Captain Scarlet

I think Carlsberg make a better one

I hear you. And when the clear and free night does appear, which scope to use? I’ve missed at least one recent clear night over indecision. M

Over here it’s Gorse burning, again seemingly a bi-annual ritual, just before the end of March and just after the start of September. But two recent such dates caused local outrage, such that the authorities finally decided to prosecute some local farmers, successfully. Thus the start of this latest September saw almost no fires as far as I could make out (I have an unparalleled view of the locale). That people think it’s OK to start fires like this in these times, especially after a long long dry spell such as was the case here, bemuses me. This was the fire that tipped the balance. It’s my own pic, making the local papers and I’ve even seen it lifted onto a couple of local-interest websites (they’re welcome). It’s from this March I think, Mount Gabriel on fire, taken at ten miles distance. The powersthatbe were within a whisker of shutting down the air-traffic control radar domes atop that hill, Europe’s western-most, one of which is silhouetted. Magnus

Great read, thanks. You’ve reminded me to put the NAN on my list, I’ve never actually looked for it despite it being mentioned to me many times. Pelican too. Magnus

No tool needed, it’s a rubber ring sitting in a shallow groove, there to provide a stop for outer-baffle-tube movement in case the focus-rod becomes detached, preventing the outer tube falling onto the corrector-plate. provide a stop for Just “roll” it out using your fingertips. I guess with age there’s a possibility that it will harden and perish at some stage, but shouldn’t be too difficult to replace at a hardware or plumbing shop. Cheers, Magnus

Just in from watching an Io shadow-transit through my Kowa 88mm spotting scope with Delos 3.5 inserted, giving me 146x. Amazing how that black spot just leaps out. Reasonable detail from Jupiter too. A clear night, I really wanted to go to bed but managed to summon just enough willpower for 20 minutes or so. Magnus

I think a sheet from the loo-roll’s former life will have wiped away the nebulosity 😉 Seriously though I too can see that haze around Merope in my binocs (also Leica) and have long accepted that it is indeed nebulosity and not light cloud or dew. Magnus

Rubber feet for me, even on grass. With my 8” Newt on a skytee2 atop Berlebach’s narrowest Uni tripod on sloping grass I’ve not had any problem. My Planet, AZ-EQ6 and 21kg 12” Newt plus counterweights are also fine. Which is a relief, as my utility room has a rather soft concrete floor and the spikes dig holes in it. Magnus

@Nicola Fletcher might be interested in this. It looks like a cost-effective way of discovering whether you get benefit from a CC without blowing £500 for a Paracorr2. Its specs look remarkably similar to the PC2 actually. Magnus

If I were you I’d keep the Mak 127 as it’s so portable and compact; and I’d keep the ST120 as a comparison from time to time to remind you of just how good the SM125 is.

Superb read. Did Saturn’s Moons look like this?

@markse68 might be familiar with the locale as well?

lol just a little shower that came through and clear after - well forecast so I came prepared 😁

