Re: [ccp4bb]: dodgy indexing

[Jan Abendroth <Jan.Abendroth@uni-koeln.de>]

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Hi,
this reminds me my (large) crystal when I measured a high resolution
data set at the synchrotron when we did not have enough time for the
low-resolution scan. Although the final mosaicity from scalepack
postrefinement was lower than the input in denzo: in the low resolution
range not all spots were detected - the mosaicity seemed to be higher.
The rest (autoindexing, chi^2, ... ) of the scaleing was very smooth.
I made a compromize, taking a mosaicity slightly higher than the
postrefined from scalepack for a second denzo-scalepack run. The
data-set was fine anyway up to high resolution!
I don't know exactly the resons for this behaviour. Maybe the crystal
cracked a bit during freezing, or a small part of twinning (although
merohedral twinning is not possible in this space group),...

Maybe someone has made similar observations and knows a reason.

Regards
Jan


Lauris Kemp wrote:
> 
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> 
> Hello
> I'm trying to index a data set with denzo. The problem is with
> mosaicity-it looks about 1 but at this value it misses out some low
> resolution spots and seems to overfit for the number of spots at high
> resolution. Thought it might be misindexed but did a direct beam shot
> and the beam values look about right. It manages to autoindex it fine
> and the chi values are also fine.
> Lauris

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Jan Abendroth
Institut fuer Biochemie
Universitaet Koeln
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