[Aerial Photo of Big Ear]
[Radio Observatory]
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Radio Astronomy Displays at
Perkins Observatory
Delaware, Ohio

By Dr. Jerry R. Ehman

Each map and the photos shown below may be viewed in a larger size by clicking on the smaller-size version shown here. The large size maps are very large and will take some time to display, especially if you use a dialup connection.


The two photos below show the Perkins Observatory Building (photo at left) and the front door entrance to the building (photo at right). The object on the lawn in front of the parking lot is a sundial (photo at the left).

Perkins Observatory Building; Sundial in Front Front Door to Perkins Observatory

Perkins Observatory began in 1923 when Hiram Mills Perkins (then 90 years old) officiated at the ground breaking ceremony that began the construction of the observatory that was to bear his name. Unfortunately, Hiram died soon thereafter and was never to see his project completed.

In 1861 the Civil War began. At that time, Hiram Mills Perkins was a professor of Mathematics and Astronomy at Ohio Wesleyan University in Delaware, Ohio. Perkins left his teaching position to join the Union Army. The 6' 4" professor (who weighed only 97 pounds) was rejected by the Army as unfit for service. Undaunted by this, Hiram did the next best thing... he returned to his family's pig farm in southern Ohio and raised hogs to help feed the Union Troops. As a devout Methodist and a man of deep convictions, Hiram felt it would be immoral to materially benefit from the pain and suffering of others (even in such an indirect way as providing food for Army troops). He therefore put his war profits into investments and returned to Ohio Wesleyan University after the war and lived out the rest of his life as a simple teacher.

Upon retirement in 1907, Hiram devoted himself to a new project. Over the next 15 years he drew up the plans for an observatory to be located in Central Ohio. Initially intended to be of modest size, Hiram soon realized that his considerable wealth allowed construction of a world-class facility. When it was completed in 1931, the Perkins Telescope was the third largest in the world. Perkins Observatory had one of the best astronomical libraries of the day, as well as facilities to accommodate visiting astronomers from all over the world. However, its location in central Ohio left much to be desired. For one, all the people who live in Columbus and Delaware very rudely turn on their lights at night. The resulting light pollution severely limited the number of deep sky objects that could be observed. Also, the low elevation combined with typical midwestern weather combined to make the big telescope quite limited in usefulness. Because of this, in 1961 the Perkins Telescope was moved to Arizona, where it is now a part of the Lowell Observatory, near Flagstaff. Perkins Observatory has another, smaller telescope to replace it (a 32-inch, small by professional standards but not small for amateur astronomers).

Perkins Observatory offers many programs to the public, involving both lectures and tours of the facilities. Perkins Observatory also has an excellent website located at: http://www.perkins-observatory.org/
There you will find more of the history of Perkins Observatory, details about their programs for the public, and an excellent section about purchasing amateur telescopes, including a set of answers to frequently asked questions (FAQs).


The following text, maps, and photos are meant to help you find Perkins Observatory (just south of the city of Delaware, Ohio on U.S. Route 23).

Map 1 Perkins Observatory is located just off U.S. Route 23 between the cities of Columbus and Delaware, Ohio, but much closer to Delaware. The map at the left (Map 1) is a small-size portion of a map of Ohio showing Columbus at the bottom and the city of Delaware at the top.

Unfortunately, in order to see what I will be referring to next, you will probably need to click on the image on the left to obtain a much larger version of Map 1, and you will probably have to go back and forth between this text and the larger version of the map. It is relatively easy to go back and forth in your browser, though. After you have obtained the large map, click the <Back> button (or equivalently, use <Alt-left arrow>) to go back to this text. You can then click the <Forward> button (or equivalently, use the <Alt-right arrow>) to go to the large map.

On the large Map 1 locate U.S. Rte. 23 connecting Worthington (a northern suburb of Columbus) and Delaware. Just south of Delaware, look for the intersection of U.S. Rte. 23 with Ohio Rte. 315 at Stratford. Follow Rte. 23 south a short distance until you see a solid red dot; left of that dot you will find the notation "Perkins Observatory". WARNING!! It looks like Perkins Observatory is just off Rte. 315 but that is wrong; Perkins Observatory is just off Rte. 23.

