2016 BC14 and Jupiter’s Influence

After learning about and publishing a few observations of Near Earth Objects (NEOs), I came across cool website titled Earth’s Busy Neighborhood. My day job is a scientific software engineer and I really admire this stunning example of a data aggregation web site. The main page shows an HTML5 animation of all of the NEO’s currently passing close to the Earth and also lists details on each one, gathered from the MPC observation database, JPL orbits, links to articles and other sites and all sorts of detail. Also, summaries of confirmation candidates, Minor Planet Circulars and risk updates are gathered and published in The Tracking News section each day. Apparently the authors gather data from various sources using Python scripts to generate the HTML pages. Great stuff!

Many of the objects on the tracker are relatively small, 5-10 meters, and pose little risk of global destruction. Unless they are close by, these smaller bodies are generally very faint and are only accessible to 1 meter class telescopes.

But looking through the list a few weeks ago, I noticed an object 2016 BC14 classified as “Approaching” with an estimated size over 200 meters. So I figured this would be a good one to try to catch. The MPC Ephemeris service showed it to be readily accessible from the Slooh Canary Island Observatory on Mt Teide so I scheduled a set of “missions” on 7 March to try to spot it.

I have a couple of telescopes at home I like to take out from time to time. But conditions are often unfavorable living near the shore in Southern New England. It can be nice and clear out during the day only to cloud up and dew up after sunset. And I’m not as included to handle cold metal when it’s 20 degrees F outside! Having access to remote telescopes helps greatly, but even those are subject to clouds, snow and ice and even strong winds and there was a spell of all that at the Mt Teide site earlier this month. It took over a week of trying to get a couple of nights of pictures of BC14 but I did get there in time.

At that point, the object had brightened to around mag 17 and was clearly seen in each individual image. After selecting images from each timepoint on the 2 nights, I had a set of observations for a potential submission. Even after a week of trying, the object was listed as “Useful for orbit improvement” by the MPC, probably because of it’s status as a Potentially Hazardous Asteroid or PHA.

Before submitting the observations, I ran them through the find_orb Orbit Determination package from Project Pluto. One of the many things this software can do is to read in a series of observations of Solar Systems objects (of any kind) and determine potential orbit solutions. It will also report on orbit “residuals” which is the difference between the expected position (based on the orbit determined) and the measured position for a given observation. So to check my observations, I can download the current set of published observations on the object and add in my values in order to check for discrepancy with published results. If there are enough reliable observations, I can see if any of mine are out of whack due to some error – such as picking the wrong object on the screen when recording a measurement. Ideally, my values should be in line with the published values and have a reasonable small error – under 0.5 arc seconds or better. And for a newly or recently discovered object, adding “good” observations should improve the orbit fit and reduce the overall residuals in the combined set of published and new data points.

After running my observations through find_orb, the residual values in declination were quite good, but the RA delta was consistently over 0.5 arc minutes in all cases. This looked odd, so I went back and reviewed the workup in Astrometrica to see if anything was off there. I find that Astrometrica is rather robust and either returns a very good image solution, or no results at all. (And if no fit is obtained it usually means that I selected the wrong configuration file so the scale is way off!) Occasionally I find I need to tweak the magnitude setting used to select reference stars if the field is unusually sparse or crowded but that’s about it.

Since the workup looked OK so I loaded the observations again in find_orb. The program determines the orbit of minor planets around the Sun (or other bodies) and will also calculate perturbations caused by other objects such as the planets. By default, it will determine which bodies perturbing to use automatically. The fit of 2016 BC14 gave an orbit ranging from just over 1.0 AU to 0.7, so this is an Aten class asteroid staying rather close to Earth. The package determined that mainly Earth and Luna could be perturbing the object and selected those for the fit.

But when I selected to include perturbations from all planets in the orbit, the residuals for my observations improved greatly and varied +/- 0.2 arc seconds or less for all values. By selecting and deselecting the various planets, it looked like Jupiter had a pretty strong effect on the values, and including it gave a much improved fit. So how can Jupiter have such an effect of the asteroid only goes out to 1.03 AU?

Jupiter is currently rising in the evening and is up high in the sky around midnight, so it is currently in opposition to Earth. (The exact opposition was on 8 March not too far off from the date of these observations). Jupiter is 5.4 AU from the Sun and currently about 4.5 AU from us. It’s mass is about 1 thousandth of the mass of the Sun and it is farther away from us than the Sun, so I would expect it’s gravitational pull to be over 20,000 times weaker on the body then the Sun. I’m not sure if that is enough to cause the difference in the position of the minor planet.

