MalcolmM

9 hours ago, John said:

There was a thread about this last yea

I thought I got it last night, a small dark spot, not well defined, on the top end of it. However, on reading the linked post above (thanks @John ), I suspect it was just an albedo marking.

Seeing was just ok, the moon was wobbling. I was using M180, Maxbrights with 1.25 GPC and Tak Abbe 18mm. Calculations would suggest this gives x150, but I'm never really sure when binoviewers and GPC are in the optical path!

Malcolm 

On 13/05/2024 at 08:19, Nik271 said:

I did not spot the vent on top of the omega dome, with a 100mm instrument I was not really expecting it. I wonder has anybody seen it visually and what aperture was needed?

According to "Discover The Moon" Gruithuisen Gamma is a circular dome, 20km across, with a 2 km diameter vent. They say it should be visible in a 150mm scope. I'm going to try tonight with the Mewlon if the seeing is any good.

Malcolm 

4 hours ago, Deadlake said:

Mewlons are not meant to good  near the coast due too sea salt carried in shore on the wind.

Now you tell me! Maybe that explains the hairy stars 🙂

Malcolm 

That's a fantastic picture. It really looks like your in a spaceship in a low lunar orbit!

Malcolm 

7 hours ago, JeremyS said:

Hang on a mo. I think myths are being perpetuated. Well have the one about them being difficult to collimate next. 😊

Mewlons aren’t that difficult. In UK the temperature swings aren’t that difficult to acclimate to. I’m a refractor man, but the Mewlons are great (if you don’t mind diffraction spikes). The resolution on planets with my M210 is significantly greater than with my Tak TSA 120.

Agree wholeheartedly! In my case, the views in the 180C are significantly better than the 100DC.

Malcolm 

6 hours ago, Doctor D said:

No worries, you don't need to convince me about Mewlon's. I love them and post on them all the time on CN, particularly the baffles. These are just a few of countless threads I have on them.

https://www.cloudynights.com/topic/894095-a-night-with-the-mewlon-180/

https://www.cloudynights.com/topic/466960-takitis/page-56

https://www.cloudynights.com/topic/920928-mewlon-250-just-acquired/#entry13425968

 

 

Very interesting video, thanks for posting. 

Malcolm 

Great report, and it provides me motivation to keep trying! I was looking last night in pretty good seeing with a Mewlon 180C but despite seeing the dark and light walls of the valley, I could not see the rille. In my limited experience, the correct angle of illumination is critical for these sort of features. I'm hoping with just the right illumination, the 180C is good enough to resolve the rille. I'll certainly keep trying. 

Malcolm 

9 hours ago, MalcolmM said:

I suspect the scope simply hadn't cooled enough

Thinking about it overnight, I now suspect my original problem was seeing, not cool down.

@John, I've mostly used my Mewlon for deep sky in the last 6 months, so have not been aware of cool down times, but before that, when using it on planets and the moon, I would agree with @JeremyS. When acclimatising in a plastic box before hand, I would get fantastic views (in my opinion!) in less than an hour.

@dweller25 uses active cooling to help acclimatise. 

Apart from my wobble which caused me to start this thread, I have had nothing but enjoyment from my Mewlon. I can't speak for the 210, but the 180 is very portable and really easy to set up. The finder handle is quite simply brilliant

Malcolm 

On 29/02/2024 at 07:42, dweller25 said:

@MalcolmM

I have the same two scopes as you and know how long the Mewlon takes to fully cool down, particularly when compared to the FC100.

I aid the Mewlon cooldown by resting a cooling fan with a USB powerbank on the front of the spider blowing air onto the primary and down the primary baffle and OPEN visual back.

Even with this active cooling it takes a good hour to fully cool the primary and primary baffle !

The fan solution is not expensive and works well.

 

Once fully cooled, to get the best out of the Mewlon it must be well collimated, I use this method - always making sure the star is perfectly central in the eyepiece before tweaking the collimation screws at x300, step 4 should be done at perfect focus.

 

Just to close the loop on this one ... I finally got some steady skies and had the Mewlon outside for 4 or 5 hours observing the moon as the sky got darker. Contrast and sharpness seemed very good so I tried a star test. No hairyness  and perfect airy disk and diffraction rings, just as the PERFECT example in @dweller25's diagram.

I suspect the scope simply hadn't cooled enough. Thanks again everyone for all the very helpful replies.

Couple of moon pics; phone just hand held at eyepiece (Maxbrights plus 1.25GPC plus Tak Abbe 18mm). Stupidly didn't take one of the star test!

