Once again, the UK weather has been dismal at best over the past month. We have had snow storms and constant cloud for three weeks straight, with no hint of a letup! If it has looked promising when I leave work at 5PM, by the time I get home it has completely clouded over again. What has been even worse though is the clouds have been goading me! It clears enough to make me go out and set all my gear up on the patio. By the time I go to polar align, the clouds have rolled back in and stay that way for the rest of the evening. So frustrating!
However, the 10th of February was clear all evening up until midnight! The whole UK astro community was going crazy over ClearOutside showing green across multiple hours.
As winter season is slowly coming to an end, and galaxy season is right around the corner, there’s a few targets that I have still yet to capture. The main target though that I have always wanted to image is the Horsehead & Flame Nebulae in Orion, which fortunately fits in the same frame with my setup.
The Horsehead Nebula, also known as Barnard 33, is a dark nebula just south of the lowest star in Orion’s Belt, Alnitak. Dark nebulae themselves emit no light photons, and therefore appear as dark regions of space. The only way that we can see them is when the light from a nearby star is reflected off the dark dust. They can also be seen when the light source is behind them; the denser dust obscuring the light and we see just the outline.
Barnard 33 lies around 1500 light years distant from Earth, with the hydrogen alpha emission nebula, IC 434, lying just beyond. Being rich in Hydrogen and Helium elements, this dark nebula forms a perfect stellar nursery for young hot stars. Unfortunately, these young stars emit a lot of UV radiation, and according to NASA they are slowly stripping the main nebula away. The horses nose is made of much denser gases though, and so it will protect the rest of the head for many millions of years to come.
The complex around Alnitak is one of the most photographed areas of the night sky. It was first discovered in 1888 by Scottish astronomer Williamina Fleming, on a photography plate taken by William Henry Pickering at the Harvard College Observatory. Fleming went on to be a part of the ‘The Harvard Computers’, an all women group who worked for the astronomer Edward Charles Pickering, and discovered many more objects in the night sky. She also became the first woman elected to be an honorary member of the Royal Astronomical Society of London.
Barndard 33’s close neighbour, the Flame Nebula (NGC 2024), lies at a similar distance of 900-1500 light years away from Earth. It’s classed a hydrogen emission nebula, and glows with a distinctive orange hue. This is caused when ionised hydrogen atoms recombine with free-electrons that have previously been stripped away by UV rays from stars at the nebula core. Both nebulae are stunning to look at and photograph, and is a firm favourite among amateur astrophotographers, such as myself.
However it turns out that nothing is that plain sailing! The clouds didn’t completely clear for a couple of hours, taking me up until nearly 9PM before I could even polar align my mount. This didn’t leave me with a lot of time to image, as the clouds were set to return by midnight.
It was also the first night that I was testing the Nightly #46 build of N.I.N.A.. Yes, I’ve gone back to the developer builds of the capture software, as I absolutely loved the sequencer 2.0 when I tried it previously. At first it’s a lot to wrap your head around, but after the initial confusion it can be really flexible. Fortunately, the developers of N.I.N.A. also fixed my debayering issues that I was having last time! Perfect colours!
I had pre-made routines for focusing and for the main imaging sequence, both of which ran perfectly. I used the star Pollux in the east to manually focus my telescope with my Bahtinov Mask. As soon as I had clicked the ‘OK’ button on the message box, the telescope straight away ran straight into my main imaging run; slewing to my target, plate solved automatically and corrected any location syncing issues, and finally started imaging with the click of the shutter. Relief.
However, everything from there went downhill…
The main problem was my EQ5 Pro mount. It was jumping around wildly in the declination axis and in a seemingly repetitively manner right in the middle of an exposure. This completely wiped out that whole image and sometimes affected the next one as well. All-in-all, I had to ditch 50% of my images!
The image below shows what I was competing with all night long!
Whereas, for some of my images, the guiding was great and was getting a total RMS error of 0.8 arc-seconds on average; just over half a pixel on my Canon 600D. That is 0.000222222º, so very accurate!
Even in a single image, the flame can clearly be seen, and if it wasn’t for the massive dust mote right in the middle of my frame, the horsehead can also be seen.
Throughout the evening, I tried balancing the declination axis both camera heavy and mirror heavy to try and remove any backlash that might have caused these massive spikes. Unfortunately they still occurred. I decided to strip the declination axis down the following weekend, and see what was going on internally.
To make matters worse, the clouds rolled in quicker than expected at around 11:30PM, and even started raining. So I had to quickly move everything inside which made taking darks and bias frames impossible as it wasn’t the same ambient temperature. Therefore I had to resort to using previous darks and bias frames from my Orion Nebula image.
When all the images were loaded into Deep Sky Stacker, I could only salvage 13 individual images out of the 25 that I did manage to take, giving me a total exposure of 1 hour 5 minutes. That’s quite a short length of exposure to capture a relatively dim target from a light polluted back garden; I ideally wanted 3 or 4 hours worth!
Even so, I pressed on a stacked the 13 images, with fresh flat frames and previous darks and bias. However, when the stack came out of deep sky stacker, I was actually pleasantly surprised at how much detail I had been able to capture!
It might be a little blocky, but for only 1 hours exposure it’s to be expected! If I get chance to add more exposure to this target before I lose it for another year, I most definitely will. I want to try and resolve some fo the finer detail in the emission nebula, as it’s filled with delicate filaments all the way along. Overall though, I’m quite happy with it as it is.
However it all depends on whether the clouds work with me, or against me. I just hope I can get some more exposure on this target before the end of winter and I lose it for another 12 months. Only time will tell!
Wherever you are, till next time, I hope you have clear skies!