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Cause of JWST guide star acquisition failures affecting NIRSpec observations in program GO 2302

Ascertain the cause of the JWST guide star acquisition failure that led to the missing NIRSpec observation of WISEPA J2018−7423 and characterize the underlying reasons for similar guide star failures encountered in this program, to mitigate such issues in future JWST observations.

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Background

During observations, one target (WISEPA J2018−74) missed its NIRSpec observation due to a failed guide star acquisition, and the authors state that the reason was unknown and not identified within the time window to request a repeat. They further note that several other targets experienced guide star failures with no clear cause, though those cases were identified promptly and reobserved.

While this is an operational rather than astrophysical issue, it directly impacted the completeness of the dataset and the authors flag it as an unresolved cause that affected their observing campaign.

References

The reason for its failure is unknown and the failure was not identified until after the period to request repeating the observation had passed. Guide star failures did occur for several of our other targets, again with no clear cause, but the others were identified quickly and the observations were repeated upon request.

— Precise Bolometric Luminosities and Effective Temperatures of 23 late-T and Y dwarfs Obtained with JWST (2407.08518 - Beiler et al., 11 Jul 2024) in Section 3 (Observations)