The JWST Resolved Stellar Populations Early Release Science Program I.: NIRCam Flux Calibration
Martha L. Boyer, Jay Anderson, Mario Gennaro, Marla Geha, Kristen B. Wingfield McQuinn, Erik Tollerud, Matteo Correnti, Max J. Brenner Newman, Roger E. Cohen, N… 展开作者
Martha L. Boyer, Jay Anderson, Mario Gennaro, Marla Geha, Kristen B. Wingfield McQuinn, Erik Tollerud, Matteo Correnti, Max J. Brenner Newman, Roger E. Cohen, Nitya Kallivayalil, Rachel Beaton, Andrew A. Cole, Andrew Dolphin, Jason S. Kalirai, Karin M. Sandstrom, Alessandro Savino, Evan D. Skillman, Daniel R. Weisz, Benjamin F. Williams
We use globular cluster data from the Resolved Stellar Populations Early Release Science (ERS) program to validate the flux calibration for the Near Infrared Camera (NIRCam) on the James Webb Space Telescope (JWST). We find a significant flux offset between the eight short wavelength detectors, ranging from 1-23% (about 0.01-0.2 mag) that affects all NIRCam imaging observations. We deliver improved zeropoints for the ERS filters and show that alternate zeropoints derived by the community also improve the calibration significantly. We also find that the detector offsets appear to be time variable by up to at least 0.1 mag.
The James Webb Space Telescope (JWST) offers unprecedented sensitivity, stability, and wavelength coverage for transiting exoplanet studies, opening up new avenues for measuring atmospheric abundances, structure, and temperature profiles. Taking full advantage of JWST spectroscopy of planets from 0.6um to 28um, however, will require many observations with a combination of the NIRISS, NIRCam, NIRSpec, and MIRI instruments. In this white paper, we discuss a new NIRCam mode (not yet approved or implemented) that can reduce the number of necessary observations to cover the 1.0um to 5.0um wavelengt…
As the James Webb Space Telescope (JWST) has become fully operational, early-release data are now available to begin building the tools and calibrations for precision point-source photometry and astrometry in crowded cluster environments. Here, we present our independent reduction of NIRCam imaging of the metal-poor globular cluster M92, which were collected under Director's Discretionary Early Release Science programme ERS-1334. We derived empirical models of the Point Spread Function (PSF) for filters F090W, F150W, F277W, and F444W, and find that these PSFs: (i) are generally under-sampled (…
We present criteria for separately classifying stars and unresolved background galaxies in photometric catalogs generated with the point spread function (PSF) fitting photometry software DOLPHOT from images taken of Draco II, WLM, and M92 with the Near Infrared Camera (NIRCam) on JWST. Photometric quality metrics from DOLPHOT in one or two filters can recover a pure sample of stars. Conversely, colors formed between short-wavelength (SW) and long-wavelength (LW) filters can be used to effectively identify pure samples of galaxies. Our results highlight that the existing DOLPHOT output paramete…
JWST transmission and emission spectra will provide invaluable glimpses of transiting exoplanet atmospheres, including possible biosignatures. This promising science from JWST, however, will require exquisite precision and understanding of systematic errors that can impact the time series of planets crossing in front of and behind their host stars. Here, we provide estimates of the random noise sources affecting JWST NIRCam time-series data on the integration-to-integration level. We find that 1/f noise can limit the precision of grism time series for 2 groups (230 ppm to 1000 ppm depending on…
We present the reduced images and multi-wavelength catalog of the first JWST NIRCam extra-galactic observations from the GLASS Early Release Science Program, obtained as coordinated parallels of the NIRISS observations of the Abell 2744 cluster. Images in seven bands (F090W, F115W, F150W, F200W, F277W, F356W, F444W) have been reduced using an augmented version of the official JWST pipeline; we discuss the procedures adopted to remove or mitigate defects in the raw images. We obtain a multi--band catalog by means of forced aperture photometry on PSF-matched images at the position of F444W-detec…
The James Webb Space Telescope (JWST) will be launched in December 2021, with four instruments to perform imaging and spectroscopy. This paper presents work which is part of the Early Release Science (ERS) program "PDRs4All" aimed at observing the Orion Bar. It focuses on the Near Infrared Camera (NIRCam) imaging which will be performed as part of this project. The aim of this paper is to illustrate a methodology to simulate observations of an extended source that is similar to the Orion Bar with NIRCam, and to run the pipeline on these simulated observations. These simulations provide us with…
JWST holds great promise in characterizing atmospheres of transiting exoplanets, potentially providing insights into Earth-sized planets within the habitable zones of M dwarf host stars if photon-limited performance can be achieved. Here, we discuss the systematic error sources that are expected to be present in grism time series observations with the NIRCam instrument. We find that pointing jitter and high gain antenna moves on top of the detectors' subpixel crosshatch patterns will produce relatively small variations (less than 6 parts per million, ppm). The time-dependent aperture losses du…
In preparation to make the most of our own planned James Webb Space Telescope investigations, we take advantage of publicly available calibration and early-science observations to independently derive and test a geometric-distortion solution for NIRCam detectors. Our solution is able to correct the distortion to better than ~0.2 mas. Current data indicate that the solution is stable and constant over the investigated filters, temporal coverage, and even over the available filter combinations. We successfully tested our geometric-distortion solution in three cases: (i) field-object decontaminat…