Malcolm 

I have tried to spot the vents in domes with a 4" Refractor and failed. The Cauchy domes, and those around Milichius and Hortensius, as described in "Discover The Moon" by Jean Lacroux and Christian Legrand. They say the vents should be visible with 'a powerful telescope'. I'm not sure what that constitutes! I intend to give them a go with my Mewlon, if the clouds ever disappear!

Malcolm 

Those are very impressive rear ends

Malcolm 

1 hour ago, tomato said:

The most stressed astronomers I have ever encountered were some visual aficionados who had their carefully cultivated dark adaptation ruined by a stray light at a star party. I’ve never got that incensed no matter how many times my camera fails to connect.😉

Now don't start me on gratuitous garden lighting, blinding street lighting, local Inn with Christmas lights still going strong ... oh, and the neighbour's dog kicking off when it senses me, maybe I should take a shower first 

Malcolm 

16 hours ago, paulastro said:

Why not just buy a Seestar S50?

The polite reply is 'because I'm old fashioned'

Malcolm 

OK, so this a mixture of imaging and observational, but I am a visual observer and I was intending to do a good visual session. That, and my approach to imaging would probably offend the real imagers! It's also a lesson on how not to do astronomy 🙂 Laurel and Hardy could have done a better job!

A couple of days ago it was looking like it was going to be a clear moonless night. So under a blue clear afternoon sky, I thought I would do a double; try some imaging and visual at the same time. I generally take one picture a year. I do not do it seriously. So a rough polar alignment, an unmodified DSLR attached to the back of a scope, and fairly short subs does for me.

For the first time in ages, I was able to prepare, so I put the scopes out at sixish to cool, and had time to get the rig ready to take some pictures. I attached my camera to the back of my FS60CB, did a test focus on some distant trees and locked it. I attached all the bits, charged the camera and USB battery pack (for the mount), didn't think I needed to adjust the polar alignment from the last time, dec should be fine, just a rough tweak in RA. I preprogrammed the intervalvometer for 40 shots of 40 seconds. I was ready. All I had to do was point and click! I had taken a picture of Markarian's Chain a couple of years ago, only 20 second subs and where you could see most of the galaxies, I thought I could double the exposure and get more detail and more galaxies. Generally 20 seconds gives no appreciable drift with the rough polar aligning. The Mewlon was also out and cooling. I was going to star hop to Markarian's Chain and see how much I could see. To this end I had created a crib sheet on my phone in order to help me star hop there, and provide a 'tour' of the area.

I was ready! Or so I thought!

I went out at 10ish thinking an hour or so should do it before coming back in and getting into bed before my partner fell asleep (she had her first day back at work after Easter the next day). First off, rough polar alignment. It was miles off, I couldn't see Polaris, all I could see was the wall of the house. Ah, the scope was too low to see over the house. I'll just move it a couple of feet. Move the tripod, that's better, now I can eyeball Polaris. Still way off though. Then I remembered I had sent the mount back for tightening up a bit of backlash and had had to adjust it way down to fit the packaging. So much for my preparation. However, no bother, a few turns on the dec screw and we're in business.

So far so good. Now to adjust the focus. To do this, I point at a dim star, turn on the LCD on the back of the camera and zoom right in. I then simply try to minimise the size of the star in the LCD. This goes well, so now try to find Markarian's Chain. It is in a fairy blank part of the sky so even with the finder, in my light polluted skies, it can be a bit tricky. Finder? What finder? In all my preparations I had forgotten to attach the finder (normally the 60CB plus a 28mm Erfle has no need for a finder and it makes the scope even more portable than it already is). So back inside, rummaging around all the bits trying to find the finder, the correct screws, and the correct size allen key. Thankfully my partner is still reading, she's not asleep yet!

Only by the grace of God did I not loose one of the screws down a drain. It dropped, it rolled, and it stopped 1cm short of ruining my evening totally. With the finder attached, it needed to be aligned now. "Bother", or words to that effect! Back inside, rummaging around for micro screwdriver, partner still reading (thank goodness), no she's not, she's fallen asleep, book in hand, light still on. Or she was untill I tripped into the coffee table! It's going well! So much for my preparation!

Back to finding Markarian's chain. I'm using my phone crib sheet and the finder to try and work from Vindemiatrix. Upside down and left to right, you just gotta love star hopping. I get to a blank bit of sky in the finder that I think might be close and I'm sure to recognise some of the star shapes from the crib sheet. A quick 10 second exposure and ... nothing. Not one star! Lens cap definitely off, intervalvometer definitely set for 40 seconds (and I interrupt it after 10). Try again a couple of times before remembering Einstein's famous quote and start to think what else might be wrong. Eventually I remembered the 'bulb' setting on the camera. So much for my prearation! A 1/1000 second exposure might just be a little to quick.

