View Full Version here: : [Info wanted] upcoming occultation of Pluto 4th June
13-05-2010, 12:27 PM
I have noted in this thread:-
mention of an upcoming occultation of a mag 15 star by Pluto.
Where might I find out more about this?
13-05-2010, 01:14 PM
This is the one:
.... note that there are some others coming up that might be suitable depending on your location. The pluto ones are all here:
.. or for all Bruno's TNO predictions:
13-05-2010, 06:25 PM
Thank you Roger.
I have looked at the maps Bruno has compiled, some of it is straightforward; some is a little obscure.
In this map, I presume the large dot is where the occultation is complete (total extinction of the eclipsed star). What would the smaller dots on either side of this be? I would have presumed that an oval of appropriate major and minor radii would have represented the zone of the earth where the eclipse would be partial / total. The rectangular zone does not make sense to me (which is a sad indication of my levels of sense).
The last six parameters in the data set are not known to me.
vel is shadow transit velocity in km/sec I believe (reading from the README) although this might mean that the occultation would be over within milliseconds, which I intuitively think cannot be the case.
K* ? These two parameters are stated in the readme as magnitudes in R* and K* (not V* and R*) but I am unacquainted with these terms. I presume they refer to particular wavelengths of light, but I don't know what they would be.
Thank you in advance for any information or links to appropriate pages.
13-05-2010, 06:39 PM
The occultation will take around 2.5 minutes, from what I've been told, Pluto is quite a large body!
13-05-2010, 06:42 PM
Don’t worry Tony, we’re all beginners at this ...well, me at least :)
From what I understand...
Pluto occultations are visible the whole way along the track (providing night-time etc). The track being the area between the blue lines. The big dot being the central point, smaller dots being indications of time before and after central point. I have forgotten the actual spacing of the dots – Bruno did once explain it in an email I received. The width of the track is the expected area to see the occultation (between the blue lines).
“R” I read as Red magnitude
“V” as Visual magnitude
... I could be wrong.
Velocity – Pluto occultations are usually slow, something like a couple of minutes. I’m not sure how to interpret the number on the chart, I just know from having done a couple, and from what people say around the place about upcoming occultations.
I’m not sure what C/A and P/A are sorry.
I always just try to find:
- Time & date
- Star magnitude (I go by “R”)
I have to admit I gloss over most of the other parameters (I don’t need RA and Dec because I plate solve on Pluto)
OccultWatcher gives all the parameters in nice easy to use language, but I haven’t been using it long enough to know how many of these TNO occultations make their way in there – definitely not all, as I know there’s about 5 suitable to me before this time in June but only one in OccultaWatcher.
I expect others like AstroJunk or DaveGee will pop up their heads with much more meaningful input than I have to offer :)
14-05-2010, 07:47 AM
Pluto's orbital velocity is about 4.6km/sec, and with a diameter of a bit over 1000km, this will block the star for up to 1000/4.6 ~ 200 seconds...quite a while!
16-05-2010, 09:17 AM
Thank you Roger, Jacqui, Trevor.
From my limited knowledge, I would have thought it would be our orbital + rotational velocity that would be the determining factor in the occultation.
16-05-2010, 12:17 PM
Occult Watcher http://hristopavlov.net/OccultWatcher/OccultWatcher.html tells me the June 5 01:35 +-2.4 min (AEST) occultation of 2UAC 24919939 by Pluto has me 152Km off the central line and in the shadow. It puts the max duration at about 1.8 minutes.
I'll attach a zip of the KML for anyone who wants to see it in Google Earth.
24-05-2010, 09:36 AM
I was just about to start a topic, then I found this thread.:thumbsup:
Details of this event, presented in the usual Occult format, can be found here...
Hristo, author of Occult Watcher (OW), previously mentioned, will be taking Bruno's predictions and converting them to Occult format and I'll be uploading them to my site...
and these will be most easily accessed by using Hristo's program and subscribing to the TNO extras (Global) feed.
Below, you'll find a map that shows the observers already signed up for the event. As you can see, there is plenty of room. in particular the southern half of the path, hint-hint...:hi:
What you'll see (provided the prediction is correct...:sadeyes:) will be similar to the event the team observed in 2008. You can see my video here...
24-05-2010, 01:40 PM
I thought I'd give a few details of why the observation of this event, and others like it, are important.
Well, apert from the "gee wizz" factor, the observation of these events gives us (mankind) a perfect opportunity to investigate enviromental conditions at Pluto, by using the light of the target star to code into the shadow of Pluto, details of Pluto's atmosphere that otherwise can not be obtained.
The fact that Pluto had an atmosphere was discovered during a 1988 occultation that was observed across Australia and New Zealand as well as by the Kuiper Airborne Observatory, by virtue of the slow or gradual disappearance and reappearance events. It is the rate of change in the light that can lead to measurements of pressure and temperature of the atmosphere. It was during subsiquent stellar occultations, that an inversion layer was discovered, and this is shown by a "knee" in the light curve, signifying a change in density. The image below shows a typical example.
