other choices – photoproject (the default HIPE mapper) and MADmap [@madmap] – because it reconstructs surface brightness maps of extended sources with the lowest noise, which is of great importance for our purposes. After processing with HIPE and Scanamorphos, we obtained far-IR surface brightness maps at 5 bands (70, 160, 250, 350, and 500$\mu$m) for 11 PNs, each covering at most $7^{\prime} \times 7^{\prime}$ unvignetted field centered at the target source.

### PACS Spectroscopy

We used HIPE track 11 with the calibration release version 44 to reduce all of the PACS spectroscopy data of HerPlaNS. Within HIPE, we selected the background normalization PACS spectroscopy pipeline script for long range and SEDs to reduce the range scan data and the same pipeline script for line scans to reduce the line scan data. Our reduction steps follow those described in the PACS Data Reduction Guide: Spectroscopy.[^3]

In the range scan mode, we used the blue bands B2A (51–72$\mu$m) and B2B (70–105$\mu$m) and each time we also got simultaneous spectra in the R1 band (103–145$\mu$m and 140–220$\mu$m), achieving the full spectral coverage from 51–220$\mu$m. Each observation results in simultaneous spatial coverage of a $\sim50^{\prime\prime} \times 50^{\prime\prime}$ field by a set of $5 \times 