  We report on the serendipitous discovery of a new X-ray source, SAX
J1802.7-2017, ~22' away from the bright X-ray source GX 9+1, during a BeppoSAX
observation of the latter source on 2001 September 16-20. SAX J1802.7-2017
remained undetected in the first 50 ks of observation; the source count rate in
the following ~300 ks ranged between 0.04 c/s and 0.28 c/s, corresponding to an
averaged 0.1-10 keV flux of 3.6 10^{-11} ergs cm^{-2} s^{-1}. We performed a
timing analysis and found that SAX J1802.7-2017 has a pulse period of 139.612
s, a projected semimajor axis of a_x sin i ~ 70 lt-s, an orbital period of ~4.6
days, and a mass function f(M) ~ 17 Msun. The new source is thus an accreting
X-ray pulsar in a (possibly eclipsing) high mass X-ray binary. The source was
not detected by previous X-ray astronomy satellites, indicating that it is
likely a transient system.
