PEARLS: Near-infrared Photometry in the JWST North Ecliptic Pole Time Domain Field*

Abstract

We present near-infrared (NIR) ground-based Y, J, H, and K imaging obtained in the James Webb Space Telescope (JWST) North Ecliptic Pole Time Domain Field (NEP TDF) using the MMT-Magellan Infrared Imager and Spectrometer on the MMT. These new observations cover a field of approximately 230 arcmin2 in Y, H, and K, and 313 arcmin2 in J. Using Monte Carlo simulations, we estimate a 1σ depth relative to the background sky of (Y, J, H, K) = (23.80, 23.53, 23.13, 23.28) in AB magnitudes for point sources at a 95% completeness level. These observations are part of the ground-based effort to characterize this region of the sky, supplementing space-based data obtained with Chandra, NuSTAR, XMM, AstroSat, Hubble Space Telescope, and JWST. This paper describes the observations and reduction of the NIR imaging and combines these NIR data with archival imaging in the visible, obtained with the Subaru Hyper-Suprime-Cam, to produce a merged catalog of 57,501 sources. The new observations reported here, plus the corresponding multiwavelength catalog, will provide a baseline for time-domain studies of bright sources in the NEP TDF.

PEARLS: JWST Counterparts of Microjansky Radio Sources in the Time Domain Field

“…Colors were derived from MAG_ISO differences and applied to MAG_AUTO from the F444W image. For HSC and MMT magnitudes, counterparts were matched to sources in the Willmer et al (2023) HSC-MMIRS catalog based on positions. In practice, the matching was unambiguous, but some NIRCam sources lack ground-based counterparts because the JWST data are deeper, and many sources are red.…”

“…Those images were publicly available in early 2020 on the SMOKA archive of the National Astronomical Observatories of Japan. Willmer et al (2023) described the source extraction and photometry. Willmer et al (2023) also reported observations with the MMT and Magellan Infrared Spectrograph (MMIRS;McLeod et al 2012;Chilingarian et al 2015) on the MMT.…”

“…Willmer et al (2023) described the source extraction and photometry. Willmer et al (2023) also reported observations with the MMT and Magellan Infrared Spectrograph (MMIRS;McLeod et al 2012;Chilingarian et al 2015) on the MMT. The data used here comprise g, i2, and z from HSC and YJHK from MMIRS.…”

“…C. N. A. W. Willmer et al (2023, in preparation) will give full details, but in brief, the observations used a 270 lines mm −1 grating to achieve spectral coverage from 4000-9000 Å with a typical dispersion of 1.30 Å pixel −1 and resolution of 1340. The sample of 209 galaxies observed, limited to r  23, was selected from two catalogs: a preliminary catalog coming from the HEROES Subaru/HSC imaging (G. Hasinger 2023, private communication) and a catalog derived from MMT/MMIRS YJHK imaging (Willmer et al 2023). Hyun et al (2023) have already published some of the measurements, specifically those for SCUBA2 sources.…”

“…¢ ´¢ at orientation differences of 90°. Figure 1 of Willmer et al (2023) depicts the field layout and location. The radio observations (Hyun et al 2023) were centered on a quasar located about 1′ south of the bright star at the intersection of the southern and eastern spokes.…”