ACE Product 3

Finder-Guiders

ACE has a complete range of Finder-Guider boxes, from simple flip-mirror arrangements to sophisticated off-axis XY-stage guider systems to meet your exacting science requirements.

Key Benefits

	Custom designed
	Available with intelligent motor control
	Fully engineered for robotic telescopes
	Simple to complex systems available

Simple Flip-Mirror Box

This flip mirror box was custom designed for the University of Georgia 24 inch (0.6-m) telescope. This is perhaps the most simple arrangement. There is no motor, just a manual lever to rotate the 45º mirror into or out of the beam.

When the mirror is not out of the beam a limit switch is activated to send a warning message to the telescope control computer that the beam is being occulted.

When the mirror is fully in the beam a red LED reticule system can be activated.

Educators find this type of simple box invaluable for public outreach programs. Visitors are shown an object (like the Orion Nebula) through the eyepiece. A short exposure with the CCD shows approximately the same view. Then a longer exposure reveals far more detail.

This box was CNC machined with the same attention to detail found in the more sophisticated ACE Finder-Guider systems. The walls have weight reducing pockets and the joints are full or half-lapped to prevent stray light entering the unit. A cap is available for placement over the eyepiece.

Adjustment was provided for the eyepiece to move in the X-Y plane so that the cross-hairs are truly aligned with the center of the CCD detector field.

An ACE filter wheel is attached under the flip mirror box.

All ACE instrumentation features black anodized aluminum and stainless steels fasteners unless otherwise requested by the customer.

4-Port Instrument Rotator

This device is used on robotic telescopes where more than one instrument is mounted at a time. A rotating tertiary mirror directs light to one of four ports, hence the name.

The photograph shows a unit designed for the Baton Rouge Observatory 20-inch (0.5-m) telescope. An ACE filter box is attached to the rear face of the instrument.

The device is fully controllable for use in a robotic environment. A small knurled knob permits manual rotation of the tertiary mirror. The mirror mount is equipped with an absolute encoder and has a precision ball-bearing detent system to ensure consistent registration. The motor has no power applied except during a move.

Split-ring clamps are used to attach lightweight pieces of equipment, such as eyepieces.

This type of arrangement is well suited to telescopes with multiple CCD cameras and eyepieces. It has a very limited guider capability. Off-axis light can exit through the bottom of the box to one of two auxiliary guider ports.

Mirror-Slide with X-Y Stage

The photograph shows a standard ACE filter box attached underneath the mirror-slide X-Y stage. This particular unit was designed and manufactured for the Lawrence Livermore National Laboratory.

These guiders are custom-designed to interface with the client's telescope and meet the science objectives.

The main science beam passes through a hole in the mirror (not visible) and then through the filter box to reach the main detector.

When the mirror is moved sideways the hole in the mirror is no longer centered on the optical beam and therefore the on-axis light is sent out of the side of the box. If the X-Y stage is sent to the (0,0) position an eyepiece or detector would see the same image that the science camera was viewing.

If the mirror slide is out of the beam (science camera sees the object) then the X-Y stage can be moved around to acquire off-axis stars.

Furthermore, by programming tracking rates of a comet into the X-Y motors and guiding on a star the comet will be followed. So it is possible obtain guided images of a fuzzy comet by tracking on a star and not the comet!

Astronomical Consultants & Equipment, Inc, recently delivered a fully automated 0.61-m telescope equipped with a Mirror-Slide and X-Y stage for the Central Texas Astronomical Society. A wide field camera with 20µm pixels is used for the science detector and a smaller detector with 7µm pixels is used for planetary observations when the mirror slide is in the beam and the stage is at (0,0). Otherwise it is used as an autoguider. The detector is very small but it is not a problem finding guide stars; the X-Y stage is used to scans multiple image fields. The smaller CCD can be easily replaced with an eyepiece for public outreach programs or visual planetary studies. An ACE Dual Filter Wheel is attached below the finder-guider system.