Occultation of Ixion (Southern Australia) Tuesday evening

[tonybarry (Tony)]

Greetings All,

Felipe Bragas-Ribas has a prediction of an occultation of Ixion (a fairly large TNO currently 40AU from the sun). Central time is 14:56 UT on 24th June (for Sydney, that's just before 1am Wednesday morning).

http://devel2.linea.gov.br/~braga.ri...NIMA_Ixion.jpg

The star is 2UCAC 209-12984, mag. 15.2, very red, and the body is at 65 degrees altitude in the west (again, for Sydney).

The field hosts a mag 6.94 star (TYC 6820-00488) about 4.5 arc minutes from the target, so it may be an easier field to ID than what we usually get.

While the chart would appear to indicate that Brisbane is out-of-luck, the error bars for this kind of occultation are such that it's worth observing anywhere in Australia.

The weather report for Eastern Australia is somewhat dismal, with snow and wind … but perhaps the Western People can take up the challenge ?

Regards,
Tony Barry
WSAAG

[Blue Skies (Jacquie)]

Western people...? I thought I was the lone observer on the west coast.

15.2 is pushing it for my current set up, but since it's likely to be crystal clear and Antarctically cold, with no Moon, plus a decent time of night for me, I might give it a crack, seeing how I had had been thinking it was a shame to waste all that clear sky.

[tonybarry (Tony)]

Best of luck Jacquie, you're carrying the flag for the Aussies as far as I know.

Alice Springs is buried in cloud and Sydney is getting blown over. No occ observing for us tonight.

Regards,
Tony Barry

[Blue Skies (Jacquie)]

Well, I got a miss, but Bill Hanna in Alice Springs got a positive! That was a big jump north in the track.

[tonybarry (Tony)]

Right now Bill Hanna is on a roll.

Three days ago he bagged a 1.51 sec occultation of Deimos (the 12km satellite of Mars) - Mars is about mag -0.7 (= very bright) and the star was mag +8.9 …

It's a first for Deimos, and likely the smallest occulter (12km) ever observed. Deimos was just 20 arc sec from Mars at the time.

John Broughton in Qld sent Bill the prediction, and 4 hours later it was in the bag.

Stirring stuff !

Regards,
Tony Barry

[rustigsmed (Russell)]

Hi Tony,

Excuse my ignorance, but what type of gear do you need to be involved in these events? is it just videoing?

Cheers,

Russell

[Blue Skies (Jacquie)]

Well, I was waiting for Tony to come back, but perhaps I can help (I have written a manual on it for questions just like this, after all!)

You need (roughly):

• A telescope: Just about any telescope will do. If it tracks then great, but if its only a dob then there are ways around that.
• A video camera: if it integrates then you have an advantage. Some are better than others, but if you have something basic like a Gstar or Malincam then that's enough to get started. The best camera doesn't exist, unfortunately, its a future development we're still waiting for, but some are better than others.
• A Video Time Inserter (or other GPS-based timing device). You can get an IOTA-VTI from the US for around $300.
• Some way of capturing the video. There are some people who still put it on the VHS machine, but ultimately you still need to digitise it to a computer for analysis.
• Software for predictions (Occult and OccultWatcher) and analysis (LiMovie and Tangra 3) are currently still free!
• Check out the RASNZ Occultation Section website to see what we've all been up to lately

It is a little more complicated than that but you may already have some of those components and just need one or two of them.

I should also mention there are lots of introductory presentations to read through from the recent Eighth Tran Tasman Symposium on Occultations (TTSO8) posted online as well in case you didn't get to NACAA over the Easter weekend.

We really need some one in Victoria (and SA and Tasmania, for that matter) The more the merrier! I hope you'll take the plunge and join in.

[tonybarry (Tony)]

Hi Jacquie and Russell,

Thank you Jacquie for filling in - I have had a bit more work on my plate than I would like just now.

Yes, Russell, Jacquie's manual is comprehensive and well worth the read.

Your goto Dob would likely do very nicely as a telescope.

Consider that Bill Hanna was using an 8" LX90 for his occ of Ixion at 3 seconds per frame - your 12" would have about double the collecting area, and pushed this up to around 1.5 seconds per frame for around the same signal to noise ratio. Stepper motion artefact might be an issue for a goto dob at long exposures, but it's well worth a try.

The two programs (applications) that you need are Occult Watcher and Tangra, both available for free from Hristo Pavlov's website. OW tells you what occs are available in your neck of the woods (weather permitting) and Tangra deals with the resultant video file to make a light curve.

Again, Jacquie's manual does deal with this in a very comprehensive manner. And feel free to ask !

Regards,
Tony Barry
WSAAG

[rustigsmed (Russell)]

Hi Jacquie and Barry,

wow that really is a 'proper' manual!

Ok i would need a bit of gear (sensitive video cam etc), it seems that there needs to be a product like virtual dub with the precise time showing over the recording to make it easier.
I can see myself getting into this - a bit further down the track.

Thanks for all the information

Cheers,

Russell

[tonybarry (Tony)]

Hi Russell,

The device which shows the correct time as an overlay on the video is called a Video Time Inserter (VTI). Essential for video recordings of occultations.

Jacqui's manual describes the devices and where to get them.

A few have come up on IceInSpace, but none recently.

Regards,
Tony Barry