Tilsotua: Reproducing Slitmask Sky Positions for use with the LRIS Multislit Archive

Abstract

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.

arXiv comment23 pages, 7 figures, Published in PASP, tilsotua repository: https://github.com/KeckObservatory/tilsotua Added DOI, fixed author name typo

References in corpus (28)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• The Structure and Kinematics of the Circum-Galactic Medium from Far-UV Spectra of z~2-3 Galaxies
• astroquery: An Astronomical Web-Querying Package in Python
• The Pan-STARRS1 Database and Data Products
• A Survey of Star-Forming Galaxies in the z=1.4-2.5 `Redshift Desert': Overview
• Diffuse Lyman Alpha Emitting Halos: A Generic Property of High Redshift Star Forming Galaxies
• Caltech Faint Galaxy Redshift Survey X: A Redshift Survey in the Region of the Hubble Deep Field North
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• A Spectroscopic Survey of Redshift 1.4<z<3.0 Galaxies in the Goods-North Field: Survey Description, Catalogs, and Properties
• The Luminosity Function of Lyman Alpha Emitters at Redshift z~5.7
• What is the physical origin of strong Lya emission? II. Gas Kinematics and Distribution of Lya Emitters
• Spectroscopic Properties of the z=4.5 Lyman-alpha Emitters
• Stellar Evolution in NGC 6791: Mass Loss on the Red Giant Branch and the Formation of Low Mass White Dwarfs
• Physical Conditions in the Low-Ionization Component of Starburst Outflows: The Shape of Near-Ultraviolet and Optical Absorption-Line Troughs in Keck Spectra of ULIRGs
• First Data Release of the COSMOS Lyman-Alpha Mapping And Tomography Observations: 3D Lyman-$\alpha$ Forest Tomography at 2.05 < z < 2.55
• The Column Density, Kinematics, and Thermal State of Metal-Bearing Gas within the Virial Radius of z~2 Star-Forming Galaxies in the Keck Baryonic Structure Survey
• Outflowing Galactic Winds in Post-starburst and AGN Host Galaxies at 0.2<z<0.8
• The COS-Halos Survey: Keck LRIS and Magellan MagE Optical Spectroscopy
• The Keck Baryonic Structure Survey: Using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at $z\sim 2$
• Galaxies probing galaxies: cool halo gas from a z = 0.47 post-starburst galaxy
• The Chemical Abundances of the Stellar Populations in the Leo I and Leo II dSph Galaxies
• Keck Spectroscopy of Red Giant Stars in the Vicinity of M31's Massive Globular Cluster G1
• Light-Element Abundance Variations at Low Metallicity: the Globular Cluster NGC 5466
• PC1643+4631A,B: The Lyman-Alpha Forest at the Edge of Coherence