michael.h.f.wilkinson

The moon is an issue, but NGC 4636is very bright, so can handle a lot of magnification. I might have a shot on Monday at 3 AM.

SN 2020ue is currently listed as mag 12.8, so even brighter than the one in M100. Details here: http://www.rochesterastronomy.org/supernova.html#2020ue Fingers crossed for clear skies

I will check out the books I had for the course "The History of Cosmological Thought" taught by John North, which I still have, somewhere at home. Note however that the fact that the number of circles is roughly the same is not enough to say the simplicity of the models is similar. The Ptolemaic system needed epicycles simply to explain major features such as retrograde motion, and further lesser epicycles to account for deviations from circular motion, whereas the Copernican needed no epicycles for the former, only for the latter. Besides, the fine tuning mentioned before was not needed in the Copernican system

Note that Galileo had direct evidence from the phases, and relative sizes at different phases of the inner planets that they orbited the sun. Having one set of planets orbit the sun and the rest the earth would be a bit of an odd mix (that didn't stop Tycho Brahe, of course). You can get rid of the deferents of Venus and Mercury (and rid yourself of the fine tuning that these deferents have the exact same period of that of the sun), and the major epicycles of the outer planets, but to correct for the ellipticity of the orbits you will have to retain a bunch. So the number of removed circles might be roughly the same, but removing just one, or the aforementioned fine tuning makes the Copernican system simpler. For Galileo, the additional evidence that the inner planets move around the sun made a system in which the earth and outer planets also orbit the sun simpler than the odd mixture of the Tychonean system.

I knew the moon would be close; it was the combination with hazy clouds that killed the chances of spotting it. Forecast quite dreadful here, alas. Good luck hunting it down

I tried last night, got up at 3:45, to find a bright moon right next to it, combined with hazy cloud blotting out all but the very brightest stars. I went back to bed after putting the telescope back in its storage

Clouds were encroaching on an otherwise clear sky when I got home from salsa lessons, so I didn't get out the scope, but instead grabbed the Helios LightQuest 16x80 bins, and headed of to Perseus. It took me just a few minutes to spot comet C/2017 T2 (PANSTARRS) as a little fuzzy ball near eta Persei (and close to open cluster Trumpler 2). I picked it up repeatedly in gaps in the clouds, so I consider comet number 26 bagged.

Plotted some finder charts with the AAVSO tool They are all with the RACI finder orientation. Fingers crossed, Clear Outside still says the skies will clear tonight

Listed as mag 13.2 now, so we'll within range of my C8. May well check it out tonight (if Clear Outside can be believed)

Interesting. Might brighten considerably, although a type 1c is typically a magnitude fainter than a type 1a SN. It will have to reach at least mag 14.0 before I can spot it with my scope

That is a beauty. Real shame about the missing parts

I hadn't checked the budget, but a mount like a mini-giro will sit on a photo tripod and provide much better balance than a normal pan-tilt head. The little VMC110L can be attached to a photo tripod, but is also somewhat over budget (OTA EUR 233 or just shy of GBP 200 at TS).

I use my APM 80mm F/6 on a Velbon carbon tripod, with Mini-Giro mount. Works nicely, even with two scopes side-by-side. I am sometimes inclined to get myself a Vixen VMC110L, which given quite a bit more aperture but restricts FOV. The APM weighs in at about 2.5 kg, the Vixen just 2.1 kg.

That is amazing

Building your own can be fun too

I use a TRF-2000 0.8xreducer with my APM 80mm F/6, and that works nicely. I have also been testing an Altair Astro 0.6x reducer, but that gives me some issues with star shapes at the edge of the FOV.

The Skyhound Comet Chasing site didn't list it, which usually means it is very faint

Had the first outing of the Vixen GP-DX mount, much to my surprise. I used this mainly as a test under bad conditions (bright moon, clouds chasing by from time to time), no effort at imaging. Got the mount working neatly with the new power supply, and got goto working well enough. After two star alignment the next object was near the centre of the field of view. Three star alignment didn't work, possibly due to inaccurate polar alignment. Well pleased, so far. As more clouds started coming in, I packed up the lot.

Nice work. The 2019 is definitely the best. I would try stacking multiple images. That would certainly bring out more detail

The 450D does have live, view, and I would say that is a must-have for AP

I first had a modded 450D, but then switched to a 550D and the difference is really big. Both were cheap second-hand cameras. For lunar I have used the 80D I have, and the flip screen makes life far easier, especially if you do not have a laptop handy. The 550D might be quite an oldie, but it can get some really neat results

I have found that the automatic neutralise background and star calibration methods in Astro Pixel Processor give a very good starting point. I then might tweak colour saturation a bit and fiddle with curves in GIMP

This just arrived, thoroughly packed by Stu: A Vixen GP-DX mount with SkySensor 2000 PC and sturdy wooden tripod. Definitely a great upgrade from my Vixen Great Polaris, which has carried my C8 for almost 25 years. It will probably continue to do so, as the GP-DX will be carrying the APM 80 mm F/6 triplet, in tandem with my ST80 guide scope. Very curious to see how that goes. Clear skies are of course nowhere to be seen.

The CCD filters block IR, which is unnecessary for visual, as the naked eye cannot see IR. CCDs are very sensitive in IR. I have fairly cheap visual-use O-III and UHC filters (and even an H-beta, for the Horse Head Nebula), and they work fine. I haven't compared them to more expensive options. Mine are Skywatcher, TS or unbranded ones.

Very nice start, indeed