  We describe the process implemented in the DASCH pipeline which applies a
reliable astrometric correction to each scanned plate. Our first blind
astrometric fit resolves the pointing, scale and orientation of the plate in
the sky using astrometry. net code. Then we iteratively improve this solution
with WCSTools imwcs. Finally, we apply a 6th order polynomial fit with SCAMP to
correct the image for distortions. During a test on 140 plates, this process
has allowed us to successfully correct 79% of the plates. With further
refinements of the process we now reach a 95% success rate after reprocessing
all our scanned plates (~11 000 in Nov. 2010). We could extract a lightcurve
for 2.85 times more objects than with the previous Pipeline, down to magnitude
17. The resulting median RMS error is 0.13" for objects with mag. 8 to 17.