Two proper sessions less than a month apart! Last was September 12th. With a clear sky forecast, apart from a band of rain due to head over around 11pm, I decided to make a night of it despite the early-rising gibbous Moon. Sctually, partly because of it, as there is a particular crater I wanted to identify and photograph if possible: the Clerke crater named after Agnes Mary Clerke. She was born in Skibbereen, my nearest town, and in her day was reputedly the most famous astronomer in the world. Also, she is the namesake for the recent storm that came through, Storm Agnes. Crater Clerke, a small 7km crater close to Apollo 17’s landing site, by coincidence was in the perfect position for observing last night. I also wanted to do more of a concentrated session, as opposed to some of my longer “tick-off” lists of late. So it was to be Saturn and as many of Saturn’s moons as I could detect; Jupiter and any detail I’ve not been ever able to see; Neptune and Triton, if possible – it was in a good position but I was worried about how close to our Moon it was. And of course the Clerke crater. Tools for the job: my Stellarvue 140 / Baader BBHS star diagonal on AZ-EQ6, controlled by Nexus DSC. I also chose to use some of my “small eyepiece” collection, what I call my “orthoscopic lookalikes”, namely the BCO 10mm, Tak 5 and 7.5 and TOE 2.5. It was to be First Light for several of these. The comparisons were interesting, too. There was one clear winner, which will become apparent as you read. There’s been some really heavy dew lately, it being Autumn, so once I’d set everything up in late-afternoon daylight, I covered the mount-head in a large Ikea bag, having read recently about putting a barrier between the gear and the clear sky ultra-low temperature (I’m irritated I didn’t think of that myself). It worked! Also, these days I always bring the actual OTA out just before the observing session, and use the alignment process as the cool-off period, staving off dew-formation as long as possible. Dinner finished, I headed out shortly after 9pm. The Ikea bag had done its job, Polaris and Markab served as my alignment stars (giving my Delos 17.3 its First Light, admittedly it’s not one of my “orthos”!) and Saturn beckoned. I put in my first observing eyepiece, a BCO 10mm (First Light), slewed to Saturn, and said “Wow”. The planet itself in all its best-ever crisp detail, the Cassini División totally obvious in direct vision (first for me), a clearly darker-coloured atmospheric band, all floating amidst myriad pinpoint planetary dots: a tableau in three-dimensions. I felt as if I could reach out and touch it all. The dots were: Titan, Dione, Rhea, Tethys, Enceladus, Mimas and Iapetus. All at just 94x with the Baader Classic Ortho 10mm. I’ve since learned that Mimas was a real catch, not least at 94x! I recall initially seeing a pair of dots, one above and one below, just off the Eastern edge of the rings, both perfectly clear, the lower one brighter than the upper. I looked them up: Tethys below and Mimas above. They reminded me of the Trapezium E and F stars, so tricky but in the right conditions, dead easy. I tried hard for Hyperion too, but it was out of reach. I replaced my BCO 10 with my Tak LE 5, for 188x, and it was all far less satisfying. I could still make out Mimas, but only barely. Most odd. I got my Celestron Ultima 2x Barlow (First Light) and put the BCO into that, to give an equivalent 188x, and it was much better again, though not as exquisitely sharp as at half the magnification. So, in direct comparison, BCO 10 + Celestron Ultima 2x defeats the Takahashi LE 5. I put in the Tak LE 7.5, and that was better than I was expecting given the 5. I did briefly put in the Tak TOE 2.5, giving me 375x, but it was too much. And the later it got, the less I could detect the three mag 10 moons, with Mimas disappearing entirely. Anyway, by now Jupiter seemed not too low, but in fact it was. Some nice detail was on show, much more than simply the main Equatorial Bands, but there was still significant CA. I moved on to Neptune to see if Triton was available. It wasn’t. At mag 13.6, given that I’d seen mag 13 Mimas I thought it might be possible but it was that much closer to the Moon, which itself was that much higher. Another day for Triton. From here I swapped between Saturn and Jupiter, spending much time on each, and as he got higher, Jupiter got better and better with plenty of detail on view. Mostly I used the BCO 10/Barlow combination. Saturn, in contrast, got worse and worse as some serious-looking cloud – brief rain had been forecast – started impinging from the West. Eventually I had to take a literal “rain check” and wait: Sky washed clear, I moved on to the Moon. I found crater Clerke quite quickly. At least I think I did. I still need to check an authoritative reference against the rubbish phone-pics I took (edit - I just checked, all good, I think). All in all an enjoyable night. Nexus DSC behaved perfectly, and First Light happened for at least three of my eyepieces. Very happy in hindsight with Mimas. I look forward to having another go at Triton, and two other ambitious targets, perhaps too far-fetched: Hyperion, another of Saturn’s moons; and Amalthea (Jupiter’s fifth-in-line) which at mag 14.5 might _just_ be possible on a very dark night, likely with my 12” rather than the 140 but who knows? I’ve reached 14.7 in this scope before. And I discovered what an absolute star the BCO 10 is. Are all the BCOs that good? Thanks for Reading, Magnus

Mimas seems well-placed again tonight.

