Hallingskies

This really is a splendid processing exercise, so thanks to the team for providing the data. The challenge for me was to show up the faint outlying galactic arms and the wonderful swirls of embedded Ha emission areas without losing the delicate dust lanes that delineate the spiral arms in the brighter central zone. It was very clean data, with little noise or gradients that I could see and all perfectly registered, which made the task a lot easier. First step was to log stretch each channel in Astroart. I gave the Ha channel a harder stretch than the others to ensure the outlying emission areas would be seen in the final blend. RGB channels merged in Paint Shop Pro to give a colour image. This was rather green, so cranked it back a bit using PSP's channel mixer. Then merged the stretched Ha channel with the red one, then added "de-stretched" blue and green channels in RGb to give a colour image where the Ha areas predominated. This was layered over the original colour image in blend lighten mode to give a colour image with the red Ha regions showing up well, particularly those interesting faint Tarantula-like areas in the outer arms. The stars did get a bit bloated with the initial log stretch. To reduce this, I ran the Ha, R, G and B tifs through Starnet, then repeated the above to give a starless colour image, to which was added an RGB star layer from the unstretched RGB data (mild gaussian blur then layered over in screen mode to avoid that "stuck on" look) to restore the reduced stars. I then layered the "re-starred starless" image over the top of the starry version in "normal" mode. About a 40% layer shrank the stars nicely without losing detail. I saw no need to use any noise reduction on the main object at all - I think M33 is an inherently "grainy" object and it only serves to chuck away precious detail. A final bit to selective sharpening and contrast adjustment in PSP gave this...

Sh2-273 in HaRGB, 10 x 600s each channel, Samyang 135mm @f2.8, Atik 460/EFW2...

New kit syndrome - guaranteed to attract clouds. I've been waiting three months to test the rig I put together and used for this shot...

Thanks. Given the short exposures it was a quite satisfying image, though I think I need to do some more work on the background gradients. This was an afterthought of a project, really, as I was originally going for some RGB on the Cone nebula area (Sh2-273) but clouds kept interrupting the 600s exposures I was after. I swung the rig around to this view as chucking a few exposures away due to passing clouds (and satellites!) wasn't a problem with lot of short ones. I would have collected more than I did but it finally clouded over completely at around 21.00. Things are going a bit better tonight, another unexpected bonus of an unforecast clear(ish) sky...

That is really good. These phone cameras are amazing...

12 x 15s each in LRGB, Samyang 135mm @f2.8, Atik 460 + EFW2.

Sh2-273, Atik 460, Baader 7um Ha filter, f2.8. 10 x 600s under a full moon...

Narrowband channels all log stretched in Astroart, then Starnetted. Layer masks in PSP used to minimise "Burn out" in bright areas. Gamma Cassiopeiae cloned out of all channels, then RGB combined in PSP, R=Ha, G=SII, B=OIII. H alpha overlaid as luminance to retain detail. For stars, the unstretched narrowband data was RGB combined in PSP, then saturation lifted to bring up star colours. Star layer pasted over nebula layer in screen mode. For this iteration, the log stretch for the narrow band channels was milder resulting in a less overpowering green from the SII channel and a more subtle rendition of the nebulosity. I think the nebulosity around Gamma Cas is genuine rather than a gradient so I have left it in (again). There is a lot of faint detail in the background and I have tried to include it but that does bring the background noise up, which I don't have software tools to handle.

Clear nights....clear nights. Nope, don’t know what they are, though the concept seems vaguely familiar.....🤔🤔🤔

Yes, my old work HP had a battery life of about 7h, though I never used it outdoors in the cold! Re. the mini computer, others here are better qualified to advise you. The idea would be to have your data and control feeding to the mini at the mount, with a remote connection to a computer that you could use to check now and then that everything was working ok (rather than continuous monitoring). If your pockets are deep you might want to think about one of these...

Laptops are real power eaters and you would need a biggish battery to run that plus your astro gear for more than three or four hours. As an example, my Lenovo requires 65W: if you assume a 12v supply, that’s about 5A straight off. If your astro equipment chews another (let’s conservatively say) 3A, that’s 8A total for every hour. You’d need a 100A/h battery to get you through a full night’s session by my reckoning. I think lithium’s at that capacity are coming in at around £600, lead/acids are a lot cheaper but you can’t run them below 50% too often without wrecking them. Be interesting to see what others say. One answer might be to get a mini-computer for mobile use, they pull a lot less power so I gather but other than that, I kno knothing...

Narrowband channels all log stretched in Astroart, then Starnetted. Layer masks in PSP used to minimise "Burn out" in bright areas. Gamma Cassiopeiae cloned out of all channels, then RGB combined in PSP, R=Ha, G=60/40 Ha/SII, B=OIII. SII overlaid as luminance to retain detail, colour balance adjusted in PSP to make it a little less green (strong SII data!). For stars, the unstretched narrowband data was RGB combined in PSP, then saturation lifted to bring up colours. Star layer pasted over nebula data in screen mode. Final colour/luminosity balance adjusted in PSP, saved as jpg....

Icy surfaces will be the main problem. The track down to my obbo is a sheet of ice now and I don’t dare use it, but I plan to set up nearer the house tomorrow night to carry on testing my new “portable” set-up. Take extra care, folks...

On January 21st. they are about a degree apart, with Uranus due south of Mars. There's a nice half Moon just six degrees to the east of Mars as well.

This is a superb image, Richard, one of the finest I've seen on these pages. You have processed excellent data with a fine touch.

I run one in my glass fibre dome because natural ventilation Does Not Work - the condensation was horrendous. I did put some P section tape around the flange of the dome and the opening hatch runners to cut down the air ingress. I have the dehumidifier wired through a humidistat and it holds the obbo nicely between 55 and 65% Rh. If things are really soggy it might come on three times an hour for around 3-4 mins a time, usually much less often. The RH readings on the datalogger go a bit haywire when things get below freezing but there is so little physical water in the air that it doesn’t mean anything in practice.

I’m not sure that RH actually means too much below 0’C as the water left in the air is from the partial pressure of ice rather than liquid water. I’m sure the physics graduates will put me straight but I think there is very little water in sub zero air. I used to run a heater in my obbo because I was worried sub zero temps would damage my dessicant dehumidifier but touch wood things have been fine without it these past couple of winters.

I agree. There are only two stars that are a little OTT. In PSP I’d just layer the stretched image over an unstretched one without the haloes, and carefully feather/erase the top layer around the flared stars to let the lower layer through. I don’t do Pixielights, can’t stand the jargon...🤪🤪🤪

My five from 2020, all with an Esprit 100/Atik 460... LDN 1622 M16, Eagle Nebula Comet NEOWISE Sh2-115, the Troll Nebula IC59, 63: Chinese Dragon Nebula (Ghosts of Gamma Cassiopeiae)

I used fibreglass car body repair filler to glue the socket back boxes and cable duct clips directly to the walls. No drilling. Works fine.

Optically I’ve found the Evoguide to be fine, but if you are looking at using this as an imaging camera then beware the focuser. The Evoguide I have has some slop on the rotary focuser, which does not lock down. It seems OK for autoguiding but I could not imagine it to be stable with a heavier imaging camera attached.

The first time I used an OAG, I was also disappointed with the result. However, I quickly traced it down to the fact that I hadn’t tightened down the height adjuster on my Atik OAG. Results were a considerable improvement over a guidescope after that. You’ve probably checked it all over three times already, but you need to make sure that everything in the imaging train really is rock solid.

Had this with my Lenovo. There is an aggravating feature in the power management menu (as I recall) where you have an option to disable USB power management. Mr. Gate’s minions keep enabling it every so often when they “update” their wretched software, and that seems to switch off some of the USB ports. Might be worth checking.

That’s a superb effort. I’ve never seen a hint of OIII on this from my Bortle 6 skies but you’ve shown me that it’s worth having a go at, maybe with faster optics. I’ll have a try with the Samyang f2 lens I’m setting up....

I put a 7nm Ha filter in front of the camera when solar imaging through Baader film, but only to reduce the amount of light getting to the camera. It gives a bit more flexibility with exposure times. Other than allowing me to increase exposure time from the minimum 0.001s, I see no difference in detail or contrast.