Has anyone here been to a demonstration of the 28" refractor at the Royal Grenwich Obervatory?

[pipnina]

I went to the observatory in 2018 as part of a kent/london holiday, and while my horrible vertigo on that hill prevented me from seeing the monster of a scope at the top (unusual I know, but these days I've been climbing cranes so if I go again, it should be no issue), I knew that in winter months they do still provide demonstrations visually and with a CCD.

Being such a monster of a refractor, I can only imagine the views in the center of field would be very good, but also very very limited in terms of off-axis quality given the era of design. I havent been able to find any of the images taken with the scope however, despite the scope's original purpose being for photography!

Has anyone here been fortunate enough to visit the scope when demonstrations and viewings were on offer?

[mikeDnight]

I haven't seen through the 28" but I've no doubt it will be absolutely stunning both on and off axis. How it performs visually off axis will largely be determined by the quality of the eyepiece used. Being made by Grubb, it would have been state of the art at its making and will still perform as a world class refractor. I'd swap my Tak DZ in a heartbeat in exchange for the 28" if it had a carry handle.😅

[Franklin]

11 minutes ago, mikeDnight said:

I'd swap my Tak DZ in a heartbeat in exchange for the 28" if it had a carry handle.😅

You'd have to build a slightly bigger observatory.

I was shown around the 28" refractor back in 1979 though I never actually looked through it. It was a tour of the observatory, Patrick Moore and Heather Cooper were there, I was just a kid.

[Franklin]

Actually, Gerald North speaks in his books about his use of this telescope and I seem to remember him mentioning about stopping it down to help with the CA.

[pipnina]

6 minutes ago, Franklin said:

Actually, Gerald North speaks in his books about his use of this telescope and I seem to remember him mentioning about stopping it down to help with the CA.

Yes I would expect it probably does suffer from CA quite badly, we really take our modern specialised glass types and curves and magics for granted! I don't think that scope will have had any fluorite lenses or asphericals!

[mikeDnight]

28 minutes ago, Franklin said:

Actually, Gerald North speaks in his books about his use of this telescope and I seem to remember him mentioning about stopping it down to help with the CA.

Same as the 24" Clarke at Mars Hill. It has been stopped down at times to ease the CA, but it was made to fit the pre existing dome and not the dome made to fit the telescope. CA or not, I'd swap the 24" Clarke for my DZ too.

 

36 minutes ago, Franklin said:

You'd have to build a slightly bigger observatory.

Do you think my owner will notice the difference? I can hear her now, - "How did you smuggle that into the garden?"  Me - "Oh, that's been there for ages. I won it in a raffle at Kettering". 🥊

[markse68]

I went a couple of times last year but it's closed for a while as they're refurbishing the dome I think. We didn't have good weather either time and were lucky to find a few gaps in the clouds. They showed us some crowd pleasers like Albireo and M1 but I really tried to get them to point it some tight doubles- maybe later this year  Albireo was very colourful- possibly aided by the CA haha.

The light pollution is so bad even with that aperture it'll struggle with fainter objects I think- M1 was just a grey blur.

Interestingly as well as being 28" aperture, it apparently weighs 28 tonnes! I think they must have used some seriously thick steel for the OTA! The lenses were designed to be reconfigured by flipping one element and altering the spacing to switch between photographic and observing modes, though at about 100Kg that wouldn't be something you wanted to do regularly! They told me the lenses haven't been cleaned in years so are probably in dire need of a clean but that apparently wasn't scheduled for this round of refurbishment. 

Mark

[pipnina]

44 minutes ago, markse68 said:

I went a couple of times last year but it's closed for a while as they're refurbishing the dome I think. We didn't have good weather either time and were lucky to find a few gaps in the clouds. They showed us some crowd pleasers like Albireo and M1 but I really tried to get them to point it some tight doubles- maybe later this year  Albireo was very colourful- possibly aided by the CA haha.

The light pollution is so bad even with that aperture it'll struggle with fainter objects I think- M1 was just a grey blur.

Interestingly as well as being 28" aperture, it apparently weighs 28 tonnes! I think they must have used some seriously thick steel for the OTA! The lenses were designed to be reconfigured by flipping one element and altering the spacing to switch between photographic and observing modes, though at about 100Kg that wouldn't be something you wanted to do regularly! They told me the lenses haven't been cleaned in years so are probably in dire need of a clean but that apparently wasn't scheduled for this round of refurbishment. 

Mark

Oh yeah I bet that scope is a MONSTER double splitter!

At least when the atmosphere wants to behave

[Astrobits]

Many years ago ( mid 80's) I had the opportunity to view through the Innes Telescope in South Africa. This is a 26 1/2" refractor, also made by Grubb and is still operational afaik. It was a group viewing for the Johannesburg Center of ASSA of which I was a member. The telescope was made for observation and measurement of double stars and probably has as much CA as other refractors of the time. The view of Mars was definitely nothing to write home about, many of us were of the opinion that the 6" refractor ( another Grubb one I think) that we used regularly just a short walk up the hill provided just as good a view.

Nigel

[zcapp96]

I studied Astronomy and Physics at UCL in the late '90's and was lucky enough to use the radcliffe 24 inch refractor. It also features in the 'Look and read' BBC schools serial 'The Boy from space’ and also was the observatory that the scientists observe the alignment of the 3 stars that signify the second coming in 'The Omen 3'. It's a fantastic scope and so large that the whole floor has to be raised and lowered to enable you to see through it! 

[Space Hopper]

I remember paying a visit to Greenwich around 10 years ago with my astro society, and were shown round the 28" as a private party and had a detailed look at it.

I noticed it had a nice Feathertouch focuser on it, just like mine 😊

 

[markse68]

4 hours ago, Space Hopper said:

I remember paying a visit to Greenwich around 10 years ago with my astro society, and were shown round the 28" as a private party and had a detailed look at it.

I noticed it had a nice Feathertouch focuser on it, just like mine 😊

 

It’s huge! the biggest focuser I ever have ever seen anyway but i guess a huge telescope needs a huge focuser 

3.5”!

Mark

[Space Hopper]

Same focuser, but only about 1/5 the aperture.

And thankfully only 9kg, not 28 tonnes !! 😆

Seriously though, the 28" at ROG was amazing, and you appreciate the engineering that went in to it all those years ago.

 

[Ags]

On 21/04/2022 at 14:07, Astrobits said:

I had the opportunity to view through the Innes Telescope in South Africa.

I recall looking at Mars through the same telescope around that time! I thought the view was very impressive. I could see all the canals 🤣

[Hawksmoor]

Mrs H treated me to an evening tour and open-evening at the Royal Observatory Greenwich - I think in 1999. I was much impressed with the whole visit. Part of the tour was a walkthrough the large dome in which there was a very large refractor.  A big video screen had been set up showing the view via the scope of part of the Moon. It was quite a view!  I must say one of the most thrilling bits of the evening at the Royal Observatory was to walk through a room in which the likes of Sir Christopher Wren, Sir Isaac Newton, Samuel Pepys and Sir Robert Hooke at one time or another sat down to dine (pre-dates sandwiches and a thermos).

The only time I've viewed the Sun in H alpha through a scope was at the Stefanik Observatory in Prague. I was very pleased to see a prominence. It's amazing how some sights stick in the memory.

George.

[Chaz2b]

On 25/04/2022 at 09:04, Space Hopper said:

Same focuser, but only about 1/5 the aperture.

And thankfully only 9kg, not 28 tonnes !! 😆

Seriously though, the 28" at ROG was amazing, and you appreciate the engineering that went in to it all those years ago.

 

That is a beautiful bit of engineering, if the clouds appear…there’s that to admire!

[Johannes]

Hi I was there over 10 years ago with my son daughter and nephew. Saw the moon Jupiter and Saturn was amazed how good it was.