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Main Authors: Sullivan, Jessica, Howk, J. Christopher, Lehner, Nicolas, O'Meara, John M., Simha, Sunil
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.08118
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author Sullivan, Jessica
Howk, J. Christopher
Lehner, Nicolas
O'Meara, John M.
Simha, Sunil
author_facet Sullivan, Jessica
Howk, J. Christopher
Lehner, Nicolas
O'Meara, John M.
Simha, Sunil
contents We present tilsotua, a code that calculates sky positions of the slits from Low-Resolution Imaging Spectrograph (LRIS) slitmasks used in multislit observations. Raw data for the Keck/LRIS spectrograph does not include information about the sky positions of the slitmask targets, making it difficult to use beyond the scope of the original programs. tilsotua translates slit coordinates from the mask design files in the mask milling machine frame to sky coordinates. tilsotua also shifts the original input astrometry to modern frames using the objects targeted by mask alignment boxes. This can be applied to the archived mask design files at the Lick Observatory Archive. We demonstrate that the final reconstructed slit positions are accurate to 0."14 (RMS) across the set of archived masks based on a comparison of our calculated mask alignment box coordinates with Gaia astrometric positions of the likely alignment objects. We make available the tilsotua code, archived mask files, and slit positions of the historical masks for the community to maximize the science from Keck/LRIS data in the Keck Observatory Archive.
format Preprint
id arxiv_https___arxiv_org_abs_2504_08118
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tilsotua: Reproducing Slitmask Sky Positions for use with the LRIS Multislit Archive
Sullivan, Jessica
Howk, J. Christopher
Lehner, Nicolas
O'Meara, John M.
Simha, Sunil
Instrumentation and Methods for Astrophysics
We present tilsotua, a code that calculates sky positions of the slits from Low-Resolution Imaging Spectrograph (LRIS) slitmasks used in multislit observations. Raw data for the Keck/LRIS spectrograph does not include information about the sky positions of the slitmask targets, making it difficult to use beyond the scope of the original programs. tilsotua translates slit coordinates from the mask design files in the mask milling machine frame to sky coordinates. tilsotua also shifts the original input astrometry to modern frames using the objects targeted by mask alignment boxes. This can be applied to the archived mask design files at the Lick Observatory Archive. We demonstrate that the final reconstructed slit positions are accurate to 0."14 (RMS) across the set of archived masks based on a comparison of our calculated mask alignment box coordinates with Gaia astrometric positions of the likely alignment objects. We make available the tilsotua code, archived mask files, and slit positions of the historical masks for the community to maximize the science from Keck/LRIS data in the Keck Observatory Archive.
title Tilsotua: Reproducing Slitmask Sky Positions for use with the LRIS Multislit Archive
topic Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2504.08118