Sydney Observatory needs your help. - Page 2

mental4astro (Alexander) · #21 01-02-2013, 07:31 PM

No, not daft.

Satchmo · #22 01-02-2013, 07:35 PM

Quote:

Originally Posted by Bassnut

I think fancy ultra wide field Is daft too, a close look at the moon beats a bunch of bright high quality dots any day

Hi Fred
I know you are an astrophotographer- so you've got an association in your mind with fast f ratio = wide field ? just a reminder that visual magnification on any 'scope is controlled by the eyepiece . The range of eyepeices and amplifiers with long eye relief even in short focal length eyepieces, available now , mean that no configuration of telescope is limited in any way to achieve the full range of exit pupils/magnifications needed. Sky background brightness and observed detail in the image is a function of the magnification, and has nothing to do with the F ratio of the 'scope.

Bassnut (Fred) · #23 01-02-2013, 08:24 PM

Quote:

Originally Posted by mental4astro

No, not daft.

awe come on, looking in an eyepeice is a completely different experience, regardless of how crappy. If I turned up just to look at a friggen screen Id walk away disappointed. Its not about what im looking at in this case, its how (for the experience Geoff is on about).

Bassnut (Fred) · #24 01-02-2013, 08:26 PM

Quote:

Originally Posted by Satchmo

Hi Fred
I know you are an astrophotographer- so you've got an association in your mind with fast f ratio = wide field ? just a reminder that visual magnification on any 'scope is controlled by the eyepiece . The range of eyepeices and amplifiers with long eye relief even in short focal length eyepieces, available now , mean that no configuration of telescope is limited in any way to achieve the full range of exit pupils/magnifications needed. Sky background brightness and observed detail in the image is a function of the magnification, and has nothing to do with the F ratio of the 'scope.

OK, fair call, sorry about that, your right of course

mental4astro (Alexander) · #25 01-02-2013, 09:02 PM

Quote:

Originally Posted by Bassnut

awe come on, looking in an eyepeice is a completely different experience, regardless of how crappy. If I turned up just to look at a friggen screen Id walk away disappointed. Its not about what im looking at in this case, its how (for the experience Geoff is on about).

Good, you won't be casting a shadow on my doorway then.

You're now on my ignore list mate. I've never read anything constructive come from you. It had been a while since anything had come from you, and nothing's change, and I've had enough of it. See ya!

Barrykgerdes · #26 01-02-2013, 09:48 PM

The discussion is drifting into an argument again. Have any of you been to the observatory and seen the look on the faces of the younger set (and some oldies too) when they get to look in the eyepiece of an astronomical telescope and see craters on the Moon, the red spot on Jupiter and the rings of Saturn? They don't want a picture on the TV. They want to see the actual object through the telescope. Fred and Trevor know this, They have been there.

This is what it is all about. There are suitable telescopes that Geoff knows about that fulfil his requirements but he would like to see one in operation so he can set about obtaining one.

Barry

Poita (Peter) · #27 01-02-2013, 09:48 PM

Video astronomy could be a good adjunct to eyepiece use. The views are just as instant, far more satisfying and available to those with vision problems.

Quote:

Originally Posted by GOTO

Hello everyone,

Geoff from Sydney Observatory here. We presently use a 16inch Meade LX200 for our public tours. It is purely for visual use. We are looking for a larger replacement but there are a few issues:

1. We don't want a German fork mount because of counterweight arm risks, ie head-butting the weights in the darkened dome. So a fork mount is preferable.

2. We can't have a Newtonian due to the height of the eyepiece.

3. It can't be a custom made one off.

4. We want a turn key solution.

So, the only option so far, other than a new 16inch, looks like a 17-20inch Planewave on a Mathis Instrument mount. Yes we know these are imaging telescopes. Despite the short focal length and huge secondary we haven't found anything else with the eyepiece in the right position, a big aperture and on a fork mount.

However one significant issue. We haven't been able to LOOK through one yet! Does anyone here have access to a large Planewave that would be willing to let our management team LOOK through it please? We are willing to travel anywhere and would appreciate your help. You can contact me here or via email at geoffw@phm.gov.au

Conversely, if anyone has a brilliant different approach please don't be shy but remember we need the bigger aperture to try and get down to the bottom of Mag 10 from Sydney's CBD, it must be visual and we don't want to use a ladder.

