Sydney Observatory needs your help.

[netwolf]

Thanks Barry, I understand now.

Now the question is what modern scopes are better for Visual astronomy. The CDK and RCOS are built more for Imaging than Visual use, though they can be used visually. I have never looked through one, so cant comment. But it seems this is what is commercially available.

The alternative is to buy a Fork Equatorial mount like the MI-750 and reuse the 16" Meade OTA. Then later perhaps upgrade the OTA with something better.

MI offer 3 goto systems, Sitech, AP GTO3 and Bisuqe TCS. While I like the Sitech, i think the AP GTO system looks like the simplest to use standalone without computer. Or you could use Sitech or Bisque with SkyFI and a Skysafari on a Tablet to control it.

[rogerco (Roger)]

Private reply? What is so secret? What is the answer to the suggestion that the electronics could be re-engineered. I find it strange that an electronic circuit couldn't be designed for less than the tens of thousands that a Planewave would cost.

[Wavytone]

Probably easier to take a set of electronics made for a smaller scope (eg. the SkyWatcher Synscan) and make an interface to drive a larger mount with higher powered motors etc - or interface to an iPad/PC and forget about handsets.

Regarding sources of larger RC scopes, Planewave aren't the only ones - there's APM in Germany (Markus Ludes) making f/9 cassegrains 40-60 cm aperture with altaz fork mounts.

[netwolf]

Roger, no secret as Barry has already mentioned the electronics are quiet old. While the engineer in me thinks yes we can patch up a solution and go, we must also consider the commercial nature of this. Consider the Windows OS, sure MS could continue to Patch XP and keep it going but at some point one must just consider an overhaul to a new OS. While we may with some work be able to patch the Servo motors and make them work with a different control system, there is the question of ongoing maintenance and availability of parts. A new system whatever is decided will come with warranty and spare parts availability.
A new mount at the very least would make a more reliable system to maintain and upkeep.
From what I have googled up even those who have jerry rigged new controllers have had to tweak the motor's and encoder electronics to work with the new control systems. Eventually these electronics and motors will wear out and need replacement again. While for private use this would be no issue and Barry and I agree if it were our scope that is what we would do. But this is a Observatory that would like at the foremost reliability and up time for its many visitors. For private use we can live with some downtime, but in a commercial setting that does not work well.

Some times young over zealous engineers can learn much from the wisdom of our elders. Especially those who have actually spent a lot of time repairing such systems.
Thanks Barry.

[Barrykgerdes]

Originally Posted by rogerco

Private reply? What is so secret? What is the answer to the suggestion that the electronics could be re-engineered. I find it strange that an electronic circuit couldn't be designed for less than the tens of thousands that a Planewave would cost.

PM in this case was Phone Message to a personal friend, Fahim, and I had a long general phone conversation about some engineering work I did for him and included general information on Meade electronics that I had already spoke of in this thread.

In regard to re-engineering we are talking of a commercial decision for a one off design. I would estimate the cost in this case at well over $100000.

This thread has gone so far off geoff's original request that was for a chance to look at some potential replacements that it is hard to see what the argued suggestions have to do with the original thread topic. A commercial decision to replace the telescope has already been made.

Mark (satchmo) quite rightly started a new thread on the merits of the different telescope types for CCD viewing etc for open discussion.

Barry

[Wavytone]

There is more to this than many here suspect:

a) There are huge questions about long-term life, maintainability and supportability. An observatory instrument really is expected to last for many decades with minimal maintenance, and maintenance than can be done locally - if there are crucial proprietary bits dependent on a foreign supplier that isn't going to be around for a long time, forget it.

Commercial electronics don't last long. Even commercial telescopes don't last long - take a look at the condition of the 16" Meade, and then think about how long old clockwork museum-pieces have served, such as the 9" Oddie at Stromlo before it was destroyed by fire. And ask yourself why people will pay huge sums for classic antique old refractors in working condition. The only modern commercial scopes that look like lasting many decades are Questars, and some of you wonder why people pay the price for these.

