Transients have always been intriguing because whether at optical, radio or other wavelengths, they usually flag an object worth watching. Consider a supernova, or a Fast Radio Burst. But non-repeating transients can have astronomers both professional and amateur tearing their hair out. What was Henry Cordova, for instance, seeing in the Florida sky back in 1999? The date seems significant, as we were moving toward the Y2K event, and despite preparation, there was some concern about its effects in computer coding. Henry, a retired map maker and geographer as well as a dedicated astronomer, had a transient that did repeat, but only for a short time, and one that may well have been entangled in geopolitical events of the time. I’m reminded of our reliance on electronics, and the fact that some 60,000 commercial flights have encountered bogus GPS signals, according to The New York Times (strikingly, the U.S. has no civilian backup system for GPS). What goes on in orbit may keep us guessing as we begin to build a cislunar infrastructure. As witness this oddity.

by Henry Cordova

At about 11:30 PM, EST on 31 December 1999, I was taking out the garbage. I live in South Florida, so the weather was warm (I was wearing gym shorts, flip-flops and a t-shirt) and the sky was crystal clear. I paused to admire Orion, high in the sky and near the meridian, when I noticed a bright (about magnitude -1 or -2) strobe-like flash just south and west of Rigel. This sort of visual phenomenon is difficult to spatially locate with any precision; let’s just say it appeared to be roughly near the SW corner of the Hunter asterism. As for the flash itself, this is not a particularly unexpected event in my nighttime sky. I often see aircraft at high altitudes where their navigation lights are not visible, but their strobes stand out clearly.

I paused for a moment to see if I could catch it again, and sure enough, about a minute later it reappeared. The same bright flash, in the same general area. But unlike an aircraft, this time the light did not seem to move as you would expect a light attached to an airplane or satellite. It was in the same general area, I couldn’t judge exactly where, but it was definitely not moving. I continued observing and sure enough, about a minute later I saw it again, same flash, same place.

It had my attention. Over the next hour or so, I remained in the yard, next to my garbage cans, eyes riveted on Orion, high in the sky at my latitude. I missed the Times Square New Year’s festivities on TV. I contemplated going into the house to get my binoculars, or a watch, but decided against it. I did not want to risk missing anything or losing my eyes’ dark adaptation. I saw several more flashes, of the same brightness, at the same intervals, and at the same location. Sometime after midnight the show ended, and I went back in the house.

The following evening (1 Jan 2000!), at about the same time, while jogging, I saw the flasher again. It’s been over twenty years now, so I don’t remember how many times I saw it, or what time of night exactly, but it was in the same place and it looked the same. It flashed more than once, two or three times, about a minute apart, and then…nothing. I’ve never seen it again.

So what was it? A few possibilities can be immediately ruled out: it was not a high-flying aircraft or a satellite in low Earth orbit, I am familiar with those objects and that is not what I saw. The flashes did not move on the celestial sphere so it must be something further out. Another possibility is a solar reflection off a geosynchronous satellite; at that time and date, the solstice Sun, Earth and flasher were roughly aligned and the celestial equator runs through Orion’s belt.

I live just north of the Tropic of Cancer so the geometry for a reflection is certainly possible. But the flasher was bright, as bright as the old Echo satellites, or the ISS. I’ve heard of amateur astronomers photographing solar reflections off geosynchronous orbiters, but they are very faint, requiring specialized equipment and highly skilled observers. And it’s unlikely to be an accidental reflection, which would not occur repeatedly, and especially at the turn of the new Millennium.

I suppose the flashers could be the manifestation of some cosmological event in deep space, perhaps something like the “X-ray or gamma ray flashers”, but if so, I’ve never heard anything about them in the astronomical press. Head-on meteors are another possibility, but I think that’s highly unlikely.

My guess is that these are reflections off surveillance satellites, spies in the skies. The flashes were not solar, but beacons or reflections from powerful lasers, used in some ranging or calibration procedure, or perhaps the sign of an actual attack on the satellite–an attempt to blind or confuse its sensors.

I also recall reading somewhere that there is a gravitational “sweet spot” somewhere along longitude 90 W. The Earth’s gravitational field is not perfectly spherical. It has bumps and wrinkles, places inherently unstable or stable, respectively, to geosynchronous satellites. An object placed at one of the dips would have a tendency to remain there and not require constant fuel expenditure to remain on station.

Such spots would no doubt be reserved for national security orbiters. A geostationary satellite placed there would be able to continuously monitor radio traffic or missile launches on the eastern USA or the Caribbean basin. To an observer on Earth, such a satellite would appear to slowly wander east and west, and north and south, of a spot on the celestial equator. These would be highly secret missions, but I suspect these are big birds, perhaps with huge antennas deployed on them.

You will recall all the concern in those years about possible “Y2K” events, errors caused by programmers failing to code their software to accommodate the change to the new century/millennium. As it turns out, not much really happened, but there was a general fear that problems might occur. I even recall reading that there might be issues with our spy satellites. As it turns out, I do recall reading in the general press a few weeks later that some “minor Y2K problems” occurred in our orbital reconnaissance vehicles, but that they were quickly taken care of. Hmmmm… even if this were true, why would they bother publicizing it?

I certainly don’t know what the flashers were, and I’ve never heard about anyone else seeing them. Perhaps someone reading these lines can suggest a solution to the mystery. Until then, I can continue to think that maybe, just maybe, I may have witnessed one of the last battles of the Cold War.