Astrochemistry

Spectral Map Making With SPHEREx

By Keith Cowing
Status Report
astro-ph.IM
March 30, 2026
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Spectral Map Making With SPHEREx
A region in Ursa Major with maps of individual simulation components and their sum; these have been evaluated for a spectral channel centered on 0.803 µm. The color schemes vary in order to best illustrate the features of the individual signals. Notice how the scan pattern manifests in several of the components. The contributing images were generated with the Sky Simulator described in B. P. Crill et al. (2025). Real flag masks (Sec. 3.2) have been applied and are most noticeable at the centers of bright stars. — astro-ph.IM

We present map-making methodologies and preliminary spectral data cubes for SPHEREx, a NASA Explorer mission that launched in March 2025 and has been performing an all-sky near-infrared spectral survey.

The SPHEREx instrument observes from 0.75 to 5.0 microns with a spectral resolution ranging from 35 to 130 and a pixel size of 6.15″. We define a nominal set of 102 wavelength channels, each of which maps the entire sky approximately twice per year. Among the main mission goals is an investigation of the cosmic history of galaxy formation through intensity mapping of the extragalactic background light (EBL), which is a primary motivation for the map maker described in this work.

The SPHEREx dataset contains a wealth of additional mapping targets, e.g., resolved galaxies and nebulae and diffuse clouds of Galactic dust and gas, which display strong spectral features such as hydrogen recombination lines, molecular-hydrogen lines and emission from polycyclic aromatic hydrocarbons (PAHs).

We describe how our map maker handles these various cases, how to mitigate foregrounds such as zodiacal light and upper-atmospheric emission and how to monitor and mitigate systematics and signal loss. Our maps are produced both in tangent-plane projection and in full-sky HEALPix format. Specialized maps will be released to accompany future publications from the SPHEREx Science Team, and a public mosaic tool will be made available by the NASA/IPAC Infrared Science Archive (IRSA).

SPHEREx -- NASA
SPHEREx — NASA

Ari J. Cukierman, Shuang-Shuang Chen, Jae Hwan Kang, Mary H. Minasyan, Giulia Murgia, James J. Bock, Tzu-Ching Chang, Yi-Kuan Chiang, Brendan P. Crill, Olivier Doré, C. Darren Dowell, Andreas L. Faisst, Joseph L. Hora, Howard Hui, Miju Kang, Phil M. Korngut, Ho-Gyu Lee, Bomee Lee, Gary J. Melnick, Jordan Mirocha, Chi H. Nguyen, Zafar Rustamkulov, Volker Tolls, Michael W. Werner, Yujin Yang, Michael Zemcov

Comments: 31 pages, 21 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2603.25790 [astro-ph.IM] (or arXiv:2603.25790v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2603.25790
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Submission history
From: Ari Cukierman
[v1] Thu, 26 Mar 2026 18:00:09 UTC (22,308 KB)
https://arxiv.org/abs/2603.25790
Astrobiology, Astrochemistry,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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