grouping area factor incorrectly used for SLCs?

[priit111]

The offending code(

sarsen/sarsen/sentinel1.py

Line 50 in a94b10c

if attrs["product_type"] == "SLC":

) has two issues:

1. np.sin expects radians, not degrees

Per S1 product definition, the value is in degrees:

xarray_sentinel metadata reads it as degrees and does no conversion:
https://github.com/bopen/xarray-sentinel/blob/368df813c16ebf4483fdd4859cf79ca8f4f7a046/xarray_sentinel/sentinel1.py#L810

2. The formula for ground spacing from slant range spacing is G = R / sin(ia), however the code calculates it incorrectly as G = R * sin(ia).