Just to get this off the table up front, this isn’t really an observatory. The Holmdel Horn Antenna (HHA) is a single piece of equipment that is sitting out in a maintenance yard behind a laboratory in New Jersey, even though it is a national historic landmark. What gets it on my list to visit is that it is the piece of equipment that provided evidence for the Big Bang theory of the origin of the universe, thus revolutionizing the field of cosmology.
I had read about the Holmdel Horn Antenna somewhere some years ago and heard about it a number of times in stories and podcasts about cosmology. When I started putting my Grand Tour together I looked it up and found an entry in the >Atlas Obscura< website, describing it and its location. For some reason, I thought having read this some months earlier would be adequate for me to find the thing without notes, maps, or GPS. Lesson learned. Little in life is that simple. Now, however, as a result of my naiveté, I have an interesting story.
I started the day at Williams College at the Hopkins Observatory with Dr. Jay Pasachoff showing me the 7″ Clarke refractor, as you may recall from this entry. I figured I had about four hours from northern Massachusetts to Holmdel, New Jersey, and it was before noon, so I expected to be there mid-to-late afternoon and on to Princeton in time for supper. Here’s why I’m not an engineer: I failed to take into account that I was driving into the greater New York City metropolitan area on a Friday afternoon, and that I did not have an exact address for my destination. These are pretty basic considerations for travel estimates probably, so my four hour estimate easily turned into more than 5 hours. Well, I knew I was going to Holmdel Road, but I had lost track of the Atlas Obscura article that has both the address and the coordinates, I did not yet have a smart phone with a data plan, and in my searches from Williamstown, Google was not precise about the location.
I got to Holmdel Road and went up and down it a few times, looking for a sign or historical marker or something to no avail. I was running low on gas, so stopped at a gas station. Full service only in New Jersey, of course, so as I was getting a fill up, I asked the fellow pumping my gas if he knew where the Horn Antenna was. He looked at me a bit and asked, “You a HAM operator?” “No, amateur astronomer,” I said. Turns out Mike (the guy’s name is Mike) is HAM who got his start looking at Saturn in a telescope at the family lake house upstate when he was a kid. Now he lives close to NYC, so Venus is about all he can see. BUT he is a HAM and has talked with the ISS as it passed over. How cool is that?! And yes, he did know where to find the Horn. Go down Holmdel to thus and such, turn left, go about a mile to the Bell Labs facility. It’s out in the yard around back, you can’t miss it. They’ll never move that thing, he said, because it’s a national landmark and it’s huge.
Okay, off I went, following Mike’s directions. I knew the turn he mentioned pretty well, as I had used it a couple times already. But his 1-mile estimate was as good as my time estimate, as it turned out to be about 3 miles to Bell Labs. I drove onto the campus and drove all around the loop, all around the extensive building. No horn. I drove around a couple times. No horn. So I went to the front door and in to find someone who could direct me, which I eventually did. This guy says “Horn antenna? Is that what they call it? I didn’t know that. But yeah, you just go out of the parking lot and turn right, and it’s right there. Can’t miss it.” Okay. Out I go, turn right. No horn. There is something there, though. It’s a small memorial to Karl Jansky that looks like two old steam heat radiators. I recognized it as essentially a stylized version of the replica they had Green Bank. Cool, but not the HHA.
Back I went to the building. By now it’s well after 5:30, and there is almost no one around. I went to a security/information desk and asked another fellow if he could tell me where the HHA was. Nope, no idea. “Can you look it up on that computer you’ve got there?” I asked. Nope, the internet was down, or he didn’t have the login, something, I don’t remember what, but no, he couldn’t look it up. “Is there anyone else here who might know?” Yeah, maybe. So, God bless him, he leads me off across this enormous lobby, half way across the building, and we find a guy who ought to know. “This guy is looking for the Horn Antenna,” says my guy. The other guy says, “Oh, they moved that years ago!” Oh really? That’s not what Mike told me, I said to myself. “Yeah, they moved over to the Nokia Labs over on Holmdel Road.” Well, I had been past that several times, so I knew exactly where it was. Thanking them both profusely, I headed out.
Got to the Nokia Labs site and found a sign: “Horn Antenna – ESCORTED ONLY.” Ugh. So I went to the building to see if there was anyone that at 6:15 p.m. on a Friday who could escort me. LOL no. Well, I hemmed and hawed for quite a while, even pulling out my laptop to see if I could wardrive their WIFI to find that article I’d seen. Finally, I decided just to take my chances with whatever security they may have (which turned out to be none), and up the hill I went. I mean, after all, it is a National Historic Landmark.
Ah, There You Are
Finally, driving into what is basically a maintenance yard with trucks and tractors and sheds and garages here and there, I found the Holmdel Horn Antenna National Historic Landmark. As I write this now, I can objectively compare this antenna to the GBT, to the Sub-millimeter antenna, and to the VLA, and say the HHA is not very big. But in the moment, after such a long search, as I stood near it the thing seemed huge! I guess I wasn’t expecting something 20 feet across the front, 40 feet high, and maybe 80 feet long. As you can see from my pictures, the front edge is curved like a scallop shell or maybe more like a nautilus, as there is an opening and a membrane over the back of the dish forming a funnel or … a horn! It is designed to rotate in altitude and azimuth to point anywhere in the sky, but they keep it pointing at the ground so it doesn’t fill up with precipitation or trash.
It was originally used to track early satellites and such in the 1950s and 60s. Then in 1964 two Bell scientists, while working on some other project, found this low level noise wherever they pointed the antenna. As they eliminated a wide variety of possible sources, they came to realize they may have found a kind of background radiation in the universe. It took some others getting involved, too, if I recall correctly, before all the pieces came together to show that what they had found was the predicted leftover light from the Big Bang that had stretched and shifted across the billions of years of the universe’s expansion from visible light wavelengths of hundreds of nanometers to microwaves with millimeter wavelengths, about 10,000 times longer.
I spent about 6 1/2 hours getting to the Horn that day and then spent about 10 minutes actually looking at it. I’m so glad I found it, though, and those 10 minutes were totally worth it. I was fascinated by this piece of industrial science, with its motors and gears and girders and bolts and all, that by chance detected one of the most sublime forms of radiation in the universe.