Unresolved discrepancy between this work’s COB measurement and Symons et al. (2023)

Resolve the inconsistency between the cosmic optical background intensity measured in the present New Horizons LORRI survey (11.16 ± 1.65 nW m−2 sr−1 at a 0.608 μm pivot wavelength) and the higher value reported by Symons et al. (2023) from LORRI archival observations (21.98 ± 1.23 [random] ± 1.36 [systematic] nW m−2 sr−1). Ascertain whether the difference arises from data selection, field choices, foreground subtraction strategies—particularly diffuse Galactic light estimation and scattered light modeling—or instrument calibration and processing, and establish a reconciled, robust COB measurement.

Background

Using 16 optimized high-Galactic-latitude fields and a self-calibrated diffuse Galactic light estimator based on Planck 350 and 550 μm intensities, the authors derive a COB of 11.16 ± 1.65 nW m−2 sr−1, consistent with integrated galaxy light estimates. They note that Symons et al. (2023), analyzing archival LORRI data, reported a substantially higher COB of 21.98 ± 1.23 (random) ± 1.36 (systematic) nW m−2 sr−1.

The authors emphasize that both measurements use LORRI but involve different data sets and processing choices. They further remark that raw total sky intensities for seven of their 16 fields are already lower than the final COB reported by Symons et al., underscoring the need to understand and reconcile methodological and calibration differences.