Equipment Library

The Seattle Astronomical Society maintains a library of small and medium size telescopes that may be checked out for a period of 1 month by members in good standing. If you are new to astronomy, this is an excellent way to learn how to use a telescope and to begin viewing the wonders of the night sky, without having to invest immediately in a telescope of your own. To check out a telescope, please check out our equipment available for loan.

If you have any questions about borrowing equipment, or do not see a specific piece of equipment please reach out to our Equipment Manager.

See the complete equipment list in alphabetical order.

All our equipment is currently on loan to other members.

Available Eventually

The following list of equipment is currently loaned out to a member, and may include other members waiting to also borrow.

AWB OneSky 130mm Reflector

Currently there are 3 requests to borrow this.



The AWB (Astronomers Without Borders) OneSky telescope is a 130 mm Newtonian reflector. It has a Dobsonian style mounting that is compact and intuitive to use. A red-dot reflex sight serves as a finder for aiming the scope. The truss tube telescope collapses into a compact size for storage and transport. Note that this telescope is designed to be placed on a small table or similar support when in use and does not come with a tripod.

Three eyepices are included. A low power eyepiece (26 mm TeleVue Plossl) provides 25 power and a wide, 2 degree true field of view for locating objects and for viewing large deep sky objects such as star clusters, nebulae, and galaxies.. A 13mm Celestron Plossl provides 50 power, and a 10.5 mm TeleVue Plossl provides 62 power for viewing the Moon, planets, and smaller deep sky objects.

This telescope is suitable for all ages and is a good choice for viewing the moon, planets, and bright deep sky objects. The red-dot finder is easy to use. However, you need to be able to see your target in the sky order to aim the scope accurately. In the city, a red-dot finder works well when aiming at the moon, planets, and bright stars. Finding faint deep sky objects generally requires dark sky unless, like the Great Orion Nebula, the object you are looking for is located near a bright star.

It is always good to set up a telescope away from any direct line of sight to porch lights or street lights, and this is especially important for an open truss tube  design like the AWB 130.

Aperture: 130 mm
Focal length: 650 mm (f/5)
Eyepieces: 25 mm (26x) and 10 mm (65x)
Tube length collapsed: 24 inches
Tube length collapsed: 14.5 inches
Telescope weight: 14 pounds

Currently Unavailable

The following list of equipment is not available to members until we are able to replace or repair parts.

Orion SkyQuest XT10g - Computerized GoTo Dobsonian

Note  This item is being serviced and it is not available for check out.

NOTE: This telescope is heavy and may require two adults to carry and set up.

The SkyQuest XT10g features GoTo pointing. It features a 254mm (10") aperture, 1200mm focal-length parabolic mirror (f/4.7).

Assembly is straightforward, but please note: This is a  very heavy and bulky telescope. The base is large and weighs nearly 40 lbs. The optical tube weighs 30 lbs and is about 12 inches in diameter by 48 inches long. It may require 2 people to lift it and a bigger vehicle to transport it. Handles on the Dobsonian base's front and side panels help to lift and carry the heavy base. Assembly is done by lifting the 30 lb. XT10g telescope optical tube into the Dobsonian base and locking it in place with a hand knob. A two-star alignment must be done to orient the telescope to the sky for GoTo operation. 

Our Orion SkyQuest XT10g GoTo Dobsonian Loaner Package includes an EZ Finder II reflex sight, three high quality eyepieces, and several useful accessories.

Orion StarBlast 4.5

Note  This item is being serviced and it is not available for check out.


The waiting list for this telescope is filled and new requests are temporarily on hold.

The Orion StarBlast 4.5 EQ reflector telescope comes with a lightweight equatorial tracking mount and adjustable-height tripod. The equatorial mount is advantagous for viewing objects in the sky but is not intuitive to use. Instructions on setting up an equatorial mount are included with the telescope. Two Orion Expanse  wide field eyepieces  (66 degree apparent field of view) are included. A 15mm Expanse eyepiece provides 30x power magnification, and a 6mm Expanse eyepiece provides 75x magnification.  An Orion EZ Finder II "red Dot" reflex sight is provided to aim the telescope. The user looks at the sky through the viewing window of the EZ Finder and sees a red dot, like a heads up display on an airplane. The user then moves the telescope until the red-dot is aimed at the intended area of the sky.

Celestron StarHopper 8

Note  This item is being serviced and it is not available for check out.

The Waiting list for this telescope is filled and it is temporarily unavailable for new requests.

NOTE: This is a heavy and bulky telescope and may not fit in smaller cars.

This Celestron Star Hopper Dobsonian is an 8 inch Newtonian telescope on a Dobson style mount. The telescope includes a Telrad finder that is intuitive to use and works well for pointing the telescope at the moon, planets, and brighter stars. Finding deep sky objects (e.g. galaxies and star clusters) requries the use of star charts and some knowledge of the sky.

Telescope Types

Types of telescopes

Copyright NIAAS, North Ireland Amatuer Astronomical Society

What are those numbers?

Types of telescopes

Copyright 2008-2012

The f-ratio is the focal length divided by the diameter of the telescope. Magnification is the focal length of the telescope divided by the focal length of the eyepiece.


To find the f-ratio of a telescope 10 " in diameter with a 45" focal length:

Divide 45 " F.L. by10" D. to get an f-ratio of 4.5.

Compute Magnification

First, convert focal length to mm: 45" = 1146 mm, then:

1146 mm focal length divided by 35 mm eyepiece equals 33 magnification.

More Information

If you are interested in learning more about telescopes, we recommend: