I haven’t done much Astrophotography in the last year or so, however I did manage to get a few clear nights in during 2021.
The target for the night was M27.
The LX90 and imaging train took about 10 minutes to setup, quite possibly the quickest setup I’ve managed. I was done before nautical darkness arrived. The SXVR-H9 was set to -10C although with the warm 18C summer night, this was pushing the ccd’s cooler.
Whilst waiting for the first stars to become visible I took the opportunity to build up a newer dark frame library in EKOS and as the first stars started to appear in the night sky, began polar alignment.
I highly recommend the polar alignment tool in EKOS. It’s saved me a lot of time compared to the previous DARV method, let alone drift aligning. The below image shows my starting position with a significant polar error. To resolve it, you simply select a bright star, then use the Alt/Az of the mount to move the star along the error triangle.
Re-running the tool should then produce a smaller offset triangle as you close in on polar aligned. The following screenshot shows an error of 3 arc minutes. Then it’s a case of rinse/repeat until you reach a small enough error.
With polar alignment out of the way, nautical darkness had just begun. That meant 3.5 hours maximum of “darkness”. Not much time, especially with the plan to test three of the new narrowband filters.
Fortunately, guiding (using PHD2) went without a hitch throughout the entire night. A rare but welcomed surprise.
M27 - Dumbbell Nebula
Whilst this is not my first time imaging M27, this is the first attempt with filters. Having purchased a complete set of Baader LRGBC filters for colour imaging as well as a set of Ha,Hb,OIII,SII for narrowband. I made use of the Ha, OIII and SII on M27.
Here’s the result from processing just the second nights data. The first night was instead spent experimenting with the filter exposure times and determining focus offsets.
|Date||2021-07-16 01:00 UTC|
|Bias/Dark/Flat Frames||100x0.0001s / 30x60s / 50x15s,2s,17s in HA,OIII,SII|
For comparison, I posted a prior monochrome attempt back in 2016. There’s a notable increase in noise with the 2021 image. I believe this is due to several factors:-
Firstly, the 2021 data was captured during the middle of summer when the sky never reaches true astronomical darkness. In addition the use of narrowband filters requires more/longer exposures to capture the same amount of data than you would achieve via a luminance filter. Add in my in-experience at processing non monochrome images and there’s a lot of room for improvements to be made.
I’m hopeful the third nights data will help improve the SNR of the final image once I get around to combining the two sets.
This is a target to re-visit once Astronomical Darkness returns to the British skies.