SH2-101 The Tulip Nebula

The Tulip Nebula after some very bad processing in PixInsight.
It goes to show that all the tools in the world are no good if you don’t know how to use them!

I imaged this nebula over 2 nights, several weeks ago in August but I had a terrible time processing the data. I was convinced I had some issues with my flats and then my subs. Then I was sure I had some light pollution leaking into the camera. I was at a loss for a solution but then I happened to read a post over at Forum | Backyard Astro that suggested to me the problem was how I used the Weighted Batch Processing script. I had recently updated PixInsight and was just using WBPP script with its out of the box default values.

That was a stupid newbie error, correcting the configuration of WBPP for the flats and light processing completely resolved the problem. As a result, I went back through all my recent images and began a methodical reprocessing.

And here is the result of more care and attention in processing the image.
This is 6hrs total, 300s subs @ Gain 200. 2hrs each for Ha, S2 and O3. Imaged using my trusty Orion Optics 250mm Newtonian with the ASI1600mm Pro.

I don’t want to go through that pain again so I have written down the steps and will publish what has worked for me.

One thing you will notice if you pixel peep the image is that the stars are vertical short lines. Guiding was close to perfect for this target so I believe the problem is caused by the RA motor drive board of my CEM70G which is a 2020 vintage, later mounts have improved RA and DEC boards. At least I hope that is the root cause as I’ve ordered replacements from the iOptron factory and I dont really want to use an OAG. [The last I heard the factory airport was in lock down due to covid so I don’t know when to expect them.] Because of the star shape it is a little more difficult to use my star reduction technique that worked so well for my IC1396 image. I shall have to see how others do it.

One thing I have learnt as a result of writing my steps down is slavishly following a process does not work well for all images. Sometimes you have to deviate from the path and experiment too. But still, a written down process is a good place to start from.

This entry was posted in Deep Sky, Nebula and tagged , , , . Bookmark the permalink.