by Ted Frimet
sheer dumb luck
Not everything is as it seems. And sometimes, despite months or years of amateur training, a gain in insight can be chalked up to “sheer dumb luck”. As most of our AAAP club members are aware, I’ve been hunting an asteroid. And J2012 TC4 came into our field of view, quite nicely in fact, on October 11, 2017 – between the wee GMT hours of 04:01:28.432 and 04:04:38.185. Ten images, at 5 second exposure each, were captured with the Prompt-8 telescope, located at Cerro Tololo Inter-American Observatory, Chile.
|FOCAL LENGTH:||4000.0 mm|
|FILTERS:||B, V, R, I, Red, Green, Blue, Lum, Clear|
|CCD SIZE:||2048 x 2048 (13 um pixels)|
|FOV:||23.8 x 23.8 arcmins|
|SITE:||Cerro Tololo Inter-American Observatory|
Snippet from skynet robotic telescope network prompt 8 status page, Saturday, October 28, 2017.
The telescope location is at latitude -30:10:3.300’, longitude -70:48:19.200’ (negative means“South”). Why, oh why is he giving us coordinates for his telescope? As I learned, a month before making a Near Earth Object (NEO) observation, the number one thing to remember in Outer Space Real Estate is, “LOCATION, LOCATION, LOCATION’ ! ! !
Sounds easy. Yet, here I am weaving a Saturday morning tale of “woe is to me”, for testing the limits of unknown parameters. I unknowingly ran smack dab into ye old Murphy’s Law. I didn’t know that Murph held title to an NEO. Despite being fenced in by my own mistakes, Murph told me that good fences make good neighbors, and he let me take a peek at the old gal for 10 decent exposures.
What went wrong? Nothing really. That is if you do not count the fact that Skynet – and I must stress – PROPERLY – dispatched my observation requests to sites other than Chile. We took a swing by the R-COP telescope, located at Perth Observatory, Australia, as well as a side-step to the Dark Sky Observatory, DSO-17, in North Carolina, USA. Neither of these observations were validated with an asteroid find. And that, my fellow amateurs, is because the detail lay in the ephemeris data.
I was feeling fresh and all squeaky clean from a visit to NASA’s JPL Horizon database for ephemeris data on our asteroid. I wistfully entered data into the Skynet Robotic Telescope Network Advanced mode. At the time of generating the ephemeris data, I changed my locus to the La Serena site, in Chile, where the Prompt telescopes are given astronomical sanctuary. I made specific requests to match the Right Ascension (RA) and Declination (DEC), gleaned from said ephemeris, right into Skynet, with a matching specified “time of capture equals past mid-night”. I was galavanting past midnight (as my Grandmother would say).
And there’s the rub. Skynet is programmed to direct your request to the next available telescope in your observers list. As I didn’t want to get cheesed out of targeting my asteroid, I left in a healthy dose of alternative ‘scopes. Sans the matching ephemeris data. And that’s when ‘ol Murphy stepped in. If you were imaging stars, your location wouldn’t be quite as critical. However, when you are locating a NEO that is one-tenth Lunar distance from the Earth, your location is important. Ouch. Parallax became the answer to a month long question, as I reviewed, and generated movies for the Australian data, some 6 or 7 times, – leading to negative results.
As I may have mentioned to one or few AAAP members, I do not fear the consequences of failure. I endure, and learn from every miss-step I encounter. I am sure that if I had allowed SkyNet to select my RA/DEC, and automatically reassign to telescopes in waiting, all would have been well. However, my ego got in the way, and I felt that exercising an additional degree of control would be for the better. Nope. I built that fence for Murph, all by myself. “Scored an own”, as the British say. As I found out, a month later, my newest neighbor even tossed in a free doorpost, as the DSO in NC, was of course, not located in a La Serena, observers location.
At the time of this writing, I was planning on establishing tighter magnitude measures of 2012 TC4. I was going to make lemonade out of the lemons of R-COP and DSO-17. The elephant in the room, is of course, parallax and that there is no data to measure in those astro-images.
I am planning to program a course of observations of Algol, a variable star, from minimum to maximum, to map out its magnitude (thanks to John Church, AAAP for pointing out the RASC data on the web). And to compare the results to knowns, so as to establish my own candlestick. And then to revisit the 10 successful images taken by Prompt-8 and re-sample the magnitudes, and make some coarse adjustments. Armed with some self-obtained results, I will be able to compare my magnitudes with the NASA data, and decide if the asteroid is closer to being 15 meters or 28 meters wide. Or perhaps, if it emits more light than predicted (thanks to Gregg Waldron, NWJAA for pointing this out) – that I have proof that 2012 TC4 is a younger asteroid, as opposed to being an old beaten space rock, not unlike my neighbor, ‘ol Murph.
Please note that although hundreds of observations were made of this NEO, there were only two observatories that posted videos that focused primarily on the science of the asteroid. That was the Kiso observatory in Japan (whose primary focus is on super-novas), and our video composited from the images taken from Cerro Tololo – whose credit of telescope stewardship can be found with Dr. Dan Reichart of UNC, Chapel Hill, as they hunt for the after glow of gamma ray bursts.
Video, as promised: