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There isn't really a direct measure you can apply - it more comes down to the size of the field of view. However, it is reasonable to say that when used for Prime Focus AP, the image captured by a camera is roughly equivalent to that seen in an eyepiece equivalent to the diagonal size of the sensor. So an APS C sensor captures what you might see with a 30mm focal length eyepiece. What magnification that represents depends on the focal length of your Scope. A webcam with a 3x4mm sensor would be equivalent to a 5mm eyepiece - so therefore more suited to planetary imaging. It's a rough and ready measure, but works to explain the principle

The height of a transit is always the same (except for solar system objects), so what's probably of interest is to know when they're due south at a good time for observing. I'd suggest a classic planisphere as the best way to see this.

As I understand it, there is some suggestion that although Dark Matter doesn't interact with 'normal' matter (except gravitationally), it may well interact with itself. The reason that this is suspected seems to relate to the way that the distribution of Dark Matter in the very central parts of a galaxy is slightly different to what would be expected if there were no interactions at all. It thus seems possible (to me at least) that this may represent a new force altogether to go along with the Electromagnetic, Strong and Weak forces, with a new boson as well to mediate the force. It's exciting of course, but tricky to see how it would be possible to run experiments that would let us find out more.

Good to hear.

Oh dear!

Hi Richard, and welcome to the fellowship of amateurs. You're probably aware that your local club is Macc Astro - a very well established club - and when the current virulence is over, they are likely to restart their regular trips to Anglesey for some better 'dark sky' observing. Neighbours with motion sensitive lights are a regular pain - if you know them well enough to ask them to move them to a better angle, that's really useful. There should be a law against lights going higher than any walls, fences or hedges. Keep an eye out for details of the Online "North West Astronomy Festival" which is scheduled for 25th September - and it is hoped that they'll be able to meet up for a 'Real Life' weekend of Astronomy in 2022 (probably near Warrington). Great to have you with us - Owen (from the Mid Cheshire AG)

It's probably not possible to make a valid assessment on the scale and spread of the impacts on the basis of their current visual appearance, when you consider that the age of Aristachus is approximately four times that of Tycho - therefore there has been four times the darkening of any ejecta. Another consideration is that Tycho is over twice the diameter of Aristarchus and 70% deeper, so it represents at least 7x the volume of material displaced.

You might want to run an anti-malware checker on your phone, as it looks as though you were subject to a redirect - and I'm not absolutely convinced that you can be sure of apks that come from Aptoide rather than direct from SkyWatcher. I would suggest you uninstall the app from your phone - then get a download direct from https://inter-static.skywatcher.com/downloads/synscanapp_1190_store.apk or if you want the 'pro' version https://inter-static.skywatcher.com/downloads/synscanpro_1190_store.apk (if necessary download to a laptop/PC and then copy it to your phone by USB/Bluetooth) Hopefully, all will be OK - but I do wonder why you were redirected and why you were required to give permissions over and above what you would expect. It would also be worth checking if Aptoides has installed its own app and permissions - get rid of them as well if you're not sure about them Edit to add: Aptoides says that a green tick next to a package should indicate that it's safe. That may be reassuring. Up to you.

I'm not sure what 'effect' you're trying to explain, and why you don't think that the usual explanation of heating due to atmospheric compression doesn't cover it.

Just a quick heads-up that the image for Jupiter and its moons is a bit misleading - at 3:30, Ganymede was actually behind Jupiter, so would not have been visible. The moon to the right of the planet would have been Io - though you may have seen it on the left in your scope as the image is reversed On my Android phone, I use the "Moons of Jupiter" app - as well as showing the positions, it gives advance notice of events such as transits or entering/leaving shadows etc

Yes, I've used Pentax dSLRs for astro imaging and I reckon they're pretty good. I have a K5 that I'm pleased with - though I'm not a great astro imager. The principle reason I would give to support anyone going for Pentax would be the longevity of the design - any K mount camera will be able to take almost any K mount lens from the last 45-50 years, and for much nightscape imaging, you don't need auto anything, so good old glass can be used, and they can often be bought for very keen prices. Other than that, I really appreciate the ergonomics, and the sensors are pretty good too (particularly those that are ISO invariant). I would say that if you are looking to do imaging straight onto the camera, then a Pentax with an intervalometer is an ideal set up - though it has to be said that if you are looking to integrate your camera with a laptop, you probably would be better going with Canon, as the software environment is far better for that brand. Declaration of interest: I started with a K1000 in the 1970s, progressed to the absolutely superb ME Super, and the P30 as film cameras. Following this, the K100 D was my first digital SLR, which was followed by the K5 (this after a recommendation by Ian Morison from Jodrell Bank). What is nice is that the K5 works very well with the original 50mm f/2 lens that came with the K1000, as well as a lovely 200mm f/4 lens that I got for a song on ebay. So I am a bit of a classic Pentaxian - it's a nice place to be.

