  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sigma level for combined ROSAT PSPC and unpublished HRI data.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=2E 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 +/- 0.12 and a neutral
Hydrogen column density N_H towards the source of 9.8_{-1.0}^{+1.4} x 10^20
cm^-2. For a double black-body fit our results are: T_1 = 2.0_{-0.05}^{+0.05} x
10^6 K, T_2 = 6.9_{-0.35}^{+0.23} x 10^6 K, and N_H = 4.43_{-1.12}^{+2.08} x
10^20 cm^-2. In both cases the derived N_H value is higher than that adopted in
earlier works, but our result is consistent with the larger distance estimate
of 331 +/- 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.
