All the lensing galaxies proved to be early-type galaxies with

Ca ii H & K absorption and, generally, strong 4000 Å breaks

We obtained quality A redshifts for four lensed sources, all at z ∼ 2, as well as one quality B redshift at z = 2.316 (Fig. 6)

In most cases, the lensed background source was revealed as a slightly offset or extended blue emission line coincident with the early-type lensing galaxy. Since the emission features did not correspond to any strong, redshifted spectral features in earlytype galaxies (which generally do not have emission lines), the most plausible identifications were lensed Lyα at z ∼ 2. One lensed source, EUCL J175555.21+635718.7, does not show Lyα emission but instead shows the classic spectrum of a Lymanbreak galaxy with multiple absorption lines due to the interstellar medium. A detailed analysis and further follow-up of this target and EUCL J174907.29+645946.3, a possible double source plane candidate, will be presented in

4.2. Additional available spectra

We visually inspected the available DESI and SDSS spectra for all 78 targets. We found that all ten redshift for the lens galaxies obtained from Palomar are in agreement with the redshifts previously reported. Regarding the source detections made by

Palomar, in most of the cases, the Lyα emission line is out of the

DESI spectra coverage or very near to the edge making its detection in DESI data impossible or unreliable. Additional spectral features were identified in only four targets, including the

EUCL J175555.21+635718.7, the Lyman-break galaxy previously mentioned. Based on insights from Palomar spectroscopic data, we believe that in many cases, the emission or absorption lines may fall outside the observed spectral range or near the edges, where noise levels are high, making detection challenging. Additionally, the integration time may not have been sufficient to capture the often faint signals from the sources. The

Table 2. Lens candidates in category B

Name RA Dec zLens σv [km s-1

VI score Modela

θE[′′

Discovery

EUCL J174557.20+655632.7 266.488341 65.942430 0.60 218 1.15 N/- - This work

EUCL J180007.48+631553.4 270.031189 63.264859 0.29 316 1.15 NM - This work

EUCL J180330.53+631941.8 270.877209 63.328302 0.92 236 1.10 NM - This work

EUCL J175605.62+635749.9 269.023418 63.963877 0.70 283 1.10 N/- - This work

EUCL J175149.82+635445.1 267.957618 63.912530 0.33 191 1.05 N/- - This work

EUCL J180621.71+663023.3 271.590471 66.506485 0.85 280 1.00 Y/Y 1.43 This work

EUCL J175633.58+662304.9 269.139948 66.384706 0.39 230 1.00 Y/Y 0.99 This work

EUCL J174704.75+655341.9 266.769824 65.894996 0.77 236 1.00 Y/Y 0.54 This work

EUCL J100130.52+021903.1 150.377170 2.317550 0.70 271 1.00 NM - [1]

EUCL J175943.34+642612.6 269.930605 64.436846 0.65 253 0.95 Y/Y 0.75 This work

EUCL J180843.14+660735.6 272.179785 66.126567 0.22 292 0.95 Y/N - This work