The oscillation method for crystals with very large unit cells

The processing of data collected by oscillation photography from crystals with very large unit cells (average cell constant ∼ 250 Å) requires important modifications of standard methods. In particular, it is often necessary to correct partially recorded intensities to their fully recorded equivalents. A procedure is described for accurate determination of relevant parameters (crystal setting, cell constants). It relies on the redundancy present in most data-collection strategies, which yields fully recorded, symmetry-related counterparts of a number of partially recorded reflections. A detailed description of one example (tomato bushy stunt virus) is presented, with complete intensity statistics.