Alternative 1: Select SRTM 1Sec (AutoDownload) instead whenever possible. These should work regardless of the location of SRTM 3Sec data.
This is exactly what I do here.
The url exists and the dems download just fine - except the ones that do not exist such as the one I mentioned N51W007.SRTMGL1.hgt.zip but also for example N54E001.SRTMGL1.hgt.zip and N55E001.SRTMGL1.hgt.zip . The location of the filename indicates that they are somewhere in the ocean and hence it makes sense that they do not exist.
My question is: should snap event try to download them if they contain no information? Also, if I read the logs correctly it can take snap up to 10 minutes to proceed when the file is not here. Is there a way to sped that up?
Also, I think the documentation is not correct and skywatch-auxdata bucket should be used as stated in the documentation event for srtm 3sec. Last time I checked it was not accessible which (amongst another issue) spawned this thread: 403 for skywatch-auxdata bucket