Double Lunar Graze Occultation (video)

[noswonky]

On October 12th, I observed two Lunar graze occultation events with a small team (4 observers) at Ilford NSW. I had observed some lunar occultations before but this was my first graze event.

Here's my video of the events of the evening:

http://www.youtube.com/watch?v=EzHMYUPeb7o

[lazjen]

Interesting video. Any results from the measurements?

[Robh]

Hi Peter,

Nicely constructed video, interesting and instructive as well.

Regards, Rob

[h0ughy]

great video - tells a great tale. we actually saw that star disappear from wallsend brickworks park at a similar time - LOL international observe the moon night which Newcastle Astronomical Society ran this year. others were watching it live in a scope - i was imaging an area on the brighter part of the moon and when i finished the capture run tried to scoot over to the area but just missed it. Very professionally edited, though the actors do need a bit of a polish up ;)

[noswonky]

Plot from Occult4 attached. Don't ask me to explain it though. I'm new to this and I don't yet know how to interpret these plots.

[lazjen]

Totally new to this as well, so the blind leading the blind? :)

Maybe someone can explain this for us both.

[Blue Skies]

Looks like it was a graze of the south lunar limb. The coloured dots and crosses are places where the star was seen disappearing or reappearing by different observers. The dark part is the solid part of the moon and the light dotty part where the true lunar profile might lie as measured in the past by either other lunar occultations/Kaguya spacecraft/the LRO or other recent lunar orbiters. Looks like the observations were quite accurate from that graphic.

Now I expect DaveG will pop in and tell me I've got it all back to front...

If you're interested in getting into this to take some accurate measurements my I point you in the direction of the recently released "Observing Occultations using Video: A Beginner's Guide (http://www.occultations.org.nz/videotime/manual.htm)" on the RASNZ Occultation Section website. :D It won't tell you how to run a grazing expedition but it will (I hope!) get you started with how to do the observations while you're on one - or at least give you idea of what you need to aim for.

[Robh]

I'm no expert but it looks to me like you have the results of two separate star grazes by three observers on the one profile. Is this correct? The upper one shows a shorter disappearance and then a longer one by one star. You need to imagine an arc parallel to the lower one. I think the lower one was a longer disappearance by a different star. The red dots indicate a disappearance and the green a reappearance (I hope that is the order). Not sure why one pair is in yellow.

The path of the star is probably in an arc which is greatly exaggerated in the vertical scale in arc seconds.

Regards, Rob

[nebulosity.]

Great movie Peter :thumbsup:

Jo

[tonybarry]

Hi Peter,

It's obviously a seismograph recording ... :lol:

Great effort, and nice miss with that roo. One occultation I am sure you are glad you did not bag.

Regards,
Tony Barry

[Steffen]

Nicely done Peter, and very entertaining!

Cheers
Steffen.

[DaveGee]

Zzzzzz Hey, did someone mention my name...



Correct.

Dots are video observations and crosses are visual observations.
Red = disappearances
Green = reappearances



the dark bit is space or nothing, and the grey/green (whatever) dots are RADAR soundings from the Kaguya Lunar Orbiter.

Back to Zzzzzz.;)

[DaveGee]

100% spot on Rob.:thumbsup:

The stars were SAO 162922 (upper) and SAO 162930 (lower) grazing at the southern cusp.