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Juno Perijove 24, December 26, 2019
Sean
post Jan 9 2020, 11:44 PM
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Detail from PJ24_24


Detail from PJ24_23


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Brian Swift
post Jan 15 2020, 11:20 PM
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Animation of lens flare and Ganymede moving over CCD from PJ24_02.
Somewhat interesting to me is part of flare in lower left that gets brighter and dimmer, but doesn't change position through the spin.
Attached Image


At closest point in this sequence, Sun is about 2 degrees outside camera field of view.
If Sun were to be imaged by JunoCam it would only be about about 4 pixels across.
Images are displayed at realtime rate, but only cover half of a spin (the other half are just black space).
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fredk
post Jan 16 2020, 12:38 AM
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QUOTE (Brian Swift @ Jan 16 2020, 12:20 AM) *
Somewhat interesting to me is part of flare in lower left that gets brighter and dimmer, but doesn't change position through the spin.

Dust on lens? Or a reflection of something fixed relative to the lens?
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mcaplinger
post Jan 16 2020, 01:52 AM
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QUOTE (fredk @ Jan 15 2020, 04:38 PM) *
Or a reflection of something fixed relative to the lens?

Could be a glint off the solar panels or something on the panel structure. The spacecraft was more or less spinning around the sun line at this time since it was so close to conjunction, so the illumination on the panels wouldn't have changed very much during the spin.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Kevin Gill
post Jan 16 2020, 02:38 AM
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The first Southern Fisheye Composite.

JNCE_2019360_24C00042_V01
JNCE_2019360_24C00043_V01
JNCE_2019360_24C00044_V01
JNCE_2019360_24C00045_V01
JNCE_2019360_24C00046_V01

Rendered from the perspective of '43


Jupiter - Perijove 24 - Composite
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Brian Swift
post Jan 16 2020, 06:53 AM
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Mike, just curious, did telemetry show any increase in focal plane temp while Sun was so close to field of view?

Also, has much analysis been done on what effect imaging the Sun would have on the CCD?
Given the1/25th Sun brightness, and spin duty cycle, I could imagine having the Sun imaged on the CCD might not be fatal/damaging.

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mcaplinger
post Jan 16 2020, 03:32 PM
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QUOTE (Brian Swift @ Jan 15 2020, 10:53 PM) *
Also, has much analysis been done on what effect imaging the Sun would have on the CCD?

Rather a lot. Even at 1 AU not enough energy lands on the CCD to damage it thermally. If you tried to image with the sun near the center of the detector, there is an electronic effect that could damage the sensor; see https://www.onsemi.com/pub/Collateral/AND9183-D.PDF for details. You may recall that there was an orbit with an unusual orientation that Junocam didn't image for, this was the reason.

I haven't looked at the temperature data but I don't expect anything significant.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Brian Swift
post Jan 17 2020, 07:19 AM
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QUOTE (mcaplinger @ Jan 16 2020, 07:32 AM) *
... there is an electronic effect that could damage the sensor; see https://www.onsemi.com/pub/Collateral/AND9183-D.PDF for details.

Thanks for the link. At the time I didn't understand how keeping the camera off would prevent damage.
It looks like the tech note came out post launch, so I wouldn't expect the system to have the shutter disable circuit.
Though it's not clear to me if the damage would occur if the shutter was only pulsed some duration after the Sun had moved off the sensor.
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Bjorn Jonsson
post Yesterday, 11:11 PM
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This is an orthographic mosaic of images PJ24_23, PJ24_24 and PJ24_25 in approximately true color/contrast and enhanced versions:

Attached Image
Attached Image


The mosaic is centered on planetographic latitude 53 degrees north. North is up.

BTW I noticed a 'gap' in the PJ24 product IDs, there is an image number 38 and image 40 but it's as if 39 is missing. Is there an image PJ24_39 that still hasn't appeared at the Juno website?
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mcaplinger
post Yesterday, 11:22 PM
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QUOTE (Bjorn Jonsson @ Jan 21 2020, 03:11 PM) *
Is there an image PJ24_39 that still hasn't appeared at the Juno website?

We're keeping that one secret because of the big conspiracy, but you caught us. rolleyes.gif

Seriously, it still has a data gap that hasn't been filled in by DSN replays.


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