As RECON prepares for our our upcoming campaign early Wednesday morning this week, we thought we would take this opportunity to point out some of the interesting information found on the Event Detail Page for each RECON event.
For our upcoming event, teams should print out both of the following important webpages:
- Event Page for 08FC76: Provides sense-up, star chart, and star field image
- Event Detail Page for 08FC76: Provides loads of information described below
The Event Detail Page for every campaign starts with useful information characterizing the event.
This introductory section provides lots of cool details:
- An object named (281371) 08FC76 is going to occult a star named UC4-565-008609.
- The predicted shadow reaches the point closest to Earth’s center at 11:55:36 Universal Time on November 23, 2016.
- We provide J2000 coordinates (the RA and DEC of the target star back in 2000) and equinox of date coordinates (the RA and DEC for the star today). Note that the coordinates are close but not exactly the same because Earth is slow precessing (or wobbling) on its axis. Our CPC-1100 telescopes use equinox of date coordinates.
- The target star is faint — magnitude of 14.6 using a Red (R) filter — but about 100x brighter than the TNO — magnitude 19.3 using a Visible (V) filter). Every 5 orders of magnitude is 100 times fainter. RECON setups can measure down to about magnitude 16, which means our sites will be able to record the star but will record no signal when the fainter TNO is passes in front of it —fingers crossed!
- The waning crescent Moon should not be an issue for this campaign. It is only 29% illuminated and reasonably far away (115 degrees) from the target.
- For our upcoming event, the centerline passes directly over the RECON network. Click the link on the page for a detailed RECON map of the network.
- To the right of the globe are details about the position, motion, size, and dynamical classification of the TNO. In this case, we are dealing with a Centaur which, at 10.6 AU, is currently just outside the orbit of Saturn. Note that we don’t know the actual albedo, or reflectivity, of the Centaur — that’s another thing we will be able to determine if we measure the object’s size.
- The 1-sigma uncertainty in time for the event is 47 seconds and the cross-track uncertainty is 595 km. This means that there is a 68% chance that the prediction times listed are good to within 47 seconds, and a 68% chance that the shadow will land within 595 km of the centerline shown. This is why we need so many telescopes and need to record video lasting longer than a few minutes.
Star Training Set:
Next, we provide teams with a star training set. This is a list of 5-6 stars, in addition to the target star, that can be used to provide an indication of how accurately the telescope is aligned and in what direction. You’ll notice that the magnitudes of the stars listed are going from brightest (mag 0.8) to dimmest (mag 14.6), and that the separation between the star and the target is getting smaller (from 11.52 degrees down to 0.24 degrees). By pointing the telescope at each object, the team can get a sense of where the target is likely to appear in the camera field of view when they use the final coordinates for TNO (281371) 08FC76.
Following this, an automatically generated star chart shows nearby stars along with a green rectangle representing the RECON camera field of view. Note that we are still tweaking how this star chart displays, and for now the star chart provided on the Event Page is a better depiction of the star field at the actual time of the event.
Finally, we provide a table listing all of our RECON sites along with useful information unique to each location. Among other information, the text just above the table provides an indication of the median spacing of the RECON network for this event (26.8 km) and the probability of success assuming clear skies (67.1%). These REALLY good odds for TNO occultation astronomy are only made possible by our awesome network of team members spanning a baseline of roughly 1,700 km. The probability takes into account the uncertainty in the position of the TNO and the target star, the estimated size of the object, and the median spacing of telescopes across the network.
For each RECON site, you can read off the following information:
- For all of our sites the Sun is down (negative altitude), the sky is dark, and the Moon is up.
- The position of the star (star altitude and azimuth) is provided for each site. 10 degrees corresponds to a fist held at arms length. Due north is 0 degrees azimuth, 90 degrees is east, 180 degrees is south, and 270 degrees is west. For Oroville during the event time, the star will be 34.8 degrees above the horizon (about three and a half fists) and in the direction of 265 degrees, or just 5 degrees south of due west.
