Temporary problems with SKYOOP

If you use the SKYLOOP script to create SCUBA-2 maps, you need to be aware that some issues have been reported recently with SKYLOOP that are under active investigation. One is that it can use more memory than is allowed by your system, with the result that it can be killed without warning in order to protect the rest of your system. No error or warning messages are issued when this happens - it just suddenly stops for no apparent reason. One way to avoid this to limit the amount of memory used by makemap. To do this run skyloop as follows:

% skyloop  extra="maxmem=120000"

where the number is in units of MiB and should be changed to suit your system.

Sadly, even with this setting, things can sometimes still go wrong. This is because makemap is currently under-estimating the amount of memory it needs.

A second issue is that if you use skyloop to create a map from a single contiguous chunk of data, and then use makemap to create a second map from the same chunk of data, there are significant differences between the two maps. In theory, the two maps should be the same - skyloop should produce better results when making maps from multiple chunks of data, but they should give the same results for single chunk maps. This indicates that something - maybe several things - is wrong with skyloop. 

I'm currently investigating both these issues and I am making good progress but have not yet completely solved them. So in the mean time, beware of using SKYLOOP and watch this space...

David