PSR 0628-28 is an X-ray emitting radio pulsar which was observed with Advanced CCD Imaging Spectrometer ( ACIS ) on board Chandra on 2001 November 04 and on 2002 March 25 for 2000 s and 17000 s , respectively .
The source countrate was 0.0111 \pm 0.0013cps .
Making PSR 0628-28 to be the longest period X-ray emitting pulsar .
The spectral distribution of counts can be described by several model fits .
A blackbody fit yields a temperature kT = 2.69 _ { -0.09 } ^ { +0.09 } \times 10 ^ { 6 } K together with N _ { H } = 0.082 _ { -0.03 } ^ { +0.04 } \times 10 ^ { 22 } cm ^ { -2 } and a powerlaw fit yields a photon index of \gamma = 2.65 _ { -0.29 } ^ { +0.28 } with a hydrogen column density of N _ { H } = 0.13 _ { -0.021 } ^ { +0.028 } \times 10 ^ { 22 } cm ^ { -2 } .
Confirming the previous ROSAT pointed observation for PSR 1813-36 , there was no positive detection from the 30ks Chandra ACIS observation on 2001 October 25 .
We obtained an upper limit for the countrate of 2.3 \times 10 ^ { -4 } cps .