MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is a facility instrument designed for the 10.4m GTC telescope in La Palma (Spain).
For fiber 623 the reduced_rss image generated by LcbImage (I assume it is the same for the blank fibers of the MOS mode when running MosImage) is set to zero. However, in the final_rss image this fiber has values that are negative and close to zero, so it seems that the sky subtraction is performed in any case.
However, there are other fibers that having null flux in the reduced_rss image (for example, in the case of fibers that have a zero in the twilight flat) also preserve this null flux in the final_rss image (which is what imho should be what megaradrp should do in all cases).
For fiber 623 the reduced_rss image generated by LcbImage (I assume it is the same for the blank fibers of the MOS mode when running MosImage) is set to zero. However, in the final_rss image this fiber has values that are negative and close to zero, so it seems that the sky subtraction is performed in any case.
However, there are other fibers that having null flux in the reduced_rss image (for example, in the case of fibers that have a zero in the twilight flat) also preserve this null flux in the final_rss image (which is what imho should be what megaradrp should do in all cases).