The Elephant’s Trunk Nebula

This summer’s target is the Elephant’s Trunk Nebula which is a small part of IC 1396, an emission nebula located in the Cepheus constellation.

IC1396 25-Jul-2021, RedCat 51, Optolong L-Extreme, 36x300sec (3 hours) Under a Full Moon

Equipment

To capture this target I am using the following setup:

  • Telescope: Williams Optics RedCat 51
  • Filter(s): Optolong L-Pro 2″ filter
  • Camera: ASI2600MC Pro
  • Mount/Star Tracker: Starwatcher Sky Adventure Pro
  • EAA: ASIAir Pro, ASI120MM Mini Guide Camera, f/4 mini guide scope, ZWO EAF

Observation Log

I live in a Bortle Class 7 area and image primarily from my backyard. I will attempt to get as much imaging time as possible with this target. The target coordinates are as follows:

  • RA: 21h 35m 37s
  • Dec: 57degrees 24′ 03″

Due to the hot summer nights, I am aiming only for about.

2021-07-17

Weather: Partly Cloudy

Imaging:
– 36x300s (25 rejects) ~ 3 hours
– 30x60s (1 reject)
– 10x120s rejected
– 1x600s rejected

Notes:
I had a lot of issues this night. I spent the majority of my time trying to figure out how to focus the telescope. The issue was that the 3D printed focus ring did not fully engage the belt, as a result I could not ever get focus. After those issues were sorted out, I was able to finally polar align and let the system run through the night. The clouds started rolling in late night, so there were not many usable images from this run.

2021-07-25

Weather: Partly Cloudy (late night)

Imaging:
– 36x300s (36 rejects) ~ 3 hours

Notes:
For this run, I had updated my ZWO EAF mount to a different design which worked much better. My focus was within 2″, which was better than I had ever achieved. The guiding was great an my RMS error was under 1″. I was able to image about 1h30 before I ran into a major issue with my autofocus routing. I had set up the autofocus to run about once every hour or every 2 degrees C in temperature change. A little over an hour in the auto-focus routine executed, and got extremely confused. I ended up losing about 30 minutes of imaging time before the clouds rolled in.

Processing:
Below is my first pass at processing the lights from this night. Overall the image is much sharper than the previous night but there are some areas I need to work on. Namely there seems to be an issue with the uneven background subtraction evident by the darker circular area to the mid right-side of the image.

2021-07-26

Weather: Expected Partly Cloudy

Imaging:

Notes:

This was the longest imaging run I had yet, but I had a few issues.

  1. The AZ lock on the mount, though tight does not prevent rotation. This can lead to some polar alignment drift when I am repositioning RA/DEC on the telescope.
  2. The EAF was flakey, probably due to backlash. I had the EAF run only when the temperature changed by more than 2 degC, but when the routine was triggered it really threw off the focus. I had to manually refocus.
  3. The SWSA mount ran out of batteries and I had to change it. This led to some images with lots of star trails.
  4. I had to do a meridian flip from the west side of the mount to the east side. This will lead to some alignment issues in the stacked frames.

2021-07-28

Weather: Mostly Clear

This was yet a better run tonight than any other before. I figured out the issue with the AZ on my mount. It turned out I just needed to screw in the base a little tighter. I set autofocus manually at the beginning of the run and did not change focus since. I expect some loss in clarity due to this, but I did get about 9 hours of imaging time. The batteries lasted all night.

Notes:

2021-07-30

Weather: Clear

Tonight, the weather is amazingly clear. I was surprised because all day it had been cloudy.

For imaging tonight, I decided to switch up filters and utilize my Optolong L-Extreme 2″ on the same target. I am also switching up mounts to the iOptron GEM45 with a Literoc 1.75″ tripod.

Notes:

I am still figuring out this mount. I am having issues with some star trailing (maybe at the meridian flip?), and some cable snags potentially.

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