- Remember the 1-sigma cross track error of 595 km above? For each site the table lists how far the site is from the centerline prediction. Note that all RECON sites south of Madras/Culver (X-track = 569 km) are within the 1-sigma zone.
All times on the page are in Universal Time (UT) and need to be converted to local time. Our teams on Pacific Standard Time (PST) are 8 hours behind UT, and our teams on Mountain Standard Time (MST) are 7 hours behind UT. Let’s take a look at three examples:
- The recording window for Oroville is 11:47:21-11:56:15 UT (see above). Because they are on Pacific Time, our Oroville team will subtract 8 hours and record from 03:47:21-03:56:15 PST.
- The recording window for Yuma Arizona is 11:46:54-11:55:48 UT (see below). Because Yuma (and all of Arizona) are on Mountain Time, our team there will subtract 7 hours and record from 04:46:54-04:55:48 MST.
- Our team in Laughlin/Bullhead City, with a start time of 11:46:56 UT, is in the funkiest situation (see below). If the team observes from Laughlin, Nevada, they will start recording at 03:46:56 PST; if they are in Bullhead City, Arizona, they will start recording at 04:46:56 MST. Both are the same Universal Time which is why astronomers prefer to use UT rather than local time!
J2000 Star Training Set (NOT for standard RECON Setups):
The final table provided on the Event Detail page is the same star training set using J2000 coordinates. Some of our volunteer sties are using scopes that use J2000 coordinates, unlike our RECON Celestron scopes. Standard RECON sites should use the star training table at the top of the page above the star chart!
RECON Prediction System at Work
As with all science, RECON is a work in progress, and we will continue to refine our predication and observation planning tools. All of the above useful information is available for each occultation prediction found on the Global TNO Event Candidate List and RECON TNO Event Watchlist. Each of these lists is updated weekly and provides predictions looking two years into the future – including our next RECON event after this week involving Centaur 14UT114 on 11 December, 2016 UT.
RECON is gearing up for an event during Thanksgiving Week involving Centaur 08FC76 on Wednesday morning, November 23. The prediction for this event places the centerline directly through the middle of our network, with over 40 RECON sites within the 1-sigma shadow zone.
What could be better than the above event, which has a 67% probability of resulting in publishable measurement of this outer Solar System object? A second event with equally good probability for success! On Saturday night, December 10 (December 11 UT), RECON will be pursuing our third campaign event this autumn involving Centaur 14UT114, with a shadow path passing over Central Oregon. For this December event, EVERY RECON SITE will is within the 1-sigma uncertainty zone, resulting in an 80% probability for success!
RECON is very well positioned to obtain results for two scientific papers from the above events. All observers participating in any of the above events will have the opportunity to also participate as a co-author.
Here’s to clear skies across the Western US on the morning of November 23 and the evening of December 10!
Just a quick reminder that all of our RECON teams outside of Arizona will be going off Daylight Savings this Sunday morning, November 6, at 2AM local time. In addition to giving participants an extra hour of sleep, turning clocks back will place the majority of our teams 8 hours behind Universal Time (UT) from now through March.
RECON teams should take care in converting UT times to local times:
- Our Arizona teams remain on Mountain Standard Time = 7 hours behind UT
- All other teams fall back onto Pacific Standard Time = 8 hours behind UT
All times listed on the Event Detail Page for 08FC76 are provided in UT and need to be adjusted for the correct time zone for each site. The event will be centered around 11:55 UT on November 23, 2016. Using the offsets above, this converts to:
- 4:55 AM MST on the morning of November 23
- 3:55 AM PST on the morning of November 23
All RECON Teams are reminded to complete the RECON Campaign Signup Form as soon as possible so that we can ensure telescope coverage for this Thanksgiving campaign!
