Aetherum

Hi there, fellow light-gatherers! It has been a while since I posted here and I'd like to present you my first take at the Messier 3 globular cluster, or M3 for short, which was the very first object discovered by Charles Messier himself dating all the way back to the 18th century, 1764. Interestingly enough, Messier was convinced that M3 was a nebula at first until the equally famous and fellow contemporary astronomer William Herschel found that the object could be resolved into individual stars 20 years later, by which it was then declared as a globular cluster in 1784. M3 contains more than 274 variable stars, which is the highest number found among all globular clusters known to date. Globular clusters play an important part in the field of physical cosmology as they can be used to study stellar evolution in the early universe, as well as estimating its age. I used my 102mm achromatic refractor on a motorised Alt-Az mount with two-star calibrated tracking. I took consecutive 30-second shots amounting to only 180-seconds, or 3-minutes of total exposure time, shot in my garden right in the city center of Ghent. I know it is only 3 minutes, which isn't considered much in DSO imaging, but does it really make that much a difference apart from having a slightly brighter image due to less noise? I kindly invite you to follow me on Instagram so I can see your work as well: https://www.instagram.com/eoasphotography/ #nightphotography #astrophotography #nightsky #stars #globularcluster #messier3 #messier #m3 #ghent

A second take on a waxing gibbous moon at 79% shot through an alt-azimuthally motorised 102 mm achromatic refractor with a good view on the Tycho and Copernicus craters. Yet again, a single-frame photograph with a focal length of 500 mm, a 12.5 mm Plössl, and a 1/100-second exposure time. I'm pleased

Rusted, thanks man, that's pretty cool! Although, I find it's pushed too far. The edges are no longer smooth but really nice detail on the spots!

I already got it, thanks! I'll try it out soon.

Thanks for the advice. Do you have any advice for software I can use on macOS?

I'll try M42, but I'll have to find stacking software that will run on macOS. Thank for the tip

Thank you for the tip. Unfortunately, I'm not running on Windows, so many applications I can't use. I only used GIMP so far and manual stacking wasn't a success. Great that it makes up for field rotation though..

Geoff, Thanks for the tip, before I can image some galaxies I have to find them first. I hope that will be possible under these polluted city skies. How does live stacking work exactly, does it accumulate the individual exposures? Kind regards, Robbe.

Luke, Thank you for your reply. I can't use autostakkert natively as I only run on Linux and Mac systems ImPPG likewise). I installed SiriL as an alternative but I haven't used it yet. I wanted to do manual stacking first to see how that worked out. The noise was likely reduced but very minimally, and the sharpness was reduced significantly. Just not worth my time. It seems like the increase in signal to noise ratio is negligible. The Russian MTO lens that I have looks quite similar to this one, I wonder if I can use it as a regular telescope with some kind of adapter for an eyepiece.

Wouter, Thank you! I'm sure stacking could improve the image, but with my last solar stacking experiment the results were rather contradictory. I will look into using autostakkert in Mac. However, I just downloaded SiriL as a Mac native alternative, but I haven't gotten into it yet. Any experience with that one? Kind regards, Robbe.

Hey there! In this single frame solar shot, I used a rare vintage 10/1000 Maksutov-Cassegrain lens of Russian origin that depicts several sunspots at the Sun's surface. I tried to stack 12 frames in attempt to get better results but it didn't seem to be better compared to the base image I used. Maybe because I used manual stacking in GIMP. I also think that with only 12 frames the amplification of the signal to noise ratio is statistically insignificant to yield clearly visible results. Does anyone have any advice regarding the above? Any advice is greatly appreciated. Clear skies to all!

Hey Luke, thank you for your reply! My setup was fixed and I actually had multiple shots but I just used the best one. Autostakkert doesn't work on Linux nor mac, so I'd have to do it manually. I don't see the use of stacking here because the opacity settings would just take away from the original image, so the result would still be 100% either way. I used GIMP to post-process. Clear skies to you!

Yes, I see how important the mount is in this case. But as said, I hadn't accounted for field rotation. Especially because my neighbor, which is an experienced astronomer, hadn't mentioned anything about it when I asked him about the mount. I know how aperture in terms of f-stops work. My 10.5 mm fisheye lens is an f/2.8, so that would gain some great results if I get the chance to shoot at a great location again. I'll just see what I can get with this, my camera is currently limited to 30-second exposures anyway. Thank you for your advice.

I thought fast refractors with an f-stop until about f/5 were perfectly ideal for imaging purposes? I have a kit lens with the D3300 going from 18 mm to 105, but at 105 the aperture is at 5.6.

I have a ST102 achromat, so 102/500 with various eyepieces. I have an ST80 as well, because that is the scope I bought originally, the ST102 came with the mount, but I will be selling it since the ST102 is just a better scope. I also have a cool vintage 10-1000 Russian Maksutov-Cassegrain lens, but that one isn't of much use for wide-field imaging.