JWST’s PEARLS: Improved Flux Calibration for NIRCam

IF 3.3 3区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Publications of the Astronomical Society of the Pacific Pub Date : 2024-02-01 DOI:10.1088/1538-3873/ad1f3e

Zhiyuan Ma, Haojing Yan, Bangzheng Sun, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Rogier A. Windhorst, Jordan C. J. D’Silva, Anton M. Koekemoer, Dan Coe, Christopher J. Conselice, Simon P. Driver, Brenda Frye, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Rafael Ortiz, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Christopher N. A. Willmer, Heidi B. Hammel, Stefanie N. Milam, Nathan J. Adams, Cheng Cheng, Nimish P. Hathi

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引用次数: 0

Abstract

The Prime Extragalactic Areas for Reionization and Lensing Science, a James Webb Space Telescope (JWST) GTO program, obtained a set of unique NIRCam observations that have enabled us to significantly improve the default photometric calibration across both NIRCam modules. The observations consisted of three epochs of 4-band (F150W, F200W, F356W, and F444W) NIRCam imaging in the Spitzer IRAC Dark Field (IDF). The three epochs were six months apart and spanned the full duration of Cycle 1. As the IDF is in the JWST continuous viewing zone, we were able to design the observations such that the two modules of NIRCam, modules A and B, were flipped by 180° and completely overlapped each other’s footprints in alternate epochs. We were therefore able to directly compare the photometry of the same objects observed with different modules and detectors, and we found significant photometric residuals up to ∼0.05 mag in some detectors and filters, for the default version of the calibration files that we used (jwst_1039.pmap). Moreover, there are multiplicative gradients present in the data obtained in the two long-wavelength bands. The problem is less severe in the data reduced using the latest pmap (jwst_1130.pmap as of 2023 September), but it is still present, and is non-negligible. We provide a recipe to correct for this systematic effect to bring the two modules onto a more consistent calibration, to a photometric precision better than ∼0.02 mag.

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JWST's PEARLS：改进 NIRCam 的通量校准

詹姆斯-韦伯太空望远镜（JWST）GTO计划中的 "用于再电离和透镜科学的主要河外星系区域"（Prime Extragalactic Areas for Reionization and Lensing Science）获得了一组独特的NIRCam观测数据，使我们能够显著改进两个NIRCam模块的默认测光校准。这些观测包括在斯皮策 IRAC 暗场（IDF）中对 4 波段（F150W、F200W、F356W 和 F444W）NIRCam 成像的三个纪元。这三个时间相隔六个月，跨越了整个周期 1。由于 IDF 位于 JWST 的连续观测区内，我们在设计观测时将 NIRCam 的两个模块（模块 A 和模块 B）翻转 180°，在交替的时间段内彼此的足迹完全重叠。因此，我们可以直接比较使用不同模块和探测器观测到的同一天体的光度，我们发现，在我们使用的默认版本的校准文件（jwst_1039.pmap）中，某些探测器和滤光片的光度残差高达 ∼0.05 mag。此外，在两个长波段获得的数据中还存在乘法梯度。在使用最新 pmap（截至 9 月 2023 日的 jwst_1130.pmap）缩减的数据中，这个问题没有那么严重，但仍然存在，而且不可忽略。我们提供了一个校正这一系统性影响的方法，使两个模块的校准更加一致，光度精度优于 ∼ 0.02 马格。

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来源期刊

Publications of the Astronomical Society of the Pacific 地学天文-天文与天体物理

CiteScore

6.70

自引率

5.70%

发文量

103

审稿时长

4-8 weeks

期刊介绍： The Publications of the Astronomical Society of the Pacific (PASP), the technical journal of the Astronomical Society of the Pacific (ASP), has been published regularly since 1889, and is an integral part of the ASP''s mission to advance the science of astronomy and disseminate astronomical information. The journal provides an outlet for astronomical results of a scientific nature and serves to keep readers in touch with current astronomical research. It contains refereed research and instrumentation articles, invited and contributed reviews, tutorials, and dissertation summaries.