This was me last night when a (forecast) mild squall came through (otherwise a superb session):

I have both a Paracorr2 and a Nexus DSC (not the pro but the only difference is the pro has a later chip more memory, functionally I think they are almost identical). I wouldn’t be without either. I nearly sold my then wide field eyepiece (Pan 35) a couple of years ago as the outer-field stars were so bad in my 12”. It then occurred to me it might not be the eyepiece at fault, I did a bit of reading up, bought a Paracorr2 and magically the coma disappeared and what had been intolerable became beautiful (Double Cluster through a 12” at wide field from a dark place is really something else). The Nexus is extremely capable, is able to work with an equatorial platform and has every conceivable catalogue built in, which you can filter in and out “in the field”. I use mine in native mode, but you can connect it to SkySafari and use that as your control as well. The only thing I’d advise is get the additional GPS auto-location feature on it, I think that may be an extra on the “pro”. You should also be able to use the Nexus to control your AZ-EQ5 if you still have that: you can store settings for several mounts in the Nexus. It completely replaces the SW handset. Looking forward to see how you get on. Magnus

It was quite odd. I was also comparing my various ortho-style eyepieces, and the first I put in was my BCO 10mm (first light for that), for only 94x but that initial view was the best all night by far. Tethys was below the easternmost ring-edge and a much fainter but perfectly obvious and sharp Mimas was above. I struggled to get it with the Tak LEs and TOE at higher mags. But there was cloud steadily rolling in as the night went on so that might’ve affected comparisons.

Just in from a mostly clear night. Only planets, with the 140. Seeing around Saturn seemed really good. I wanted to get as many moons as possible and managed Titan, Dione, Rhea, Tethys, Enceladus, Mimas and Iapetus. I tried hard for Hyperion but no luck. Jupiter again the best I’ve seen it. And I also found the Lunar Crater Clerke, named after Agnes Mary Clerke, born very near here, who was responsible for our recent storm Agnes. Worthy of a full report, will write it up tomorrow. Cheers, Magnus

Don’t let your 10” know! It’ll put it right out of collimation.

Nazgûl?

I’ve heard that Hotech laser collimators are reliably true out of the box. Although not dirt cheap, they are not crazy like the Glatter ones. £145 from FLO. @Stu has had experience of them I think.

It could be argued that the centering is actually less important for AP than for visual, because you can even out the illumination with flats.

Collimation is the process of aligning the optical elements. In a Newtonian, that means aligning (making coincident) the axes of the eyepiece and the primary mirror. Which in turn means somehow aiming the eyepiece axis directly at the centre of the primary mirror; and aiming the axis of the primary mirror directly back at the centre of the eyepiece tube. Both these two steps can be done independently of the other, luckily. In a perfectly-collimated Newtonian (using a laser and barlowed laser, as it's easiest to describe): 1. a perfectly-collimated laser-pointer inserted in the focuser tube will strike the primary in exactly the centre (using the tilt of the secondary as the beam-director); 2. (using a Barlow in front of the laser) the reflected shadow of the primary's centre-marker should fall exactly in the middle the face of the inserted laser. Once you've achieved 1 & 2, the Newtonian is collimated. Two things, though: i. notice I've not mentioned anything about "centring the secondary". A Newtonian can be considered collimated according to the definition above (aligning the optical axes) almost regardless of how well-centred the secondary is. The actual _location_ of the secondary only affects illumination levels across the image. A thought experiment: if you place black tape across four edges of the secondary, rendering it rectangular, of if you snap off an edge of the secondary, the scope is still collimated. Obviously, for ideal illumination, you'd like the secondary to catch as much of the returning light-cone as possible, but getting the secondary to appear "round" is far less important than the alignments. ii. almost all techniques for collimation require the centre-spot of the primary to actually be in the centre. In both primary mirrors I have measured, this was not the case, one grossly so. Magnus

I find the site www.lightpollutionmap.info the best for predicting LP levels. Select the "Atlas 2015" tab, which shows a modelled prediction of what your SQM might be based on the then-latest VIIRS readings from above. I find it to be quite accurate, based on lots of SQM data I've collected over the past few years at two different sites, one near London and the other here in rural West Cork. On the map, simply click where you want to check and a pop-up with estimated SQM will appear. Cheers, Magnus