StevenEvan The AAP installed index files are a total of 2.47GB in size and ZWO load all of these into memory and search "in parallel" to speed up the search. However, if you add another 2.5GB for the 4203 index files you don't have room in the RPI and you need to change the config file for sequential search on the SD card. This is much slower and can take many minutes to find a match.
Ah, so this is what prevents the FOVs in the original ASIAIR to be expanded for the long focal lengths.
Also, searching in parallel must mean that it is an I/O and memory bound problem and not a processor bound problem. A future release of Raspberry Pi might fix that.
This also explains why some of the plate solve threads stay around. Often, even after you abort a plate solve, it would, a few seconds later flash a window up to announce that plate solve has succeeded. All sorts of threads in ASIAIR not properly killed. (Not just in plate solving but especially noticeable in the Focus window; or when you switch cameras.)
One possibility with file size limitation to actually remove the files that you will not ever need (not for the faint hearted). If you are far enough in the northern hemisphere, you will never need too plate solve stars in the south. Ditto when you add the higher resolution files -- only add the files with the asterisms that you ever need. Even better, preprocess the files from astrometry.net to throw the unneeded asterisms away.
And the way to mitigate the memory size limitation is perhaps to edit the index files to remove unneeded stuff too.
I see a fun side project coming up -- a program to filter the asterisms from astrometry.net to produce files that matches a latitude (should speed up searches too, not that we really need any speedup when the plate scale is known), ha ha.
Chen
