A Chunk is a unit for SDSS data export. It is a part of an SDSS stripe, a 2.5 degree wide cylindrical segment aligned at a great circle between the survey poles. A Chunk has had both strips completely observed. Since the SDSS camera has gaps between its 6 columns of CCDs, each stripe has to be scanned twice (these are the strips) resulting in 12 slightly overlapping narrow observation segments.

Only those parts of a stripe are ready for export where the observation is complete, hence the declaration of a chunk, usually consisting of 2 runs.

Aliases: sxChunk

Data Members of Chunk:
Member Name/AliasesDatatypeDescription
chunkNumber int16 Chunk number
startMu int32 Starting coordinate in Great Circle coordinates
endMu int32 Ending coordinate in Great Circle coordinates
stripe int32 Stripe number
exportVersion char[32] Export version
ManyAssoc(Segment) Link to all segments of this chunk (a multiple of 6, depending how many runs make up this segment)

© Copyright 2000 Peter Z. Kunszt Alex S. Szalay , Ani R. Thakar
and The SDSS Collaboration