Welcome to the Minnesota Astronomical Society's Eagle Lake Observatory website!
The Eagle Lake Observatory is the main public outreach facility for the MAS. The site consists of the Onan Observatory, the Sylvia A. Casby Observatory and the HotSpot Classroom.. The Sylvia A. Casby Observatory and the HotSpot Classroom became operational in the 2013 observing season and accompany the existing Onan Observatory which held its first public star party on April 28, 2000.
The Onan Observatory, houses more than a dozen telescopes on four observing platforms. The observatory is open to the public and MAS members at scheduled times during the year. Public star parties are all-weather events (see FAQ below), assuring the observatory will be open to visitors.
The newly opened Sylvia A. Casby Observatory houses an 8" TMB design refractor, a Takahashi Mewlon 300 Dall-Kirkham and a SV102 refractor. These telescopes set on an Astro Physics 3600 GTO mount, under a 12.5 foot Ash-Dome. Each observatory has the capability to display live video images of what the telescopes are viewing. These images are shown on monitors in each observatory as well as in the HotSpot Classroom. The HotSpot classroom provides a much needed building to conduct our presentations as well as a warming room for our guests to relax and enjoy live video feeds from the observatories telescopes throughout the night.
Select a topic of interest from the table of contents at the left. If you have a question about the observatory that's not answered here, please send an e-mail to
or leave a message in the Minnesota Astronomical Society's voice
mail box at 952-467-2426. Thanks for your interest in the MAS and the Eagle Lake Observatory. We hope you can visit us soon.
Information on Baylor Park and the Eagle Lake Observatory, including “What to expect”, Star Party Guidelines, and Directions, can be found following these links or the links in the left hand column.
Additional information on the history of the Onan Observatory, or ‘’How the Onan Observatory Came About’’, can be found HERE.
The vast majority of the equipment at the observatory has been due to the generosity of our Anonymous Benefactor. With these donations over the past several years, the MAS can claim to have one of the premier public observing facilities anywhere in the United States, if not the world. There is no other all-volunteer public observing facility with a similar range of capabilities.
Come out to an upcoming event at the Eagle Lake Observatory and prepare to be astounded by the glories of our universe!
Two state-of-the-art systems - one primarily for visual observing, the other intended for video - enabled observing. Each system has multiple refracting and reflecting telescopes, each selected with a specific purpose in mind and installed atop computer-controlled Paramount ME mounts.
Photo by Merle Hiltner ©
This telescope platform is primarily for visual use. All telescopes are equipped with interchangeable eyepieces for MAS members and guests to see first hand celestial wonders of the sky.
The largest scope on this platform is a Celestron C-14, with more than 2500 times the light gathering capability of the unaided eye and a minimum of 100 power. This is an excellent scope for deep sky objects as well as planetary viewing.
Our largest refracting telescope at the observatory is also on this platform. The StellarVue 152 is exceptional at viewing planets, stars and clusters. The scope can also be fitted with a solar filter for viewing the sun and sunspots.
Next, we have a Tele Vue 102 telescope dedicated to solar viewing. This scope is fitted with a Coronado H-Alpha solar filter for observing solar prominences, faculae and granulation.
Photo by Merle Hiltner ©
With a similar array of telescopes as the Visual Platform, the Imaging platform of telescopes is equipped with a variety of cameras that allow images to be projected onto the monitors in the observatory. The sensitive cameras give a more detailed look at objects and can be viewed by a large audience at once.
The largest scope on this platform is another Celestron C-14. This scope is equipped with a Astrovid StellaCam3 and utilizes the Fastar capability of the scope.
The Takahashi TOA-130 has an Astrovid PlanetCam and a 2.5x or 5x Powermate attached. This provides higher powered views of the sun, planets and moon.
For wide field views, we have a Takahashi FSQ-106N equipped with a StellaCam II.
Another scope, a Tele Vue-76, is equipped with a Coronado H-Alpha solar filter for both visual and imaging capability.
Photo by Merle Hiltner ©
Meade LX200 Platform
A computer controlled Meade 16" LX200GPS f/10 Schmidt-Cassegrain is the longest focal length scope at Onan. This scope allows the highest potential magnification of any scope on site. The scope is sitting atop a massive concrete pier that was originally designed for the 1000 pound Larson Telescope **
The 16” LX200 provides excellent views of both deep sky and planetary objects.
Sitting on top of the LX200 is a Tele Vue NP101 telescope. This is an exceptional scope with low power, and wide field of view for large clusters of stars.
This platform is also equipped with a Meade ETX 125. This scope is dedicated to imaging, having both a StellaCam II as well as a PlanetCam. The images are displayed on a small monitor attached to the fork arm of the LX200. This allows guests waiting in line to see what is being shown through the eyepiece of the telescopes.
** The Larson Telescope was donated to the city of Eden Prairie in 2006, where it is being used today at the new Staring Lake Observatory.
Photo by Merle Hiltner ©
Donated to the MAS in 2008, this ''truss tube'' Dobsonian-style reflecting telescope has a 20" primary mirror, making it the largest telescope at the observatory in terms of light gathering ability! Thanks to Father Eugene Brown for his generosity!