Downloading the Windows app onto your laptop might be worth trying. If you're still on Android 10, you shouldn't need to download the new APK from the Skywatcher Downloads page, but if all else fails, again, it might be worth trying. The only other thing I can suggest is to ask whether you have switched off mobile data on your phone? I can't think of any reason why this would make a difference, but since you're effectively stuck unless you can get a firmware update, it's worth trying as well.

Go to Settings - then Connect Settings, and make sure you have the Network mode selected (not Serial) Does that help?

What sort of mod are you thinking about? I would say the only thing to check is whether the Sony lens you bought has the right mount for the A6000.

Highly recommend Pete Williamson's talk to round off the day.

And occasional hot big bangs I assume

I'm not exactly sure what you're doing - but as far as I can tell, there shouldn't be any need to use the home wifi router. For me, I switch on the mount, disconnect the laptop from the home network and connect to the mount's wifi instead - which will be something like SynScan_aa99 and the IP address shows as 192.168.4.1 I can then control the mount from the laptop.

I'd say for printing out purposes, Cartes du Ciel is a good place to start. I've prepared finder charts that I print onto A4 pages that go inside clear plastic display wallets. These are made up of chart screenshots that are pasted into a Word / Open Office page and then saved as a PDF Finder view and eyepiece views can be selectively reversed depending on your individual set-up of course

I'm afraid I don't know whether the A6000 can send its image stream directly to a PC, which you might want to do for planetary imaging. Certainly, for deep sky or skyscapes you could use an intervalometer to capture multiple images to be downloaded and stacked separately.

Ian Morison (ex Gresham Professor of Astronomy and Jodrell Bank) has an Astronomy Digest post about the similar A5000. The A6000 is better as it's easier to disable automatic Noise Reduction, which you don't want to use on Astro photography. I have the A5000, which works very well on my smaller scopes (its body is ⅓ the weight of my dSLR) http://www.ianmorison.com/the-sony-a5000-apsc-mirrorless-camera-an-astrophotography-bargain/

With a Baader full aperture filter, there's no need to be concerned regardless of the optics. You can make a DIY filter up to 200mm aperture with an A4 sheet of Baader film

with regard to scratches on the Baader film, my view is that our eye has an aperture of several mm^2, and even if there is a bit of damage to a solar filter, it would need to be really obvious to let more light through than our eye already allows. Yes, I appreciate that we don't spend a lot of time looking directly at the Sun in normal times, but we often have it visible to some extent and it doesn't irreperably damage our vision - so small scratches and pinpricks on the solar foil won't have an immediate and catastrophic effect. Certainly, hold the filter up to the Sun to check for major damage or thinning before mounting it on the scope, but don't worry too much if you can't see anything obviously wrong.

My understanding is that refractors are the only scopes that are suitable, as glass has more or less 100% transparency for the IR light that is going to cause problems. Reflectors and Catadioptric systems are more likely to be damaged because reflecting surfaces may only reflect about 95%, and if the light has been brought close to focus, the 5% that's absorbed can be pretty intense. However, this assumes glass throughout, if the light goes through any plastic optical elements close to the focal point, there is the likelihood of damage being caused. I've used 50mm binoculars for projection for tens of minutes at a time without any problem, so I would expect anything up to 70 or 80 mm should be OK for reasonable length periods - though maybe make a cover for the objective to pop back on between observations

No need to apologise.

Bear in mind that moving the secondary will imply moving the focuser as well - which needn't be a problem, but will be more things to move and line up again. You might also consider getting a filterwheel and some filters for the refractor - as that should eliminate a lot of the Chromatic Aberration - Yes, you may need to set the focus each time, but it should be do-able Caveat - not done this myself - so it may be rubbish advice