A lot of fiddling later and I was pointing at the right place. I think! My crib sheet seems to bear no resemblace to what I'm seeing. Very little is visible with a 10 second shot. So I give it 40 seconds and wow ... enormous star trails. Is the mount on? Has the polar alignment shifted? Everything looked OK. Maybe 40 seconds was just too much; I had never taken such long exposures before. I'm getting fed up (as you, the reader, probably is too!) so I go back to 20 second subs and just let it go. I want to do some visual observing.

I start at Denebola and hop across to M65 and M66. It's at this point I remember I usually have the 60CB dual mounted with the Mewlon and use it, with a 28mm Erfle as a finder. So much easier than straight through viewing and dealing with upside down as well as left to right! But the 60CB is taking pictures! Call me vain, but I will not alter the beautiful lines of the Mewlon, so it's down on hands and knees and squinting through the otherwise excellent finder - I'm too tired to raise the tripod and besides, a bit of Mewlon worship is no bad thing 🙂 M65 and M66 are easy in the Mewlon. I can see the different shapes, M65 being thinner and M66 possibly looks a little lumpy. I can also, with averted vision, just occasionally see a smudge where NGC3628 sits between the 2 stars of the upright of a 'T' asterism. I can even sense the plane of the galaxy is perpendicular to the upright, so it's a definite sighting. I can see all three in the same FOV and in the moments when I can see NGC3628, it's a very immersive view.

I then roughly point the scope half way between Theta Leonis and Regulus and look for 52 Leonis. From there it's an easy hop down to M95, 96 and 105. I can fit M95 and M96 into the same FOV, but need to pan to see M105. All are just appearing as misty orbs, no structure.

A quick look at M81 and M82 as they are easy and I'm getting cold and I'm concious I'm going to awaken my partner when I go in. A very obvious difference in shape between the two and a lumpy appearnce to M82. These two fit in the same FOV (32mm 85 degree Masuyama) and there is something humbling about seeing multiple galaxies in the same FOV and ponder on the sheer scale of what you are looking at. I never did get to Markarian's Chain.

The imaging is still going but I cut it short as it's now one in the morning! My one hour has turned into three. Pack everything away, bring it inside, knock the door rims with the tripods, wake my partner, fill a hot water bottle, go to bed wondering how the images will look. Can't sleep so get up to look at the images on a laptop. They're awfull. Big star trails. Something's badly wrong. A total wash out. Back to bed and thinking what might be wrong. I come to the conclusion that there must be some setting in the handset that is wrong. Lunar rather than sidereal tracking, though I didn't think there was such a dramatic difference.

The next day I went through all the menu options on the handset. Turned out that the tracking speed can be set to be loads too fast or too slow. I can't think why you might want this option, but it's there. Again, so much for my preparation!

I need to try again some night. I want to know if rough alignment will allow me to take 40 second subs. But, in reality, the attempted imaging just got in the way of a good night's observing 🙂

If you've got this far, thanks for reading!
Malcolm

15 hours ago, Nicola Fletcher said:

My new Mewlon 180C double mounted with an FC100DZ on an AZ-EQ5. I’m still not sure if I like this mount. I’ve started using it in tracking only mode rather than GoTo which is better. The very quick session with the Mewlon was fantastic though - barely first light as the clouds rolled in but M42 and the Pleiades looked fantastic, and the double cluster with the 41mm Panoptic was the best view I’ve ever had of this target. I’m looking forward to getting to know this beautiful scope a lot better!

Fabulous!

Malcolm 

8 hours ago, Epick Crom said:

NGC 2362

This is the one marked C64 in my crib sheet. I was actually looking at this when I knocked the tripod which brought the double into view! It was a lovely cluster despite the brightish sky.

8 hours ago, Epick Crom said:

continue to enjoy observing

I went out the next night to try and actually record my observations but a thin high hazy cloud prevented me being able to find half of them, and the half I could see were just smudges! 

Have you managed to see the little planetary embedded in M46 @Epick Crom?

Malcolm 

48 minutes ago, josefk said:

Lux finder 🙂 

 

Actually more seriously - i bet that was quite a nice combo for two different perspectives. I have the capability to dual mount but i hardly ever do it in reality - it can be a faff to manage two scopes versus the dew for one thing. 

Roll on spring!

 

Yes, it is a very extravagant finder

But it is nice, giving a different perspective on what you are seeing, and I couldn't bear adding a botch to the Mewlon in order to create a right angled finder!

Should have added in the report that I got all the targets except for C54. I tried star hopping to it from every which way, but I failed to catch it.

Malcolm 

Spent an evening looking at clusters in Canis Major and Pupis, also taking in Hind's Crimson Star which really is a beautiful sight in a scope. 

I don't often look at this region as it's low, and also plagued by a bright sky glow from industrial lights!