And for something really scary, go take a look a Porter Garden Telescope in good working condition (its just a 6" Newtonian, after all) - serial #3 in working condition http://www.considine.net/mac/pgt/ sold for over $18,000 a few years ago, and a modern homage (ie reproduction) faithful to it was made recently in a small batch - they went for $59,000 http://www.astrosurf.com/re/unusual_...ell_porter.pdf

Mitigating obsolescence is thus a very real problem.

b) Aesthetics. Most people expect to see a big, impressive piece of equipment which justifies the 6-figure price paid by the taxpayer (and the astronomers salary) - and with an eyepiece at the back end, something you swing at the target.

They don't expect to see a bunch of flimsy sticks that look like an overgrown bagpipe, with a mirror you mustn't sneeze at, and an eyepiece in the "wrong place" (Dobs).

c) It has to be visual. As any who have done public viewing nights, people will PAY to actually look at Jupiter through a big, impressive telescope while standing in the dark. They WILL NOT pay to watch a video or look at photos that may as well be from Youtube, or a book.

I am quite sure almost ALL OF YOU would leap at the chance to look at Jupiter visually through a big scope on a nice night.

It's no different with my paragliding hobby - people will pay $600-700 per hour to experience a tandem flight, despite most tandem flights being a boring trip to the beach below, yet most have never watched helmet videos on Youtube - even in HD and 3D it's just not the same as DOING it.

d) Visual also means it has to be safe and convenient for the public to use, in the dark. For anything bigger than the Meade 16" this virtually forces the solution to be an altaz mount, and a fork.

For any solution a human-factors study is needed, to:

- identify how the telescope is used,
- ensure a wide range of people (male and female) of varying heights and physical abilities can use it without injury,
- ensure those with disabilities can use it, within reason; and
- conduct a safety-hazard analysis to identify risks and mitigate them.

e) Maintainability and access. If it is permanently mounted it has to fit into the building, physically and structurally, and consideration given to removing major parts for maintenance (not just the optics).

With respect to the above, by way of example consider the replacement for the Oddie at Mt Stromlo - even though it long ceased to be much use at the academic level as a teaching instrument, the observatory is replacing it with a beautiful refractor, although the optics are modern it remains faithful to what the public expects of a museum-piece. And it happens to work, ie you CAN look through it.

[Barrykgerdes]

There are many references in this thread about refurbishing the Meade 16" LX200 classic. This is impractical and if you know these telescopes you will know why.

I have worked on the electronics and mechanics of the 16" LX200 and they bear little resemblance to the smaller LX200's or any of the other GOTO telescopes. I have had access to parts and maintenance data that is not available to the home maintainer, particularly replacement motherboards that have in themselves been faulty. The electronics has been upgraded a number of times to address "bugs" and the maintenance instructions are only basic. Many critical parts were over rated for the job and do not have replacements. Continued repair is just not an option.

Barry

[ausastronomer (John Bambury)]

I seriously think there is a lot of money being aimed in the wrong direction here.

The telescopes under discussion namely Planewave DK and various RC's are imaging instruments and not the greatest for visual use, for a number of reasons based on the physics of their design.

The whole purpose is partly self defeating when one considers the prevailing sky conditions, making lunar, planetary and double stars the targets of choice. For these targets a scope like a 6" or 7" Maksutov housed in the dome would give far better visual lunar planetary views than these photographic instruments you are considering. I was in Sydney about 15 years ago one Friday night and I took my wife up there to show her the Observatory. I remember looking at Saturn through that 16" LX200, which was pretty new at the time and I can tell you the view was downright poor. I didn't announce to anyone that I actually knew what I was looking at and the view was very poor, because that would have just spoiled the enjoyment of those people who didn't know what they were looking at. My thoughts at the time, which I kept to myself and my wife were, "why did they waste all that money on this POS, when a 7" Mak would eat it on lunar/planetary views", which is all the location is really capable of supporting.

One far less costly option may be to consider a much smaller telescope housed in the dome for lunar/planetary views and then a compact large aperture dob for use in the grounds on DSO's. eg a 20"/F3.3 which adults could use without a ladder and kids would only need a small step stool to use. I can appreciate that the dome helps with light pollution but the light pollution is such that the view of DSO's is going to be poor wherever you set up the telescopes.

