(Results also apply to BOTS mode when considering the net extracted absolute, as opposed to relative, spectra.) 

Broadband absolute flux accuracy

It is generally better than 5% absolute for sources well centered in the aperture.

Caveats:

• The lack of a correction in the pipeline for differences between nodding patterns, which subtract some source flux along with the background, limits the accuracy to about 5% for most modes. The current calibration is optimized for the 3-point nodding pattern for the S200A1, S200A2, and S400A1, and is a compromise between the 3-point nod and no nod correction for the S1600A1. Note that the 5-point dither pattern in the S1600A1 is currently not well handled by the pipeline default settings, leading to a 20% flux underestimate for level 2 and 3 products, although this is easily fixed with customized reprocessing.
• PRISM observations in the narrow S200A1, S200A2, and S400A1 slits may show somewhat lower absolute accuracy than the above, as the standard star used to calibrate these combinations was close to saturation with the smallest supported subarray.
• The accuracy of flux corrections for off-centered sources is less well established.
• Achieving the above-quoted accuracy may require rerunning the pipeline with altered parameters, including changes to outlier rejection, weights used for resampling, and the source extraction location.

Photometric Repeatability

Typical broadband flux repeatability over a time scale of months is approximately 0.5%. Any time-dependent trend appears to be smaller than 2% per year.

Limiting S/N

For a bright source observed at multiple dither positions, 50:1 is achievable with modest modifications to default pipeline parameters. At least 100:1 should be possible with more specialized data reduction techniques.

1/f Noise

The removal of the 1/f noise has not been optimized yet. There is ongoing work to reduce the 1/f noise using the NS Clean algorithm.

Resampling of 2D spectra

The stage 2 and 3 of the pipeline resample the 2D spectra before doing the final 1D extraction. The resample of the 2D spectra has been found to introduce extra artificial noise that gets reflected in the 1D spectra, and significantly decreases their signal-to-noise.

Flux in off-center dithers/nods

In some cases the flux of the spectra obtained at the off-center dithers/nods is higher by a few percent in flux from the center spectra. This issue is under investigation.