Shooting Messier 1, The Crab Nebula

Two years ago, a friend of mine from Pennsylvania, Joe, suggested, after reading my #2018goals, that I add Messier 1 to the list. As he put it at the time, “it would be a worthy addition.” Two years later, after many attempts, I’ve finally produced an image that I can say I’m happy enough with to show publicly, and that does my friend’s suggestion justice.

The setup was my standard one for deep sky imaging; the ED72 (Miranda), mounted on the EQ5 Pro, using the ZWO ASI178MC to capture the data, and guiding with the ZWO ASI120mm through a 9×50 finder.

bhatinov mask, ed72, skywatcher
Focusing with a Bhatinov mask

Software-wise I would be using the SynScan app for Windows, and have PHD2 connected to that, with APT capturing the light frames, or subs, and then running the dark frames plan straight after capture. With the 178MC this seems to be the best way to go with the calibration frames, as in shooting them immediately at the end of the session. For some reason the amp glow doesn’t seem to fully calibrate out otherwise, but I’ve read this is an issue with the 178MC. It’s no real biggy as I can just slap the lens cap on, drag the rig into the shed and leave it to shoot the darks as it’s all still at the same temperature anyway.

Once I got myself polar aligned using SharpCap (and I’m loving how easy and precise that makes obtaining a decent polar alignment these days!) I immediately slewed to M1 in the constellation Taurus.

Messier 1, the Crab Nebula, is located on the tip of the left horn of the constellation Taurus. Image courtesy Stellarium

I’ve recently dropped PlateSolve from APT and swapped it out for ASTAP. I found PlateSolve to be buggy and it would often not actually solve the image, which led to a few quite frustrating sessions. I have to say that I’m massively impressed with ASTAP. It quite literally platesolves the image in under 5 seconds. I’ve now added it to the “Software” tab at the top of the page.

Within moments of having a very precise polar alignment (my total error was 0.09), I was on Messier 1 and shooting the first 3 minute sub. Waiting that three minutes for the first image to come through on screen seemed to take forever, but when it did, there it was, right slap bang in the center of the screen. No issues, no dramas, no equipment failures, everything working in perfect unison. It was almost like ballet in it’s syncronicity for once.

Any astrophotographer will tell you that there are any number of 1001 things that usually can and do go wrong on any given night, be it equipment or weather related. But not tonight. For once everything went absolutely perfect. Out of the 45 odd images I captured in the end, I only ditched 5 due to guiding issues, which for me is good. I’m still having those declination backlash problems that seem to plague me, but after running the guiding assistant in PHD2 before every run, it seems to be less of an issue.

I was planning on slewing to a second target tonight but in the end decided to call it after just this one and for once have an early night. It’s been a week of clear nights and those kind of catch up after a while, especially when you’re up against an underlying condition as well.

For post processing I initially stacked in DSS, but was finding I couldn’t get the nebula core detail to even remotely come through. So I restacked and carried out the initial stetch and star/background calibration in Astro Pixel Processor, then switched to PhotoShop and LightRoom for the bulk of the editing. In the end I managed to get an image I was finally happy with after two years of trying and failing. So thank you Joe, for suggesting this one two years ago. It’s tested my patience and perservence, but the result has been worth it.

Messier 1 Crab Nebula 84 x 180 seconds, gain 200, ASI 178MC


I’ve since been able to add a couple of more hours worth of data to the original image, with the result that more of the nebula detail has become apparent, especially after using the Bayer Drizzle function in Astro Pixel Processor. That concludes M1 for this season, but I’m looking forward to retrying it next time around with Jessica (the Mak 102.)

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