JEMS: A Deep Medium-band Imaging Survey in the Hubble Ultra Deep Field with JWST NIRCam and NIRISS

We present JWST Extragalactic Medium-band Survey, the first public medium-band imaging survey carried out using JWST/NIRCam and NIRISS. These observations use $\sim 2$ and $\sim 4\ \mu\mathrm{m}$ medium-band filters (NIRCam F182M, F210M, F430M, F460M, F480M; and NIRISS F430M and F480M in parallel) over $15.6\ \mathrm{arcmin}^{2}$ in the Hubble Ultra Deep Field (UDF), thereby building on the deepest multiwavelength public data sets available anywhere on the sky. We describe our science goals, survey design, NIRCam and NIRISS image reduction methods, and describe our first data release of the science-ready mosaics, which reach $5\sigma$ point-source limits (AB mag) of $\sim 29.3-29.4$ in $4\ \mu\mathrm{m}$ filters and $\sim 28.2-28.7$ at $4\ \mu\mathrm{m}$ . Our chosen filters create a JWST imaging survey in the UDF that enables novel analysis of a range of spectral features potentially across the redshift range of $0.3 < z < 20$ , including $\mathrm{Paschen}-\alpha$ , $\mathrm{H}\alpha+\mathrm{[NII]}$ , and $\mathrm{[OIII]}+\mathrm{H}\beta$ emission at high spatial resolution. We find that our JWST medium-band imaging efficiently identifies strong line emitters (medium-band colors $> 1$ mag) across redshifts $1.5 < z < 9.3$ , most prominently $\mathrm{H}\alpha+\mathrm{[NII]}$ and $\mathrm{[OIII]}+\mathrm{H}\beta$ . We present our first data release including science-ready mosaics of each medium-band image available to the community, adding to the legacy value of past and future surveys in the UDF. This survey demonstrates the power of medium-band imaging with JWST, informing future extragalactic survey strategies using JWST observations.

The Astrophysical Journal Supplement Series, Volume 268, Issue 2, id.64, 15 pages