Astro Physics 1600GTO Mount

[Jessun]

Hello all,

I thought I'd share a few thougts here on the Astro Physics 1600GTO as I learn more and more about it. It arrived an hour ago!

As with all AP products, the first thing that strikes you is how well packed and marked everything is, even the included Hex Key kit is bubble wrapped! The mount comes in three boxes, one for the fork and RA assembly, one for the Dec head and one with all the extras. It isn't delivered with CWs or polar scope so a bit of pre planning for this is required.

When it comes to overall finish, workmanship and attention to detail, well personally I never saw anything like it. It's very heavy indeed, at 52kgs without weights, but the pieces fit like the finest scale model, and every single piece or bolt, big or small fits so well that I kept checking for oil on my fingers, and trying to wipe clean on my jeans. But there is no oil! It all just fits so remarkably well!

Once assembled it adjusts in alt/az for polar alignment with one hand. Four big bolts secure the mount in Ra, and once loosened a single massive wheel can be turned with no effort at all to raise or lower. (The tip of this massive bolt did have a drop of lubrication on it). A clever feature is that this bolt is held in place by gravity only. It runs through a crossbar between the fork sides, and this bar simply slots in recesses made every 10° or so. Very efficient and user friendly.

The Az adjustment is just as good - even better! The Ra fork base plate has a rotaring pier adapter built into it - and this slides into a big 10" ring you install on the top of your pier. Once lowered into the ring you align the adapter assembly and secure it with 6 bolts. The beauty of this is that the whole mount actually rotates inside this assembly now limited by the travel of the Az bolts. An estimation is that there's about +/- 5 degrees of adjustment. There's nothing to tighten! It's very, very clever indeed and makes initial setup an absolute breeze!! Ok the weight is there, and it's big and bulky, but it really is a gentle giant!

The mount features internal cable routing with plenty of space. You unscrew the end cap of the Dec house - where the CW attaches - and the whole cap comes off so that you can reach in to fish up cables from below. It's so roomy I had both arms in there!!

Ok, need to continue putting it together and power it up!

/Jesper

[DirkSteele]

Roland Christen and his team really do produce products that are second to none.

[Jessun]

After some lifting and general gymnastics, the OTA's are on! The eagle eyed observer will see that the mount has done a 180° turn in the ring to get the correct orientation. It was easily spun around fully loaded! (In noooo way recommended but it demonstrated the easy handling :-)

I've had a first look at the handset to set location and time. You can store locations in the handset, and assign them a number only to recall these at a later time. When you startup the handset will simply ask for location and you press 1 for instance for your normal stored observation site. The clock runs in the handset even when it's off! This is very handy for preparations at home if you want to travel to another location - the handset is the same for the AP range, but I'd probably want to leave this particular mount at home...

The manual is nicely prepared, and it is easy to follow. It suggest you do a bit of thinking here and there before bolting stuff together or setting off to a dark site. It's almost like having an experienced mate with you. Well done AP!

Balancing is something I'll look into. Even with clutches disengage the mount doesn't move easily until you put some weight on one end. I can slide a 12.5kg cw inches back and forth without noticing an immediate effect. I can appreciate this for heavy loads as you balance but with the tiny load I use, I'll have to rethink my usual method.

It's naturally cloudy here so I won't be able to test pointing and tracking etc, but I gingerly slew around indoors at the moment just enjoying the sound of it. In volume it reminds me of a HEQ5, but there's no 'gravel' in the machinery on this by the sound of it.

More to come one clear night!

/Jesper

[Jessun]

Time to arrange the cables inside the mount. As per the manual I'm thinking first !

The control box has nice screw secure socket for motors, power and handset. A standard 12V plug as per Synta etc fits fine too and my 10 amp power supply has no problems feeding the mount. It will be very interesting to see how the little Lodestar can run the show via the guide socket.

/Jesper

[3ggman]

That is one hell of a mount, (excuse my ignorance) what is the unit its sitting on, did that come with the mount or did you build it (it looks like some kind of modified weights bench)

[Jessun]

This is the unit:

http://stargazerslounge.com/topic/159170-my-personal-sky-crane/

It's built from scratch, angle profiles cut in my kitchen and the whole thing welded together on my balcony. It weighs 135kgs without mount.

