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.

    This telescope is suitable for all ages and is a good choice for viewing the moon, planets, and bright deep sky objects. It has a Dobsonian style mounting that is compact and intuitive to use. A red-dot reflex sight and a seet of eyepieces is included.. It is designed to be placed on a small table or similar support and does not come with a tripod.

  • Celestron StarHopper 8

    Currently there are 3 requests to borrow this.

    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.

    NOTE: This is a heavy and bulky telescope and may not fit in smaller cars. The tube is 52" long by 10" diameter and the Base is 22" in diameter by 23" high.

  • Orion SkyQuest XT10g - Computerized GoTo Dobsonian

    Currently there are 2 requests to borrow this.

    The XT10g is a 10" aperture Newtonian telescope in a motorized Go-To mount.  A red dot reflex sight finder and eyepieces are included. 

    This is a  very heavy and bulky telescope and it is usually loaned for extended periods. 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.

  • Orion SkyQuest XT10i

    Currently there are 3 requests to borrow this.

    This is a heavy and bulky telescope and it is usually loaned for extended periods.  It may require 2 people to lift it and a bigger vehicle to transport it.

    The Orion SkyQuest XT10i IntelliScope is a 10" aperture Dobsonian Reflector with a Push-To computer system for aiming the telescope. 

  • Orion StarBlast 4.5

    Currently there are 2 requests to borrow this.

    The Orion StarBlast 4.5 EQ reflector telescope comes with a lightweight equatorial tracking mount that is advantagous for advanced amateurs but is not intuitive to use.  A "red dot" finder is provided to aim the telescope. 

All our equipment is in good condition!

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: