  The X-ray burster GS 1826-24 shows extremely regular Type I X-ray bursts
whose energetics and recurrence times agree well with thermonuclear ignition
models. We present calculations of sequences of burst lightcurves using
multizone models which follow the rp-process nucleosynthesis with an extensive
nuclear reaction network. The theoretical and observed burst lightcurves show
remarkable agreement. The models naturally explain the slow ~5s rise and long
~100s tails of these bursts, as well as their dependence on mass accretion
rate. This comparison provides further evidence for solar metallicity in the
accreted material in this source, and constrains the distance to the source.
The main difference is that the observed lightcurves do not show the distinct
two-stage rise of the models. This may reflect the time for burning to spread
over the stellar surface, or may indicate that our treatment of heat transport
or nuclear physics needs to be revised. The trends in burst properties with
accretion rate are well-reproduced by our spherically symmetric models which
include chemical and thermal inertia from the ashes of previous bursts. Changes
in the covering fraction of the accreted fuel are not required.