Map 2 At the left is a portion of a map of Delaware County, Ohio (which contains the city of Delaware); this is Map 2. Click on the small version at the left to obtain a large version and use the same <Back> and <Forward> procedure as before.

Looking at the large version of Map 2 locate the intersection of Rte. 315 and Rte. 23 (to the right (east) of Rte. 315; Rte. 23 is shown as a double line). Just below (south) of this intersection are shown 4 black squares labeled in succession from north to south: (1) Methodist Theological School in Ohio; (2) Perkins Observatory; (3) Delaware Country Club; and (4) Tanglewood Golf Club. The new name for the Delaware Country Club is: Dornoch Golf Club.

Perkins Observatory is south of the Methodist Theological School in Ohio and north of Dornoch Golf Club (Delaware Country Club on the map). Although there is a concrete barrier dividing U.S. Rte. 23, the barrier ends just south of the entrance to Perkins Observatory, so you should have no problem being able to turn in to the entrance to the observatory. Caution! Watch out for oncoming northbound traffic if you are coming from Delaware. Also, watch out for golfers and their spherical dimpled projectiles, since the entrance to the observatory crosses the 3rd fairway of the Dornoch Golf Club, and the golfers may not be looking at you as you drive on the road that crosses that fairway. Also, your vehicle may receive a free wash if the sprinkler system is turned on.

Displays About the Big Ear Radio Telescope

Entrance to Room with Displays About Radio Astronomy This photo shows the doorway to the room that contains displays about radio astronomy that were created by the staff of Perkins Observatory (in particular: Gary McCool). There are several displays dealing with the Big Ear radio telescope. There are also displays that deal with other aspects of radio astronomy. See the photos below. Be aware, however, that these displays may change from time to time; hence, the photos you see here may not be absolutely current.

Aerial Photo of Big Ear Radio Telescope This is an aerial photo of the Big Ear radio telescope looking northwest. Both the flat reflector (to the north) and the paraboloidal (curved) reflector (to the south) are aligned east-west. The flat level surface in between the two reflectors (mirrors) is a reflecting ground plane used to shield the telescope from the radio waves generated by the ground underneath (which is 'hot' in the radio band compared to the 'cold' sky).

Explanation of Big Ear website display Perkins Observatory has downloaded a copy of the Big Ear website (www.bigear.org, the website you are now visiting). The computer is not connected to the Internet so that the viewer is not able to link to external websites. [See the descrition in the photo to the left.] The leftmost photo below shows the home page of the website copy. The second photo below shows the page that identifies 7 hotspots on the aerial photo of the Big Ear radio telescope, that allows the viewer to read more about each of the main structures of the radio telescope.
Big Ear website, home page Big Ear website, 7 hotspots

Model of the wire mesh and sash weights used on the Big Ear Plaque describing model of the wire mesh and sash weights used on the Big Ear The leftmost photo shows a model of the the wire mesh and sash weights used on the Big Ear radio telescope. The second photo is a closeup of the plaque attached to this model.

Scale Model of Big Ear in Display Case This shows a scale model of the Big Ear radio telescope contained in a clear plastic case.

Drawing of Big Ear at Time When It Was Planned to be 
720 feet Wide In the early days of designing the Big Ear radio telescope, its designer, Dr. John Kraus, had planned for the reflectors to be 2000-feet wide in the east-west direction and 200-feet high. It became obvious that there wouldn't be enough money to build a facility that large, so he decided to reduce the east-west dimension to 720 feet, the height of the paraboloidal reflector to 70 feet, and the slant height of the flat reflector to 100 feet. The drawing in the photo to the left shows that latter design. However, a second reduction in size had to be made when Dr. Kraus again determined that there would not be enough money for the 720-foot widths, so he reduced the width of the paraboloidal reflector to 360 feet and the width of the flat reflector to 280 feet. Thus, the "Big Ear" was constructed with those dimensions. Construction began in 1956 and was completed in 1961. Several years into its operation, funds were available to widen the flat reflector from 280 feet to 340 feet.

Painting of Radio Sky at 1420 MHz Used as Background 
for Other Displays Painted on the wall and serving as a backdrop for several displays is a representation of how the sky would look at a frequency of about 1420 MHz (where the Big Ear did most of its observations). At the bottom is painted a representation of the "Big Ear" viewing it toward the east.