However, it's quite rich in some lovely clusters, and purely by chance, having accidentally kicked the tripod while looking at C64, discovered a beautiful double with a striking orange primary, and what looked like a grey/white secondary. A bit of research identified this to be 145 Canis Majoris or 'The Albireo of Winter'. A first for me, and one I'll keep going back to!

Many of the clusters show lots of stars with that mottled haze in the background that hints of many more stars, just out of range. I would love to observe these objects from a darker site.

Here's my crib sheet cobbled together from resources online plus my observation of Hind's Crimson Star. 

FS60CB as a finder, dual mounted with a Mewlon 180C on a Giro Ercole on an Innorel tripod. 28mm Tak Erfle in the 60CB and a 32mm 85° Masuyama in the Mewlon.

Malcolm 

20 hours ago, JeremyS said:

That’s odd about bending. I’ve never experienced that on my TSA 120 (or FS 100DZ). I wonder if the focuser itself was too tight (can be user adjusted).

I have noticed the spongy feeling, but only when I've had the draw tube clamp tightened and forgotten to loosen it! So what @JeremyS says seems very possible to me.

Malcolm 

6 hours ago, Gfamily said:

I don't know whether you are familiar with the Irish National Inventory of Historic Scientific Instruments which is available as a PDF from Google Books - it has a list of Grubb telescopes amongst other items

https://www.google.com/books/edition/Irish_National_Inventory_of_Historic_Sci/vwXPDwAAQBAJ

It might be useful if you've not seen it before. 

No, I have not seen that before thanks. My supervisor may well have seen it, and I've been going off a list from Ian Glass's book about the Grubbs. I'll certainly check that out. Thanks again, 

Malcolm 

3 hours ago, JeremyS said:

Is that Armagh Obsy, Malcolm?

That's correct @JeremyS. They have a number of beautiful old medium sized scopes, but the Grubb refractor is the nicest by far

Malcolm 

I'm currently co-authoring a paper on the Armagh 10" Grubb refractor. As part of our research we are trying to find out about other Grubb Standard Equatorials of 8" to 15". Are they still in use? Did they do scientific work?

There are a number of these still in use around the world, a testament to their longevity and craftsmanship.

Is anyone able to share any information on Grubb Standard Equatorials? Particularly around whether they are still in use and have done any scientific research?

I've posted these pictures before, but here they are again, just because it is such a lovely instrument!

Many thanks, 

Malcolm 

42 minutes ago, The60mmKid said:

but will still provide nice lower-magnification views

I think this is why I have not paid much attention to collimation to date. I mostly use the Mewlon for low(ish) power DSO and open clusters. I did a star test very early on and reckoned (to my inexperienced eyes) it was spot on, and never questioned it further. I have only recently started looking at double stars!

Malcolm 

1 hour ago, dweller25 said:

@MalcolmM

Took the M180 out of the house at 5:40pm, started the fan running on the front and left it until 6:10pm.

Looked at Jupiter at x178 and it was ok but not super sharp,  could make out the GRS and several bands but a bit soft. Jupiters moons were trying to show an airy disk but it was not steady. 

Turned the scope onto Bellatrix and defocussed a little, the outer ring shows small protruding spikes - this could be the hairiness you see ?

The scope had clearly not cooled down.

But there was no lateral air movement across the out of focus image - so seeing was good.

Fan put back on and waited until 6:30pm.

Back onto Jupiter at x178, much better views and the moons were showing airy disks.

Back onto Bellatrix and that was much better too, the outer ring showing much more stability and slight spikes/hairs. In focus showed perfect collimation then slight mis collimation - scope still not cool.

Fan back on until 6:45pm, back onto Bellatrix and it was almost stable at x178, very slight spikes when defocussed and perfect collimation.

Fan back on until 7:05pm, back onto Bellatrix at x178 - stable.

Turned the scope onto Al Kab at x321, stable, no spikes, perfect airy disk, good seeing.

So even with active cooling it took 1 hour and 25mins to cool from the house !

BUT - an obstructed telescope will never quite match a refractor for sharpness 👍

Hope that helps.

 

 

That's a very helpful post. Thanks @dweller25

Malcolm 

On 15/02/2024 at 09:01, Gfamily said:

If people are looking for a 'step up' book from TLAO, I can suggest the Illustrated Guide to Astronomical Wonders. It only covers constellations visible from the Northern Hemisphere, but it has a wide range of targets, and a lot of useful information.

Google Books preview available

https://books.google.com/books/about/Illustrated_Guide_to_Astronomical_Wonder.html?id=ymt9nj_uPhwC#v=onepage&q&f=false

Great tip thanks @Gfamily

Arrived a few days ago and looks excellent!

Malcolm