This telescope can provide breathtaking views of many deep sky objects. The scope is equipped with the Argo Navis & StellarCat systems that drive the scope and give it the go-to capability of the rest of our platforms.
S.A. Casby Telescope Platform
Photo by Merle Hiltner ©
Sylvia A. Casby Observatory telescopes
The new Sylvia A. Casby Observatory houses an 8" TMB design refractor, a Takahashi Mewlon 300 Dall-Kirkham and a SV102 refractor. These telescopes set on an Astro Physics 3600 GTO mount, under a 12.5 foot Ash-Dome. As with the Imaging platform of telescopes in the Onan Observatory, cameras will allow live images to be displayed on the monitors in the observatory as well as into the HotSpot Classroom. These sensitive cameras give a more detailed look at objects and can be viewed by a large audience at once.
The 8" TMB will be the largest refracting telescope at the Eagle Lake Observatory. The Takahashi Mewlon 300 will arguably be the best reflecting telescope on site as well. Each of these telescopes will provide exceptional views of the stars and planets.
Additional Equipment - In addition to the main telescope platforms mentioned above, Onan Observatory also has portable equipment for MAS members and guests to use, which include: A Coronado PST solar viewing telescope, Coronado binoculars equipped with white light solar filters, 15x80 binoculars on a parallelogram mount for the ultimate wide field experience.
Total observatory attendance at public, special and other events
in 2013 suffered a decline in attendance with 3109 estimated visitors.
Of the 25 scheduled public star parties in 2013, only 10 had clear skies. Not to be deterred, we continue to be optimistic that 2014 will bring clearer skies for us to enjoy!!
Attendance from past years
| Year || Attendance || Note |
|2003||2500|| 1900 at Star Parties, 600 at Mars Watch Event. |
|2010||3848|| 4th straight year of record attendance!!|
|2011||3345|| - |
|2012||4012|| All Time Record Attendance|
"THANK YOU" to the keyholders and other volunteers who helped conduct these events and who contributed in so many
other ways to maintenance and ongoing improvements at the observatory.
None of this would be possible without your support!!
Frequently Asked Questions
What is a star party?
Public Star Parties at Onan is the opportunity for MAS members to share our passion of the night sky with the public. Public nights at Onan are held about every other Saturday night from March till November with several "special" events throughout the year (Astronomy Day, Our annual Camping with the Stars event or possibly if there is an astronomical event such as a meteor shower or lunar eclipse).
Onan Public Nights are perfect for anyone wanting to be fully immersed in what a star party can be. If the sky is clear, we can begin observing well before sunset at whatever daytime things we can find. Planets, stars and of course the sun are all possible and worth seeing. We have the standard “white light” solar filters for observing sunspots as well as several telescopes dedicated to solar observing with H-alpha filters that show solar granulation and prominences.
On a clear night, the sky is literally the limit... planets, stars, galaxies, nebula, clusters, comets, asteroids, minor planets. Virtually anything astronomical can be observed and explained with the volunteer staff at a public night. In addition, many members and even non-members bring their own telescopes and set up around the observatory and are willing to share what they are observing with the public.
When are the public star parties?
The schedule of public Star Parties at Onan can be found at http://www.mnastro.org/events/showonanpublic.php web page. If you are new to public star parties, please review the "Star Party Guidelines" on the MAS website.
What are the hours you are open?
Generally, public star party hours are from 7:00 pm to 10:00 pm. During the summer nights when the sun doesn't set until later, we will be there at least by 7:00, but the stargazing won't really begin until maybe 9:30 or 10:00. We can be viewing the Sun and possibly star & planets during the daytime if it's clear. In the spring and fall when the sun sets earlier, there will likely be someone there to open the observatory by sunset, even if sunset is before 7:00 pm.
Is there a charge to attend a star party?
There is no charge to attend a public star party, however, Baylor Park will charge $5 for a daily parking fee. If you have a Carver County Park sticker, the fee is of course waived. To help us maintain the observatory, purchase door prizes and to pay the bills, donations to the MAS are also welcome.
Will the star party be cancelled if it’s cloudy?
All Onan public star parties are "all weather" events. Even if it is cloudy, someone will be there to show a video, give a presentation, give a tour of the observatory or answer any astronomy questions you may have. However, there may be a need to cancel due to hazardous weather conditions such as severe thunderstorm, tornados and/or snow storms. If any of these conditions are threatening, please check the MAS website homepage at www.mnastro.org and/or call the MAS info line at 952-467-2426, after 4:00 pm the day of the event for cancellation notices.
Do I need to register for a star party?
No registration is required, you can just show up. If you have a large group of 20 or more, please let us know by emailing us at email@example.com so we know to expect you.
I can’t get to a public star party. Are there any other times I can visit the observatory?
If the public nights don't fit into your schedule, you can also request a "private" outreach event that one of our volunteers would staff. You can post an outreach request on the MAS Discussion Forums or email the outreach list at Outreach@lists.mnastro.org
Additional Frequently Asked Questions on the MAS can be found HERE.