XTE J1946+274 = GRO J1944+26 is a 15.8 s Be/X-ray pulsar discovered simultaneously in 1998 September with the Burst and Transient Source Experiment ( BATSE ) on the Compton Gamma Ray Observatory ( CGRO ) and the All-Sky Monitor ( ASM ) on the Rossi X-ray Timing Explorer ( RXTE ) .
Here we present new results from BATSE and RXTE including a pulse timing analysis , spectral analysis , and evidence for an accretion disk .
Our pulse timing analysis yielded an orbital period of 169.2 days , a moderate eccentricity of 0.33 , and implied a mass function of 9.7 M _ { \odot } .
We observed evidence for an accretion disk , a correlation between measured spin-up rate and flux , which was fitted to obtain a distance estimate of 9.5 \pm 2.9 kpc .
XTE J1946+274 remained active from 1998 September - 2001 July , undergoing 13 outbursts that were not locked in orbital phase .
Comparing RXTE PCA observations from the initial bright outburst in 1998 and the last pair of outbursts in 2001 , we found energy and intensity dependent pulse profile variations in both outbursts and hardening spectra with increasing intensity during the fainter 2001 outbursts .
In 2001 July , optical H \alpha observations indicate a density perturbation appeared in the Be disk as the X-ray outbursts ceased .
We propose that the equatorial plane of the Be star is inclined with respect to the orbital plane in this system and that this inclination may be a factor in the unusual outburst behavior of the system .