Greetings from Palmia Observatory
Well, my bags are packed and ready to travel to Austin, TX tomorrow for the 230th American Astronomical Society meeting and I have run out of time to do any late night observing, but no matter, I just wait for the images to come to me! First image in is an artists conception of the just announced black hole merge event GW170104. The second set of images and analyses is for an image of Sombrero Galaxy (M104), shared by OCA Civil civil-engineer, Marcelo, in which he has coincidentally noticed a slow moving object, possibly an asteroid. So, lets get right to it!
|Artist conception of the two merging black holes in event GW170104 (Source: www.LIGO.caltech.edu/news)|
Ok, if you don't get out yourself to do any observing, well, just wait for some of the younger OCA folks to spend all night at Anza and then share an image with you. This image of the Sombrero Galaxy (M104) has in addition a slow moving object that is visible in the stacked image as the three little dots that show the slow motion movement over about 47 minutes. Pretty neat stacking and tracking to get a good image of M104 and good eyes to notice the moving object. Thanks and great job Marcelo!
|Original image showing unknown moving object near M104 (Image Source: OCA Civil civil engineer Marcelo)|
Marcelo, used some freeware, DS9, which we both discovered while taking a free internet course on astrophysics and analysis of Chandra x-ray images, to plot the measured RA and Dec of the moving object. He asked what databases that I was using to identify potential asteroids. Oh, oh, now this is a different type of problem from what I did as explained in earlier posts, where I was searching for bright asteroids like Ceres and Pallas, and I just had to compare my image with a little moving dot of light to the predicted location for those two asteroids. In this case with Marcelo's image, we don't know what asteroid, if at all, is the mystery moving object.
I said, yes, this should be a fun learning exercise to try to find an existing asteroid to match the image and started by cropping Marcelo's image and submitting that cropped image to astrometry.net to double check the measured RA and Dec of the object. Check out the cropped image below.
|Cropped image with three observations of potential asteroid at different times (Source: Civil Civil Engineer Marcelo)|
This image was submitted to astrometry.net and the resulting sky location of the image came back in agreement with Marcelo's original triangulation.
|Use Astrometry.net to find plate center RA and Dec|
|Use AIP4WIN with Megastar Catalog of background stars to find RA and Dec of possible asteroid|
Source: Palmia Observatory analysis of image from Civil civil engineer Marcelo
|AIP4WIN Report showing location of unknown moving object at times T1, T2, and T3|
Now, we have to look up in some database the possible asteroids that might be the mysterious moving object. But this is the step of finding what real asteroid in the catalog might be the mysterious object that I had not done before. It seemed like I should just be able to use the Megastar software and let it search through the known asteroid data base available for the Minor Planet Center and see what it found. Well, the screenshot below shows the first pass of this operation. Note that the screenshot shows M104 as the blue oval and the field of view of the cropped image is shown as the yellow rectangle. Note that the reference stars in the yellow triangle as just barely visible in this screenshot and show the orientation of the image with the other background stars. Now after searching through the brightest 6000 asteroids in the catalog, the tracks of two asteroids, Alvarez and Benua, are shown. The tracks were selected to consist of three data points, each 1 day apart, so that the motion of the asteroids across the night sky could be more easily observed. The sad thing is that the tracks do not cross the cropped image rectangle and therefore don't represent the unidentified moving object in the rectangle. The ecliptic is shown as the doted blue line in the screenshot and M104 is shown close to the ecliptic also, and this is a good thing because many of the asteroids are found close to the ecliptic. The motion of the two asteroids is noticed to be upwards, that is toward the top of the screenshot, which is also the direction the mysterious object is found to be moving in Marcelo's original image. So that is a good thing. But why don't the asteroid tracks cross the image rectangle?
|Initial overlay of out of date asteroid orbital elements (Source: Palmia Observatory)|
M104 Sombrero Galaxy in Blue; Image outline in Yellow; Asteroid tracks in Red
Well there are a couple of possible reasons. First, the mysterious object might be dimmer than the 6000 brightest objects which I searched for in the catalog. I tried searching through more of the catalog and couldn't find anything. But, a further possible explanation is that my asteroid catalog file is out of date. I have not updated or downloaded a new version of the catalog file for at least a year now. This is probably the best explanation. Maybe the latest asteroid file with the newest orbital elements for the asteroids, which do change over time due to interaction with Jupiter and other planets, etc., and the latest file might then predict that some known asteroid will cross the rectangle just where the mysterious object is found. Now that would be neat! Also, what might be neater is that the mysterious moving object is a new, not observed before asteroid. Ok, ok, yes that would be neat but not very likely. Besides, there is bound to be many chances of operator error in trying to get all of the catalog data to be plotted correctly, etc. I'll just have to download the latest file from the Minor Planet Center and unzip the file to get about 145 megabytes of latest asteroid orbital parameters for several hundred thousand, maybe a million known asteroids.
So, sad to say, since I am out of time for now, we just have to let the mystery ride until next week. Maybe some other alert reader will know the answer right away and let us know?
Until next time,
Resident Astronomer George