Kind regards and thanks for your help.
Geoff

brian nordstrom (As avatar) · #28 01-02-2013, 10:14 PM

Spot on Alexander , when I lived in Whangarei NZ building the ANZAC Frigate's for the OZ and NZ navy's I was a hard core member of the Northland astro Society ( founding member. ) and with lots of hard work , grants , members , but over the years we watched 'light pollution'

encroach on the observatory from the expanding city .
Over there we have a CG14 on Losmandy Titan , 4 steps at eyepiece to clear the OB's walls for Joe , Jane amateure atronomer's ,,,
,, amateur astronomer's , are Safe . . And about this time the C11 that gets pressed into service as a Zoom Lense 2800mm long and played on the TV screen via a Meade 'Lunar Planetary ' , where 10-15 people will watch as they stand in line to see the real thing in the C14 ( if they are lucky , ) , Wets the appitite's .
And as has been said ,,
" Peaole aint stupid "

They pay their entrance fee and get a show .

ps. Because of the the light pollution in Whangarei , 2009 , the Northland society looked at a larger locally built Cassegrain, but we to discovered that the 6inch Saxon Mak and 100mm binos gave better views in the orange haze ..
They still have the C14 and C11,
I hear you Alex.

Keep the 16 inch OTA , and look into a few new mount designs that are out there . As been said .
Brian.

Quote:

Originally Posted by mental4astro

I disagree with you Trevor.

It comes down to actually seeing something in the middle of Sydney or not in this case.

But, you also flippantly mention YouTube. A couple of years back I volunteered to show the night sky to kids in NSW's only kids palliative hospital. I took my modest little C5 & my 17.5" dob, along with a modified webcam just on a hunch I had. I did not even assemble the dob that night. What that little webcam & C5 showed those no YouTube clip can replace. Those kids had no hope in hell of looking into an eyepiece. You tell those kids that they were ripped off when they saw Saturn come into view, the image shaking slowing coming to a standstill. Tell them they may as well look at a DVD when we were able to slew the camera to different parts of the moon. The thrill these kids had that night of actually seeing a scope, even a little C5, tell them to go see a YouTube clip. Tell them their experience was a fraudulent one. After what I experienced that night, I have never questioned the legitimacy, value & power of a video camera as useful tool in astronomy.

One's experience at a telescope is not cheapened if a camera is needed. Folks are smart enough to understand what a live image is. It is not ripping them of if this is the only way to show them a galaxy. As things stand now at Onservatory Hill, you have no chance in appreciating any galaxy, let lone the full expanse of M42, or even Omega Centauri to what it can really offer. To say otherwise is not understanding the situation of both the observatory & its night sky - this, coming from a die hard visual man.

A video camera also doesn't mean no direct viewing through the scope - the Moon & planets don't require a camera. But it makes all the difference in both seeing a DSO, AND appealing to the younger generations who best relate to a monitor than an eyepiece. It is easy to forget that a novice's eyes cannot see what we can!

Wavytone · #29 01-02-2013, 10:27 PM

Back to Geoffs original question...

I suggest that ultimately the problem to be faced is that beyond a C14 or the Meade 16", the only commercially produced large scopes are dobsonians. Anything else (cassegrain, etc) is a specialty made to order, so you can't just "go see one" and if you like it, buy another off-the-shelf.

GOTO (Geoff) · #30 01-02-2013, 11:19 PM

Hi all,

I really appreciate your ideas but please I did not wish to cause a fight. We have long given up on deep sky objects bar the few everyone here knows about.

Not long ago we (Powerhouse Museum) commissioned some market research and found one of the key reasons people come is to LOOK through a telescope.

My love of video astronomy led me to install a GSTAR-EX with a 300mm Nikon lens on the belly of the 16inch. The view of the two main globulars, open clusters, even the Moon and Sun was great imo but the public weren't interested. Each person wants to have his or her turn at the eyepiece. Don't forget we have a 3D theatre and planetarium to enhance the experience.