I present an overview of the JWST Advanced Deep Extragalactic Survey (JADES), a joint program of the JWST/NIRCam and NIRSpec Guaranteed Time Observations (GTO) teams involving 950 hours of observation. We will target two well-studied fields with excellent supporting data (e.g., from HST-CANDELS): GOODS-North and South, including the Ultra Deep Field. The science goal of JADES is to chart galaxy evolution at z > 2, and potentially out to z > 10, using the rest-frame optical and near-IR though observations from $\approx$ 1 - 5 $μ$m. Multi-colour NIRCam imaging with 9 filters will enable photomet…
A Detailed Investigation of HD 209458 b HST & JWST Transmission Spectra with SANSAR
School of Earth & Planetary Sciences, National Institute of Science Education and Research (NISER), Homi Bhabha National Institute (HBNI)（地球与行星科学学院，国家科学教育研究所（NISER），霍米·巴巴国立研究所（HBNI））
Grisms are dispersive transmission optics that find their most frequent use in instruments that combine imaging and spectroscopy. This application is particularly popular in the infrared where imagers frequently have a cold pupil in their optical path that is a suitable location for a dispersive element. In particular, several recent and planned space experiments make use of grisms in slit-less spectrographs capable of multi-object spectroscopy. We present an astronomer-oriented general purpose introduction to grisms and their use in current and future astronomical instruments. We present a si…
The James Webb Space Telescope near-infrared camera (JWST NIRCam) has two 2.'2 $\times$ 2.'2 fields of view that are capable of either imaging or spectroscopic observations. Either of two $R \sim 1500$ grisms with orthogonal dispersion directions can be used for slitless spectroscopy over $λ= 2.4 - 5.0$ $μ$m in each module, and shorter wavelength observations of the same fields can be obtained simultaneously. We present the latest predicted grism sensitivities, saturation limits, resolving power, and wavelength coverage values based on component measurements, instrument tests, and end-to-end m…
We use JWST NIRCam short wavelength photometry to capture a transit lightcurve of the exoplanet HAT-P-14 b to assess performance as part of instrument commissioning. The short wavelength precision is 152 ppm per 27 second integration as measured over the full time series compared to a theoretical limit of 107 ppm, after corrections to spatially correlated 1/f noise. Persistence effects from charge trapping are well fit by an exponential function with short characteristic timescales, settling on the order of 5-15 minutes. The short wavelength defocused photometry is also uniquely well suited to…
Fast Lensing And Sub-minute High-accuracy photometry (FLASH) with JWST: Pipeline and Primordial Black Hole Microlensing Constraints from M31
University of Hawai‘i at Mānoa（夏威夷大学马诺阿分校）；E.O. Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Institute for Astronomy, University of Hawai‘i at Mānoa（夏威夷大学马诺阿分校天文研究所）
In a cold and stable space environment, the James Webb Space Telescope (JWST or "Webb") reaches unprecedented sensitivities at wavelengths beyond 2 microns, serving most fields of astrophysics. It also extends the parameter space of high-contrast imaging in the near and mid-infrared. Launched in late 2021, JWST underwent a six month commissioning period. In this contribution we focus on the NIRCam Coronagraphy mode which was declared "science ready" on July 10 2022, the last of the 17 JWST observing modes. Essentially, this mode will allow to detect fainter/redder/colder (less massive for a gi…
JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: Wisp Subtraction with the Non-negative Matrix Factorization Algorithm
Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；Department of Physics and Astronomy, The Johns Hopkins University（约翰斯·霍普金斯大学物理与天文系）；Space Telescope Science Institute（太空望远镜科学研究所）；Department of Astronomy and Astrophysics, University of California, Santa Cruz（加州大学圣克鲁兹分校天文与天体物理系）；Kavli Institute for Cosmology, University of Cambridge（剑桥大学卡弗里宇宙学研究所）；Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）
A parameterised approach to disequilibrium retrievals in the JWST era: Application to NIRCam observations of HD 189733b
University of Oxford（牛津大学）；University of California, Riverside（加州大学河滨分校）；Institute of Astronomy & Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）；Université Côte d’Azur（蔚蓝海岸大学）；Observatoire de la Côte d’Azur（蔚蓝海岸天文台）；CNRS（法国国家科学研究中心）；Laboratoire Lagrange（拉格朗日实验室）；Arizona State University（亚利桑那州立大学）
研究系外行星大气非平衡化学对反演结果的影响，通过生成合成 JWST 观测数据，将传输诱导淬灭纳入反演框架，应用于 HD 189733b 观测，发现淬灭及光化学活跃区域初步证据。
We observed HD 19467 B with JWST's NIRCam in six filters spanning 2.5-4.6 $μm$ with the Long Wavelength Bar coronagraph. The brown dwarf HD 19467 B was initially identified through a long-period trend in the radial velocity of G3V star HD 19467. HD 19467 B was subsequently detected via coronagraphic imaging and spectroscopy, and characterized as a late-T type brown dwarf with approximate temperature $\sim1000$K. We observed HD 19467 B as a part of the NIRCam GTO science program, demonstrating the first use of the NIRCam Long Wavelength Bar coronagraphic mask. The object was detected in all 6 f…
A Next-Generation Exoplanet Atmospheric Retrieval Framework NEXOTRANS for Emission Spectroscopy: New Constraints and Atmospheric Characterization of WASP-69b Using JWST NIRCam and MIRI Observations
The James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based telescopes. Here, we aim to characterize the performance of several extreme angular resolution imaging techniques available with JWST in the 3-5 micron regime based on data taken during commissioning. Firstly, we introduce custom tools to simulate, re…
