(Note: this article was originally published in 2005 on my defunt astronomy tourism site: ScopeSeeing.com. A related press release may be found here. 2003 UB313 was ultimately named Eris, and in the process helped to dethrone Pluto to “dwarf-planet” status.)
On the morning of October 9th, 2005 a small team of amateur astronomers visually observed the 10th planet using McDonald Observatory’s 2.1m Otto Struve Telescope. Keith Murdock completed the first observation at 1:08 AM CDT. Louis Berman made a second confirming observation at 1:15 AM CDT. Over the next hour the planet was subsequently observed by seven additional team members and two McDonald Observatory staff.
Scopeland: The planet is around 18.75 apparent visual magnitude. This fact alone says that it can only be observed visually through big scopes with 2m apertures and above. Needless to say, very few of these scopes sport eyepieces in regular use. Indeed, I could only find three—all in the United States : the 2.1m Otto Struve, the 2.7m Harlan J. Smith (also at McDonald Observatory) and the 5m Hale at Palomar. There may be a couple more that I am unaware of but the ultimate list is without a doubt very very small. In any case, getting access to any one of these on a reasonable night is a non-trivial undertaking. Also, the Smith and Hale scopes can only be used visually through their high F-ratio Coude foci; a sub-optimal solution at best.
Dimsville : The planet is an extremely dim object. Edwin Hubble might have had little problem picking out an object of this class but you can take it as an article of faith that very few living humans have ever observed anything at this magnitude with their eyeballs. It’s an even harder task when the visual limiting magnitude of the scope is close to the apparent magnitude of the object itself. The Otto Struve could only resolve 19.2 – 19.4 magnitude objects depending on object location, seeing, extinction, etc., which didn’t leave us a lot of breathing room. Beyond this, the brightest stars in our observing window were 14th magnitude, making visual orienteering a difficult process at best. As it turned out the planet was the single dimmest averted vision object that I’ve ever seen. Nothing in my experience even comes close.
Howington: Developing an observing protocol good enough to turn mere bragging into repeatable verified fact is no small task. In our own case we started by generating a series of ephemeredes using JPL’s Horizons system. Next, Jim Burnell (co-author of The Handbook of Astronomical Image Processing and the only team member who didn’t join us in Texas) imaged the planet on 9/25, 9/28 and 10/1. This helped to prove that we had a clean set of orbital elements to match up with real world observations. We subsequently confirmed that the MPCORB database, which we used with TheSky to research individual guidestars in the field, was similarly accurate. This became especially important when it came to projecting the location of the planet during the actual observing window and generating finder charts. One unexpected difficulty was revealed at this stage when comparing the projected star charts on my laptop against printed versions of Jim’s images. My pixels were a bit squashed; a significant error that had to be compensated for. The next task was researching the magnitudes of the surrounding objects to aid in eyepiece orientation. This was surprisingly important since 15th mag and above was visual Terra Incognita for us. Finally, Keith prepared a set of printed finder charts overlaid on Jim’s images which were used during our final prep and at the scope.
Realia: No amount of preparation can cover every eventuality at the eyepiece. Therefore, the ultimate the success of the project came down to skill. For starters, the attempt would have been impossible without Jim Burnell’s deft hand with a CCD. Then again the finder charts would have counted for little without Keith’s superlative observing ability. Happily, we lacked for neither. The finder charts were particularly good and Keith had some serious game on that night. We spent an hour or so warming up on the scope then around 12:45 AM CDT we slewed it to the general area. Keith focused the scope and got down to refining the aim. It took some twenty minutes until Keith finally bagged the little beastie. At1:08 AM CDT he formally announced that he’d observed the planet and was confident that his observations were good. I was up next and (after five excruciating pain-in-the ass minutes with the ridiculously twitchy electric focus!) I saw it too! I described the star field in great detail which was then validated against the charts; a protocol that was followed by the subsequent observers. It took another hour for the rest of team and staff to rotate through, with much of the time spent fighting the focuser. Ultimately, everyone observed the planet and confirmed that reality matched the finder charts very, very well. Two months of dreaming and all of our hard work became an “abrupt” success.
Coolsburg: 2003 UB313 co-discover Mike Brown assured me a couple of weeks ago that we were the only group he knows of with plans to visually observe the planet. Now it’s certainly possible that someone else got there before us. If so then I unreservedly applaud them. Regardless, I have no interest in claiming any sort of primacy for our efforts. It seems a bit silly, like claiming to be the first person who attended a rare concert. Yes, you could be the first audience member inside the hall. You might even be able to document your “accomplishment” with photos, ticket stubs, whatever. Regardless the real artists (Mike Brown, Chad Trujillo, and David Rabinowitz) were there way before you. Much more to the point, it’s their show, not yours.
Even so, there’s something amazing about doing something so rare, so very esoteric. My friend and team-member Jim Small said, somewhat pompously for effect, that “Twelve men stood on the moon, but only eleven astronomers have seen planet 10 with their own eyeballs!” Yes, he’s overreaching big-time, but he’s also captured something essential. Astronauts and astronomers do indeed share at least one particular; our persistent outward-facing vision. Yesterday, a few humans, dare I say humanity itself, peered outward once again.
Louis S. Berman
St. Louis, MO, October 10th 2005