fix(csub): CSUB observations

[jdhughes-usgs]

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Checklist of items for pull request

• Replaced section above with description of pull request
• Closed issue Incorrect documentation of "theta" CSUB observation type #1447
• Referenced issue or pull request Incorrect documentation of "theta" CSUB observation type #1447
• Added new test or modified an existing test
• Ran ruff on new and modified python scripts in .doc, autotests, doc, distribution, pymake, and utils subdirectories.
• Formatted new and modified Fortran source files with fprettify
• Updated develop.tex with a plain-language description of the bug fix, change, feature; required for changes that may affect users
• Updated input and output guide
• Removed checklist items not relevant to this pull request

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Closes #1447