Pixies

@Stu1smartcookie - how tight are your secondary mirror vanes? I thought I had some mirror slip with my 8" dob, but it turned out it was the secondary assembly flexing between horizontal and vertical positions. If you have a laser, see whether its position in the doughnut moves as you change altitude.

I have been camping near Weybourne a few times, usually (as with most UK holidays for us) it was cloudy! I remember one clear night, though, trying to guide people to see Andromeda through hand-held binos. The campsite fires/lights broke dark adaption unfortunately. Thanks for the inspiring report @John - I need to head back to the local SQM 21.7 site soon. Hopefully next new moon.

Does anyone know the RAL code for Vixen green? Not that I'm decorating the 'study', or anything like that! I might take the Super Polaris polar scope cover down to B&Q for a colour-match!

Can I ask where you got this from?

AAVSO:

Not meant to be a silly question, but how dark-adapted were your eyes?

Do you have a Cheshire / sight-tube? You need something like that to confirm your secondary mirror is aligned under the focuser and not twisted. A laser won't help with that. Or alternatively a concentre?

It's hard to say for sure. It's probably fine for visual observations - you can check with a star test. If you want to be precise though, you would do better with a bright background behind the secondary, so that we can see the circles of the focuser and secondary mirror, so that we can check they are concentric.

Just for comparison. the FOV for this combo is similar to using a 6mm Plossl (x250) Not surprised you are having trouble landing on it, even with a GoTo. Even without a flip mirror, with the AZGti mount tracking the target, can you centre on it using a wide-field EP first, then switch to the cam?

Blogs - never looked at these before - but saw an entry along the 'side' of the home page. Nice reports. The dumbbell REALLY benefits from a UHC or Oiii filter though.

OK. I have been thinking a little more. Forgetting about the correct offset/size of the secondary for now. 1) make sure the focuser is set up correctly. I.E., its central axis intercepts and is perpendicular to the central axis of the scope. 2) the centre of the primary is marked. Now - it doesn't matter about the offset or size of the secondary, as this only affects field illumination. Worry about that later! Just adjust the secondary angle so that the primary centre spot is directly central to the focuser view. You will have to make sure the secondary is facing the focuser by rotating it and looking for the widest angle as seen through the focuser. As long as 1 and 2 above are correct, you now know for certain that the secondary is at 45degrees and the central axis of the focuser is aligned to the tube axis (via the centre spot). All you now need to do is the usual primary collimation so that the primary is aligned back up the same axis - either laser or Cheshire/collimation cap. When the primary centre spot is dead-centre to the focuser and the primary reflects the collimation device back to the same central point - it's all aligned and straight. Just assuming 1 and 2 above. Then you can worry about secondary size and offset. But this is all to do with field illumination. Any comments? I think that's correct.

I've seen articles on how to calculate the correct size and offset for a secondary mirror. Scope builders will be very familiar with this, I'm sure. However, I also recall seeing an article about offset that shows an older method where the secondary is offset differently with the primary slightly tilted. Perhaps that's more applicable to a spherical primary mirror, where off-axis objects are less affected by coma, rather than a parabolic one. Anyway - I'm not an expert and I'm sure a few will be along shortly. But I reckon some scope-builders will be a good source of advice. As for your cunning plan to align the primary first, then (I assume) align the secondary from that... The trick will be making sure you can accurately align the scope with the laser. I would have thought it easier to make sure your focuser is straight/perpendicular to the tube, then you can use a correctly configured/offset secondary. The issue will be finding the correct secondary configuration, but that must surely just be a case of finding the correct advice/experience?

Hi Mark, In modern scopes, the shape and offset of the secondary are such that when they present a perfect circle concentrically under the correctly aligned and perpendicular focuser when collimated correctly. As for off-axis targets. That's a fact of Newtonians - the more off-axis it is, the more coma you see. That's why when you are collimating a scope with a star-test, the star has to be dead-centre. As you move the star away from the central axis, you'll see the diffraction rings start to 'bunch-up' to one side as the coma increases. Our scopes are usually slow enough that coma doesn't really bother us visually if viewing objects off-axis in a well collimated scope. Well - that's how I understand it to be.