Of course, the position I’m seeing is relative to Earth’s place in the sky. So if Jupiter is having an effect on the Earth’s position as well that could increase the effect on the observed location perhaps. I’m not sure how to sort this out – maybe it’s a good question to ask folks on the Minor Planet Mailing List.

Anyhow, after confirming the observations I formatted the report and submitted it to the MPC – with some help again from my friends on the Slooh A-team. Since this was my first report from the Canary Island location (observatory code G40), I’ll need to have a program code assigned for that location as well. So I’ll wait and check from time to time for the observations to be published, and think about what to look for next when the moon starts waning again.

2016 EL56 – a newly discovered PHA

After having my first NEO observations accepted and published, I’ve been looking to observe some other interesting objects and thought I would try some brighter entries on the MPC NEO Confirmation Page. This page lists newly discovered minor planets or comets thought to be in or potentially reaching our neighborhood in the Solar System. Most of these are very faint bodies picked up by large telescopes used in the various sky surveys and are typically confirmed by high powered professional or amateur observatories dedicated to follow up confirmation and recovery work.

Still, a few brighter objects can be found on the list, and it looks like these are a little more common in the Southern hemisphere. So I thought it would be worth trying some of these from the Slooh observatory in Chile.

The first one I tried was a NEO candidate designated M50sG6S on the list on March 8th. It had an estimated magnitude of 18.2 and a projected declination of 35S so it looked like it should be detectable from Chile. I scheduled missions from W88 that night but did not see any moving object in the images obtained. No confirmations were made for this object over the coming week so it was removed from the list and not confirmed.

The next day, I saw an entry A100jOx in the southern sky with an estimated brightness of 18.9 at declination 25S. This magnitude is a bit of a stretch but it looked to be fairly high up in the sky on a moonless night so I gave it a go. Image files came in the next day, and I also noticed that the object had already been confirmed and given the designation 2016 EL56 by checking on the previous designation page. So other observatories had already confirmed the object!

The images looked quite good, so I took a look in Astrometrica to see if I could pick up the new object. First, I updated the MPC orbit database since the object was just designated and should now have an orbit available. A faint moving object was seen in most of the images, near but not at the exact location predicted by Astrometrica. Since this was a newly discovered object with 2 days of observations, the orbit would have a significant degree of uncertainly and this discrepancy was to be expected.

Since the object was faint, I tried the “Stack and Track” feature in Astrometrica. Using the Slooh protocol “Faint Mono” normally produces 4 monochromatic or luminence files, though sometimes these are not all produced. I had 4 images from the first timepoint and 3 from the second, so I made 2 stacks from each set.

“Track and Stack” will read in a series of images and shift them according to the expected motion of the desired target. The motion can be entered, but if the object is known it can be looked up from the orbit database. So I selected the newly minted designation 2016 EL56 and the program shifted and stacked the images from the estimated motion rate and position angle or direction. Here is one of the stacked and shifted images:


In the picture above, the images are shifted so the stars in the picture show up as a series of dots or a solid line. An object moving at the expected rate and direction will fall around the same position and show up as a single spot. So the weaker peaks in the individual images can add up to give a stronger signal over the background. The position will be a little less uncertain but the curve fit will work better so it can enhance the measurement overall. I’ve noticed that noise on a single image will also show up as a single spot so it’s important to look over the individual frames!

Running the observations in find_orb showed consistency with the other observations made to date and a positive influence on the overall fit. So I prepared a report and submitted it to the Minor Planet Center that day. Since I had a program code already assigned, this time the observations were published the very next day in the Daily Orbit Update MPEC 2016-E112 and later in the Minor Planet Supplement MPS 690473.

Minor planet 2016 EL56 is a Potentially Hazardous Asteroid (PHA) with an estimated size of 150 meters. The ESA site classifies it as an Apollo class asteroid ranging from around 4 AU down to about 0.3, with the next expected close approach in 2045 at 0.15 AU from Earth. It looks like the object was picked up after it passed by us in February, so it is now heading away and fading in brightness. It is not expected to have in impact in the future but any observations made while it is still accessible will help greatly in predicting it’s position and recovery when it returns!


(163243) 2002 FB3 – First Submission!

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!