NGC2070 - Tarantula Nebula Recaptured
OK, a bit of a long(er) post here. Then again, maybe not…
As you’re aware, I picked up an Optolong L-Enhance filter for my astro setup a while back. Because of the weather (way too many cloudy and/or rainy nights) I haven’t been able to get any imaging done. However, we’ve had a couple of clear nights (and a couple more are forecast) so I had the rig out last night and imaging away.
I chose to do the Tarantula Nebula (NGC2070) again to compare how it looks through the filter when compared to my previous attempt. (Hey, nothing like a bit of scientific method, eh??)
However, I also did some reading about why I was getting such a massive blue-shift on my images. Well, it turns out that the ZWO cameras have two in-camera white balance controls - WB_B and WB_R. WB_B is for the BLUE channel, and WB_R is for the red channel. The default values (on a scale of 0 - 100) are 95 and 52, respectively. So, any guesses as to why my images were having a fit of the blues?
The ASCOM software for Windows has it’s own white balance values so the default values are never seen. As I use KStars/Ekos for my imaging, the default white balance values are used. Once I set the WB_B and WB_R values to 50, the images suddenly looked a lot, lot better.
One other impact of having the filter is that I can now do much longer images. The images below were taken from a stack of 180, 30 second exposures, for a total of 90 minutes of integration time.
I expect that I could take longer exposures at the same gain and offset settings. It’s something I’ll have to investigate - although brighter objects such as the core of M42 (The Orion Nebula) will require short exposures to precent everything being blown-out to pure white. (Not a good thing!)
I am much happier with my astro work now, and can’t wait for winter to arrive with it’s many hours of darkness, cold and still air and the return of the southern nebula such as Eta Carina.
I do have a lot further to go with my imaging, as there is a lot of red noise in these images. I’ve hidden it reasonably well, but someone with sharp eyes will be able to see it.
Image details:
- Gain: 50
- Offset: 10
- Temperature: 0 degrees C
- Exposure: 30 seconds
- Lights: 180
- Darks: 25
- Flats: 25
- Dark Flats (Bias): 25
- Stacked and proc’d in Affinity Photo
The slightly copped image showing off the Tarantula Nebula and the clouds of gas and dust around it.
A tighter crop of the above image, showing more of the fantastic detail present in the nebula.