How well will the spectroscopy pipeline handle extended objects?
The spectroscopy pipeline is designed to handle point-source (unresolved) objects. The extraction width or aperture for spectra is fixed at 10 arcsec. Unresolved sources generally have a PSF between 5 and 6 arcsec, resulting in a flux loss of a few percent (see FAQ 102 and FAQ 124). Resolved sources will have a somewhat larger flux loss (e.g. 24% for a source FWHM of 10 arcsec). Large FWHM sources and sources which are broken up into pieces during the direct image source extraction may require a special spectral extraction. Also, non-radially-symmetric sources require special considerations for the grism position angle. A grism image is always provided as a standard product and can be used to extract spectral data by a knowledgeable data analyst. Background subtraction may also be an issue for very wide sources since the sky (background) region begins at 11 arcsec from the center of the source (22 arcsec full width). Estimating the S/N for an extended object must take into account the
