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   61043
   Recently it has become evident that there is a small subgroup of X-ray
   pulsars, with pulse periods close to 6 sec. These pulsers are
   characterized by the very steep soft spectrum, relatively low
   lominosity and secular spin-down trend. 4U0142+61, 1E2259+586, and
   1E1048.1-5937 are the typical example of this subclass and they were
   once observed with ASCA in 1993 to 1994. Currently the most likely
   interpretation is that these pulsars are single neutron stars accreting
   matter from a disk, the recent remnants of the common-envelope
   evolution of a high-mass X-ray binary. We propose that the observations
   of these pulsar with ASCA again in five years' interval is crucially
   effective to examine the currently proposed hypotesis for the origin of
   this cluss pulsars.
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