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An unexpected visitor at Andromeda


Miklós Lovas hunted extragalactic supernovae for three decades with the Schmidt telescope at Piszkéstető. Many different phenomena also showed up on the countless photographic plates used to record the images of galaxies. Though some of them, the more interesting asteroids and comets were followed, resources did not permit it in all cases. And sometimes they were simply overlooked. The same happened with the pair of plates where a curious little visitor left its traces. Miklós showed me the photographs and asked me whether the story could be recorded as an interesting piece of history during the interview about Luna-2.

The two photographs were collected on the night of 15th and 16th of december, 1974. It was a tumultous period for the Konkoly Obsevatory: the 1m telescope was inaugurated during that time and László Detre, director for three decades died only a few months before. Those episodes may contributed to the neglect of the small streak next to the magnificent Andromeda galaxy: Miklós overlooked it too, might be considering it as a meteor or other error. He looked at them about half a year later when somebody asked for pictures of the Andromeda galaxy. Them, because photographs were always collected in pairs during the supernova patrol to have a control image. When he looked at the plates they almost knocked his socks off – the streak was there on the second plate, continuing where the first ended, fingerprints of a fast-moving, hence very close asteroid.

The asteroid appears as two almost straight streaks under the great Andromeda galaxy.  Both plates have been projected to a single piece of photographic paper and a small offset creates the "double vision" effect. Supernovae would be easy to identify as single stars without pairs. - Courtesy of Miklós Lovas, © Konkoly Observatory

It was obvious because all objects of the Solar System obey the Keplerian laws of motion – the farther something is from the Sun the slower it moves. So, if we know the exposure time of the photograph, we can estimate the distance of the object from its apparent motion on the sky. That's how Clyde Tombaugh knew the amount of motion to expect from “Planet X” for example and recognized Pluto instantly on his plates. And the visitor next to Andromeda was indeed racing: it covered around 10 arcminutes on the 10- and 12-minute exposure plates. Miklós, with the help of Imre Tóth, measured the end points of the streaks and calculated 20 degrees per day for its apparent motion. Though the exact distance requires correction for the motion of the Earth itself, it was evident that the asteroid passed the Earth roughly in the distance of the Moon.

Back then, before the time of automated asteroid-searching surveys covering large portions of the sky, such discoveries were really rare. Less than a hundred near-Earth asteroids were known during the seventies. An asteroid coming as close as the Moon (would have) meant a much greater discovery than nowadays. So Miklós and his fellow colleagues didn't abandoned the case so easily and wrote a letter to Brian Marsden, director of CBAT (Central Bureau for Astronomical Telegrams). Marsden was a prominent figure of the research of asteroids and comets and the CBAT was the IAU's main hub of discovery reports (supernovae, comets, etc.) – the best place for such message. As half a year already passed, new observations were not expected. They hoped though that a notice would be issued whether somebody else had recorded the asteroid but nothing really happened. Did they announce the discovery right after developing the photograph, the situation would have been different of course: but months later, even if a few more photographs would have emerged, finding the asteroid was as good as hopeless. The asteroid that zoomed past as close as the Moon was lost.

A copy of the letter Miklós Lovas and his colleagues sent to Brian Marsden (click for the full version) - Courtesy of Miklós Lovas, © Konkoly Observatory


...or was it? The body the Schmidt telescope recorded wasn't that small, its diameter could have been somewhere between 0.3-1.5 km (~ 0.2-1 mi), depending on the exact distance and albedo. One of the asteroid-hunting surveys could have recorded it quite plausibly since then, so I've checked the database of NASA's Near Earth Object Program. And there it was, an asteroid discovered only this May whose orbital calculations showed a passage of about 15 times the distance of the Moon on th 15th December, 1974. It looked promising initially, but the distance was one magnitude greater. A more relevant argument was the size: 2011 JV10 is only a 3-7 m (10-20 ft) large (small) piece of rock, it could in no way be the same asteroid. The visitor observed in '74 is still hiding.

The Schmidt telescope at the Piszkéstető Mountain Station. It's nowadays once again used for asteroid and supernova hunting, and have already discovered the second Hungarian near-Earth asteroid. - © Miklós Rácz, Konkoly Observatory


But that's the life of an observer. All sorts of phenomena occur on the sky continuously and no one could pay attention to all of it at once. Miklós himself encountered many more curiosities during the supernova patrol. Five comets discovered, two of which are shor-period ones while the other three moved almost perpendicular to the Ecliptic. Numerous asteroids including a single near-Earth object, 3103/Eger, found in 1982. And yet more curiosities like the variable star CZ Cancri that on one day showed up on a plate, left faint traces on a second two hours later and disappeared. It turned out later that CZ Cnc is a really dim red dwarf star and, like its siblings, it's capable of producing huge eruptions called flares. But the super-flare of 1976 was something we hadn't seen before, brightening the star by a couple of thousands for a short period of time. Or the image where four, similarly moving asteroids showed up, though today no one really remembers any more when did that happen. As Miklós stated, there were some great adventures during that three decades. Some became discoveries, others only interesting stories – ones that are nice to tell.

László Molnár

Last Updated (Friday, 10 June 2011 19:47)

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