RE: [ccp4bb]: MOSFLM Warning

["Flip Hoedemaeker" <flip@keydp.com>]

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Dear Ricardo,

(Maximum slippage is    0.13 degrees which is more than a quarter of the sum
  of the beam divergence and mosaic spread.)

Calculate divergence plus mosaic spread, if is around 0.5-0.52 you might be
OK in this case.

If you integrate only the fully recorded reflections you rule out slippage
between images, since all reflections reside on a single image. If this
message disappears, then indeed slippage can be the problem, otherwise
there's something else wrong. So compare full only with full+partial. Also
look at the statistice for each individual image in tha scala output to see
if at some point something weird has happened. You might also have
underestimated either the mosaicity, the divergence or both.

Hope this helps,

Flip
-----Original Message-----
From: owner-ccp4bb@dl.ac.uk [mailto:owner-ccp4bb@dl.ac.uk]On Behalf Of
Ricardo Aparicio
Sent: Tuesday, April 29, 2003 12:18
To: 'ccp4bb@dl.ac.uk'
Subject: [ccp4bb]: MOSFLM Warning


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***          CCP4 home page http://www.ccp4.ac.uk         ***

Dear all,

I am getting the crystal slippage warning message (bellow) when integrating
a data set
collected at 100 K. I have seen it before but this time I can't solve it.

Rmerge values for partials and fulls are similar, no weird behavior.
All the parameters plots seems OK.
Crystal was correctly centered in the beam and mosaicity value seems to be
OK.
I would like some help:

- to find the probable cause for this message
- to solve the problem.

Also, the message says that
"
There may be serious errors in the intensities of partially recorded
  reflections. This can be checked by merging only fully recorded
reflections
  in SCALA/AGROVATA
"
How to check it in SCALA ? I mean, to merge only fully and compare what? The
very
intensities themselves?


Should I worry about this message?


Your help is very welcomed.

Many thanks,

Ricardo Aparicio
IFSC-USP/Brazil


*** Warning messages ***

  CRYSTAL SLIPPAGE
  ================
  There is significant slippage between successive images
  (Maximum slippage is    0.13 degrees which is more than a quarter of the
sum
  of the beam divergence and mosaic spread.
  There may be serious errors in the intensities of partially recorded
  reflections. This can be checked by merging only fully recorded
reflections
  in SCALA/AGROVATA. In extreme cases it may be helpful to increase the
  mosaic spread or beam divergence parameters to improve processing.