Hi, Your scope will get you reasonable views of the bright planets. Bands on Jupiter, the rings of Saturn, the phases of Venus. Mars is to far away just now and you'll have to wait for next year before it comes back round to us. Now then - the first thing you will normally hear is that the eyepieces (not 'lenses' btw) that come with these scopes are very much just to get you started and would benefit from replacement. Normally I'd say you can keep them and see how you get on, BUT (and I really hate saying this) the ones that come with this scope are particularly poor. New eyepieces will really benefit you. x100 magnification is a good starting point for the gas giants. They can take more but your scope will really only go up to x150 depending on seeing conditions. Your scope has a focal length of 1000mm, so to get x100 magnification, you divide the focal length of the scope by the magnification wanted (1000/100) - a 10mm eyepiece. A decent wide-field eyepiece would be something like a 25mm (magnification = 1000/25) = x40, good for views of star fields and finding objects. Also, your scope is what's known as a Bird-Jones design. There is a type of barlow lens built into the focuser tube - that's why you can get a 1000mm focal length in a short 500mm tube. A separate barlow lens won't really work for this scope, it'll make the view pretty mushy. So, ideally look to get some better eyepieces around 10mm and 25mm focal lengths. That'll be a good starting point. If you get into the hobby, your eyepiece collection will grow rather rapidly, and they can be used in different scopes if you ever decide to expand or upgrade! Worth having a look here to temper your expectations on planetary viewing:

Hi Mark, In my non-expert opinion.... The issue is not the angle you show in your diagram, its the fact that in such a case - where the parabolic mirror would be tilted slightly off-axis - the incoming parallel light rays will not be on-axis to the mirror. This will cause coma (I think) See p3 and p4 of http://scipp.ucsc.edu/~haber/ph5B/parabolic09.pdf

Transparency here was poor. Seeing was variable. Straight up was good, but local conditions meant that the seeing for the gas giants was variable. At times it was OK. For Saturn, I could make out the Cassini Division most of the time. Titan was bright but Rhea was coming and going with the seeing. I think I got a hint of Tethys at times, too. Jupiter was better, being a little higher. I've been spoilt with some great seeing recently, so it was a bit off-and-on tonight. It had its moments though, with 4 bands clear and detailed at times. Some festoons visible in the equatorial zone. Could split Iota Cas at x100 - but it was close to the zenith. The Pleiades revealed themselves at the end of the night too. Which was nice!

Popped by the nova in Cas tonight, even though it was near the zenith by the time I got round to it. It looks like it's brightening again! Much brighter than HD220770 (mag 7.8) and nearly as bright as (and close to) HD220057 (mag 6.9). I'd say mag 7.0!

Same here. I'm expecting a lot of observing reports tomorrow morning!

Dark skies trump everything for visual DSO observing. IMHO

Hi, What scope do you have? The resolution of stars in a globular like M13 depends a lot on your aperture.

Before we spend your money, what's your budget?

Ah - Eta Lyra - that's a double, but not "Double Double" - Epsilon Lyra. Perhaps that's where the confusion is coming from. I blame the Greeks! (not personally)

Clear Outside had been showing red all day so I hadn't been planning anything for tonight. But when I posted something a little while ago, the CO table in my signature showed green! I checked outside and it was clear! The waning crescent moon was up but low behind some houses, so I grabbed the binos, a deck chair and settled down for quick session. North east is the best direction from my back garden. Although a 3 storey tenement nextdoor stands in the way, it's towards the sea and little light pollution in that direction, so the darkest views are there. I always feel a little uncomfortable though, as I'm viewing over the roof and probably look like I'm peeking into the top flats' windows! First I checked the nova is Cassiopeia. It's dimmer now and I had to use averted vision to see it. Hopefully it'll flare up again! Then over to M31. The sky was pretty transparent and dark, so the core of the galaxy was nice and bright. The dust lanes on the NW edge making the fuzz fade more abruptly than the opposite side and I really got a feeling of something wider than the central core. M32 was visible too. Counting upwards, M33 seemed the next obvious target! I've not yet observed it but the sky seemed pretty good and after a year of observing faint fuzzies, I wondered whether I might have my eye in now? But no - still no luck. I know where it should be and spent a good 20 minutes on the target. At times I thought I had it, but probably just "averted imagination" (as someone wittily put it, recently). I'll try again at a dark site soon. OK - M34 then! Nice and easy to find Quite a large cluster and a good bino target. Then hopped over to NGC752, which I found using a 'hockey-stick' pattern of stars just to the west of it. Wide and loose, I need to try this in the ST80. The moon was starting to make its presence felt now and the sky was brightening, so I had a quick shot at Jupiter and could only see 2 moons. Turns out that to the east, Europa and Io were very close to each other, plus Callisto was hidden by the glare of the planet as it is starting to transit. No going to stay up that late though!

@markse68 I've been hearing reports that an amber lamp is better than a red, because you can use it at a lower setting than just a plain red. Shame all my lamps are red LED. I'll need to find a white one and use some kind of orange tape/paint. Although I'm quite new to sketching, as @mikeDnight says, it's more a case of 'note-taking' at the telescope and then completing the sketch proper later indoors. But if you are sketching star positions, it's important to get it accurate at the time - in which case use a soft pencil (4B say) which is pretty dark. Here's an example of the 'notes' I was taking for sketching Mars last year. However, one isn't so worried about dark-adaption with planets. In fact, it makes it worse!

What the flip was going on with Vixen in 1991?