Here is another shot of Jupiter from Thursday night/Friday AM. The first photo in near IR (740nm), better showing the big storms, GRS, Oval BA, and LRS. The second a conventional RGB. These were taken under mediocre seeing, and worse yet, terrible transparency, so bad that I had to run more than X2 the usual exposure time (and 1/2 the frame rate).

Sometimes the weather forcasts, ie., winds, turbulence, scintillation, transparency, are not just off base, their not even in the ballpark. Such was the case this week.

Robert

Nice results. I always enjoy alternate filtering schemes, so much can be learned using specialized filters etc.

I understand that a methane line at somewhere near 840nm is a good one for Jupiter too.

Out of curiousity what camera / sensor are you using for the IR work?

Richard Crisp:

a methane line at somewhere near 840nm is a good one for Jupiter too.

This is true, Astronomik, and others offer multiple near IR filters, the version I used is best for Mars, the 840, Methane line filter, best shows the large storms on Jupiter.

Richard Crisp:

what camera / sensor are you using for the IR work?

All planetary work I've been doing uses the Lumenera 2-0 (Sony Ex-HAD CCD) through various Astronomik filters.

Robert

IR can be challenging for a sensor to handle. The issue is that the IR photons penetrate rather deeply into the silicon. Often times they penetrate more deeply than the depletion regions surrounding the pixels.

 when that happens, the electrons are formed in a field-free region in the device layer and have no controlling electric field to force them into the pixel where they belong

 The net result is that they move via thermal diffusion in the substate and have a high probability of winding up in the wrong pixel. The end effect is an image that looks a bit out of focus. In reality the optics are in focus but there's this MTF issue with the sensor.

 The data sheets generally will not give you a clue that this can be an issue and the QE curve doesn't really speak to it either because of the way that QE is measured. It is measured by using the entire chip as a photodiode with a known light flux being applied and a current measured. That will measure the carriers no matter what pixel they end up being captured.

So usually the thing to do is to first measure the camera's ability to image a NIR line by using it with all reflective optics on the ground on a target and to filter or otherwise restrict the light to the wavlengths of interest. Reflective optics are preferred since they don't exhibit wavelength dependent aberrations.

this is an example of the diffusion MTF issue as it is sometimes called:

http://www.narrowbandimaging.com/field_free_a_page.htm

 sensors that will be used with NIR are usually designed specifically for that task to avoid the issues I raised. Oftentimes they will be backside illuminated and they may feature a high bias voltage applied to the substrate side to increase the depletion region depth.

 You can certainly have fun using the EX-HAD sensor you have and I am not trying to discourage you in any way, but I thought you may experience what you may deem to be some focusing issues and wanted to point out that it may not be focus that is the issue but may be the characteristics of the sensor when exposed to NIR light.

It is a non-trivial problem to produce a sensor that gives sharp NIR images.

 The NIR image shows the LRS as quite spread out.  That's similar to what was seen last week in the Methane Band images I saw.  Thanks for sharing your data! 

As always, excellent image.