/Jesper

[3ggman]

Thats a really impressive build. Theres some difference between the iQ45 and the AP1600

[ollypenrice]

Thats a really impressive build. Theres some difference between the iQ45 and the AP1600

Not as many as AP think there should be. AP tell their delears it's one or the other. They weren't amused by some of the borrowing of ideas... Personally I don't really see iOptron as likely to dent AP sales!

Wow, this is a fine beast, is it not. It looks absolutely magnificent and the term 'future proofed' takes on a new meaning. APs cable management is brilliant. Why don't other people remember that AP means cables?

You could probably do weekend work using it to lift barges out of the Rhone...

What a mount. You have all you need to move on and on with this.

The great day came at last, eh?

Olly

[Jessun]

The great day came at last, eh?

A year and a bit I think, during which I had some conversations with AP about dimensions etc (for the 1200GTO initially), and the answer was always that 'we don't know as it will change...". And change it did! The RA gear, motors, handset and control box on the mount are identical to the 1200 I believe though so it does no new tricks out of the box. It will take a bit more load though, it will take 0.2 arc second absolute encoders enabling pointing models etc and it will tidy up the cables. A whole range of details have been refined, but the heart is that of a 1200.

I never thought I'd put my hands on something like this, and certainly not that I'd be able to put both hands IN it!!! (OK, I had some plans brewing....)

/Jesper

PS Astro Physics' latest polar scope has a reticule pretty much carbon copied from iOptron's so they got back at them!

[alan potts]

Jesper,

Well that really is one hell of a piece of kit, it looks unbelievable. So now it is time to get an Astro Physics scope? What sort of tracking accuracy do you get with that?

One thing is for sure if the the bomb ever drops the mount will still be in tact. It is of course true everything with the letters AP cannot be anything but good.

Alan Potts

[Jessun]

Luckily Alan, it shrinks over time. I mean you get used to it. When I unpacked it my reaction was "My G, what have I done!!" But it fit as planned, there's room for a 40cm mirror and the Crane shrugs it off like a fly.

I can't comment of the tracking accuracy, but the PE is tested at the factory to be +/- 2.5 arc seconds before applying the pre recorded PEC curve. Sounds solid to me! Pointing accuracy with the optional encoders is 0.2 arc seconds.

I can put it this way. The mount is no longer a weak link.

/Jesper

[alan potts]

Trust me I would be sleeping with it.

I have to say it is the strangest looking mount I have seen but the cost makes my HEQ 5 P look a bit tame. I guess if you are really into imaging then this is the type of kit that will deliver but it is not really necessary for my Televues. I nearly passed out when I saw the price of it on TS site but I bet the wind will not move that, it wouldn't dare.

Alan

[Jessun]

Still covered with clouds I've been busy reading the manual and tidying the cables up.

Below you'll see the excellent cable management, where any size cable goes in below the polar scope, and then winds its way up the Ra and Dec parts to come out through one of two exits under the mounting plate. A clever plastic insert forces the cables out of the way from the polar scope's light path, so its view remains unobstructed.

It's a brilliant sollution to what can be a tangle problem.

The alignment routine is a bit different to what I've used before on the HEQ5 and iEQ45. The AP will assume perfect orthogonality within the mount itself, so if you want to use Polaris as an alignment star you need to be spot on with the OTA mounting. Best avoided with my gear I think. You will center one star and then select star two. The mount will slew there. Unlike routines I'm used to, the AP routine expects no internal errors, but instead assumes your polar alignment is off if star two isn't on the cross hairs! So you use the alt/az adjusters to physically center star two. A few iterations of this will have you aligned with the NCP to great accuracy. To target cone error you'll need to flip and do a routine to cancel the effects of a misaligned OTA. (I don't flip so won't bother with that until I take this one out to a dark site).

I really, really need some clear skies now to try it out!

/Jesper

[Brian Nordstrom]

Not as many as AP think there should be. AP tell their delears it's one or the other. They weren't amused by some of the borrowing of ideas... Personally I don't really see iOptron as likely to dent AP sales!

Wow, this is a fine beast, is it not. It looks absolutely magnificent and the term 'future proofed' takes on a new meaning. APs cable management is brilliant. Why don't other people remember that AP means cables?

You could probably do weekend work using it to lift barges out of the Rhone...

