Casitas de Gila, Gila, New Mexico and Mesa, Arizona

October 22, November 10-14, 2020

I started imaging the Bubble Nebula in New Mexico in October and finished it in Arizona in November. NGC 7635 was captured with narrowband filters, Hydrogen-alpha (Ha), Oxygen-III (OIII) and Sulfur-II (SII). This is a false color image is combination of 80% Ha and 20% SII in the red channel, 20% SII and 80% OIII in the green channel and 150% OIII in the blue channel using the SHO-AIP multichannel combination script in PixInsight. Red, Green and Blue filter data were obtained to create a star color image that was combined with the false color nebula image.

NGC 7635 is a large emission nebula in the constellation Cassiopeia. The bubble formed when the hot, young central star blew out gas into a “bubble” shape. The elongated bubble is about 10 light years across. NGC 7635 is about 11,000 light years from Earth (SkySafari Pro).

This object was a real challenge for me, and I am not satisfied with the result. First, I discovered that the ZWO ASI 1600MM Pro camera has a defect with the sensor protection cover. The cover reflects light from the sensor back to the sensor to form reflection/diffraction rings around bright stars. This appeared in the OIII, Green and Blue filter data. I attempted to remove the artifacts with the clone stamp. Also, a large halo appeared around the brightest star in the Green and Blue filter data. The details in the bubble are not as sharp as they should be. Finally, I could not get the colors right in a Hubble Pallet SHO image. So, I created a red image by putting Ha and some SII in the red channel, some SII and OIII in the green channel and OIII in the blue channel. Later I did produce a Hubble pallet image using the ColorMask script that has the color combination I was looking for. I will return to this image later in Oregon’s rainy season to sharpen the details.