Occultation Season Returns

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The Milky Way and plane of our solar system (the ecliptic) cross in the constellation Sagittarius, which is most prominent in the night sky during the summer months. Panorama by Matt Dieterich.

As many RECON team members have noticed, the frequency of occultation campaigns drops off during the summer months.

Interestingly, the reason for this has to do with the orientation of our Milky Way Galaxy and the plane of our solar system (known as the ecliptic), as well as the tilt of Earth’s axis. During the summer, daytime is longer but nighttime is shorter, and while the Sun is high in the northern sky, the ecliptic is low in the night sky. In addition, the ecliptic crosses through the center of our galaxy in the constellation Sagittarius, which is up in the night sky the longest during the summer. Because it is difficult to discover trans-Neptunian objects within the crowded star field of our galaxy, as well as their low positions in the sky and shorter nights, there are fewer high probability events that we can pursue during the summer.

As we approach the start of the new school year, however, conditions become more favorable for RECON campaign events. Toward this end, we have already announced two upcoming events on the night of August 16-17 involving Centaur 08YB3 and the night of September 3-4 involving Centaur 13NL24. In addition, looking at the RECON Campaign Prediction Page, there are eight additional campaign opportunities before the New Year with probabilities greater than ~20% that we are currently considering as full network campaigns. The 2019-20 academic year promises to be the most productive occultation cycle of our project to date!

Despite being a slow occultation season, this summer has been exciting on several other fronts. We have been working on four publications related to positive TNO occultation campaigns during the last academic year. The project also continued to collect data from Apache Point Observatory, the Discovery Channel Telescope, and Canada France Hawaii Telescope to augment our occultation prediction system. And in June, we submitted a proposal to the NASA Solar System Observations Program for RECON 2.0. Informed significantly by our RECON science team meeting discussion back in March, RECON 2.0 will both upgrade and significantly enhance the efficiency and productivity of our citizen science project into the 2020s.

Asteroid 45 Eugenia

An Interesting Main Belt Asteroid and Recent Occultation Observation

From Wikipedia:  “Eugenia was discovered on 27 June 1857 by the Franco-German amateur astronomer Hermann Goldschmidt.   His instrument of discovery was a 4-inch aperture telescope located in his sixth floor apartment in the Latin Quarter of Paris.   It was the forty-fifth minor planet to be discovered. The preliminary orbital elements were computed by Wilhelm Forster in Berlin, based on three observations in July, 1857.

Eugenia is a large asteroid, with a diameter of 214 km.  It is an F-type asteroid, which means that it is very dark in coloring (darker than soot) with a carbonaceous composition. Like Mathilde, its density appears to be unusually low, indicating that it may be a loosely packed rubble pile, not a monolithic object.”

In 1998 astronomers discovered that Eugenia had a moon.  It was the first discovery of a moon orbiting an asteroid by a ground based telescope.  The discoverers name the moon Petit-Prince.  The moon, about 13 km in diameter, orbits Eugenia in about 5 days.  Discovered in 2004 a smaller moon, at about 6 km, orbits Eugenia every 4.7 days and is designated S/2004 (45) 1.

Earlier this month, 45 Eugenia was predicted to occult an 11.8 magnitude star (UCAC4-369-175949) in the constellation Sagittarius.  The maximum duration of the event was predicted to be 20.6 seconds with a magnitude drop of 0.4 – 0.5.  The predicted path extended from central Montana, through Idaho, northern Nevada and northern California.  An announcement of the event was distributed to observers across the west in an attempt to perhaps observe the known moon, Petit-Prince.

Predicted event time was approximately 08:12:45 +/- 2 sec UT (01:12:45 PDT).  There have been a number of previous occultation events by Eugenia over the years, with 13 positive chords recorded in 2014 and 7 positive chords in 2017.  

Because of its size, Eugenia is a fairly bright object at mag 11.2 and is easily discernible from the target star as seen on the two images below.  These images were extracted from integrated video taken as the asteroid approached the target star and after the predicted event.   Time stamp data for each of the images is shown at the bottom of each frame.

 I was able to record the event with a 304 mm SCT equipped with a 3.3 focal reducer, WAT910 HX B/W video camera and IOTA-VTI time stamp inserter.  Video was recorded with no integration at 2X.  Light curve data and occultation event timing extraction was completed using a new set of programs authored by Bob Anderson in conjunction with the North American International Occultation Timing Association (IOTA).  

The recently released PyMovie is available at: http://occultations.org/observing/software/pymovie/.

 PyOTE is available on the IOTA web page at:  http://www.asteroidoccultation.com/observations/NA/.   

