Flexure updates to MOSFIRE on the Keck I telescope

TL;DR

This paper evaluates and updates the flexure correction systems of MOSFIRE on Keck I to address slight drifts during long integrations, aiming to improve data quality for extended observations.

Contribution

It identifies potential causes of mask star drift and discusses recent testing and updates to the flexure compensation and correction systems of MOSFIRE.

Findings

Detected slight drift in mask stars during long exposures.

Identified three possible causes: FCS, guider camera flexure, DAR corrections.

Outlined future testing plans to pinpoint the primary cause.

Abstract

We present a recent evaluation and updates applied to the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on the Keck I telescope. Over the course of significantly long integrations, when MOSFIRE sits on one mask for $>$4 hours, a slight drift in mask stars has been measured. While this does not affect all science-cases done with MOSFIRE, the drift can smear out signal for observers whose science objective depends upon lengthy integrations. This effect was determined to be the possible result of three factors: the internal flexure compensation system (FCS), the guider camera flexure system, and/or the differential atmospheric refraction (DAR) corrections. In this work, we will summarize the three systems and walk through the current testing done to narrow down the possible culprit of this drift and highlight future testing to be done.