yet observed from NGC 7538. Of the remarkable number of
maser species in IRS 1, H_2O and, now, ^{14}NH_3 are the only masers known to
exhibit emission outside of the velocity range -62 km/s < v_LSR < -51 km/s.
However, we find no significant intensity or velocity correlations between the
water emission and ammonia emission. We also present a non-detection in the
most sensitive search to date toward any source for emission from the CC^{32}S
and CC^{34}S molecules, indicating an age greater than \approx 10^4 yr for IRS
1-3. We discuss these findings in the context of embedded stellar cores and
recent models of the region.
