Large Scale Spectrophotometric Relative Flux Calibration for the Roman High Latitude Wide Area Survey

Fuente: arXiv
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Autores principales: Nguyen, Alan B. H., Walth, Gregory, Ross, Ashley J., Colbert, James W., Swanson, Jaide, Padmanabhan, Nikhil, Wang, Yun
Formato: Preprint
Publicado: 2026
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author Nguyen, Alan B. H.
Walth, Gregory
Ross, Ashley J.
Colbert, James W.
Swanson, Jaide
Padmanabhan, Nikhil
Wang, Yun
author_facet Nguyen, Alan B. H.
Walth, Gregory
Ross, Ashley J.
Colbert, James W.
Swanson, Jaide
Padmanabhan, Nikhil
Wang, Yun
contents We consider the application of a ubercalibration-like relative flux calibration to the grism observations of the Roman High Latitude Wide Area Survey (HLWAS). We propose a simplified model of the calibration with an independent flat field for each detector in each exposure of the focal plane. In addition, we include two wavelength dependent components: a single wavelength throughput curve, modulated by a simple parabolic model for the throughput as a function of a source's focal plane position. We consider the impact of the dither scale, as well as the calibrator magnitude cuts. We show that the width of the calibration residuals can be reduced to less than 1.5 mmag, or 0.15% in flux, within the optimal dither range 50-240". This wide range allows for significant flexibility in optimising other parts of the observing program without diminishing the effectiveness of the relative flux calibration. We also discuss some improvements to the methodology that must be strongly considered before the calibration can be applied to real data. Finally, although we focused on spectroscopic component of the HLWAS here, our formalism and results should carry over to the imaging surveys as well.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24839
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Large Scale Spectrophotometric Relative Flux Calibration for the Roman High Latitude Wide Area Survey
Nguyen, Alan B. H.
Walth, Gregory
Ross, Ashley J.
Colbert, James W.
Swanson, Jaide
Padmanabhan, Nikhil
Wang, Yun
Instrumentation and Methods for Astrophysics
Cosmology and Nongalactic Astrophysics
We consider the application of a ubercalibration-like relative flux calibration to the grism observations of the Roman High Latitude Wide Area Survey (HLWAS). We propose a simplified model of the calibration with an independent flat field for each detector in each exposure of the focal plane. In addition, we include two wavelength dependent components: a single wavelength throughput curve, modulated by a simple parabolic model for the throughput as a function of a source's focal plane position. We consider the impact of the dither scale, as well as the calibrator magnitude cuts. We show that the width of the calibration residuals can be reduced to less than 1.5 mmag, or 0.15% in flux, within the optimal dither range 50-240". This wide range allows for significant flexibility in optimising other parts of the observing program without diminishing the effectiveness of the relative flux calibration. We also discuss some improvements to the methodology that must be strongly considered before the calibration can be applied to real data. Finally, although we focused on spectroscopic component of the HLWAS here, our formalism and results should carry over to the imaging surveys as well.
title Large Scale Spectrophotometric Relative Flux Calibration for the Roman High Latitude Wide Area Survey
topic Instrumentation and Methods for Astrophysics
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2603.24839