The image was taken through a monochrome hydrogen-alpha (Hα) filter. The data was collected over seven different nights during September and October 2020. It was done from my backyard in the city under varying moon conditions including full moon. The total integration time is 18 hours and 45 minutes.
The entire California Nebula is huge and it is far too large to fit in the field of view of the telescope used to take this image. This image shows about ten percent of the entire nebula and it depicts a section near the north-west corner.