If you must have a big telescope in the dome you could also consider the 16" Parks HIT series. This is a 16" F4 newtonian with an F15 Classical Cassegrain focus. You would only be able to use the Cassegrain focus for reasons already stated, but this will be a far better visual instrument than the Dall Kirkhams and Ritchey Chretians you are considering. Their is no free lunch. Unfortunately being a 16"/F15 telescope with a 6 metre focal length even an eyepiece like a 55mm Televue Plossl will give 110X. A 41mm Panoptic, which is as wide a FOV as you could get, will give 146X at about .46 degrees.

Cheers,
John B

[mental4astro (Alexander)]

Why isn't the current fork mounted Meade 16" being considered? The LX600. Yes there is the same problem of the electronics, but this will not change regardless of the solution. And as has been repeatedly mentioned, a bigger scope here is a step backwards.

The way things are going now with light pollution, it won't be long before mag 9 or even 8 will be near impossible to see. Yes, folks want to look through a scope - that goes without saying. But to give them a crappy view too isn't much chop either.

Yes, I'm on the outer here, but to offer ONLY visual without an adjunct of video in a no win situation, doesn't seem a good long term thing.

Please understand, I don't do astrophotography. I have no interest in it, I don't care for it. My intersest in astronomy is a purely visual one. But I do also care for giving novices a chance at seening something that would not be visible, and that's intelligable to them. Hmmm, are there even any eyepieces are Siding Springs?

Even if it is a piggybacked refractor (and it's a scope that novices will identify as a telescope) with a camera, it doesn't stop the visual component, but helps to also highlight the problem of light pollution too - that it isn't the scope or the objects in the sky that make for poor viewing. Like John said too, the current image is very poor because of conditions, and it won't improve with a larger instrument either, particularly one not optimised for visual use.

And I don't agree with the YouTube arguement. It's dismissive and shows little consideration for your target market. There's a distinct difference between a heavily processed image taken at a dark site to a live one from where ever you are.

If this is the way you want to do it, go for it, and I'll begrudgingly still suggest Observatory Hill to visitors. But, it's my tax money too that's being spent, so I do want to see it spent wisely, not on solutions that are not well considered. If nothing else, just NOT a larger scope that will make things worse from the very start.

[Wavytone]

All... many of you aren't listening to the simple needs Geoff has clearly stated and are instead leaping to push specific solutions that don't fit the needs and constraints that apply, by a wide margin.

The observatory is a functioning MUSEUM and IMHO we should all be quite grateful the Powerhouse museum considers it appropriate to open the observatory to the public at night and equipped with a working telescope OF ANY SORT.

Which is a lot more than can be said at Greenwich in London - the damned beancounters slashed the budget there so heavily it has NO functioning telescope at all, and has been renamed a "museum of time". The permanent exhibits have been reduced to little more than Harrison's clocks, a pathetic 3 metre GOTO portable plastic planetarium in one room, another room running a powerpoint slide-show and a gift shop that flogs badly made indian replica junk. As one who remembers what the museum used to have, it was such a shock that I had to apologise to my wife, having dragged her out to see Greenwich in appalling bad weather.

The philistines demolished the Paris observatory long ago, just a stone pillar remains in a park, rather like what's left of Parramatta observatory...

[Satchmo]

How about one of these ?

http://www.meade.com/max

$USD 35K ?


Put heavily padded vinyl sock/boot over the dec./ counterweight shaft to save anyone who bumps their head on it , and wrap the boot in red LED light strip turned down low so its presence is obvious....

[dannat (Daniel)]

to Alex & others - the observatory being a historc/museum type setting the telescope will be used as it would have been -via an observer looking thru the eyepiece;
same situation exists at Melbourne observatory -the general public come along to look thru the eyepiece, it adds to the exp. for them to look thru as once what an observer did, people seem happier to line up & wait a turn to look thru at saturn rather than watching it on the screen

GEoff do you have a pic of the observing rm so we can see what room there is available?
AT Melb obs we make people stay seated while we move the 8" frac on German EQ -the counterweights are substantial, & would surely knock you out if someone swung the scope quickly
in the other obs we use a 12" long f/l Newt - on a twin pier mount with steps for users to get up/down to the ep -the Newt also has a convenient rotating turret to get the ep in the best position

[mental4astro (Alexander)]

I get that. I really do. But without an alternative no matter the aperture you stretch things out to, the image quality will always be poor, and ultimately disappoint if humans eyes are the only tool used.

