We present a 2 - 10 keV ASCA observation of the field around the soft gamma repeater SGR1900+14 .
One quiescent X-ray source was detected in this observation , and it was in the SGR error box .
In 2 - 10 keV X-rays , its spectrum may be fit by a power law with index -2.2 , and its unabsorbed flux is 9.6 x 10 ^ { -12 } erg cm ^ { -2 } s ^ { -1 } .
We also find a clear 5.16 s period .
The properties of the three well-studied soft gamma repeaters are remarkably similar to one another , and provide evidence that all of them are associated with young , strongly magnetized neutron stars in supernova remnants .