NEXUS: Quick Release Notes

Abstract

NEXUS is a JWST Multi-Cycle (Cycles 3-5) GO Treasury imaging and spectroscopic survey around the North Ecliptic Pole during 2024-2028. It contains two overlapping tiers in depth and area coverage. The Wide tier ($\sim 400~{\rm arcmin}^2$) performs NIRCam/WFSS 2.4-5 $μ$m grism spectroscopy with three annual epochs over 3 years (final spectral continuum ${\rm S/N/pixel>3}$ at F444W $<22.2$), accompanied by NIRCam multi-band imaging in F090W, F115W, F150W, F200W, F356W and F444W. The Deep tier ($\sim 50~{\rm arcmin}^2$) performs high-multiplexing NIRSpec 0.54-5.5 $μ$m MOS/PRISM spectroscopy for ~10,000 targets in total, over 18 epochs with a 2-month cadence, along with F200W+F444W NIRCam imaging for each epoch. Parallel imaging observations with MIRI and additional NIRCam filters are also performed within the Wide and Deep tiers. The primary data covering the Deep tier (including NIRCam imaging, NIRSpec/MSA spectra, and vetted MSA spectroscopic redshifts) are released in regular Quick Data Releases to facilitate follow-up studies. This evolving document describes the MSA targeting information and observing status for each of the 18 Deep epochs, which started in May 2025 and continue on the regular 2-month cadence. We also describe the content and caveats of the quick release data and report selected cases of diverse scientific interests.

Figures (5)

• Figure 1: Left: Cumulative number counts of targets observed with NIRSpec MOS PRISM spectroscopy as a function of number of NEXUS-Deep epochs. Magenta, blue, red, green, orange, and brown lines represent Class 0--5, respectively, while the black line represents all source classes combined. Middle: Visually-vetted spectroscopic redshifts ($z_{\rm spec}$) versus F444W magnitude for Deep Epochs 1--4 combined, with magenta, blue, red, green, orange, and brown indicating Class 0, 1, 2, 3, 4, and 5 targets, respectively. Note that transients (class=0.1 and 0.2) and objects with negative F444W fluxes are not shown here. Right: Histogram of $z_{\rm spec}$ for Deep epochs. Colors represent different epochs with correspondence indicated in the legend.
• Figure 2: Top: Targets layout (left) and distribution of target classes (right). Class 0, 1, 2, 3, 4, and 5 are indicated by magenta, blue, red, green, orange, and brown open circles, with stacked F444W image shown in the background. Blue and black bars indicate the number of objects in current epoch and all observed epochs (including the current epoch). Bottom: Two-dimensional (2D) and one-dimensional (1D) spectra of two noteworthy targets from this epoch. The inset shows the color composite image (RGB: F444W–F200W–F090W) together with the slitlet configuration. Prominent emission lines are labeled and marked with vertical dashed lines.
• Figure 3: Same as Figure \ref{['fig:deep01']} but for Deep Epoch 2.
• Figure 4: Same as Figure \ref{['fig:deep01']} but for Deep Epoch 3. In the example target shown in the lower-left panel, the red labels and dashed lines indicate emission lines from a background galaxy at $z=4.886$.
• Figure 5: Same as Figure \ref{['fig:deep01']} but for Deep Epoch 4.