  A pulse timing orbit has been obtained for the X-ray binary XTE J1855-026
using observations made with the Proportional Counter Array on board the Rossi
X-ray Timing Explorer. The mass function obtained of ~16Mo together with the
detection of an extended near-total eclipse confirm that the primary star is a
supergiant as predicted. The orbital eccentricity is found to be very low with
a best fit value of 0.04 +/- 0.02. The orbital period is also refined to be
6.0724 +/- 0.0009 days using an improved and extended light curve obtained with
RXTE's All Sky Monitor. Observations with the ASCA satellite provide an
improved source location of R.A. = 18h 55m 31.3s}, decl. = -02o 36' 24.0"
(2000) with an estimated systematic uncertainty of less than 12". A
serendipitous new source, AX J1855.4-0232, was also discovered during the ASCA
observations.
