Part 4 - Assembling the Hardware

The assembling of a permanent observatory either with roof or without, you still require a considerable of equipment. The mount will be the main whereby you would have to build around it.




The AP mount 1100GTO is an excellent mount for precision astrophotography. This particular mount does not include the Absolute Encoders. AE are the latest technology in precision guilding.On axis encoders have many advantages, they should not be considered a panacea for taking long unguided photos. External factors such as optical tubes that bend and differential refraction that conspire to degrade pointing and tracking accuracy cannot be fixed with on axis encoders.

Advantages of on axis encoders:

1. Mount is marginally easier to use by eliminating the need to initialize the mount's position (through homing or synchronization) at start up or after power loss.

2. Provides improved pointing and tracking accuracy by continuously monitoring the position of the main gear, as opposed to an encoder mounted to the motor's drive shaft.

3. Virtually eliminates errors caused by periodic error as well as the need to train periodic error.

4. Transparent operation; the on-axis encoder hardware and electronic sensors are integral to the mount's mechanical design, control system electronics and control software.

Disadvantages of on axis encoders:

1. Cost. On axis encoder technology is expensive. Not everybody can afford it, although I am sure that everybody would like to have it. 

On,y two others mounts provide AE, 10Mircon & APA, apart from these three supplier, I am not aware of any other.

The Mount would need a pier to hold it steady and strongly fixed, I decided on a 8" diameter steel pier with a top movable flange to avoid complication when the mount is fixed on.

This is the top flange with the AP adaptor that will hold the AP mount

I also included a tray for the mount.

Finally the RAPA polar alignment scope.

 

The final setup with all the units assembled.

Apart from the setup, there are all the bits & pieces that will assist me to control better the mount.

The Mount Hub Pro, is an excellent addition to all mounts, it will provide just a single USB cable from the unit to the laptop. From the hub I will connect (input)at least five accessories, like;CCD, AO, Dew Heaters, gilder camera and so on. Instead of having all these units cables running from the pier to the laptop, only one output will be used from the hub.

Part 3 - Testing software to make the mount and all other units function 

This diagram comes from AP and shows the mount control panel, hardware & software connectivity 

First endeavour on the new Astro-Physics mount 1100 GTO

The alignment routine is a bit different to what I've used before on the HEQ6 and CGEM. 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 centre 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 centre 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)

It's an absolute joy to use in short. It adjusts with no effort at all in alt and az to find Polaris. Polar alignment was extremely easy using 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.

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 good PA and then I synced on Kochab. 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.

I set guide rate to 0.5 sidereal, on the AP Ascom V2 in Maxim DL 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 EQ6, I've seen Dec just trail off never to return... I used to resort to high aggressiveness and max one second interval to hold it by the ear. Not so this time around!

First alignment only using a one polar alignment, then selected the first star (Kochab) and it when directly to the center of the cross-hair. This is a 10 seconds unguided.

Kaypad