MOAG
(Manual Off-Axis Guider)
for ST and STL Cameras Equipped with
the AO-L Adaptive Optics Device
February 28, 2007


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MOAG Off-Axis Guider

MOAG MANUAL OFF-AXIS GUIDER

Beginning in February 2007, SBIG will offer the Astrodon MOAG accessory for controlling the AO-L Adaptive Optics device with the Remote Guide Head in front of the filter wheel.   The MOAG is a manual off-axis guider assembly intended to be inserted in the optical path between the AO-L Adaptive Optics device and the STL camera body.  Its large aperture is made to accommodate CCDs up to the 35mm sized KAI-11002 used in the STL-11000 cameras.  The threaded adapter mates to the 2.1" threads on the STL's standard front accessory plate.  The MOAG has an adjustable pick-off prism just outside the light path of the main CCD that directs light from a guide star to the Remote Guide Head.  A lens system within the MOAG places the focal plane for the Remote Guide Head at the correct distance to achieve fine focus using the Borg helical focuser. 

Motion of the guide star is used for determining the corrections that need to be made by the AO device to stabilize the image on the main CCD.  The benefit of this configuration is that light from the guide star is intercepted before going through any filter that might be used for the imaging CCD, allowing the AO-L to be used to full advantage when imaging with dark or narrowband filters that naturally attenuate light from guide stars.  The MOAG has been specifically designed for use with the STL camera, but may also be adapted for use with the ST series cameras using the appropriate adapter ring. 

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Adjustable pick-off prism inside the
2.4" entrance aperture of the MOAG

This version of the MOAG now provides you with the opportunity to guide in front of your filters, potentially increasing signals over RGB filters by a factor of 3 and over an H-a filter by a factor of >100.

Light comes from the telescope passing through the transparent AOL movable optic, through the MOAG and into the STL camera. The AOL screws into the MOAG as it would into the STL. The MOAG includes a special adapter with 2.1" male threads that screw into the STL accessory plate.  It has a V-groove that fits into the MOAG and is tightened down with 4 set screws.  In this way, the AOL/MOAG can be rotated to the vertical position shown below and locked into place. A variety of adapters can then be used to connect the assembly to the telescope.  The MOAG takes up 2" of backfocus and the STL v-groove adapter takes up another 3/8".  A pick-off optic extends into the internal opening of the MOAG from the top. It is attached to a plate that contains a screw-in holder for various beam reduction/extension lenses. A BORG helical focuser is secured into this plate that holds the guide CCD with a 1.25" nose piece.

REPLACEABLE LENS SYSTEM

The distance between the pick-off optic and the focal plane of the guide CCD must be identical to the distance between the pick off optic and the focal plane of the imaging camera.  This distance will vary due to the use of different imaging cameras, filters wheels and other accessories, such as in-line focusers.   The MOAG designed specifically for the STL cameras comes with a -250 mm plano-concave lens in the replaceable lens holder, since that focal distance is fixed.   This will place the focal plane for the Remote Guide Head at correct distance to achieve fine focus using the Borg helical focuser.

ADAPTERS FOR ST SERIES CAMERAS

The MOAG can also be adapted to use with the AO-L with any ST-7/8/9/10/2000 camera equipped with a Remote Guide Head.  All that is needed is a replacement v-groove ring with a T-thread camera interface instead of the 2.1" thread required for the STL cameras.  These will be available in the very near future.


  

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MOAG fits between the AO-L and the ST or STL camera
Remote Guide Head fits the Borg helical focuser

Adapter ring for the STL cameras screws directly
into the STL's accessory plate.

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MOAG with SBIG Remote Guide Head
require only 2.4" of additional backfocus

MOAG attached to AO-L

moag_aol_st2k_2.jpg (53156 bytes) moag_aol_stl2.jpg (75874 bytes)

AO-L and MOAG attached to an ST
series camera with CFW10, ten slot filter wheel.
Remote Guide Head (not shown) controls
the AO from in front of the filter wheel.

AO-L with MOAG attached to an STL camera
equipped with internal 5 position filter wheel.  Also works
with the new 8 position 50mm filter wheel for the STL.

AO-8 and MOAG attached to an ST series with a CFW9
Remote Guide Head (not shown) controls the AO from in front of the filter wheel.


Manual Off-Axis Guider

* Guide in front of your filters
* Guide stars are brighter since no filter is used for better guiding
* Find more guide stars
* Use SBIG STL/AOL technology even with narrowband filters
* Lower cost than the ROAG for those who do not need rotation
* Stand-alone version works with any CCD camera

Features

* First OAG to work with the SBIG AOL and STL cameras
* Or, stand-alone OAG for any system
* Adapters for AOL/STL, 2.7" AP threads used on most RCs, SCTs
* V-groove adapters to rotate and lock MOAG in any orientation
* Manual (non-rotating)
* Accepts 1.25" nosepiece from guide camera
* Replaceable lens system to achieve coarse focus
* Precise fine focusing with helical focuser
* Additional extensions for extending the pick-off optic into the optical beam


Price and availability
As of the date of this announcement we are accepting orders for the MOAG and have some in stock.
The list price as of this date is $780.  Please check our Price List for the current price at the time of your order.
Prices and availability are subject to change without notice.


Revised: April 02, 2008 07:49:41 AM.
Copyright 2007 Santa Barbara Instrument Group, Inc.  All rights reserved.

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