Mandy D

You have a Skywatcher 200P with a fabulous homemade base, if I recall corectly. Perhaps you could add your opinion on that scope to what @fwm891 and I have said.

Yes, I read that. I have to say that the secondary mirror is very well supported in the 200P and 250PX and I've never had to touch it on either scope. It's sizing on these two scopes has never presented an issue to me. I also have and iOptron RC6 which is 50% obstructed and I find it OK, both visually and photographically, although you do lose some contrast, which is easy to regain in GIMP on images. Likewise, I've had no issues with the focusers on either of my Dobs, although it might be nice to have a fine movement control on them like the RC6 has.

I totally agree with @fwm891. I picked up my 200P Dob for £200. If you can transport and handle a scope of this size, it will certainly perform better on the deep sky and works well on the Moon, too. For the planets, you can image Jupiter and Saturn, but would be better adding the Barlow. I've had some nice views of planets in my 250PX and these should show up nicely in the 200P. I agree that the eyepieces included with these scopes are not great, but the 25 mm works quite well, but I don't like the 10 mm. Get the scope first and use whatever eyepieces it comes with. You can always get better ones later. Be warned that a second-hand reflector may require collimating before you can use it, but that is something you need to learn anyway.

You know me so well!

I use Sharpies! Mostly, I get the ink on myself rather than the paper, though!

Obviously! We all knew the clouds would clear as soon as it was over! I did M42 several years ago, but not very good at all. So, plans are to have another go this year. I'd like to get Andromeda and the Pleiades. I might as well go for the Horsehead whilst I'm in M42. I've attached my M42.

Great work with those crayons! Looks nice.

Yes. I have a Startech dual redundant SATA array external enclosure with a pair of 2TB HDDs in it that are in a RAID 2 config. It is 12V d.c. input, so should work OK in a car at 14.4 V, but I don't guarantee it. Have a look at www.startech.com and I am sure you will find what you need.

@Mart29, they're nice clear images of Jupiter, but why the blue caste? It looks like your white balance is off. Are these all with your mobile phone?

Wouldn't that be obvious, once you have carved a Bahtinov mask into it?

Nice improvement. I see extra detail and sharpness without over doing it. Both images are superb. I'm planning a session on M42, shortly, but there is no chance I will get close to your result. Congratulations on your superb work.

And the girls, too! You got some lovely shots of the Moon there, especially considering no stacking. Some of my stacks have come out worse! I'm restricted to camera and lenses at the moment, which is rather annoying. Did you see Uranus occultation, last night? Clouds have cleared here this morning, but refused to budge last night, of course!

I will second MPB and add the following: https://www.parkcameras.com/ https://www.castlecameras.co.uk/

Nice! Looks like an upside down panda. So, extra points for cuteness.

So pleased you got it! That is a nice result for a single frame.

Thanks. Glad you like it! Details of the Uranus occultation by the Moon in the link below. https://www.skyatnightmagazine.com/advice/uranus-pass-behind-moon/

I spotted the crescent Moon hanging low in the south western sky on the way home tonight, so set up the camera and 600 mm lens to capture it. D800, 600mm, f/8, ISO-6400, 1/2s. D800, 600mm, f/8 ISO-400, 1/100s.

Nothing that is on any of your lists. PIPP Autostakkert GIMP

Making the job of thieves unacceptably lengthy and risky or uncomfortable is about the best you can do. Use very bright strobe lights and loud shrieking alarms which irritate them. Chains and padlocks can be cut in under a second with bolt croppers, so will do little to deter, but perhaps enough of them will make thieves feel less inclined to bother with your kit. Bolting everything down solid with secuity fixings would perhaps be a good idea. Remember, professional criminals will have set themslves a time limit (usually under ten minutes) and will almost certainly be armed, probably with crowbars or sledge hammers.

It may have been written by an AI, but I think it more likely that it was written by a young person with an emphasis on getting keywords into the body text and then translated from the original language into English by a non-native english speaker.

I asked OpenAI a question about a business and it replied that it suspected this was a person or business and that it could not go onto Google to find an answer, instead only being able to answer from it's own programmed database of knowledge [gathered from the internet, one presumes].

I'm not sure what you are (or I am) missing here, but I asked it to provide a comparison between two totally different physical forces, not to simply calculate their ratio. The answer could (and should) include the ratio you mention, but I was also expecting the nature and origin of the forces to be compared, all of which the AI did, at least in it's original and detailed answer.

@vlaiv I totally agree. I had an argument with someone on Facebook a few years ago, who was claiming that drinking lemon juice is a cure for an acid stomach! I pointed out that lemons contain citric acid, which is an acid and you can only neutralise an acid with an alkali - chemistry 101. THey insisted that there is a special reaction that takes place in the stomach between the two acids that results in them both being neutralised! They then provided a link to an article on the webernet that made the same claim. Obviously, I googled it for further information and every link that came up made the same bizarre claim! It was only through using Google Scholar that we could find any articles that contradicted this. I tried another question with this bot: "Compare the electrostatic force between the nucleus of an atom and it's orbital electrons with the gravitational force" It took a very long time to come up with an answer, but when it did, it was detailed and remarkably correct. It was also much lengthier than answers to previous questions and contained a tabulated list at the end, but unfortunately, it then declared and error and cleared the text. Repeating my question gets the much shorter and simpler answers that we might expect.

For amusement, I asked https://openai.com "Describe the optical system of a ritchey chretien telescope" It's response is given below. A Ritchey-Chretien telescope is a type of reflecting telescope that uses a particular optical design to correct for distortion and achieve a wide field of view. The Ritchey-Chretien design uses a hyperbolic primary mirror and a hyperbolic secondary mirror to eliminate coma and other optical aberrations. The optical system of a Ritchey-Chretien telescope consists of a primary mirror, a secondary mirror, and a focuser. The primary mirror is a concave mirror that is made of highly reflective material, such as aluminum or silver. It is usually paraboloidal in shape, but in a Ritchey-Chretien telescope, it is hyperbolic. The secondary mirror is a smaller, convex mirror that is mounted in front of the primary mirror. It reflects light from the primary mirror back towards the focuser, which is the part of the telescope where the eyepiece is located. The focuser allows the user to adjust the focus of the telescope and to direct the light from the secondary mirror towards the eyepiece. In a Ritchey-Chretien telescope, both the primary and secondary mirrors are hyperbolic in shape. This is important because it allows the telescope to correct for coma, which is a type of distortion that occurs in other telescope designs. Coma is caused by the fact that light rays from different parts of the field of view are focused at different points, resulting in distorted images. In a Ritchey-Chretien telescope, the hyperbolic mirrors ensure that all light rays are focused at the same point, providing a sharp and undistorted image. Overall, the optical system of a Ritchey-Chretien telescope is designed to correct for distortion and to provide a wide field of view. It uses a combination of hyperbolic mirrors and a focuser to achieve these goals.

I accept what you say about focal ratio and depth of field, but at astronomical distances it becomes totally irrelevent. Referring to Thierry Legault, Astrophotography, pg 74, he states that for a focal length of 1000 mm the difference in focus position for the Moon and a star hundreds of light years away is of the order of one billionth of a millimetre! I don't know about you, but I am certain that I cannot make such a fine adjustment of focus, myself. 😉