At my observing location in Gardnerville, Nevada I observed an occultation event with duration of 19.1 seconds (starting at 08:12:43.489 and ending at 08:13:02.574 UT).  Calculated mag drop was 0.44.

Unfortunately, of the six other observers that had planned to also participate, all were clouded out of the event.

2019 Spring Updates

It’s been a busy spring for the RECON Network. Following a highly productive science team meeting in Boulder City, Nevada in early March, the network has collected data for two campaigns: one involving Centaur 16FH13 on April 23 and the second involving Centaur 98BU48 on May 1 (both UT dates). The May 1 campaign was particularly challenging for our RECON teams due to twilight sky conditions during this early evening event. Only teams to the south of Reno were able to participate in this campaign given sky conditions. Meanwhile, RECON leadership from Boulder Colorado deployed three telescopes in northern New Mexico, where the sun had set an hour earlier, to support the campaign.

Below are some photos taken on May 1 from Mills Canyon Rim Campground by RECON Co-PI John Keller. The “occulting” moth shown below was attracted to the visible and thermal IR given off by the laptop screen!

2019 February Updates

We’ve had an active RECON campaign season over the past two months, with six full network observation campaigns since October!  We have one more campaign this month involving Resonant KBO 14YJ50 on 10 February at 04:01UT.  Thanks to all of our team members for your dedication and perseverance!

We are also looking forward to our upcoming 2019 RECON Team Meeting to be held at Lake Mead National Recreation Area near Boulder City, Nevada.  We will be holding an Orientation Training Session for newer team members starting Thursday February 28.  Veteran team members will join for the full team meeting Friday through Sunday, March 1-3.  We ask that team representatives register by Monday, February 4. 

What’s new with RECON in October 2018

Congratulations to all of you that have been a part of RECON.  It’s been six years since we began the pilot project and four years since the start of the full project.  We’ve all learned a lot together and it’s been an amazing project throughout.  We are known in the scientific community throughout the world for our work on the Kuiper Belt.

While we’ve been hard at work, the rest of our colleagues have also been probing the boundaries of knowledge of the outer solar system.  Rings around tiny Centaur objects!  Maybe a Planet X out there (or maybe not).  Binary objects remain an important component of these objects and it’s widely recognized that RECON is the perfect tool to expand that study.

Artist representation of Gaia spacecraft. Credit: ESA.

The Gaia mission from the European Space Agency has delivered on its promise to pin down where a huge number of stars are.  As I’ve talked about many times, this is essential to the long-term success and productivity of RECON and any other occultation-based study of objects in our solar system.  It took a couple of extra years to get to this point but we are now starting to see the benefits enabled by Gaia.  In the early days of the project we were limited a bit by having to work with a much less accurate star catalog and also much poorer knowledge of the positions of the TNOs.  The explosion of occultation opportunities is now upon us.

PanSTARRS – Panoramic Survey Telescope And Rapid Response System. Credit: IFA

Within the project we have continued to work on measuring where candidate TNOs are to help increase the number of good events to observe.  That work continues but we are now working closely with the PanStarrs survey in Hawaii.  Their dataset is an amazing resource that has, in the past few months, provided thousands of observations of more than a hundred objects.  With the telescopes we have available ourselves, this contribution would take us 300 nights of observing on giant telescopes to equal.

A good example of this is our campaign observation for RECON of the TNO 2014TA86 This object was discovered in 2014 by PanStarrs and the recent effort located nearly 10 years of data that had already been collected on this object by PanStarrs but not yet processed.  As a result we know where this object is with much more precision that is usual for something discovered in 2014.  Without the support from PanStarrs, we wouldn’t even know this object existed and now we are poised to make critical measurements of its size and position.  If it turns out to be binary (which is quite likely), we’ll be adding more to our understanding of these distant worlds.  Note that the shorter than usual notification of the impending campaign was a result of this recent data dump from PanStarrs coming in.  This event popped up in our scans, and it was just too good to pass up, so we made an exception to our normal procedure of providing a month’s notice.

Artists depiction of MU69. Credit: NASA

The context of our efforts is greatly expanded with the historic event to come on Jan 1, 2019.  New Horizons will have a close flyby of (486958) 2014MU69, a TNO that I discovered by in 2014.  It’s a neighbor of this month’s campaign target and whatever we learn from New Horizons will provide a broader understanding of our RECON target.  What’s even more exciting is that our observations will provide a broader understanding of the New Horizons data as well.