The dome walls do add a complicating factor and we are aware of the skyglow problem from the CBD. Our first government astronomer Reverend Scott knew it was not a good place to build an observatory but 155 years later we are stuck, somewhat happily I must say, as it is one of the most beautiful workplaces in the world. But I digress.

We looked into a Nasmyth without any luck and though we do have a budget, $185K is beyond it I'm afraid. Putting the 16inch onto a new mount is an option. So, this is why we would like to look through a Planewave. If the view isn't great we will return to the proverbial drawing board.

Again thanks for everyone’s input and I'm thankful for the private messages, which I will respond to shortly.

Kind regards
Geoff

brian nordstrom (As avatar) · #31 01-02-2013, 11:30 PM

Geoff , thank you .
The OTA Meade 16 inch . if The Observatory aint going to recycle it ?Where will she go? Bro?
, As a Kiwi , I dont know this LX200 16inch personally ( but I have heard of her ) , quite a few here know this scope as well , reading this cool thread .. she is moving ...
Dont GIVE her away .
Brian.

Brian.

Quote:

Originally Posted by GOTO

Hi all,

I really appreciate your ideas but please I did not wish to cause a fight. We have long given up on deep sky objects bar the few everyone here knows about.

Not long ago we (Powerhouse Museum) commissioned some market research and found one of the key reasons people come is to LOOK through a telescope.

My love of video astronomy led me to install a GSTAR-EX with a 300mm Nikon lens on the belly of the 16inch. The view of the two main globulars, open clusters, even the Moon and Sun was great imo but the public weren't interested. Each person wants to have their turn at the eyepiece. Don't forget we have a 3D theatre and planetarium to enhance the experience.

The dome walls do add a complicating factor and we are aware of the skyglow problem from the CBD. Our first government astronomer Reverend Scott knew it was not a good place to build an observatory but 155 years later we are stuck, somewhat happily I must say as it is one of the most beautiful workplaces in the world. But I digress.

We looked into a Nasmyth without any luck and though we do have a budget, $185K is beyond it I'm afraid. Putting the 16inch onto a new mount is an option. So, this is why we would like to look though a Planewave. If the view isn't great we will return to the proverbial drawing board.

Again thanks for everyones input and I'm thankful for the private messages which I will respond to shortly.

Kind regards
Geoff

Satchmo · #32 01-02-2013, 11:39 PM

Geoff - here is a link to the RC OPTICAL 20" RC tube.

http://www.rcopticalsystems.com/telescopes/20tube.html

I think it would be really worthwhile for someone to come along one night with a portable 20" and you can compare on site the views through a 20" at the equivalent magnifications you would be using with a Cassegrain to get some kind of idea what the public would see and you can compare in real time with the 16" . My guess is with the heavy light pollution there that the extra aperture is not going to make a substantial difference to a member of the public and certainly not on the Moon and Planets ,which are mostly seeing limited with large apertures, meaning you won't be able to exploit higher powers the extra light affords.

AstroJunk (Jonathan) · #33 01-02-2013, 11:51 PM

Quote:

Originally Posted by GOTO

Conversely, if anyone has a brilliant different approach please don't be shy but remember we need the bigger aperture to try and get down to the bottom of Mag 10 from Sydney's CBD, it must be visual and we don't want to use a ladder.

Don't sell stars that faint

To be brutal, if you can't see mag 10 with the 16", then the conditions are now simply too poor. One mag deeper would require a 25" and regardless of the design (of Dob), is not going to be as swish as the Meade if you entertaining a corporate party for example.

Similar has been mentioned already: Piggyback a 100mm refractor with a colour integrating video eyepiece (choose your price point, it matters little when looking at a almost non-existent star field) and show the image on a wall monitor with the star dedication, photo and other trimmings as an overlay. At the same time try to locate the actual star within the bounds of an illuminated reticle on the 16". 99 times out of 100 the donor will 'see' the star either real or imaginary and go away happy.

When asked to show these things, many of the amateur community do the polite thing and show a 4-5 th mag Star in the rough direction of the one they bought...

netwolf · #34 02-02-2013, 12:19 AM

Gama has a CDK 20" from Planewave on a MI-750 mount.