What a mount. You have all you need to move on and on with this.

The great day came at last, eh?

Olly

I hear you Olly , thats a fine mount ! , I have the IEQ45 thats a good mount , but its like comparing a Ford escort to an Aston Martin , still both cars , but ... I need to win the Lotto to afford one of these beauties , onya mate !

Brian.

[ollypenrice]

Still covered with clouds I've been busy reading the manual and tidying the cables up.

Below you'll see the excellent cable management, where any size cable goes in below the polar scope, and then winds its way up the Ra and Dec parts to come out through one of two exits under the mounting plate. A clever plastic insert forces the cables out of the way from the polar scope's light path, so its view remains unobstructed.

It's a brilliant sollution to what can be a tangle problem.

The alignment routine is a bit different to what I've used before on the HEQ5 and iEQ45. The AP will assume perfect orthogonality within the mount itself, so if you want to use Polaris as an alignment star you need to be spot on with the OTA mounting. Best avoided with my gear I think. You will center one star and then select star two. The mount will slew there. Unlike routines I'm used to, the AP routine expects no internal errors, but instead assumes your polar alignment is off if star two isn't on the cross hairs! So you use the alt/az adjusters to physically center star two. A few iterations of this will have you aligned with the NCP to great accuracy. To target cone error you'll need to flip and do a routine to cancel the effects of a misaligned OTA. (I don't flip so won't bother with that until I take this one out to a dark site).

I really, really need some clear skies now to try it out!

/Jesper

It appears to be causing your flat to subside, Jesper! (Or you're still reeling from signing the cheque!!)

Olly

[Jessun]

I had a go last night in the typical smog, mainly looking at the basic setup, alignment, pointing accuracy and guiding. This is what it looks like in the 'obsy' and note the internal cabling:

It's an absolute joy to use in short. It adjusts with no effort at all in alt and az to find Polaris. At the moment I'm using a standard Losmandy polar scope with some constellations and lines etched in, but I await the new RAPAS - Righ angle polar alignment scope. This has a built in diagonal, and the reticule has circles and hour markings rather than the constellations. It will make for even easier setup with less neck strain. (Polaris was too sadly dim tonight to show up on my PA cam...).

It slews very precisely, and I can't see any traces of backlash judging by star movements on the CCD. I didn't go through the full routine, but did a visual PA and then I synced on Capella. In theory this is all you need to do to get going - and it sure was! Any target I picked from the keypad appeared almost on the cross hairs straight away. It will be interesting to see how well it points with a proper PA routine, as it turned out mine was off by a bit.

I set guide rate to 0.5 sidereal, and PHD calibrated quickly using 1 second intervals - from then on it was plain sailing! I have been used to the graph constantly going off scale with the iOptron, I've seen Dec just trail off never to return... I used to resort to high aggressivenes and max one second interval to hold it by the ear. Not so this time around!

Here's a first graph without tinkering with settings:

The intervall is 5 seconds so the graph covers 8 minutes and 20 seconds - more than a complete worm cycle I believe. PE is advertized to be slow and easy to guide out - and it looks like that holds true. I could even pick up on the graph when I had been walking around inside the flat, PHD had turned into a seismograph !

I noticed that the graph seemed to linger under the 0 line, and I wonder if that was due to the slow Ra and Dec drift due rough PA. Someting to investigate next time. I've seen a lot of people post essentially flat graphs with all sorts of mounts, so at a first glance this doesn't stand out from the crowd as such, but sure made me very happy.

The keypad is really nice to use, the buttons are extremely responsive and the manual still looks like new - no need to use it for the basic functions. The only thing I haven't figured out is how to change slew rate whilst calibrating. You seem to be stuck with what ever you had selected last - which could be way to fast for precise movements - but this may well be something I'm doing wrong.

All in all the AP1600 did what AP mounts are famous for - it disappeared. 52 kgs just vanished, and all I was left with was a few warm red lines on the display of a rugged handset asking what I'd like to do next. (And before you ask if it vanished off the balcony, no no, it all holds solid )

/Jesper

[Jessun]

Here are some PE curves (source ovision.com in France). It seems the optional encoders do the job just fine. I don't foresee a need for them myself until I have the mount on a permanent pier in some distant future - perhaps not even then. They do add about 60% to the price of the mount...

/Jesper