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30th Anniversary of the Voyager 1 Flyby of Jupiter
tasp
post Nov 19 2009, 04:13 PM
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I really appreciate this thread as 30 years ago I totally missed the Voyager 1 Jupiter encounter. I had signed up for the Eclipse over Big Sky Country and was in Montana enjoying the Huntley Lodge and watching the last total solar eclipse visible from the continental US till 2017. The eclipse was grand and a lifetime memorable event, and it was just about the only thing that could have kept me from watching the Jupiter spectacular.

I was surprised shortly after the trip to note Time magazine had covered the flyby and the eclipse in the same issue. There were roughly 400 eclipse chasers in the Eclipse Bus Caravan (LOL) and we wound up watching from just west of Roundup, Montana. The trip organizers had access to weather satellite imagery (I have no idea how they did this in 1979) and managed to put the Eclipse Bus Caravan under a break in the clouds as the eclipse passed over us. We did have some high altitude haze, but it actually enhanced the view.

To make up for missing the Voyager encounter I ordered every 35mm slide set I could find and bought a slide projector. Much more handy to have the enhanced pictures here at UMSF.

Thanx!


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tedstryk
post Nov 20 2009, 02:36 AM
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Great work! If I might suggest something, flat fielding the images would get rid of the bright corners in the images.


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elakdawalla
post Nov 20 2009, 03:03 AM
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What do you use for a Voyager flat field, Ted?


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DrShank
post Nov 20 2009, 03:34 AM
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QUOTE (elakdawalla @ Nov 19 2009, 10:03 PM) *
What do you use for a Voyager flat field, Ted?



um actually not always. I use the standard calibration flat fields in ISIS and sometimes the corner flares persisted.
The VGR vidicon usually but not always obeyed its own rules. In that case I just crop the corner. Image calibration is not always
a 1-2-3 procedure!


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JohnVV
post Nov 20 2009, 04:55 AM
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QUOTE
I really appreciate this thread as 30 years ago I totally missed the Voyager 1 Jupiter encounter.

i did not quite miss it but i was 12 . What i remember is I was sitting in the auditorium of the Modem Languages Building at U of M for Jim Loudon's AstroFest . I think i was one of the youngest there for the voyager 1 and 2 encounters .
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machi
post Nov 20 2009, 10:32 AM
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QUOTE (tedstryk @ Nov 20 2009, 03:36 AM) *
Great work! If I might suggest something, flat fielding the images would get rid of the bright corners in the images.


Thanks!
I used only the dark frame subtract from these images. Flat fields (which I have) cause partially destruction of the details. Normally I use the images from dark side of Neptune or Saturn. Yesterday I downloaded the plaque images, but I don't see any advances over the dark side images. Maybe the problem is in the setup, so I'm still trying new procedures.


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ugordan
post Nov 20 2009, 11:29 AM
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QUOTE (machi @ Nov 20 2009, 11:32 AM) *
ThankFlat fields (which I have) cause partially destruction of the details.

That doesn't sound right. They should only affect vignetting, dust rings, and other static noise (differences in sensitivity, etc.) in the instrument. Do you mean the introduce even more noise into the images? When you say you use images of Saturn/Neptune dark sides, how do you get a flatfield out of them?


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machi
post Nov 20 2009, 12:13 PM
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QUOTE (ugordan @ Nov 20 2009, 12:29 PM) *
That doesn't sound right. They should only affect vignetting, dust rings, and other static noise (differences in sensitivity, etc.) in the instrument. Do you mean the introduce even more noise into the images? When you say you use images of Saturn/Neptune dark sides, how do you get a flatfield out of them?


The dark side images are for the dark frames (but in the past, I was experimenting with some adjustment in brightness level, inverting images and so on, and applicating this like flatfield). Flatfields (from the plaque images) don't introduce more noise. They correct images, but too much! Faint details are gone. Maybe I'm working with wrong images, so I'm experimenting with setup and different images. For now, I'm still not satisfied with the results.


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4th rock from th...
post Nov 20 2009, 02:29 PM
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Tho have good results in image calibration, you should use a master flat field, composed of an average of many many individual flat field images (dozens).
The same goes for the dark fields. Also, don't forget the bias fields that are necessary to prevent introducing noise in the process. Everything should be processed in at least a 16bit depth to prevent any data loss.


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tedstryk
post Nov 20 2009, 03:50 PM
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I use different dark frames and flat fields for different parts of the mission - it isn't consistent, and I do some other black magic to cut down on detail destruction. It doesn't perfectly fix the corners, but it does subdue it somewhat. I also convert everything to 16 bit before beginning any processing. This cuts down on detail destruction as well.


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machi
post Nov 24 2009, 09:22 PM
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Io shadow on Jupiter (and interesting clouds). Resolution is around 9.7 km/pix. Color is from CH4_JS, orange and violet filter. Finally I found good flatfield image, so It's flatfielded.
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machi
post Dec 7 2009, 10:49 AM
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Callisto colorised mosaic. Mosaic is composed from nine NAC images and color information from WAC images (blue, orange and clear filter). Voyager 1 distance from Callisto approximately 326 000 km. Resolution is 3 km/pix.
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machi
post Dec 19 2009, 05:12 PM
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Maasaw Patera from Voyager 1. Colorised from WAC images (violet, orange) and clear NAC images.
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tedstryk
post Dec 19 2009, 05:22 PM
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NICE!!!


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nprev
post Dec 19 2009, 06:58 PM
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Damn straight! That's beautiful, Machi.


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