Analysis of a JWST NIRSpec Lab Time Series: Characterizing Systematics, Recovering Exoplanet Transit Spectroscopy, and Constraining a Noise Floor

Rustamkulov, Zafar and Sing, David K. and Liu, Rongrong and Wang, Ashley (2022) Analysis of a JWST NIRSpec Lab Time Series: Characterizing Systematics, Recovering Exoplanet Transit Spectroscopy, and Constraining a Noise Floor. The Astrophysical Journal Letters, 928 (1). L7. ISSN 2041-8205

[thumbnail of Rustamkulov_2022_ApJL_928_L7.pdf] Text
Rustamkulov_2022_ApJL_928_L7.pdf - Published Version

Download (4MB)

Abstract

The James Webb Space Telescope's (JWST) NIRSpec instrument will unveil the nature of exoplanet atmospheres across the wealth of planet types, from temperate terrestrial worlds to ultrahot Jupiters. In particular, the 0.6–5.3 μm PRISM mode is especially well suited for efficient spectroscopic exoplanet observations spanning a number of important spectral features. We analyze a lab-measured NIRSpec PRISM mode Bright Object Time Series observation from the perspective of a JWST user to understand the instrument performance and detector properties. We create two realistic transiting exoplanet time-series observations by performing injection-recovery tests on the lab-measured data to quantify the effects of real instrument jitter, drift, intrapixel sensitivity variations, and 1/f noise on measured transmission spectra. By fitting the time-series systematics simultaneously with the injected transit, we can obtain more realistic transit-depth uncertainties that take into account noise sources that are currently not modeled by traditional exposure time calculators. We find that sources of systematic noise related to intrapixel sensitivity variations and point-spread function motions are apparent in the data at the level of a few hundred ppm but can be effectively detrended using a low-order polynomial with detector position. We recover the injected spectral features of GJ 436 b and TRAPPIST-1 d and place a 3σ upper limit on the detector noise floor of 14 ppm. We find that the noise floor is consistent with <10 ppm at the 1.7σ level, which bodes well for future observations of challenging targets with faint atmospheric signatures.

Item Type: Article
Subjects: STM Open Press > Physics and Astronomy
Depositing User: Unnamed user with email support@stmopenpress.com
Date Deposited: 28 Apr 2023 05:46
Last Modified: 17 Oct 2024 04:02
URI: http://journal.submissionpages.com/id/eprint/1086

Actions (login required)

View Item
View Item