The Discovery, Re-discovery and Recovery of Comet Pigott-LINEAR-Kowalski

There has been a long held rule that comets can not be named after more than 3 discoverers. In the days of slow world-wide communications, it was not uncommon for a comet to be discovered by numerous observers before the official discovery announcement could be made. As a result, many comets had three names attached to them. With the internet, the frequency of triple named comets has decreased. The latest comet to bear three names is Comet Pigott-LINEAR-Kowalski and 226 years passed between the time it acquired its first and third name.

Edward Pigott of York, England first spotted Comet Pigott on November 19, 1783. Astronomy ran in the Pigott family as his father was also a well known astronomer. The comet was lost after the 1783 apparition. Due to the primitive state of measuring comet positions as well as orbit determination, it was not unusual for comets to be lost until rediscovered at a later time.

That later time came in January of 2003 when the LINEAR survey found a “new” comet with their telescopes outside of Socorro, New Mexico. Within days of its discovery the LINEAR comet, now designated Comet C/2003 A1 (LINEAR), a suggestion was made that it might be a return of long-lost Comet Pigott. Unfortunately, it was not possible to made a definite link between the 2003 LINEAR comet and Piggot’s 1783 find. The comet would have to wait till it was observed at yet another apparition.

A few weeks ago on the night of Sept 10, Rich Kowalski of the Catalina Sky Survey was surveying the sky for unknown comet and asteroids when he came across a possible new comet. Rich shared some of his thoughts on his latest comet find:

The Catalina Sky Survey, along with most of the observatories in the American Southwest, do not observe during July & August each year due to our rainy season, known locally as the Monsoon. It gives us the time to repair and maintain our telescopes and upgrade instruments and facilities. Time that is precious and isn’t used for these things during the other ten months of the year which is our “Observing Season”.

This year’s season started right after the Full Moon of September and as luck would have it the first night was rainy and cloudy. Even though I was at the Catalina Schmidt telescope, I could not observe. The second night of my run and the actual first night of the new season was much better. I could observe most of the night, even though some clouds remained during the first few hours. It wasn’t long before I discovered a new Near-Earth Asteroid, 2009 RH, a small rock only about 50 meters (150 feet) across. The rest of the night continued with our normal pattern of observing various parts of the sky systematically, looking for these asteroids.

A few hours before dawn, with the waning gibbous moon climbing high in the sky, our software showed me an object that was faint and very diffuse, almost a wisp of light like the reflections off the optics we sometimes see when there is a bright star close by, but this one was different. It isn’t uncommon for us to spot comets on our nightly search and after a while your eye becomes trained to see the differences between asteroids, galaxies, reflections in the optics and comets. This one looked like a puffball of a comet, with no tail or the central condensation that many comets have, but I knew right a way it was a comet. As I said, spotting comets is not out of the ordinary and almost every time we see one the comet is already know. I copied the coordinates of this comet into the Minor Planet Center’s “Comet Checker” web page, fully expecting it to identify the comet just as it had done several times before during that same night.

This time it did not come back with an ID.

“Oh really?” I thought to myself.

It had been nearly two years since my last comet discovery, P/2007 T2, a comet I discovered on my birthday. After seeing that it was not identified, I took a closer look to make sure it was actually a comet before reporting it to the MPC and the Central Bureau for Astronomical Telegrams (CBAT). CBAT is the clearinghouse for reporting comet discoveries, just as the MPC is the clearinghouse for positional observations and discoveries of asteroids and planetary satellites.

I then proceeded to have our software schedule additional observations of the comet later that night and continued searching for more NEOs. I secured these observations before the sky started getting bright from the coming dawn.

The next night was mostly clear again and I continued the search for more NEOs. By the time this new comet rose high enough in my sky for me to observe it again, no other observations had been reported, so I made some additional ones to confirm it was real and to help determine it’s orbit. Before the night was over a few other observatories had reported additional observations.

When the Circular announcing the discovery of the comet was released I was a bit surprised that it had been determined by Dimitry Chestnov, an astronomer in Moscow, that this comet was actual the return of an object that was found by a fellow NEO survey in New Mexico called LINEAR in 2003. It was also thought that it might also be the comet Edward Pigott discovered in 1783, but no one could be sure. After my discovery, the two objects, my comet and the one found by LINEAR were clearly one and the same, but its position was very far off from where it should have been in the sky. It was found that this comet had a close encounter with Jupiter exactly three years to the day before I picked it up with the Catalina Schmidt. The recent observations, along with those made in 2003 made it obvious that this was indeed the comet that Pigott had discovered in 1783 and had been lost for 226 years!

It was an interesting and exciting way to start off the new observing season and whets my appetite to the other things my colleagues and I will discover in the coming year!

With the identification of the latest Kowalski comet with P/2003 A1 (LINEAR), it was possible to link the comet with the 1783 Pigott comet. The comet is now known as P/2009 R2 (Pigott-LINEAR-Kowalski) and will probably be officially numbered as comet 226P/Pigott-LINEAR-Kowalski.

Though the comet was bright enough to allow small telescope users to see it in 1783, it no longer gets as bright. It is likely that the comet was in outburst in 1783 which caused it to get brighter than usual. Also in 1783 the comet approached within 1.46 AU of the Sun. Now the comet only approaches within 1.77 AU of the Sun. Since it is 4 months past perihelion the comet barring another outburst will slowly fade from its current brightness of 17th magnitude.

The 4 recovery images of Comet Pigott-LINEAR-Kowalski taken by Rich Kowalski at the Catalina Sky Survey on 2009 Sept 10. The comet is located within the small purple circle. Credit: Rich Kowalski/Catalina Sky Survey/NASA