Frequently Asked Questions

Data Requests

• How can I tell whether polarization data, as well as the UV spectrum, are available for a particular object?

Reading Files

• How do I read the WUPPE data files?
• How do I convert the Stokes parameters Q and U to linear polarization parameters?

Data Requests

• How can I tell whether polarization data, as well as the UV spectrum, are available for a particular object?
  In the search results page, the polarization and position angle will both be set to 0.000 if no polarization data are available. In this case, only the ultraviolet spectrum is available from the archive. In addition, the FITS file for an observation including polarization data is significantly larger (typically 34560 bytes uncompressed) than one with only spectral data (11520 bytes).
  
  

Reading Files

• How do I read the WUPPE data files?
  The image files are in FITS format, and should be readable with standard FITS readers. See Reading WUPPE Data for more information.
  
  
• How do I convert the Stokes parameters Q and U to linear polarization parameters?
  Linear polarization = sqrt(Q² + U²), while position angle = 1/2 tan^-1(U/Q)