  During normal Type I outbursts, the pulse profiles of Be/X-ray binary pulsars
are found to be complex in soft X-ray energy ranges. The profiles in soft X-ray
energy ranges are characterized by the presence of narrow absorption dips or
dip-like features at several pulse phases. However, in hard X-ray energy
ranges, the pulse profiles are rather smooth and single-peaked. Pulse
phase-averaged spectroscopy of the these pulsars had been carried out during
Type I outbursts. The broad-band spectrum of these pulsars were well described
by partial covering high energy cutoff power-law model with interstellar
absorption and Iron K_alpha emission line at 6.4 keV. Phase-resolved
spectroscopy revealed that the presence of additional matter at certain pulse
phases that partially obscured the emitted radiation giving rise to dips in the
pulse profiles. The additional absorption is understood to be taking place by
matter in the accretion streams that are phase locked with the neutron star.
Optical/infrared observations of the companion Be star during these Type I
outbursts showed that the increase in the X-ray intensity of the pulsar is
coupled with the decrease in the optical/infrared flux of the companion star.
There are also several changes in the IR/optical emission line profiles during
these X-ray outbursts. The X-ray properties of these pulsars during Type I
outbursts and corresponding changes in optical/infrared wavebands are discussed
in this paper.
