Category: solved_distributed

A major bug sneaked in while implementing the Sault method in Mosaics, early 2024. Mosaics in which each field had a different phase center could no longer be processed correctly, because of a pre-existing bug in UV_SHIFT command.

The bug has never been reported by any outside user, only locally at LAB, so we hope it did not affect any of you. The bug has been fixed locally a while ago (> 6 months) but the fix was not distributed until October 2025 due to local re-organization of the distribution.

We strongly recommend you to upgrade your IMAGER version as soon as possible.

Bug corrected in the distributed version 4.0 (and beyond):

PIPELINE /MODE SURVEY was not working properly when strong lines were present in spectral window, because line subtracting was improperly done, and contaminated the full bandwidth.

Note that the PIPELINE /MODE ALL with NO Catalog was similarly affected, whereas other modes (including PIPELINE /MODE ALL with a Catalog) were not affected by this issue.

Bug corrected in the distributed version 4.0 (and beyond):

Description: PIPELINE crashes (in Survey mode): Continuum image could not be created.

This was due to incorrect channel flagging when a strong/broad line is present close to the edge of a frequency band. In some cases, too many (if not all) channels were flagged, resulting in no continuum channels.

Recommandation: you may test first the line identification with the UV_PREVIEW command before starting the imaging process with the PIPELINE (adjusting TAPER, SMOOTH and CLIP variables may help, if the problem persists in exotic cases).