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Originally Posted by AstroJunk
I'd love to know too. I have my eye on that fabulous camera!
Of course, you can test it between now and then - just find a 14th mag star and set the iso so that you can see it clearly with a low exposure - Our cameras will be something around .25 to .5 second exposure for 14th mag.
The star that will be occulted is much brighter at mag 12, but we are looking to get a good result at the minimum brightness (14.2)
Its a balancing act between amplification and exposure, so it would be great if you could post some frames here so we can see what your set up is capable of - Its my guess that it could be fantastic!
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that's a good idea, next time I set up i'll do some investigating.
Quote:
Originally Posted by tonybarry
Hi Russell,
The Sony A7s has a good reputation for low light, low noise imaging.
You would need to test it out on the star in question, with your chosen scope, to see how it would go as a movie mode device. That would be an easy first step, and something you would do anyway to get a good experience with the field of view and the behaviour of your camera.
Traditional occultation recordings have precise timekeeping as a major input to the science. As Jonathan says (above) the central flash is the big money for the science crew, but good timekeeping will still be very important. For example, if you are close to (but not right on) the central line, your central flash recording will display a different behaviour to a dead centre line. Now if the field of observers is densely packed and we get a lot of chords, then yes we may be able to retrofit your chord to the rest of the pack based on your location. This is not ideal, but desperate people can do desperate things :-). Also bear in mind that Pluto has an atmosphere, and the soggy ingress and egress light curves do nothing to make that retrofit alignment task easier.
If the field is not packed and we have few chords, then timekeeping, preferably to the millisecond and referred to UTC, is really quite necessary. At the very least, syncing the camera with the computer clock will get you to within a second if the computer is running Network Time Protocol and it is properly peered to a local server. But be aware that NTP has to be running, and working, and for that something like Dimension4 or TARDIS, and a good ADSL link, might be helpful.
Most of the regular occ people who correspond here use GPS based video time insertion of one flavour or another, and analog video cameras.
I am currently reading Bruno Sicardy's paper on the central flash of an occ of Neptune in 1998:-
http://www.lesia.obspm.fr/perso/brun...s_icarus98.pdf
which is a bit to get through but I am getting to appreciate the science behind the observing of the central flash, and in particular what observers (such as us) might want to do to prepare properly for the event.
Again, I would encourage you to observe the Pluto event. It is probably a once-in-a-decade occultation for brightness, and a once-in-a-lifetime chance to help out with a NASA space probe data collection.
Regards,
Tony Barry
WSAAG |
Hi Tony, thanks for the indepth replies. I maybe just outside Canberra also, but its fascinating that there can be such differing predictions. Is there any particular reason you follow the prediction for the north of Melbourne?
Unfortunately my laptop is fairly terrible and
just runs PHD2 and BYEOS, while attempting to obtain video in Backyard eos the fps was very low probably around 8-10. I know the A7s has a gps in it i'm not sure how accurate it would be and useful in the exif data in addition it also has timecode although I don't know much about that either (perhaps it could be linked to the KIWI OSD).
First things first I need to check the video capability out.
Quote:
Originally Posted by Blue Skies
I've got an old KIWI-OSD I could lend you Russell, but it needs to be "rebooted" because it hasn't been used in so long (something I will need to ask other occ section members about, but I think I've seen someone else do it). I'm planning on coming along to the MPAS members night on Sat, might see you there? Could always drop it off another time, too, if you're keen.
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Thanks for this, unfortunately I rarely make the MPAS meetings due to being so busy! I am not familiar with the KIWI-OSD does it include a camera or do I plug one into it then use through a laptop? Potentially I could have the A7s going on the 12"f4 and another camera on my dob 12"f5 (lodestar?)... I've got a bit of reading to do!