After getting my feet wet observing and measuring a few bright minor planets, I’ve been working on how to find and observe Near Earth Objects or NEOs. The resources and guidance I’ve been getting from the “A-Team” at Slooh.com have been invaluable in helping to identify and image NEOs, and to analyze and confirm results. And I even was able to get a set of observations accepted by the Minor Planet Center, and published just this week!
The first step is to identify objects that can be observed and are useful to report. One key resource is the European Space Agency’s Priority List. It classifies newly discovered and critical objects into priority categories for follow up observations. Many of these are recent discoveries of asteroids approaching Earth where it is vital to get accurate observation over as many days as possible in order to better determine their return time and potential risk. The list includes many small minor planets that can only be seen with very sensitive telescopes, but can be filtered by visual magnitude to highlight the current brighter targets.
The MPC also maintains lists of newly observed potential NEOs needing confirmation. It looks like these often originate from the large scale surveys and are confirmed by public and private observatories with high power gear. But there are usually a number of known minor planets needing follow up for various reasons and the more accessible ones can be found on the Bright Recovery Opportunity page. Note there is link near the top to customize the page allowing input of magnitude and position ranges. Again, filtering this list to mag 19 helps narrow this down to the lower hanging fruit. (Note that the magnitudes are approximate and can increase or decrease over time so its OK go a bit below what you can detect).
Back in early February, I noticed the minor planet (163243) 2002 FB3 on this recovery list. The body is numbered, so it has been observed for some time and should be well characterized. (The designation 2002 FB3 is the working identifier before it graduates with a permanent number). But the body had not been observed in a couple of years and turns out to be one worth checking up on from time to time. The object is fairly bright and was at a high southern declination, so I thought it would be worth a try from the Slooh observatory near Santiago, Chile.
The declination was actually very low, at over -70 degrees. From the Chile observatory W88 it would be found to the south at an elevation of 45-50 degrees. That is reasonably high up in the sky, but the Slooh observatory is on a mountain north of the city, so the view looking south over the town is subject to a fair amount of light pollution. But after solving the images in Astrometrica a moving object was visible right where expected:
Astrometrica has a feature that marks known objects according to the MPC orbit database currently loaded. The position can be approximate for newer objects with approximate orbits but it generally spot on for numbered objects. In the image above, there is moving object in the position expected for #163243 which should be our target. The identified object can be selected and the position determined from each of the images. Note the image above has a long streak which is fairly common in these pictures and are probably trails of meteors or artificial satellites.
The object was visible again on the following night, so it looked like I would have enough data for a submission to the Minor Planet Center!
After working up the observations for both nights and sharing with the “A-team” at Slooh, it was pointed out by the group’s mentor, Tony Evans, that the object I had picked up is on the MPC Critical NEO list and well worth reporting. It is a large enough asteroid to be classified as a Potentially Hazardous Asteroid (PHA), and at an estimated diameter of 1620 meters it would definitely be a bad day if it were to directly cross our path. The object has no predicted close encounters in the next 100 years, but is on the MPC Critical List as body worth checking on from time to time. Minor planet 163243 is also an Aten class asteroid. This class has an orbit that lies primarily between the Sun and the Earth. These have a relatively short orbital period (243 days in this case) and they are harder to observe since they are often located towards the Sun.
After checking my observations using a tool to calculate residuals and a few attempts at formatting everything properly, I got the green light to submit the data via email to the MPC. An acknowledgement was promptly received, so it looked like my report was accepted – the only thing left to do was to wait for publication!
If I were to establish my own observatory at home and wanted to submit results to the MPC, I would need to qualify for an observatory code by submitting observations of known objects for evaluation. The Slooh observatories have gone through this qualification and have received codes from the MPC – W88 for their Chile observatory for example. But in order for multiple people to observe from the same site, the MPC assigns a Program Code for each observatory user or team based upon their contact information, and one of these needed to be assigned to me before publication. This is a manual process and takes some time as the staff is quite busy. But after a few weeks the observations were published and I was assigned Program Code #7 at the the Chile site.
The MPC has daily updates known as MPECs or Minor Planet Electronic Circulars. These are released for new objects that have been found and confirmed with their temporary designations and current observations. There is usually a daily orbital update with recent observations all other objects. My results were included in MPEC 2016-E22 Daily Orbit Update on March 3 and look like so:
G3243 7C2016 02 04.06008 01 37 08.54 -71 51 22.2 16.3 VqEE022W88 G3243 7C2016 02 04.07019 01 37 22.37 -71 51 10.5 16.4 VqEE022W88 G3243 7C2016 02 05.10001 02 00 41.70 -71 27 30.0 16.4 VqEE022W88 G3243 7C2016 02 05.11556 02 01 02.27 -71 27 01.4 16.0 VqEE022W88
This gives the object and epoch in compressed format, the date, time, location and brightness of each time point. That’s it!
The thousands of observations received each week are consolidated into bi-monthly publications and supplements as the official record. But the results are also included in the database of observations maintained for each body and these can be retrieved when calculating orbits to confirm new observations or other scientific work. So every bit contributes to further orbit refinements and risk assessment.
Now that I have a program code for the Chile observatory, accepted observations should go through more quickly, so on to other targets!