Look, it is only an alternative addition to the status quo I have put forward. But I still see no one arguing the case that one will actually see as much or more with the larger scopes originally proposed for Observatory Hill, and that they will be viable visual instruments long term.

As a die hard visual devotee of astronomy, it saddens me the situation faced at Observtory Hill. I don't care for C3PO telescope or R2D2 cameras. Nor have I mentioned any. I just want the best decision to be made with ALL alternatives given a fair hearing. Help was asked for, and it will come in many forms, and sometimes not the ones that are expected or originally considered.

All the best with Observatory Hill, Geoff. You are in one heck of a situation.

[gregbradley]

You'd be better off with a 6 to 8 inch APO than a compound scope.
Seeing is the issue with larger longer focal length scopes. Its all blurry.

My CDK17 is supposed to be good as a visual instrument. Mine is usually setup for imaging but I have looked through it two times. Yuck. Its all blurry from seeing issues. Lousy. Perhaps it would be good in great seeing at a dark site. Additionally the CDK are not well baffled (I think they may have corrected that now and they sent me a free baffle kit which I installed and have yet to test). As a result you often get light streaks from bright out of view stars. I also once had a 12.5 inch RCOS which has a large secondary obstruction (50%) and therefore optimised for imaging rather than visual - double yuck for visual. At least the CDK I have has a smallish secondary % (around 30-35%). (they recently changed the secondary mirror size to around 45% I think to make it better for imaging so even less suitable for visual with the 17 inch).

Whereas looking through a good 150 to 180mm APO - wow. APOs are known to cut through the seeing. Stars never look better than through a good APO. Next best would be a big dob but I imagine they need dark skies to excel.

For that observatory perhaps you should be looking for a nice largish APO. 6 inch APOs are often regarded as a sweet spot for APOs. But an APM 203mm might be nice. APO's probably cut through the light pollution better as well. You could put filters on the diagonal like a light pollution filter (well you could do that with any of them).

For compound scopes and visual you need a small secondary (30% say).

Takahashi Mewlons are often very highly regarded for visual as being the closest to a good APO. The Mewlon 300 is very highly regarded and is long focal length which may serve you well in bad light pollution.

So I would suggest looking for a nice big APO or a Takahashi Mewlon 300 for high impact visual.

There are many internet reviews of the Mewlon 300 and I think you'll find they are rave reviews about how great the views are. Its not great as an imaging instrument due to the small corrected circle and slow F ratio.

The best visual views I have had through many scopes have been:
1. TEC180 fluorite
2. Tak FS152
3. AP140
4. Big dobs at a dark site.
5. Celestron 11 inch go to.
Probably the FS152 had the biggest wow factor being a fluorite doublet and excellent contrast, the TEC180 is very good and the AP140 is quite a wide view but with unbleivably pinpoint stars. TEC140 hits above its aperture as well. Teh TEC180 and AP140 woul outresolve the FS152 though. I think due to the better colour correction and higher Strehl. Triplet is the way to go.

But don't expect to see galaxies from Observatory Hill unless its Cent A or Sculptor and that's about it.

Greg.

[ausastronomer (John Bambury)]

Originally Posted by gregbradley

You'd be better off with a 6 to 8 inch APO than a compound scope.
Greg.

Hi Greg,

I would agree with your recommendation of a 6" to 8" APO refractor as being telescopically the best option. However, I am not sure that the Dome configuration is conducive to using and mounting such a scope. I believe they have a need for a fork mounted scope.

Cheers,
John B

[gregbradley]

I see.

Is an APO unable to be mounted on the fork mounted scope? Is the problem how much of the scope sticks into the fork? In which case depending on how many mms that clearance is, they are limited to a scope that mostly sticks out the front with very little at the back like SCTs or CDKs.

