Added orbit nomenclature condition

[SteffanDavies]

Some orbits are not found, must be (date, date+2days)

[AlexeyPechnikov]

This is not an expected orbit, use the configuration below to download the correct one:

from datetime import timedelta
ASF.poeorb_start_offset = timedelta(seconds=(12 * 86400.0) // 175.0 + 60)

For now, the offset is defined to 0 to overtake issues when orbit is unexpectedly short; but I see now, that the fix can produce other issues. It seems better to set the standalone offsets as default and fix them is case of incomplete orbit.

[SteffanDavies]

This is not an expected orbit, use the configuration below to download the correct one:

from datetime import timedelta
ASF.poeorb_start_offset = timedelta(seconds=(12 * 86400.0) // 175.0 + 60)

For now, the offset is defined to 0 to overtake issues when orbit is unexpectedly short; but I see now, that the fix can produce other issues. It seems better to set the standalone offsets as default and fix them is case of incomplete orbit.

Are you saying these orbits are not viable despite being within the time interval? There is still at least a 30min offset between the product and the orbit, so I assume there is overlap between orbit files.

[AlexeyPechnikov]

The start offset is defined by the Sentinel-1 orbital period. I haven't verified the accuracy of the orbit file start records, but there's no need to risk using potentially incorrect records when well-specified orbit files are available.