  We report the association of the INTEGRAL source IGR J18027-2016 with the
BeppoSAX source SAX J1802.7-2017. IGR J18027-2016 is seen to be a weak,
persistent source by the IBIS/ISGRI instrument on board INTEGRAL with an
average source count rate of 0.55 counts s^-1 (~6.1 mCrab) in the 20-40 keV
band. Timing analysis performed on the ISGRI data identifies an orbital period
of 4.5696 +/- 0.0009 days and gives an ephemeris of mid-eclipse as, T{mid} =
52931.37 +/- 0.04 MJD. Re-analysis of archival BeppoSAX data has provided a
mass function for the donor star, f(m) = 16 +/- 1 M{sun} and a projected
semimajor axis of a{x}sin{i} = 68 +/- 1 lt-s. We conclude that the donor is an
OB-supergiant with a mass of 18.8-29.3 M{sun} and a radius of 15.0-23.4 R{sun}.
Spectra obtained by XMM-Newton and ISGRI indicate a high hydrogen column
density of NH = 6.8 x 10^22 cm^-2, which suggests intrinsic absorption. The
source appears to be a high mass X-ray binary with the neutron star emitting
X-rays through wind-fed accretion while in an eclipsing orbit around an
OB-supergiant.
