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Pluto occults 14th mag star UCAC4 345-180315 for Europe
on the 19/20th of July 2016

and its "Pathfinder Occultation" on the 13/14th of July


Attention! A more precise prediction for the occultation on the 19/20th of July has been derived from a GAIA position of the target star and from observations of the Pathfinder Occultation on the 14th of July. Bruno Sicardy and his team sends the two following maps (15th of July):



This is the post occultation map derived
from the observed pathfinder occultation on the 14th

Pluto post occultation 14th July 2016




This is the new prediction for the occultation on the 19th
as derived from a pre-release of the target star position from GAIA catalogue
and from the observation of the pathfinder occultation (above)


Pluto new Prediction for 19th July 2016

!! The north-south error is < 200 km, the timing error < 5 sec.!!



For the new prediction, local circumstances can be got from the graphics below

The following maps give a more detailed view of the occultation track and the local circumstances.

Red is the center line and blue is the southern limit of the occultation.The dotted lines in each color are the uncertainties for the central line and the southern limit.

The shaded areas give the elevation of the sun below the horizon, from 0° to 5°, 5° to 10°, 10° to 15°, 15° to 20° and the darkest shading is more than 20° below.

The iso-elevation lines of Pluto above the horizon at the time of the occultation are plotted in light blue.

Pluto occultation 19th July 2016





General and older information

The Occultations - Main infos about the 2 occultations

FOVs - from DSS2 red....

Finding Charts - How to find the stars....

Informations - Positions and Brightness

Pluto occults a 14mag star UCAC4 345-180315 visible from many parts of Europe on the evening of the 19th of July 2016 around 20h 51min UTC. According to the latest prediction by the RIO team and B. Sicardy, the central flash of this event will be visible from Europe too. But as you know, the occultation track may still shift a lot, so possible observers should be alert to wait for new predictions.

The occultation will not only allow to improve Pluto's orbit, but will also allow to follow the development of its thin atmosphere, when Pluto's distance to the sun is increasing with the years. In the last two years Pluto's atmosphere has further increased its density, as recently published in ApJL as can be find here. The upcoming occultation is a good chance, to continue the monitoring work.

For measurement of the Central Flash (CF) a good occultation track is necessary. Because the atmosphere is nearly spherical shaped, the CF is very small and sharp. A good opportunity to determine the exact occultation track is the occultation of UCAC4 345-180583 on the 14th of July just 5 days before. And it is also visible from Europe! A little more western and northern than the "main" occultation on the 19th. The star is much fainter, only 16mag1 in V. This gives a light decrease of only about 10% for the occultation, but it may be enough, to determine the exact offset of Pluto with respect to its ephemeris. This is specially important, because the position of Pluto has always been disturbed by the light of its moon Charon.

The occultation may pass one of the most highly "telescope" populated areas in the world with countless instruments in the 16inch and up class. Such kind of instruments are perfectly suited for observation, but even with smaller instruments important scientific results can be gained. From Bruno Sicardy and Diane Berard...

Keep in mind, that all prediction still have large errors, in the range of +/- 400km or more!!

The "pathfinder occultation"
on the 13/14th of July

The star is only 16m1, but with about 0.5sec integration time an observation is possible even with a 12 or 16 inch telescope. Click on the map, to have a larger view!
Pluto occultation on 14th of July
The following maps give a more detailed view of the occultation track and the local circumstances.

Red is the center line and blue is the southern limit of the occultation.The dotted lines in each color are the uncertainties for the central line and the southern limit.

The shaded areas give the elevation of the sun below the horizon, from 0° to 5°, 5° to 10°, 10° to 15°, 15° to 20° and the darkest shading is more than 20° below.

The iso-elevation lines of Pluto above the horizon at the time of the occultation are plotted in light blue.

13/14th of July

Pluto occultation 14th July 2016

Expected chords for the 13/14th of July
occultation

Chords for the 14th July 2016 occultation

Expected light curve for the 14th of July
occultation (simulation)

Infos from Bruno Sicardy, Paris:
    The plot below shows the expected shape and depth of the event as seen from Europe and Morocco. Uncertainties in timing should be about 1 minute. I chose an arbitrary time step of one second and added some arbitrary noise to the light curves. The Morocco curve is shifted vertically by +0.1 for better viewing.
Expected light curve for the 14th July 2016 occultation
    The event in Europe lasts for more than one minute, so do not hesitate to increase your exposure time to get more SNR if needed. For instance, with 10 sec exp. time, you will have some 6 data points in the event, still useful to fit a model, and thus improve the astrometry.
Note that in Morocco, the event is expected to be extremely shallow. However, even a southern drift of the shadow as small as 100 km (5 milli-arcsec in the sky plane) will be enough to create a detectable dip there. In other words, even if negative, Morocco may still constrains the astrometry.

