Extrapolation is wrong to wavelengths < 1.2 micron

[janerigby]

The JWST Background Model uses an extrapolation of COBE/DIRBE data to wavelengths below 1.2 micron. Analysis of commissioning and early Cycle 1 science data shows that the model predictions for lambda < 1.2 micron are systematically higher than the observations. See Rigby et al. 2023, PASP in press, https://arxiv.org/abs/2211.09890

It is hypothesized that this discrepancy is due to an error in how the background model generator (BMG) extrapolates the DIRBE data to short wavelengths. Since the JBT simply uses the results of the BMG, this issue is not the JBT's fault, but it will be noticed by users of the JBT. The purpose of this Issue is to make JBT users aware of the issue with short-wavelength predictions.

We are working to address and correct this issue in the BMG. This Issue will be updated to reflect that progress.