So, believe it or not, an amateur astronomer using modest equipment can produce data that can lead to further understanding of Pluto's atmosphere. Of course, I have no idea how to take it to the level of "atmospherics", and here is where the "professional" astronomer takes over. Typically the light curve data is given to the Principal Investigator, in previous cases Bruno Sicardy of Paris Observatory takes the combined observations and in the end, produces a paper of "our" results. The reward of providing data that is used in the paper is to be mentioned as a co-author.
Why is this all important? Well apart from the pure knowledge of the dynamics of Pluto's atmosphere, The New Horizons spacecraft is enroute to Pluto and is due 2015 and it would be nice to know what the atmosphere will be like before it gets there, so the various planned experiments can be optimised.
I hope this helps...:thumbsup:
03-06-2010, 08:23 PM
Sorry Ron, but it's raining here and looks to be that way for a while. Hope it's better for you down south.
04-06-2010, 11:02 AM
The forecast in Sydney is bleak to say the least!
I'm planning on heading out to West Wyalong way (I've labelled
Desperationville) on Occult Watcher.
Good luck to everyone.
04-06-2010, 07:15 PM
Not looking good here in Perth, either. Still some time to go yet...
04-06-2010, 07:50 PM
Dave, if you have the ability to post from West Wyalong, let us know how it goes. I am afraid that this evening is rather wet in Sydney.
06-06-2010, 04:51 AM
after a 842km round trip, all I can report is that the sky was perfectly clear at West Wyalong and that I observed a miss, my light "curve" is below. also attached is an image I took about 1 3/4 hours before the event showing Pluto appulsing the star. Warning - it's mirrored.
The good news is that Alan Gilmore and Brian Loader reported - "We saw the occultation at Mt John last night, using Brian's Watec 120N camera on the 1-metre telescope.":thumbsup:
06-06-2010, 09:03 AM
Kudos to you Dave for the effort. Well done.
The next one will be ours! ... or something :-)
06-06-2010, 10:14 AM
As I hinted in my previous message, Alan Gilmore and Brian Loader observed a positive at Mt John. I've just received their permission to post a note here. They write...
We saw the occultation at Mt John last night, using Brian's Watec 120N camera on the 1-metre telescope.
Mid event was about 15:35:38, with total occultation lasting about 1m 07s. Atmospheric ingress and egress both lasted 32-35 seconds. Attached (below) is a preliminary light curve.
Atmospheric conditions were good: excellent seeing with perhaps some very thin cirrus crossing.
06-06-2010, 02:48 PM
That's good to see the light curve.
1 metre telescope ... makes the LX90-8" look a bit meagre!
Is there a way to find out how others went with the occultation? Some central repository of information? Or do we wait for the paper?
06-06-2010, 04:53 PM
Yes, it would be nice to have a 1m telescope for these events. But the 8" would have seen it, albeit at a slower frame rate.
That's a good question Tony,
This is a pro-am effort, as distinct from a pure professional observation, where sometimes results are kept secret untill the paper is published. You can't blame the pros. really because some times their funding hangs on the results of papers, but our PI, Bruno Sicardy is very open and happy to share, at least the preliminary results, after all, he is getting our observations for free.:thumbsup:
Everyone is encouraged to report their results (positive, negative, clouded or technical failure) to John Talbot of RASNZ and to Bruno Sicardy or Paris Observatory.
John would like to receive the report in the correct spreadsheet format, so that your coordinates and times get imported straight into Occult with the minimum of fuss. The form can be downloaded here... http://occsec.wellington.net.nz/
about 3/4 the way down the page. Early during the month, John produces the detailed results of the previous month. So the detailed results of this Pluto event will be available on the RASNZ site early in July.
If you observed a positive or negative (miss) you can send an email direct to Bruno. Contact me off-line for Bruno's email address.
I'm sure John and Bruno will compare results from time-to-time, to make sure no one's observation is missed.
If there is a paper to be written, and that's up to Bruno, he will include you in the co-author list if you contributed to the observation.
In any case, I'll keep this forum in the loop in the interest of attracting more observers to become involved.:welcome: The more keen observers there are, the more observations are made, the more knowledge is gained.
Of course, everyone is encouraged to observe the many asteroid occultation events that criss-cross the ground. You can read about last month's results on the RASNZ site or by installing Dave Herald's Occult and downloading the asteroid update.
06-06-2010, 10:02 PM
Perth was clouded out. Roger posted a pic in this thread http://www.iceinspace.com.au/forum/showthread.php?t=62013 and you can easily see what we were up against. Oh well, on to next year's possibilities for Pluto (the rest of this years ones are too faint for me).
07-06-2010, 06:35 PM
Below you'll see a (very) preliminary plot of the results, courtesy of John Talbot. Many observations are being worked on and refined and the final plot will be available on the RASNZoccsec site by early July.
The southern shift is very apparent.
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