We performed timing and spectral analysis for PSR B1929+10 , one of the oldest ( about 10 ^ { 7 } years ) of the ordinary pulsars detected in X-rays , using archival ROSAT , ASCA and RXTE data .
Pulsed emission was detected at a more than five sigma level for combined ROSAT PSPC and unpublished HRI data .
Our pulse profile is in agreement with that obtained by Yancopoulos et al .
( 1994 ; ROSAT PSPC ) but now with better statistics .
An investigation of the behaviour of the pulsed signal as a function of energy , based on PSPC data , provides indications that the pulsed fraction is changing with energy .
The most important new result from this work is derived from the spectral analysis .
We found that the combined ROSAT PSPC and ASCA GIS spectrum can satisfactorily be described by a power-law as well as by a double black-body model but not by a single black-body model , as was presented earlier by Yancopoulos et al .
( 1994 ; ROSAT ) and Wang et al .
( 1997 ; ASCA ) .
Fitting the combined ROSAT/ASCA 0.1 - 10 keV spectrum by a power-law model we obtain a photon index of 2.54 \pm 0.12 and a neutral Hydrogen column density ( N _ { \hbox { \@setsize { \footnotesize } { 10 pt } { \viiipt } { \@viiipt } H } } ) towards the source of 9.8 _ { -1.0 } ^ { +1.4 } \cdot 10 ^ { 20 } ~ { } cm ^ { -2 } .
For a double black-body fit our results are : T _ { 1 } = 2.0 _ { -0.05 } ^ { +0.05 } \cdot 10 ^ { 6 } ~ { } K , T _ { 2 } = 6.9 _ { -0.35 } ^ { +0.23 } \cdot 10 ^ { 6 } ~ { } K , and N _ { \hbox { \@setsize { \footnotesize } { 10 pt } { \viiipt } { \@viiipt } H } } = 4.43 _ { -1.12 } ^ { +2.08 } \cdot 10 ^ { 20 } ~ { } cm ^ { -2 } .
In both cases the derived N _ { \hbox { \@setsize { \footnotesize } { 10 pt } { \viiipt } { \@viiipt } H } } value is higher than that adopted in earlier works , but our result is consistent with the larger distance estimate of 331 \pm 10 ~ { } pc from new parallax measurements performed by Brisken et al .
( 2002 ) and with the Hydrogen distribution measured in the direction of the pulsar ( Frisch & York , 1983 ) .
No significant pulsed signal is found in the RXTE data .