globular

I found this online... I've been observing Jupiter at about 20° (or 70° Zenith Distance) so I should be seeing something like 5 arcsecond separation between red and blue. And in my 8" that should be pretty noticeable..... shouldn't it? Same goes you for @markse68 I guess?..... a year ago Jupiter was around 13° wasn't it..... so maybe 7 or 8 arcsecond separation of red and blue. Does that extra 2 or 3 really make all the difference between needing ADC and not? Maybe the UK has a much more back-ended curve than Mauna Kea? 🤔

I'm using an 8" EdgeHD and have been actively looking for AD on the planets the last few sessions. Maybe I've just never looked "low" enough?... I don't have a great horizon (trees not houses) so they have to be 15° or so for me to pick them up. Jupiter has been very stable and I've picked out all sorts of greys, browns, creams, tans etc... so I'm seeing colour just not "bad" colour. I'll try Antares next clear night.... but I'll have to jiggle things to be able to see it... it's a bit too low.... so maybe this is the answer.... my horizon is high enough for my aperture not to be impacted by AD... ?

Hope it's ok if I tag on to this old(ish) thread... I've read it all with interest.... and I'm keen to tap into the expertise of ADC users and AD sceptics alike. My understanding of AD is that it is caused by different wavelengths of light being refracted by different amounts by The Earths atmosphere.... so all the wavelengths don't fully converge in a telescope.... and you get colour distortions (and possibly softer images too?). And the lower in the sky the object being observed is, the more atmosphere the light passes through, so the more AD will be present. And my understanding is that an ADC contains 2 prisms that can be rotated relative to each other and, when set correctly, they refract the light back into line.... correcting the colour distortions (and sharpening the image). Now I'm happy with the physics of all of this.... and would happily get an ADC to correct AD..... but so far in my observing I'd don't ever recall seeing the issue. Why aren't I seeing it? I'm not complaining or anything.... but surely I should be seeing this phenomenon as it is atmospheric.... and I look through the same atmosphere as everyone else. This thread is full of people who see AD and benefit from an ADC and others who don't. I don't like not knowing why there is this different experience.... it's a gap in my understanding.... and I don't like gaps. Can anyone explain what's going on?

Lots of different data sources and models..... seem to suggest a clear night for you..... But seeing and / or jet stream might not be the best... ... although the model used for that also has high cloud.... so might be more pessimistic than the others.

18" in a dark site must be wonderful. It certainly allows you to pick out some lovely detail in your sketches.

Just for completeness, I got it off All I needed to add was just a small amount of..... confidence. I now have a shorter barrel added which is still gripped nice and firmly and squarely by my ultrashort clamp... but with a shorter overall light path. Sorted.

Get well soon..... for the goodness of your health wealth

I've been getting so few clear nights and have so much stuff I'm keen to observe that I keep forgetting to hunt this down. Last night, though, I found myself at M52 (which presented itself rather well), remembered John's typo (above) and went looking for the nova. It wasn't as red as I was expecting but I was pretty sure I had it from the faint redness... later confirmed from maps earlier in this thread. I'm not experienced at magnitude estimation but based on neighbouring stars I put it at 7. I now have 1 nova in my nova observation list. ✅😀

I didn’t go that route because I don’t want to have to screw on and off different configurations. Instead I’ve gone for a custom visual back that has a 2” nosepiece clamp (with compression ring and 3x 120 degree offset thumb screws for solid centered clamping) but with only a 21mm light path. This means I need to replace the current 27mm barrel on this diagonal with a 21mm one. Hence needing the old one off. I can then easily switch between my 2” diagonal for cyclops viewing or T2 diagonal + binoviewers… all while keeping the light path as close as possible to the optional one for the telescope. (bang on (F10.5) for cyclops and only a little worse than YKSE for binoviewing… but with more convienience. YKSE got F10.9 with his binoviewers and lock ring and I’ll get F11.0 (without GPC) …. if they ever arrive)

Sounds like yours has the same connections as mine, but is a slightly different model. Baader have lots of similar looking stuff but they all have different # numbers. The barrels on my other diagonals screws on and off easily enough.. just nice and stiff… nothing too tight. I’ve had filters (M48 thread) that sometimes seem to jam… but a change of temperature or a light tap tends to free them…. it’s important to try and apply even pressure around the barrel so as not to distort it as you twist. But the barrel on this diagonal (2” SC thread) feels so firm, and is not responding to my usual persuasion, that it feels like it’s glued or fixed with a screw somewhere. I know it shouldn’t be… because this particular model has all sorts of connection options on baader’s website… but I wanted to check with the knowledge bank here at SGL before I attempted anything that may break this rather expensive item.

Thanks @jetstream….So it just unscrews….I’m not going to break some hidden fastening….? I’ll give it some welly tomorrow then.

Hi All, I'm looking for some help with my Baader 2" Prism Diagonal (#2456117). It looks like this: And from Baader's website I know it can look like this: But for the life of me I can't unscrew the barrel. Is there a 'trick' to getting it off? A hidden locking grub screw somewhere perhaps? Or do I just need to be braver and really go for it? Thanks in advance

awww don't spoil it with practicalities 😁

Do you mean these: https://neilross758.wixsite.com/cygnus-astro-covers/breathable-covers

I think he typoed M52 as M57.... must be dartmoor jet lag.

I've had some lovely "wow" views of the Heart Nebula with my DGM NPB filter (similar to UHC) when exit pupil is large (>3mm). Without the filter, with smaller exit pupil or with poor viewing conditions and I can't make out the nebulosity. So keep trying in the darkest conditions you can, with well dark adapted eyes, a nice low mag / large exit pupil eyepiece and your UHC in place. If you have an OIII it's worth trying that too... especially if you have a lot of light pollution as this filter darkens the sky more than a UHC. There is bright, faint and dark nebulosity to be found here. I like it a lot.

Fair enough. Was worth checking. I'm out of ideas. It seems to me that starsense is working fine in terms of capturing stars and platesolving.... but isnt controlling your telescopes Ra and Dec correctly. Hope someone else turns up to sort you out.

And you aligned the mount (not the telescope) roughly north?

Actually sticking with this a bit longer.... you say you "levelled mount" and "pointed the scope at polaris"?? With an EQ mount you need to set the inclination to match the degrees at your location.... not "level". If yours is not set to the correct angle then this too will result in the telescope pointing in odd directions.

Perhaps not then. I suggested it because it sounds like it is plate solving and finding the right position.... but is sending the wrong movement commands (e.g. alt az rather than ra dec).... so it's not slewing to correctly. Presumably you have tried a factory reset? Worth a go if not.

I control mine with Skysafari on my iPad so I'm not sure how you do it on the hand controller. Maybe check that you can get to some of the RA only settings?.... like these....

Your avx is an equatorial mount. Starsense can be set in Eq or Alt-az.... have you made sure it's on the right one?

It seemed to go on forever... then curve round... hence ending up at the triangle. Maybe it was averted imagination as John calls it 🤣

Ok so I was viewing it last night. I'll have to go back and have another look.... there was some popping nebulosity but I didn't think "tube"... funnily enough I though "Mr Messy". (In structure not shape).

Do you mean one of "a" or "b"? I followed "c" and then got distracted by "d".