lukebl

I rarely do lunar imaging but I stayed up late last night (well, late for me) to try and capture a transit of the ISS across the moon. It was predicted to be a good transit, with the ISS at its closest and consequently quite big. I had it set up perfectly, and did a bit of lunar imaging to while away the time. I then realised I'd got the day wrong, it was tonight, not last night! So tonight I got ready again, only to find that the ISS has done one of its orbit corrections (to stop it falling to earth, basically), and there's not going to be a transit after all! Anyway, I thought I may as well process the captures from last night and I was quite pleased with the result. This is a mosaic of 8 captures with a ZWO ASI290MM Mini, 2x TAL Barlow, 200mm f/5 Newt. 1000-frame AVIs, best 50% processed in Autostakkert. And a detail of Copernicus:

Knowing my luck, I’d end up with Bradley Walsh, rather than Jenna Coleman.

Ok, this isn't going to win any prizes, but it was an interesting experiment. I thought I'd have a go at getting a detailed view of the Trapezium using a planetary camera, Barlow and lots of very short exposures. There are some issues with the star shape (maybe the cheap barlow), but the result was interesting. There are stars down to about magnitude 15 here. This is the result of around 700 x 200 millisecond exposures. Yes, 700 x 1/5 second exposures. ASI290MM Mini cam, Tal 2x barlow, 200mm f/5/ Newtonian. Stacked in DSS.

Some of you might recall my Tardis roll-away observatory, which I had made a few years ago. Here it is in its heyday. Sadly, the elements haven't been kind to it. It was never really waterproof, and serious rot has set in in the base, so it's time to say goodbye to it and build something more practical. Anyway, my eldest son , who's now 18, is rather embarrassed by it. He thinks that having that thing standing in the garden made us look like a family of nerds, when in fact the only nerd is me. So here's the first stage. Now to build its replacement.

Happy New Year, folks, and Blwyddyn Newydd Dda as my Grandfather would say. I captured this view of the lovely 2.2% illuminated crescent of Venus at exactly midday today, 12.5 degrees from the sun. Banham, Norfolk. ASI290MM Mini Cam, Baader U-Filter, Tal 2x Barlow, 200mm f/5 Newt. It was a really lovely sight through the eyepiece. I couldn't see it at first due to the extreme brightness of the sky, but I stopped the scope down with the hole in the front dust cap and it was much clearer.

It was nice to see Venus this evening in a rare bit of clear sky, just over a week till Inferior Conjunction, with the 60 sec disc only 2.6% illuminated. The crescent looked pretty big through my 8 x 32 bins. This is a capture with a Canon 700d, and basic 75-300mm canon zoom at 300mm, plus an enlargement from one of the frames

Interesting. Like I said. A pointless exercise!

Slightly off-topic, but I remember this oft-quoted claim from decades ago, and it's always bothered me. As I've got older, I've realised that it must be an urban myth or even a wind-up. Firstly, if you were at the bottom of a very deep well, the field of view (i.e the opening at the top of the well) would be absolutely tiny. After all, you're at the bottom of a very deep well! If you're, say, 100m down a 2 metre-wide well, the field of view would only be just over a degree. Secondly, wells are (presumably) vertical so you'd only be able to see stars exactly at the zenith. Thirdly, the chances of there being a star bright enough for you to see, and precisely in a narrow field of view at the zenith when you were viewing, seem pretty remote! Fourthly, it seems a pretty pointless exercise!

Interesting fact. If you look closely at the curve, you’ll see that the star didn’t disappear immediately. Rather, it look about 8 frames (i.e. about a third of a second) to disappear and the same to reappear. I thought that this might be a fault of my camera or, and my mind was going wild at the point, because of the actual width of the star. Could it be that I’d measured the actual diameter of the star? No. The experts (well, Eric Frappa, THE European expert on asteroid occultations) tells me that it’s caused by something called Fresnel Diffraction, which I’d never heard of. It occurs when a light wave goes past a hard edge. You’d have to Google it. Well, you learn something new every day.

Just look at the latest satellite image of NW Europe. The weather is mocking us and our relationship with the rest of Europe. An immovable bank of low cloud whilst across the Channel it's blazing sunshine!

Exactly the same thing happened to my NEQ6. I eventually re-tapped the hole with a slightly larger thread, put in a bolt matching the new thread and it works fine. As you can see here, it's not at all pretty, and the NEQ6 has seen better days, but it works fine now.

True. Astronomy is a lot more affordable now. You can't beat a basic 200mm Newt, which now costs about the same as the little basic 60mm refractor I used as kid (but which still enabled me to get a grade A in O-Level Astronomy, I might add!)

I don't think that guy's going to see very much. It's daytime and it looks like it's cloudy!

That reminded me of an article in a copy of Sky and Telescope which I just dug out. 1975. I was a young man then! I would have thought collimation would be a nightmare, with three mirrors to align.