Radio Contours and Photo of Andromeda Galaxy (M31) This photo shows a photograph of the Andromeda Galaxy (M31) taken with the original 69-inch optical telescope of Perkins Observatory overlaid with contours of radio strength of the same area as measured at about 1420 MHz by the "Big Ear" radio telescope. This photo got considerable worldwide attention after it was published because it clearly showed the usefulness of comparing optical and radio results (previously, there had been little cooperation between optical astronomers and radio astronomers).

Wow! Signal Computer Printout; photo with flash [Caution! The large-size version you get when you click on either this photo or the one below is very large and will take considerable time to download under typical dialup speeds.] This photo is that of a color copy of the computer printout of the "Wow!" signal. It shows in red pen Jerry Ehman's handwritten exclamation of astonishment after recognizing the importance of the sequence '6EQUJ5' in channel 2 (shown circled, also in red pen). At the request of Gary McCool of Perkins Observatory, Jerry wrote a short message and autographed this display copy. [Note. This photo was taken with flash.]

Wow! Signal Computer Printout; photo without flash [Note. This photo is the same as the photo above except that it was taken without flash. The brownish color is due to the incandescent lights in the room.] At the bottom is a portion of the caption for this display; this caption is shown in the next photo.

Caption for Wow! Signal This shows the caption for the "Wow!" signal computer printout display shown above. Originally, there was some confusion about the date of the observation, whether it occurred on August 15, 1977 or August 17, 1977. Later, it was determined to be August 15, 1977 and that date was handwritten on the computer printout in the upper right corner. The caption here references the incorrect date.

3-Dimensional Chart of Wow! Signal [Caution! The large-size version you get when you click on this photo is moderately large and will take some time to download under typical dialup speeds.] This photo shows a graph (plot) of the "Wow!" signal data. Time increases from left to right, channel number (for just the first 6 channels) increases from front to back, and signal strength, measured in multiples of the noise background (standard deviation of the data excluding the strong signals), increases vertically. The "Wow!" signal is the biggest response just right of center.

Russ Childers' Memorial to Big Ear At the Ohio Historical Society/Ohio Bicentennial Commission Big Ear Marker Dedication Ceremony held on November 5, 2000, Russ Childers read his composition "A Memorial to Big Ear" . It is reproduced in the framed document shown in this photo. Russ was the chief observer during the last years of the operation of Big Ear. He wrote the computer programs for LOBES (LOw Budget Extraterrestrial Survey), our narrowband sky survey that followed up on the original narrowband survey in which Jerry Ehman saw the "Wow!" signal.

Other Radio Astronomy Displays and Projects at Perkins Observatory

Computer Predicting Radio Bursts from Jupiter In the same room that contains displays about the Big Ear radio telescope are other displays dealing with radio astronomy. This photo shows a computer monitor showing when radio bursts from Jupiter may be viewable.

Radio Listening for Radio Bursts from Jupiter In this photo we see a computer monitor showing the output of a receiver connected to an antenna pointed at Jupiter. It's purpose is to display Jupiter's bursts of radio waves in the frequencies near 20 MHz.

Twin Yagi Antennas Receiving Radio Bursts from Jupiter This photo shows the antenna system used to receive the radio burst signals from Jupiter referred to above. This antenna system is a "phased array" of two Yagi antennas. A Yagi antenna (named after the Japanese inventor) has the property of high directivity (which means that it is quite sensitive in one direction and quite insensitive in most other directions). A phased array is a system in which 2 or more antennas are wired together to further enhance the sensitivity in a certain direction.

Twin Yagi Antennas on the Roof This photo shows the twin Yagi antennas used to receive radio bursts from Jupiter. These antennas are located on the roof of Perkins Observatory, as seen from this photo.

Computer Display of SETI@home Millions of folks have downloaded the SETI@home screensaver to analyze data taken with the 1000-foot dish located at Arecibo, Puerto Rico. Perkins Observatory has done so also.

Dish Antenna for Radio Telescope This satellite dish is the first one installed as part of an array of dishes used as a radio telescope.

PHOTO CREDIT: The two maps were scanned and all photos were taken by Jerry Ehman.



Copyright © 2003-2006 Ohio State University Radio Observatory and North American AstroPhysical Observatory (NAAPO).
Designed by Jerry Ehman.
Last modified: January 20, 2006.