As I say my CDK is not good for visual but that may be mostly due to the seeing not being up to handling a 3 metre focal length scope.
1200-1500mm may be the max for what the local seeing is likely to be.

Tak Mewlon may be the way to go then. I think there are a few with Mewlon 210's or 250's on this site that could comment.

Greg.

[Wavytone]

Greg,

I know of an 9" observatory refractor - and its for sale too - that fits that description - it has folded coude optics with a weighted OTA so that virtually none of it hangs below the dec axis, and the focus is brought out down the polar axis at desk height.

Ideal, in some respects.

The snag is, it's an old achromatic airspaced doublet, f/15 probably made in the 1960's from the look of the mount, so I'd bet its not coated either. The collective light losses from 4 mirrors and the uncoated doublet would be fairly bad so I didn't mention this before.

Adding a modern coated APO objective, rejigging the mirrors for a faster lens, and shortening the OTA would however blow the budget, I'm sure.

Marks suggestion re the 20" Meade Max is probably closer to the money BUT - and it's a big BUT - poses exactly the same issues as the 16" Meade does now - ie complex proprietary hardware and electronics that probably won't last 10 years - and the question of support is mighty interesting as Meade's future looks decidedly shaky. Perhaps ok for an amateur who will give it relatively light use and probably won't keep it 10 years, but its not a long term solution for observatory use.

In some respects this raises the question whether its actually cheaper over a long period - say 50+ years - to buy cheap amateur grade telescopes and consider them disposable, replacing them every 10 years to take advantage of the current technology, vs buying one considerably more expensive telescope that might last this kind of time frame.

[netwolf]

Maybe something like the one Deitmar uses 9" TMB
http://www.iceinspace.com.au/index.p...41,465,0,0,1,0
His images through this are amazing, also I think he uses a single Arm fork mount for this.

Actually for Visual why not a Folded Achromat might be fine.

[strongmanmike (Michael)]

Having worked at the Canberra Observatory as a public explainer for 10 years between 1985 and 1996, for me, if the dome configuration can support it than I am with Greg, something like an 8" refractor on a good mount (AstroPhysics, Takahashi, Paramount etc) would not only give the best and crispest views but also look impressive and classic. Like the Sydney Observatory, the Canberra Observatory was located in a very light polluted location. The Observatory had a 7" Starfire refractor riding piggyback on a wonderful Takahashi-like 16" F5/F16 Newtonian Cassegrain on a spectacular professional grade GEM. WE almost always used this scope in Newtonian focus but while the sight of the 16" impressed people when they walked in, in the end I simply stopped showing people through it as the views under light polluted skies were very disapointing and essentially a waste of time, many people after seeing such a beast when they walked in felt robbed. The 7" Starfire however gave wonderful rewarding views of the planets, double stars and even globs and planetaries and the handful of bright galaxies available looked good too, the scope could handle high powers too so it allowed for some pleasurable variations in the viewing sessions.

I also used the late 9" Oddie refractor at Mt Stomlo Observatory on many occasions as a young man and this gave far and above the overall best views of almost everything and was probably equivalent in wow factor to about a well collimated 20" Dob. It had some focal length and just delivered in spades.

I always imagined had I ever been in the position to equip a public observatory... with a decent budget at my disposal I would have gone with the largest APO refractor (on an appropriately solid mount), that the budget would allow, 8" to 10" (or larger) if possible

Cheers

Mike

[Wavytone]

Hehe... I remember that 16" well, Mike... it was at the back of the Tradies Club in Dickson.

When it opened I think half of CAS were wondering WTF ? while the other half were laughing at the waste of putting a telescope like that in that awful location. I walked away shaking my head in disbelief when it opened.

After restoring its predecessor (Colonel Oddie had a 4.5" Cooke first, on a very beautiful mount which was originally used to do the site survey leading to the selection of Stromlo for an observatory), subsequently I had its big brother (the 9" Oddie at Stromlo) to myself one night a week, for several years before you. Both were great examples of what a refractor could do, and it is little wonder it is being replaced with a slightly smaller and faster APO.

The trouble is, nobody makes 'scopes like that as a "commercial off-the-shelf" item - they're all one-offs built to order. Even in Oddies day.