Thanks! Well, the asteroid is a Trojan orbiting way out in Jupiter's orbit, so I guess it's moving fairly slowly and it's quite big. I still can't quite get my head around the fact that I was lucky enough for everything to be aligned for me to be under the shadow of that distant star!

Not the most exciting video, by any means! Here's a short capture of the 7 second occultation! The occultation starts about 10 seconds in.

Bingo! Had a positive occultation here. Despite bright moonlight, and fog so thick that no stars were actually visible to the naked eye, I captured a seven second occultation. Amazing to think that a mere 60 km asteroid, far out in Jupiter's orbit, should cast a shadow from a distant star briefly over my observatory. Mind boggling. Here's the light curve. The green and yelllow curves are of the only other stars which were visible in the field of view at the time. RunCam Night Eagle Astro Camera, 200mm f/5 Newtonian.

Thanks for the input folks. And thanks for those links, @vlaiv. I’ll try the hacksaw option first, and if that fails I’ll buy a new one.

Anyone know where I can get a slimline adapter with an M42 x 0.75 thread to connect a camera to a filter wheel? I have one of these, but the thread on one side is too deep. If I screw it into the filter wheel, it just pushes up against the wheel, and if I screw it into the camera it only goes half-way in. I need it so that there's a narrow thread each side

Interesting. Clear Outside is predicting 100% cloud cover for Thursday night, Metcheck is predicting completely clear. Accuweather and BBC Weather also predict cloud. We'll see. 🤔

On Thursday evening at around 21:14, 17th magnitude Asteroid 11395 will occult a relatively bright 5.5 mag star TYC639-1485-1 for around 7 seconds, visible in East Anglia and parts of Southern England. It's not often such a bright star is occulted, and should be easy to see although the bright nearby moon will hamper things a bit. Worth a look. I'm on the centre line, although the weather forecast isn't too promising.

And the next problem is getting the old connector off the camera. It is stuck fast, and as you can see I've somewhat wrecked it in my attempts to remove it (although the camera's fine). There are no end of discussion threads about this on various forums (using mole grips, rubber shoe soles, etc), but I haven't found anyone with a satisfactory answer. Sorry, I seem to have hijacked this thread!

Thanks for that. It certainly sounds more promising! I'll have a look more closely at the connectors and see if I can get something more slimline. I was measuring the CC from the wrong point, so the distance was closer to around 72mm but still too much. My current connector also separates the Atik from the filter wheel by about 6mm so it's not flush like yours. I'll see if i can reduce that.

I appreciate that the CC goes inside the drawtube, but the problem is still an inability to focus in far enough. However, I found that the problem was with a Skywatcher Coma corrector. Using a Baader Coma Corrector I can reach now focus. UNFORTUNATELY, there is another problem I hadn't forseen in that the CC is over 80mm from the focal plane, rather than the corrrect 55mm, resulting in terrible coma. In fact, worse coma than without a CC at all! This all arose because I downized recently (now deeply regretting selling my RC8 and Atix428ex camera) and am just left with a 200mm Newt and an Atik 383L. I think that basically, It's just not possible to use a CC, an OAG (even a slimline one), and the Filter wheel with an Atik 383L and 200mm Newt. Unless someone can prove me wrong. This is the current unsatisfactory setup.

Last night I tracked down a couple of Near Earth Asteroids which are both on close approaches and fairly whizzing by. And they're big ones. I note that the online version of 'The Sun' had an 'exclusive' report headlined ROCKY HORROR Giant asteroid will skim Earth’s orbit tomorrow in hair-raising near miss. They suggested that an impact in Coventry, for instance, would wipe out most of the Midlands and cause damage as far as Leeds in the North and Southampton in the South. Yes, it probably would, and probably will one day, but it's not going to happen this time. You can trust The Sun for calm, factual, intelligent reporting to keep the nation calm! They were referring to Asteroid 4660 Nereus, which is big for an NEO at 750 metres across, and which passes by today at a distance of around 10.3 Lunar distances at magnitude 13. Discovered in 1982 by the late Eleanor Helin who co-discovered more than 900 asteroids. It'll be down to mag 17 by February. This is a single 2 minute exposure, Atik 383L, 200mm f/5 Newtonian. Firld of view 61.6 x 45.9 arcmin. As you can see, it's moving pretty fast. It's high up in Ursa Major, and I had to wait till elevenish till it cleared my house roof. This is an animation of it over a period of about 25 minutes (please excuse the jerky animation - due to dithering and not-very-good polar alignment) Another one is Asteroid 163899, which is bigger at over a kilometre across, and passes by on the 17th December at a distance of 14.2 lunar distances. It's shaped like a whale and was discovered in 2003. It's currently around mag 13.5 in Cepheus, and by February it's down to below mag 21. It looks like it won't be this bright or this close again in my lifetime.