Developed masked data support for world coordinate system (WCS) transformations in the astropy/astropy repository, enabling the world_to_pixel and pixel_to_world functions to process Masked inputs reliably. The work involved implementing type checks for MaskedNDArray and ensuring that masks are correctly applied throughout the transformation process, which enhances the robustness of the WCS API. By reducing the need for manual preprocessing, these changes improve the accuracy and usability of coordinate conversions for masked astronomical data. The feature was built using Python and focused on API development, data transformation, and thorough testing to ensure reliable handling of masked data in scientific workflows.