A New Year, A New Target

Well only a few days after the new year, we had our first clear skies of 2022; a much welcome change! It was a cold, frosty evening after work when I set up the rig, but I also had an early start the following morning. So, I only had chance to grab a few hours of exposure, plus factoring in the time for calibration frames – the one drawback with using a DSLR camera is a non-cooled sensor

This time around, it took me a little longer to erect the rig, as I had to set up everything from scratch – DSLR, coma corrector, OTA, mount, guidescope, cable loom – the lot!

I fortunately was gifted a flight case for my telescope over the festive period, but the guide scope requires removing each time I pack it down or erect the rig. A sacrifice I’m willing to take in order to protect, transport and store my rig safely.

Telescope Flightcase

As you can just about see from the tailors chalk outline, I tried to also fit my camera and guide scope in the same flight case. However, I’d rather it just be the scope itself rather than cram everything into the same box and possibly sacrifice the integrity of the protection; the DSLR will live and travel in my camera bag in any case. Overall though, it was quite easy to cut the foam to the shape of the optical tube assembly, and a contour cut for the focuser using a long sharp knife. At least now I won’t be struggling to secure the scope to the back seat of my car.

Eventually though, after fighting the cable loom for five minutes and rebalancing everything, the rig was built and the guidescope re-calibrated within PHD2, just incase. Around 8:30PM, I finally got underway on my target.

Telescope Tracking

I decided upon Messier 45 – The Pleiades – as the target for the evening, as it was nice and high in the constellation Taurus. This position increases the seeing quality while also reducing the risk of catching any rooflines or TV aerials.

Messier 45 contains more than 1000 extremely hot and luminous B-type stars. At 444 lightyears from earth, it is one of the closest star clusters to us. It is also one of the easiest targets to view with the naked eye, as it occupies the same apparent size as four full moons at around 110 arc-minutes across. The best views can be had with a pair of decent binoculars from a dark sky location; the cluster has the appearance of a blue smudge in the night sky, with bright specs of light in the middle.

N.I.N.A. Screenshot

As can be seen in the single 300-exposure above, the brighter seven stars are easily visible, giving the cluster its nickname of the ‘Seven Sisters’. Each star has a faint reflection nebula surrounding it, grouped together under the name of ‘Maia Nebula’. The dust and stars in the cluster are not actually related in any way. Scientists have determined that they developed separately, and are moving in different directions and at different speeds; the stars are just passing through the dust as we see them.

As M45 is a reflection nebula, I swapped out the dual narrowband NBZ filter that I have been using recently for its broadband brother, the IDAS NGS1. Due to its increased light transmission, it also allowed me to reduce the ISO of my DSLR back down to a more manageable 800 and also reduced the exposure length to 300-seconds. In hindsight, I could have reduced this down to 3-minutes or even reduced the ISO again, but from my newly classified Bortle 7 back garden, I really wanted to capture the nebulosity, so kept everything to what I know works well.

Over the course of a couple of hours, I managed to capture 27 exposures (with none thrown out), giving me a total exposure length of 2 hours 15 minutes. This was followed up by 15 dark frames, and 30 bias frames; 30 flat frames were also taken the following day. I wished I could have stayed out longer as it was a truly clear night all the way through, but I had work early in the morning so didn’t want to have to rush around moving gear about – I really need an observatory!

However, for just over 2 hours exposure, I’m really impressed with my final stacked image. I honestly like the star diffraction spikes on the brightest stars, I personally think that they add to the image; Astrophotographers that are used to refractors don’t tend to appreciate them as much.

It’s certainly not without its faults though, most notably the noise level, but with greater integration time this could be greatly reduced. Just got to wait for another clear night to add to it!

Messier 45 – The Pleiades Star Cluster

2022 has started well, and I have some plans in the pipeline this year that will hopefully see me diverge from my current format of DSO’s, weather dependant of course! So please stay tuned for that in the upcoming months!

Till then though, wherever you are, I wish you clear skies!

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