4. Flatten Background by selecting 150 dark background areas. Note the pattern.

4. Flatten Background by selecting 150 dark background

5. The result after manual flattening - stretched to demonstrate the effect.tiff

0. The raw file from the CCD astrocamera has despite LPS filter is light polluted due to the city lights

0. A quick check via histogram specification command reveals strong gradients - Now press CANCEL please.tiff

1a. Select the menu item Auto Remove Gradient.tiff

1b. - The result after automatic gradient removal - It looks better - Photo stretched to demonstrate the effect - Press CANCEL please.tiff

2. Select the menu item Auto Flatten Background for further improvements.tiff

2b. The result after the automatic flattening. That function made the background more unique but it is still darker at the edges.tiff

5. Save the file - Repeat these step for all your FITS raw files.tiff

4a. You can also try this pattern to select the background areas.tiff

00. The IDAS LPS P2 light pollution filter is your best friend.