Gfamily

My experience with using telephoto lenses is that the variable aperture iris gives multiple diffraction spikes, which a nifty fifty will avoid. The only scope in that range that I've any second hand experience of, is a RedCat 51 that a friend has used. It makes a very compact until, and being a Petzval design doesn't need a separate Field Flattener.

The shame is that if NASA had been able to design the SLS from the ground up, it is quite possible that it would already be around the Moon. It seems to me that the Senate imposed obligation to reuse Shuttle engines and technology is what's causing a lot of the problems.

Mid Cheshire Astronomical Group

Hi Francis If you're from Liverpool, have you found out about the Liverpool Astronomical Society? They do talks in the City Centre that might be of interest, and they have an observatory in Pex Hill (Widnes) that you can go along to on Wednesday evenings for observing (7-9pm). I'm sure you'll be very welcome. I'm not a member, but I know some of the people there, and they're great. Here's their event calendar http://liverpoolas.org/events/

You can reduce the effects of tube currents by lagging the outside of the OTA with radiator foil. It sounds anomalous because it increases the time for the internal temperature to reduce, but it seems to be the speed of temperature adjustment that causes the internal currents that affect the seeing. Also, when observing the planets in the summer, they will be at low altitude and more affected by atmospheric conditions. Of course, if we were observing them in the winter we could well be affected by the Jetstream - you just can't win! In principle, you might consider getting a focal reducer to increase the field of view - to be honest, my biggest bugbear of SCT and Maks is the narrow field of view, which means that many open clusters lose their impact. As for dew, yes, a heated shield or a 12v hair dryer could be of value.

Hi @alexwolf Can I ask a question about the calculations for the minima of the eclipsing binary star Algol? If I use the Sky and Telescope calculator, I get the following date/time for the upcoming minima However, Stellarium is not giving the same times As you can see, S&T.org predict the minimum at 22:19 UTC, whereas Stellarium is giving a time almost 4 hours earlier. Is it possible that Stellarium is giving the time of the start of the next dip rather than the actual minima? Thanks ETA - I am using v0.22.2

Yes, so long as the mask is centred on the objective, it should produce the correct image pattern to allow you to get good focus.

As mentioned last month, MrsG's new binoculars set up for some planetary observing list night. Jupiter, Saturn and Neptune spotted.

I tried to order through our local bookshop, but it's out of stock, though it is being reprinted. I'm hoping to be able to get the author to come to our Astro Group sometime to talk to us about the book. He's fairly local to us, so it's a possibility.

Try here for details and some reviews https://www.firstlightoptics.com/sky-watcher-az-gti-wifi/sky-watcher-az-gti-wifi-alt-az-mount-tripod.html Here's the 'owners thread' on this forum https://stargazerslounge.com/topic/387014-skywatcher-az-gti-mount-owners-thread/

The Skywatcher Az GTi is a good one. There's a thread in the Discussion Mounts forum.

Oh dear, you're going to be getting me imaging again!

Very impressive. Was that using an AltAz mount? If so, I may try some long exposure imaging

Apologies - the initial "not really" was in regard to your 'You've said it doesn't need any star alignment routine, but '... and there is no need for a star alignment. My later edit was to allow for the fact that 'it needs some idea where North is' and to recognise that it does (internally) ETA - in my defence I would say that the edit was made only 3 minutes after the original post, and had actually been completed before you had posted your reply. But apologies all the same.

Except for two points: There is no need to start with it initially pointing North (or even nearly pointing North) The Sun is only given as a Solar System Menu item if you are using the Synscan Pro version of the app, and you have enabled Observing the Sun in the Advanced Settings

Can you let us know if it works, the online Synscan app manual says So it would be useful to know if it adjusts the tracking to RA only if in EQ mode

Yes, I could have been clearer - What I meant is that You don't need to do anything to give it an idea where North is As you say, because it knows a), b) and c), then it can work out where North is without any 'initial conditions' such as starting from Level and North.

Not really (or rather, yes!) When I set it to Point and Track the Moon, it was at 9:30 am and the app could calculate the Moon's then Azimuth and Altitude (256° 59' , 37° 48'). Because I was already pointing at the Moon, it knew it was at 256° 59', so it would thus know where North is. It only works if you are already pointed at the thing you want to P&T.

Not really - if you centre on a target, and it knows where that target should be, then once you have it, it can compute what its path should be. It assumes that the mount is level, but apart from that it's relatively straightforward (in principle - I wouldn't like to have to work it out on paper of course 😀) . Do you have one ? Try it out. ETA - to be honest, it came as a surprise (and a delight) not only that it worked, but also how well it worked.

Nope - if you can see something and it's in the app, you can 'Point and Track' - so long as the mount is level, it will track remarkably well. It doesn't set the encoders, so its internal pointers aren't aligned automatically (so if you then connect with another app it won't necessarily give you the right scope location) ETA - as per the handbook, this only works in AltAz mode - but it is a great thing for a very quick set-up.

I feel like an idiot that I've not really looked at the 'Point and Track' functionality before. This morning however, the waning gibbous moon was looking lovely in the clear blue sky, so I quickly dragged the mount out. I wasn't sure how it was meant to work, but I manually moved the scope to point to the moon, before selecting Moon from the Solar System menu and hitting Point and Track. 20 minutes later the Moon was still centered. Not only that, but it keeps tracking even after you've disconnected the app.

We have a 130P Heritage and haven't had any problems with collimation - and I'd expect the 150P to be the same.

MrsG is a big fan of binocular astronomy - and probably sees far more than I do with my telescopes. Yes, she uses a tripod and trigger head, but that's still very straightforward - and the wide field of view means that star hopping from brighter stars is easily done and very easily checked off against a star atlas or a tablet/phone. She uses the suggestions that Steve Tonkin ( @BinocularSky ) includes in his monthly newsletter (link to binocularsky.com ) and is very satisfied. Although starting with a pair of 10x50s, she has recently moved up to a pair of 20x80s - for which she'll be using our heavier tripod. She's very much looking forward to our next star party to take advantage of decent dark skies. That said, I would say that binoculars complement telescopes, so if someone is looking for a telescope, the best advice is get both. And for the OP - the suggestion of the 150P Heritage collapsing Dob is probably one that would not disappoint.

Hi Ash. You may have seen that there's an occultation of Uranus by the moon this evening (Sept 14th). The Virtual Telescope project is planning to stream the observation this evening, which may be something you'd like to follow. Details here https://www.virtualtelescope.eu/

The planets will be highest above the horizon at night during the winter months. So you shouldn't get a lot of distortion due to heat rising from the sun-warmed rooftiles at least. A good reason for making sure that your loft is well insulated, I guess.