Though I am not certain a CDK is exactly a good fit for a Visual scope, its full potential would be under used.

http://www.iceinspace.com.au/forum/s...&highlight=CDK

Another Alternative is as some one else mentioned maybe an RCOS EQ Fork, which has a relatively small foot print.
http://www.rcopticalsystems.com/moun...quatorial.html

I still recall my school visit to the Observatory and the Meade scope, I hope there is some way to keep it going. Maybe place it another Observatory in NSW. Or perhaps you could just defork the OTA and get a new Mount for it.

mental4astro (Alexander) · #35 02-02-2013, 12:53 AM

Geoff, I certainly agree with everyone wants to look through a scope. But in suggesting video I did not say exclusively. With a combination of both visual & video a larger scope won't be needed. A larger scope won't help short term or long.

I would also love to see a larger, state of the art scopes being used at Observatory Hill. I don't see an exclusive visual solution as the best.

Barrykgerdes · #36 02-02-2013, 08:10 AM

Quote:

Originally Posted by netwolf

Gama has a CDK 20" from Planewave on a MI-750 mount.

I still recall my school visit to the Observatory and the Meade scope, I hope there is some way to keep it going. Maybe place it another Observatory in NSW. Or perhaps you could just defork the OTA and get a new Mount for it.

Refurbishing the existing early version of the 16" LX200 classic is not really an option. The main problem is the age of the electronics that drive it and they are beyond repair now. The OTA could be fitted to a new Goto fork mount but that would be no easier than getting a new updated telescope. I know because I have been involved in their repair at times. The 16" Meade has different electronics than the smaller versions and supplies of spares are now exhausted.

The Macquarie University has a similar 16" LX200 that also is getting beyond economic repair.

Regarding Dobsonian telescopes I am sure the observatory has quite a few of the various sizes of Dobsonian telescopes that are trundled out for special viewing occasions. However as Geoff says that is not what the viewers want. They want to look through the eyepiece of a telescope from inside the dome.

Barry

tlgerdes (Trevor) · #37 02-02-2013, 09:35 AM

As an adjunct to this, there could be a very well kept 16" LX200 OTA going for a good price soon

, as it is just the mount that is giving problems.

netwolf · #38 02-02-2013, 01:30 PM

Barry but could the electronics be replaced with a diffrent system.

Argo Navis with ServoCAt on LX200 Classic.
http://www.chesmontastro.org/node/7365

Sitech Servo refit of 16" LX200 classic
http://finance.groups.yahoo.com/grou.../message/14294

AWR Goto have pictures on there site of a LX200 classic that was retrofitted.
http://www.awrtech.co.uk/ih/lx-upgr.htm

It seems to me the CDK and RCOS alterntatives would be far more expensive and would be under utilized if only used for Visual astronomy.

I am guessing if the Motors in the LX200 are still funcational and are Servo motors then it would be very easy to fit the Sitech to this. I will even donate my Sitech for testing if that woud help. I would hate to see it put out to pasture, it has so much history to it. So many people have used it.

Wavytone · #39 02-02-2013, 10:11 PM

Geoff,

So...it's back to a 16"-20" cassegrain on an altaz mount; perhaps a Nasmyth; or alternatively, taking the 16" Meade OTA and finding a new mount for it.

Barrykgerdes · #40 03-02-2013, 07:40 AM

Quote:

Originally Posted by netwolf

Barry but could the electronics be replaced with a diffrent system.

Argo Navis with ServoCAt on LX200 Classic.
http://www.chesmontastro.org/node/7365

Sitech Servo refit of 16" LX200 classic
http://finance.groups.yahoo.com/grou.../message/14294

AWR Goto have pictures on there site of a LX200 classic that was retrofitted.
http://www.awrtech.co.uk/ih/lx-upgr.htm

It seems to me the CDK and RCOS alterntatives would be far more expensive and would be under utilized if only used for Visual astronomy.

I am guessing if the Motors in the LX200 are still funcational and are Servo motors then it would be very easy to fit the Sitech to this. I will even donate my Sitech for testing if that woud help. I would hate to see it put out to pasture, it has so much history to it. So many people have used it.

Replied by PM

Barry