I wasn't able to find detector coordinates for the missing reflections, but looking at INTEGRATE.HKL from XDS at the reflections flanking the missing spots, it seems that the gaps do indeed correspond to tile boundaries on the detector. The crystal orientation reported in GXPARM.XDS is:
      80.653679      35.122337    -128.664032
     -46.708992      29.071186     -21.343992
      14.929770      87.118011      85.985352
Which doesn't look particularly inauspicious to me.

And yes, I was treating this as a curiosity rather than a pathology.

Thanks
Kevin

On Thu, Feb 18, 2016 at 10:37 AM, Graeme Winter <[log in to unmask]> wrote:
Easiest thing to do is plot the detx and dety positions and see if the missing ones form a nice pattern of tile joins. Two pounds gets you one they will.

If you have a multi axis gonio two sweeps good. If not deliberately misaligned xtal and 180 or more degrees a good thing.

In real life the problem is rarely a big one.

Best wishes Graeme

> On 18 Feb 2016, at 18:30, Phil Evans <[log in to unmask]> wrote:
>
> Is it just the Pilatus tile boundaries?
>
>> On 18 Feb 2016, at 17:55, Kevin Jude <[log in to unmask]> wrote:
>>
>> Dear all-
>> I am working with a data set that is 96% complete that I have assigned to space group C2 with cell dimensions 155.87 59.01 123.32, β=110.72°. I noticed a strange pattern of missing reflections in the data (the h0l slice in 2D and a 3D view approximately along 211 are in a dropbox at http://preview.tinyurl.com/zvqlex7).
>>
>> The missing data are in elliptical shells (for k=0, minor axes 10.9 Å, 5.45 Å, 3.64 Å, major axes 8.44 Å, 4.27 Å, and unmeasured). I can find other patterns, eg along the surface of a cylinder approximately around the (2,1,1) projection. The dataset was collected in a single wedge on a Pilatus detector. Does anyone have thoughts about what might give rise to these apparently systematically missing reflections?
>>
>> Best wishes
>> Kevin Jude

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