Jump to content


Celestron Cosmos 90GT Wifi

Recommended Posts

Hi, I'm about to buy my first telescope and one of my friends from NY has mentioned to me Celestron Cosmos 90GT. He tells me it's a good option for a beginner like me because it's really easy to use it. Has anyone had any experience with it? Any advice for other alternatives? Many thanks.

Link to comment
Share on other sites

From what is said it is fairly new so I doubt much chance of other people having one to comment on.

Scopes will have to go down the wifi/tablet/phone route eventually, it is geting to be the normal approach these days.

Looking like a first foray into the wifi area so the decision is try it as one of the first or leave it to get more established.

Makes for interesting thoughts, what if 2 are at the same site (have Celestron built in sort of password logon to the network?

I would have liked to have seen it on one of their "bigger" scopes, I just get the idea that this is a sort of test set up to find out how it works and what has to be fixed or added in the future.

Any idea what the app looks like?

Is it sort of a 2 line display as the handset or is it more like a planetarium interface.

Reading the blurb it sounds like a planetarium based system. so needs phone etc with GPS and accelerometer - but they are fairly normal.

As said I think scopes will need to go this route, the present technology is basically 15 years old, and bolting bits on the side to get around things never really works too well.

One thing I never like to see is the information that on the scope is:- the eye nebula adorns the refractor tube. As if that improves the performance.

As said I think scopes will have to go down this route to wifi control so really do you get one now or wait. There appers to be no handset operation to fall back on.

Link to comment
Share on other sites

£375 seems quite a lot, sure it was £100 less before xmas. The wifi seems a bit of a gimmick. Imo, if wifi was the way forward it would have launched on one of the the midrange £800 mounts. Like with cars, the best and latest tech starts out on the merc s class or lexus ls, then over time finds itself in vauxhalls.

The 102slt might be worth a look, the goto software is really good, you dont need to know the names of stars/planets either to align. The £100 you'll save can be put towards a power pack, eye pieces and a webcam. Can also control from your pc or win tablet with a £10 cable

Link to comment
Share on other sites

Just looked at one on the UK site.

I think they are over optimistic with regards magnification at 213x...more like 180 0n a very good night.

As for wifi...undecided. + if you visit a dark skies site then getting a mobile signal to ensure that the location you need to input cabn be input might be an issue.......

Link to comment
Share on other sites

I have this scope and I've been quite happy with it so far. It's not without weaknesses but overall my experience is positive. Re wifi, the connection between the phone and the scope is via an inbuilt independent WiFi network, so no real issues with mobile signal. If anyone is interested, I have a written a more detailed review here: http://www.stargazing.me.uk/best-beginner-telescope-celestron-cosmos-90gt-wifi/.

Link to comment
Share on other sites

Cosmos 90 wifi telescope

waste of money.

I wouldnt reconmend a goto mount for beginners.

Id reconmend the celestron astromaster 90 eq

because its only £130 with the motor drive included and a motor drive can follow the objects in the night sky and you can even get apps like the night sky lite on your tablet its free and the app shows what is up in the night sky so cosmos 90 telescope complete waste of money in my oppinion

Link to comment
Share on other sites

  • 2 years later...

I have just purchased a second-hand model, and it seems OK to me, but Celestron could do a much better job with the user's manual. The basic mechanical setup is covered reasonably well, but the operational side is lacking.

I use an Android tablet, running Celestron's Sky Portal App. In a domestic environment, the tablet reverts to the home's hub as soon as the scope is turned off. Most tablets will not make it obvious that this has happened, and neither will Sky Portal - it will just give a "failed to connect" message. 

There are 3 red LEDs, which are very dim; OK when it is dark, but difficult to see when performing initial setup in daylight. The manual mentions "indicating power and WiFi-ready status" but not which LED is associated with which function. By trial and error this seems to be - (top) +12V ON if permanently illuminated, (middle) WiFi active when blinking, and (bottom) blinking during data transfer.

There is a small slider switch which you are instructed to make sure that it is in the LEFT position. There is no indication as to what happens, or does not happen if it is in the RIGHT position. There is also a small hole that leads to a PCB-mounted push-button switch, but again, nothing about this in the manual.

The power socket had obviously seen some heavy usage, and was not giving reliable contact, so I replace it and added an adjacent clip to give strain relief to the external power cable. I also added a glue-on plastic hook, on the front sloping face, to attach the battery pack satchel, and avoid cord-wrap.

Having selected a star about 180 degrees from the current position, I used Sky Portal's GOTO function, the mount started slewing and then I turned off the tablet's WiFi. The mount continued to turn without the possibility of stopping it! I have now added a normally-closed push-button KILL switch in series with the mount's +12V line.

I also added an altitude scale, based on the one on my Skymax mount (similar plastic cover), printed on paper, stuck on to the altitude gear cover, and then covered with clear varnish. I added a white line on the top of the dovetail clamp to act as a moving marker for this scale. This is not strictly necessary, but it is nice to check that the scope and Sky Portal are in sync.

The manual also mentions an optional hand controller, but just points you to Celestron's web site for further details. I believe that Celestron has recently discontinued the production of this model, so I hope that I can find the information. The connection port is labelled "AUX", but I understand that the RJ12 socket uses a standard interface for a hand controller and other auxiliary devices. I have not managed to read, using Sky Portal, any firmware versions from the mount, so finding a compatible hand controller may be a challenge. I have Just tried the "Celestron.com/cosmos link and been re-directed to (http://www.celestron.com/browse-shop/astronomy/telescopes/series/cosmos) with a "Page Not Found" message.


Edited by Geoff Lister
Link to comment
Share on other sites

  • 7 months later...

Hi ,

Good to find some discussion on this. I bought one used and struggled a bit with the wifi setup. I've just hooked it up to a Nexstar (older type) handset and also a Skysync GPS (borrowed from my 4SE setup) and it all talks to each other (as far as controlling motor drives). The clouds have arrived so can't confirm a successful alignment or if it will track.

Will update when weather (and my circulation) improves...



Link to comment
Share on other sites

Since my reply, above, in March, I have not used the mount very much, preferring to use my Skywatcher Skymax with Synscan and Celestron Skyprodigy with Starsense.

When looking into the eyepiece, I find it very difficult to locate the "virtual" up/down/left/right buttons on the edge of the tablet's display. With a normal handset, as found on the Skymax & Skyprodigy, you can easily locate the buttons whilst still looking through the eyepiece, and get tactile feedback to know that you have pressed them, even before the mount moves.


Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.