Subject: Re: Crab fluxes

Hello:

I have tried to illustrate the improvements which
can be obtained by adjusting the description of the
collimator for tilt of the lamellae in X and in Y
and allowing the the width of the collimator lamellae 
as a free parameter. (This corresponds to non-flat
lamellae and (partially) to statistical variations
in the tilt parameter). I have also introduced a
curvature of the collimator, but so far this has not
had any big effect.

It appears that we may reduce the scatter in our fluxes
by a significant factor (30%) by introducing such 
effects. So far I have optimized using Crab data from
orbits 43, 44, 102 and 170. The 43+44 dataset dominate
the optimization. This is apparent from the plots,
the points from orbits 43 and 44 looks quite good,
whereas the data from 102 and 170 are more scattered.
I will now see if I can tune the parameters better 
for the 102+170 alone.

The plots CRAB_SL_1/2_all.pdf show the total Crab flux
as function of off-axis angle for the four datasets
used (revs 43, 44, 102 and 170). The second plot is a
zoom using the rev 102 and 170 data only. Stefan may
be able to comment on how these plots compares to his
similar plots - Stefan plots spectral normalizations
I plot the integrated counts rates.

To illustrate the improvement compared to a simple 
collimator description I include the plots:
CRAB1_T2200_E1.pdf and CRAB1_T2200_E1_orig.pdf.

With best regards
 
 niels