During the week of Thanksgiving, the RECON community is looking forward to the best TNO occultation opportunity since the start of our full network last year! On Wednesday morning, November 23, around 3:55AM Pacific (4:55AM Mountain), Centaur 08FC76 will be occulting 14.6 magnitude star UC4-565-008609 in the constellation Taurus.
This event is EXACTLY the type of campaign that RECON was designed to pursue. As shown on the map here, the predicted centerline for the occultation shadow passes directly through the center of our network! Recently kicked into an orbit neighboring Saturn, Centaur 08FC76 will be only 9.6 AU from Earth. Based on how well we know the orbit for this object, the 1-sigma cross-track uncertainty in the shadow path prediction is only 595 km. Importantly, this places every RECON telescope site from Madras, Oregon to Idyllwild, California within this zone of high probability for detection. That’s 43 of our 60 communities!!! Based upon our calculations, there is at least a 67% probability that RECON will capture this event, more than double any of our previous events.
And, as with all RECON events, each telescope site is crucial for mapping out the region of space around this TNO. Does this Centaur have a smaller moon . . . or moons? Does it have rings? How big is it actually? How bright is it? What is its shape? We plan to address all of these questions and more through data collected during this upcoming holiday campaign!
Marc has also taken the extra step of incorporating recent data from the Gaia Mission in to the prediction above. With the additional precision provided on the position of the target star, the prediction path has remained in the center of the network. This makes for an even stronger prediction that the shadow of this Centaur will passing over our network on the morning of November 23. This is the highest probability event we have had since the start of the project!
For more information on this event, visit the Event Page and Event Detail Page for 08FC76. RECON Teams are asked to sign up for the event using the RECON Campaign Signup Form. We are extremely thankful to all of our RECON team members for supporting this upcoming campaign and for all of the preparation and dedication that has gotten us to this point.
During our event last weekend, cloudy skies and rain impacted most all of our Washington, Oregon, California, and Nevada sites. The clouds parted south of Kingman and at least five communities along the Colorado River collected data along with pockets in Lee Vining, Searchlight, and elsewhere. We will be analyzing these video files in the coming week. For a snapshot of how things went for each of our telescope sites, you can check out an Event Summary for 12UT68.
Teams that have not yet submitted a RECON Campaign Observation Report Form for the event have until this Sunday evening (one week following the event) to complete this dataset. Also, stay tuned for our next event on the Wednesday morning before Thanksgiving. This is going to be our best TNO occultation opportunity since the start of the RECON Project!
It’s been four months since our last campaign, but RECON is prepped and ready for our first full network campaign of the 2016-17 school year!
Tonight’s event involves Centaur 12UT68. Formed out beyond Neptune, this object was recently kicked inward to the solar neighborhood near Saturn and Neptune. Estimates place its size at 30-75 km, but RECON is trying to determine this with far greater precision. Although the predicted shadow path is slightly off the network, the 1-sigma uncertainty in this prediction is 600 km. This means there is a good chance the shadow may pass over communities to the south, and all of our scopes are well positioned to probe the region around 12UT68.
As with all ground-based astronomy, weather and sky conditions are always an important factor. As of this morning, the weather is not looking great for many of our teams in the Northwest and spotty for several Northern California and Nevada teams. The sky cover prediction map below was produced using tools available at www.cleardarksky.com.
For our teams with partly cloudy skies, they will be aligning their telescopes and finding the star field using patches of clear sky. Then it will be a matter of waiting it out to see if the target region of northeastern sky stays clear during the 20-minute observing window just after 11:10PM PDT/MST tonight. And hopefully the prediction for better weather will hold for our teams in southern California and along the Colorado River closest to the shadow centerline prediction!
For more details on this event, visit our Event Page for 12UT68. Good luck to all of our teams able to observe tonight despite less than ideal weather! Also, stay tuned for our next event on the morning of Wednesday, November 23, with a predicted shadow passing directly through the center of the RECON network!!!
