michael.h.f.wilkinson

It's been pretty dismal here too

Got the Coronado SolarMax-II 60 mm out for a spin during my lunch break. A huge prominence between the 10 and 11 o'clock positions immediately jumped out at me. It looked like a huge candle flame, probably some 120,000 km high. It is in the same area as the big prom I spotted two days ago, but it has clearly changed shape (if it is the same). Just below the 9 o'clock position, a detached prom, showing up as a red blob at about half the height of the big prom from the sun's limb. There are many minor proms around the eastern limb, in particular near the big sunspot close to the limb at the 3 o'clock position. About halfway between the disc centre and the limb, in the 10 o'clock position, two very compact, very dark filaments are visible. Detuning did not show much in the way of sunspots at this location, so despite their dark appearance on-band, they are not sunspots. above them some weak plage can be spotted. Lower on the disc, towards the 7 and 8 o'clock position, various areas of brighter plage can be spotted. Several students and faculty members dropped by to have a look, and they were all suitably impressed with the show the sun was putting on.

Well deserved! Congratulations

Just had another look, and it is still going strong

Just took the Coronado SolarMax-II 60mm for a spin during my morning tea break, and there is a huge prominence high up on the northern limb of the sun. It looks like two huge, near linear flames emanating from the disk, the right-hand one a lot bigger than the left-hand. There is quite bit of other activity in the form of smaller proms along the western limb, a couple of sunspots, and a scattering of plage areas and filaments on the disk. Well worth a look. Pity I do not have imaging gear at work

Magnificent stuff!

I have a Meade Schmidt-Newtonian, and just attach the camera (ASI183MM) and filter wheel into the focuser, and achieve focus quite easily. I would assume the same works on the Mak-Newt

I gather the new software version didn't support the feature any more. Pity, as I was on my way from neutron star to supernova, as I recall

Very nice shot indeed, Especially at such a modest integration time

Regarding eye relief: I need to wear glasses while observing (due to cylindrical astigmatism), and require a minimum of 16 mm usable eye relief, I find. The Vixen SLVs are perfect in that respect, as are the (far more expensive) Pentax XWs, which give a larger FOV. If you don't need glasses, by all means use the cheaper short-eye-relief EPs. Note that a 12" Dobson is a fast scope, so it does put correction of eyepieces to the test.

I don't think so. They look much more like the earlier Helios Apollo 10x50s or TS Marine 10x50s

Lovely image!

I have no experience with the 150PL, but I did build a 6" F/8 "planet killer" Newtonian in the distant past. Mine had a secondary of just 36mm or so, just some 24% secondary obstruction (SO), which made it perfect for planets, and no slouch on deep sky viewing. The 150PL has the same 36 mm SO (according to this pdf), so performance should be similar. An 8" with 33% SO will show more detail, but with slightly softer contrast. My current C8 shows more detail on planets, despite its higher SO.

My portable solar set-up. Currently the tripod, mount and Coronado scope are permanently parked at work, so I can have a look at the sun during lunchtime. The little APM 80 mm F/6 triplet is at home, and usually sits either on the Great Polaris mount, or on the EQ3-2.

I would need to find space to store it first, or better still, a permanent observatory

Great image. If (when ) I buy myself a RASA, I will almost certainly say something like "Now look at what you made me do, Olly!" 😛

The short form (with some arms waving) for me has always been: When the universe cooled enough for ionized hydrogen to recombine into neutral hydrogen, visible light could travel largely unhindered. By contrast, the universe became opaque to the 21 cm wavelength of neutral hydrogen. Thus, transparency is wavelength dependent. Only when stars and galaxies formed, and the neutral hydrogen got partly ionized, and concentrated in regions of higher density around galaxies and clusters did the universe become (largely) transparent in the 21 cm wavelength.

Incidentally, much depends on the type of varifocals. The usable field of view varies a lot. Cheaper ones have the narrower usable FOV.

Hi Jason. It is not so much the varifocals (I use them too) but glasses by themselves combined with eyepieces with comparatively short eye relief (the optima distance between rear of eyepiece and eye). If you do not have problems like (cylindrical) astigmatism, observing without glasses is fine. However, if you do have such astigmatism (like I do) then the best option is to get eyepieces with long eye relief (like the Vixen SLV series and many others). These tend to be more expensive, however. Varifocal glasses can cause issues with only part of the field of view being in focus at any given setting. This depends largely on how strong your reading part of the glasses is, and the width of the field of view. I tend to get along quite well with my varifocals, others prefer to keep a separate pair of glasses without varifocal lenses for observing.

A simple way to test whether the EPs where at fault is to rotate them in the binoviewer, which is easier than rotating the whole binoviewer. I have never noticed any difference in sharpness between top and bottom and left and right edges (until I started using varifocal glasses, obviously). EPs are generally very close to perfectly rotationally symmetric, so I would not expect any difference between the north-south and east-west edges

Outstanding image, as ever!

I have had a chance to look through a Baader Hyperion Aspheric 36 mm in an F/8 scope, and the TMB Paragon 40 mm I had at the time (of which the Aero 40 mm is a clone), and the edge performance was noticeably better in the latter, even at F/8. I have used the Paragon 40 at F/6 and that worked fine. Having said that, the Paragon 40 mm is reported to be better than the 35 mm, so it is hard to be sure about the 35 mm vs the Baader 36 mm. I must say I was a bit underwhelmed at the performance of the Baader 36.

First of all, they are sold separately. I did a quick google for illuminator for eyepieces and this was one of the first hits: https://www.stellarvue.com/ei002-illuminator/ Have you replaced the battery of the illuminator? Is it really broken or is the battery just flat? These illuminators usually can be opened by unscrewing one half, exposing one or two small batteries inside.

Great catch! I did have an observing session over lunch, but must have just missed this

Just had a quick look at the comet again, using the Helios LightQuest 16x80 binoculars once more. It is a really easy find at the moment, neatly placed near the centre of the triangle formed by epsilon, eta, and zeta Aurigae. Very easy object in the big bins, although it seems a bit fainter than before (might be moonlight, of course). I hope to get a better chance tomorrow, when the forecast is good, and I don't have all sorts of other tasks in the evening. The comet should be close to the Flaming Star Nebula, and I might try to get it with the good old EOS 550D and Samyang 135 mm F/2. I also aim to set up the big comet catcher, i.e. my Meade SN6 6" F/5 Schmidt-Newton with the Tele-Vue Nagler 31 mm T5 (24.5 x 152mm with a true FOV of 3.34 deg). Maybe I can spot more detail with that. Fingers crossed