Realizing the potential of the Dragonfly Spectral Line Mapper: Calibration methods and on-sky performance

Deborah M. Lokhorst; Seery Chen; Imad Pasha; Victoria Purcell; William P. Bowman; Qing Liu; Zili Shen; Aidan MacNichol; Evgeni I. Malakhov; Roberto G. Abraham; Pieter van Dokkum

arXiv · 2406.17979

Realizing the potential of the Dragonfly Spectral Line Mapper: Calibration methods and on-sky performance

Deborah M. Lokhorst·Seery Chen·Imad Pasha·Victoria Purcell·William P. Bowman·Qing Liu·Zili Shen·Aidan MacNichol·Evgeni I. Malakhov·Roberto G. Abraham·Pieter van Dokkum

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Abstract

The Dragonfly Spectral Line Mapper is an innovative all-refracting telescope designed to carry out ultra-low surface brightness wide-field mapping of visible wavelength line emission. Equipped with ultranarrowband (0.8 nm bandwidth) filters mounted in Dragonfly Filter-Tilter instrumentation, the Dragonfly Spectral Line Mapper maps H$\alpha$, [NII]$\lambda$6583, and [OIII]$\lambda$5007 line emission produced by structures with sizes ranging from $\sim$1 to 1000 kpc in the local Universe. These spatial scales encompass that of the exceedingly diffuse and faintly radiating circumgalactic medium, which is singularly difficult to detect with conventional mirror-based telescope instrumentation. Extremely careful control of systematics is required to directly image these large scale structures, necessitating high fidelity sky background subtraction, wavelength calibration, and specialized flat-fielding methods. In this paper, we discuss the on-sky performance of the Dragonfly Spectral Line Mapper with these methods in place.

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Deborah M. Lokhorst, Seery Chen, Imad Pasha, Victoria Purcell, William P. Bowman, Qing Liu, Zili Shen, Aidan MacNichol, Evgeni I. Malakhov, Roberto G. Abraham, Pieter van Dokkum. 2024-06-25. Realizing the potential of the Dragonfly Spectral Line Mapper: Calibration methods and on-sky performance. https://arxiv.org/abs/2406.17979

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