Saturn with Tethys and Mimas' shadow

I created two separate RGB images, one aligned on Saturn's limb and the other aligned on Tethys and Mimas' shadow. I then pasted the Tethys-Mimas layer on top of the first layer in Photoshop and used a Layer Mask to hide the second layer. Next, I used the Brush tool to erase part of the mask to reveal the aligned images of Tethys and Mimas' shadow.