failure is assigned in place of the redshift.]{}

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Figure \[figure:example\_spectra\] shows C3R2 spectra from 2016A as examples of Q=3, Q=3.5, and Q=4 redshift assignments.

Failure Codes
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It is important for C3R2 to track redshift failures, as well as the reasons for the failures, in order to avoid systematic biases in the sources selected for calibration. Failed targets that were expected to yield a redshift given the instrument and exposure time can be prioritized for additional follow-up. On the other hand, if no spectroscopic redshift was obtained because of a problem with the observing conditions or data (i.e., bad rows, or the target ended up in a region between two detector arrays), no additional prioritization of that source may be needed.

With these considerations in mind, we developed a system to flag different “failure modes” for objects not yielding a redshift. Four categories of failures are used, with the corresponding code assigned in place of a redshift in our catalog. The failure modes we identify are:

1.  [Code = $-$91: Object too faint to identify the redshift. Indicates that a deeper exposure and/or different instrument and/or different wavelength coverage is required to obtain a secure redshift. 