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In the table, below, we list some typical types of spectroscopic observations and recommendations as to whether observers should use COS for their observations. These are general guidelines only, with the ultimate choice of instrument left as a decision to the proposer. Please consult the COS Instrument Handbook for further details.

Is COS Right For Your Observation?
Type of Observation Comments
Medium resolution FUV/NUV spectroscopy (point source) R ~ 20,000, high throughput
Low resolution FUV/NUV spectroscopy (faint point source, above background limit) R ~ 2500, high throughput, low 
background, large wavelength coverage
Low resolution FUV/NUV spectroscopy (faint point source, background-limited) Choice depends on details of background and wavelength
Low resolution FUV/NUV spectroscopy (bright point source) R ~ 20,000 binned to produce very high throughput
FUV/NUV spectroscopy of very bright objects May be too bright for COS, choice depends on resolution
Rapid UV variability, timing information required TTAG mode
Crowded-field FUV spectroscopy (<1 arcsec confusion limit) COS may be acceptable if confusion limit is >1 arcsec
Last Updated: 06/02/2023


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