Below are details for an optional main belt asteroid campaign for RECON teams from Lake Havasu to Yuma. For more details, refer to Occult Watcher and following link:
Date: 05 October 2016 UT
Recording Window: 06:06:00 – 06:09:00
Star training set for 451 Patientia, (2016/10/05 06:08UT)
Object RA Dec mag sep mel
Fomalhaut 22:58:34.4 -29:31:59 1.2 3.75 96
PPM 274650 23:10:38.8 -27:59:51 5.9 0.76 100
PPM 274716 23:14:12.4 -28:19:26 8.3 0.39 100
451 Patientia 23:14:04.0 -27:56:21 9.2 100
Positions are for equinox of date
For any of you needing the J2000 coordinates, here is your list:
J2000 Star training set for 451 Patientia
Object RA Dec mag sep mel
Fomalhaut 22:57:39.5 -29:37:23 1.2 3.75 96
PPM 274650 23:09:44.7 -28:05:19 5.9 0.76 100
PPM 274716 23:13:18.5 -28:24:55 8.3 0.39 100
451 Patientia 23:13:10.1 -28:01:50 9.2 100
Positions are for J2000
On 2016, August 13 at 06:30 UT, main belt asteroid (19) Fortuna occulted the star TYC 5780-01169-1 in the constellation Aquarius. Four RECON teams and two other observers recorded the event. A total of five teams actually observed an occultation and one team observed a miss. Observing a miss can be just as important as observing an occultation because misses help define the size of the asteroid. For a more comprehensive overview about the data analysis process for main belt asteroid occultations, see Tony George’s blog post from January, 2016.
Here is the path for the event, which passed over the northern part of the RECON network. Even if you don’t have access to the Occult Watcher program, occultation announcements and maps such as this can be found at the asteroid occultation website.
Here are light curves from the three RECON teams that recorded an occultation. Note that the horizontal and vertical scales on each of these light curves are different.
Occultation scientists, such as every member of RECON, can use these light curves to determine the disappearance and reappearance time of the occulted star. IOTA, the International Occultation Timing Association, uses these disappearance and reappearance times, along with the location of the observers to estimate the outline of the asteroid.
Each of the chords in the plot below shows when and where the target star is visible. When the asteroid occults the star, there is a gap in the cord equivalent to the amount of time the star disappeared. When all of the chords and gaps are combined, you can start to see the size and shape of the asteroid. The gray area shows a model of the asteroid’s shape based on existing data. Notice how chord 1 fits the model almost exactly while chord 4, measured by RECON Ellensburg, starts and stops inside the predicted shape of the asteroid model. This could indicate a slight error in Ellensburg’s timing. But it could also mean that the actual shape of the asteroid is a little narrower along that line than predicted. Less likely but still possible, there are deep indentations in those portions of the asteroid. Chord 7, measured by RECON The Dalles, has a very small gap indicating that just the tip of the asteroid occulted the star.
Main belt asteroid occultations are a great way to train new RECON participants in occultation science. One of the main reasons for this is that you can often see the target star and the asteroid. So even if your site does not record an occultation, you can still observe the dynamic nature of the Solar System by watching the asteroid move towards and then away from the target star.
Credits: We give a big “Thank You” to Tony George for generating and extracting precise timing information from our light curves.
This past week, the European Space Agency released its first dataset produced by the Gaia Mission, a spacecraft in orbit around the Earth-Sun second Lagrange point (L2). This dataset provides precise position and brightness information for over 1.1 billion stars in the Milky Way and satellite galaxies, along with distances and proper motions for 2 million of these. With still more data to come, Gaia provides the most comprehensive 3-dimensional map of the stars in our galaxy.
The release of this dataset is extremely significant to RECON, as it essentially eliminates previous uncertainties in the positional information of occultation target stars. This will allow us to make more precise predictions of occultation paths for trans-Neptunian Objects (TNOs). Uncertainties remain in our measurements of TNO positions, but Gaia provides a significant improvement to our occultation prediction efforts.