If you get a light-curve, could you send it to Erick Meza and Bruno Sicardy *asap* so that to derive the post-event astrometry?
    In order to save time and avoid back and forth emails, could you specify the telescope diameter, camera, exposure time, your position and estimation of your timing accuracy? Ideally, you should provide an ascii file with two columns,
- one with the UT mid-exposure time (in seconds after 00:00 UT, July 14)
- and one with the target flux, normalized to unity outside the event
This file will be used to feed our adjustement procedure. Other, equivalent ascii file(s) for nearby reference star(s) will be useful for monitoring and correcting sky transparency variations.

Field of view with Pluto positons from DSS (14th)

FOV 15min for the 14th July 2016 occultation


FOV 7.5min for the 14th July 2016 occultation


Finder Charts for the event on 13/14th of July

Field size:

5 min

10 min

1 degree

5 degree

10 degree

20 degree

40 degree

This is the main occultation on the 19/20th of July

The main occultation is with a 14th mag star, therefore the dip in the lightcurve should be around 50% for the V or R bands. Here the latest update of the prediction. Click on the map to have a large view:
Pluto occultation 19th July 2016
The following maps give a more detailed view of the occultation track and the local circumstances.

Red is the center line and blue is the southern limit of the occultation.The dotted lines in each color are the uncertainties for the central line and the southern limit.

The shaded areas give the elevation of the sun below the horizon, from 0° to 5°, 5° to 10°, 10° to 15°, 15° to 20° and the darkest shading is more than 20° below.

The iso-elevation lines of Pluto above the horizon at the time of the occultation are plotted in light blue.

19/20th of July

Pluto occultation 19th July 2016

Expected chords for the 19/20th of July occultation

The red dot marks the area of the Central Flash. Expected Chords for the occultation on the 19th of July for observatories in Marocco and south western Europe have been calculated by Bruno Sicardy. Keep in mind, that the north - south error of the prediction is still very large !!! Chords for the 14th July 2016 occultation


The next graphic is an enlarged view of the expected region of the Central Flash.

Chords for the 14th July 2016 occultation



























Field of view with Pluto positons from DSS2 red (19th)

Detailed field of view with Pluto positions on the days before the event (17th, 18th, 19th and 20th of July, each 0h UTC)

FOV 15min for the 19th July 2016 occultation


FOV 7.5min for the 19th July 2016 occultation

Finder Charts for the event on 19/20th of July

Field size:

5 min

10 min

1 degree

5 degree

10 degree

20 degree

40 degree

Pre-pointing the telescope for Pluto occultation on the 19th of July 2016

For all areas of Europe, the time between a sufficient dark sky and the occultation event is very short. Even more, the event is not very high in the sky. This makes finding the star field very difficult. Therefore we suggest to use pre-point stars. Here you can find more.

Information about the target stars and Pluto

13/14 JULY 2016 (AROUND 01:15 UT JULY 14)

Coordinates:
-----------
 19h 07m 58.08s 
-21d 08' 52.5" (J2000)

 19h 08m 58.15s 
-21d 07' 03.9" (apparent at epoch)
 
Magnitudes:
----------------------------
Object      V      R     I
----------------------------
Star       15.7  15.4  15.2
Pluto      14.6  14.1  13.7
Star+Pluto 14.3  13.8  13.5
drop (mag)  0.3   0.3   0.2
----------------------------

TARGET FOR THE 19/20 JULY 2016 (AROUND 20:50 UT JULY 19)

Coordinates:
-----------
 
 19h 07m 22.12s 
-21d 10' 28.4"    (J2000)

 19h 08m 22.27s
-21d 08' 40.5"    (apparent at epoch)

Magnitudes:
----------------------------
Object      V      R     I
----------------------------
Star       14.1  13.5  12.9
Pluto      14.6  14.1  13.7
Star+Pluto 13.6  13.0  12.5
drop (mag)  1.0   1.1   1.2
---------------------------