I’m very excited to see what we will learn from New Horizons.  I’ve been unbelievably busy this year and last organizing and chasing occultations by MU69.  Many of the lessons learned with RECON were a key to the success of those occultation expeditions.  I sent 25 teams of astronomers out on three separate occasions. South Africa, Argentina, Senegal, and Colombia were all visited by these dedicated teams of astronomers, braving clouds, storms, high winds, mosquitoes, insane urban traffic, and more.  It was an exhausting, yet fulfilling effort, and the team work was truly amazing.  All of you that have been a part of RECON can take pride in knowing that you helped make these other efforts a success.

Now it’s our turn.  Early in the morning, on Friday, October 12, we will have a shot at our own historic observation of this distant TNO.  What will we find?  Should we let a minor inconvenience like having to get up in the middle of the night, during the week, to get in our way of learning more about our solar system?  I’ve said all along in this project that astronomy isn’t always at a convenient time.  We’ll continue the fine tradition of making a special effort to learn more about the universe around us.  I’ll be observing from home along with all of you to add my own efforts but you are all truly the stars of the project.  I should also warn you that we’re looking at a lot of very nice opportunities in the coming six months during our peak season.  It will be RECON like never before.  How exciting!

The Importance of the Pluto Occultation

Our campaign tonight, August 14th, involves Pluto, a dwarf planet with an atmosphere. The nature of the experiment is a bit different from what RECON is mainly designed for.

Rodrigo Leiva, a RECON Postdoctoral researcher at Southwest Research Institute has explained the science of this Occultation:

For an opaque object, a positive detection will look like a sudden dimming of the star, followed by a sudden back-to-normal brightness. If you put an atmosphere around an object, then part of the light is refracted away from us by the atmosphere (because its refraction index is different than 1), and some light is also refracted toward us.

If an observer is close to the central line, the atmosphere acts as a magnifying glass and the refracted light is concentrated. This is called the central flash. For a brief time, the star will look even brighter than when not occulted, i.e. you see a ‘flash’. The central flash allows us to study the lower atmosphere of Pluto, a few kilometers above the surface.

Is Pluto’s atmosphere finally collapsing? Did you know that the atmosphere has been expanding and this could be the first time we detect a change in that trend?

Our role is to give a correct interpretation of the central flash. It is necessary to know where the central line is very precisely – down to single kilometers. This is possible if we have a good sampling for the whole atmosphere. And we have the right network for that, RECON! According to the prediction, we could sample a big portion of the north half of the occultation, which will give a good constraint for the atmosphere modeling and also in determining if the atmosphere is finally contracting.

It is possible that some stations will detect gravity waves, small variations of density in the atmosphere. These waves are visible as short changes in brightness in the light curve during the occultation. It is a very exciting experiment!

Here is the sky coverage map for around 2AM EDT.

 

 

 

 

 

 

 

 

 

 

Good luck to everyone! Go RECON!

Upcoming Pluto Occultation

RECON is gearing up for an important science opportunity involving Pluto.  As shown below, the shadow path of Pluto passes over most of the United States as the dwarf planet occults star GA0680:34878053 on Tuesday evening, August 14 (August 15 around 05:30UTC).

Shadow path prediction for Pluto occultation provided by RECON

We’ve posted a star field image of GA0680:34878053 on the Pluto Occultation Event Page.  Because the target star is relatively bright (mag 13.0), RECON sites will be recording this event with a sense-up of 32x.

Pluto starfield at senseup 32x

As with all RECON campaigns, we ask that team members practice taking a recording of the target star field prior to event night. This provides an opportunity to test out RECON equipment and build confidence in recognizing the star field. During the practice session, we also encourage team members to confirm that their Camera Settings are set properly.

Good luck to our RECON sites as well as all other observers planning to participate in this important occultation opportunity!

New Horizons 2018 Occultation Campaign

On Saturday morning, August 4, Marc and John were in Senegal with roughly 60 other observers from the US, France, and Senegal and Rodrigo was in Columbia with a dozen astronomers.  Both groups were pursuing the shadow track of 2014MU69, the ~30km Kuiper Belt Object that New Horizons will fly be on New Years Day, January 1, 2019.  Rodrigo’s teams in South America were rained out, and Senegal teams faced cloudy conditions.  However, all teams persevered and several Senegal sites were clear enough to collect useable data.  These data are currently being analyzed and synthesized with last summer’s campaigns to inform the New Horizons team as they plan for the upcoming flyby.  We will provide updates as added details are made available.

https://www.nytimes.com/2018/08/05/world/africa/astronomy-senegal-nasa-new-horizons.html

In addition to collecting useful data, the expedition was a valuable opportunity for US and French observers to work with researchers from Senegal and to build international ties.  The link above points to a New York Times article featuring the occultation expedition in Senegal.