Messier, mystery, and SWAN and Halloween
Updates:
Comet SWAN, toodling through Hercules on its way back out from the sun, presented a wonderful opportunity for education – but then it got zapped by space aliens!
Well, maybe not aliens, but help me out here! See, I had some visitors and I thought it would be great to talk a little about how Comet SWAN and M13, which in binoculars look roughly the same, are really very different. And for the past several nights they have been quite close to one another. I mean heck – SWAN was just the sort of think Messier was looking for back in the 18th Century and M13, the great globular cluster in Hercules, was just the sort of "nuisance" thing he was finding and noting on his charts. Hey, if you don't want it in your garden it's a weed, no matter how beautiful it might look to some.
Of course M13 and the other 109 objects on Messier's list are certainly more interesting and more varied than any comets he found . . . but about those space aliens! Take a look at the sequence below. You'll see two, then three, then four little lights that move from frame to frame and eventually appear to go right through Comet SWAN. They start at the top right in frame one and end up at the bottom left in the last frame. (The tracking wasn't so good, so the stars show as small streaks – but not the intruder!)
Now, of course I don’t think anything hit Comet SWAN. I even have a rational theory for what this is. But I may be all wet. It may be some artifact of the video camera I used that I simply don’t know about. Or maybe there's another good natural explanation. So take a look and tell me what you think. I'll publish my thoughts after the images.
The first image above is meant to simply set the scene – identify the field as best I can. (I wasn't keeping an accurate time – in fact, I didn't notice this event until after folks had gone home and I took the DVD in the house and took a look at it. But as best I can judge this was taken about 7:40 pm EST on October 30, 2006. The two field star identifications and magnitudes I took from Starry Nights software.
Keep in mind that these shots were taken with a MallinCam Color Hyper set for six second integration. As I understand it that means each still frame really represents 6-seconds of accumulated video. (Oh - click the picture for a larger image - you may not be able to pick up the "invader" too easily on this s maller version. I had to break these into two blocks of four for technical reasons I don't understand - so if you enlarge them you only get four at a time.) So what we have is an object that is covering about half a degree in a bit less than a minute.
In this second block of four I really like image six where it actually brackets the comet - sort of a Saturn effect ;-)
So what is it?
Meteors just streak right through in the blink of an eye. They would have taken only a single frame. So I don't think it's a meteor.
Satellites would take this long, perhaps - but they're usually more steady in terms of their brightness. Irium satellites are known to flare from time to time - but when they do they are extremely bright - this object (s) is quite dim. Again, according to Starry Nights software Irium 35 passed within about 7 degrees of the comet around this time. The path shown on the image from one corner to another is roughly half a degree. But maybe the software is off? Another satellite candidate is one known as SL-3 R/B. But it too should be around magnitude 6 - much brighter than what I perceive this to be. (Judging from known stars in the field I would say this object is about Magnitude 13 or 14.) If nothing else, this little mystery does illustrate how much space junk there is up there now. As a child in 1957 Ilay on my front lawn, enthralled as Sputnik, the first satellite, pased overhead. I can't remember if I saw it, but I know I was looking. Now there's so much stuff that you frequently see it in the eyepiece. What stood out for me about this event was the "direct hit" on Comet SWANN.
But, what if you have a piece of space junk - say an abandoned rocket motor tumbling end-over-end - it alternately reflects light, then shows nothing. I am assuming that's what we're seeing here and that it tumbled every 1.5 seconds or so. Then again, a satellite like SL-3 R/B cover this distance in less than two seconds and htis took closer to a minute, so ifit's a piece of space junk it must be pretty far out - but not nearly as far out as the comet which doesn't appear to move at anything like that speed. Then again,there are things like "near Earth asteroids" - really scary things that can't be matched by anything we do on Halloween. This is the right day for scary stuff and an asteroid can be an odd shape and tumble and. . . but that's sooooooo, unlikely - just ask the dinosaurs who got wiped out 65 million years ago because . . .
IK - enough silliness. Must be a simple explanation. I'm wide open for a something better than what I've guessed. . If you have one, please feel free to send me an email.
Oh, and if you want to see some real good pictures of SWAN and learn more about this comet, go here.
Updates - solutions!
My friend Bruce Cartwright, who has a keen mind for this kind of problem and an interest in astronomy, played with the images some and writes:
Very Interesting. I kind of like your theory though, at first, I wasn't sure I bought into it being space debris. The object is obviously orbiting the earth as its trail takes the same path as the stars yet much to fast to be out of orbit. My FIRST thought is that it is orbiting the earth perpendicular to the polls in order to produce that effect but then I got to thinking.What kind of space debris would be in perfect orbit? Probably non unless it was moving VERY slowly, essentially geosyncronosly (SP?). I would think you could calculate the speed knowing the time between the first frame and the last and the speed of your telescope tracking. (I also think that it follows the same path should pretty much rule out an optical anomaly with the camera.) Now, if it IS moving that slowly and it is space debris, something that may SUPPORT your tumbling theory: Within the frames, the space between the objects (blinks or reflections) varies and is very noticeable BETWEEN the frames. What I did to illustrate this is to take Frame 4 (just before it eclipses the comet) and Frame 8 (just after it eclipses the comet) and, using photoshop, overladed the images on separate layers as closely as I could. Then on a separate layer I placed a dot on each of the spots with a larger one on the comet for reference. You can see that the spacing between the spots varies significantly suggesting to me that it may be an irregular tumbling reflecting light back at us.
Mystery solved!?!
From Matt Paine, astrophotographer and past vice president of Astronomical Society of Southern New England (ASSNE):
Anyway, I am an astrophotographer myself and have seen the "mysterious dots of lights" in some of my images before. What I think you captured in the Swan comet image is a geo-stationary orbital satellite. The reason you see the multiple dots go across your image in groups of two, three, or four is because the satellite is stationary. With your tracking motors running, usually stepper type motors, the motors with there multiple drive steps, create the tiny "mystery dots of lights" going across your image.
I like this explanation - but some say the ServoCat runs continuously, not in steps . . . then again, maybe mine was misperforming.
Posted by Greg Stone at October 31, 2006 12:38 AM Comments? Please email me: gstone@umassd.edu