Archive for category Planets

Saturn “Serpent Storm” with Celestron EdgeHD 11″

Date: 2/27/2011 at 2.23am PST

Location: San Bruno California

Telescope: EdgeHD 11 with DMK 21AU04.AS Camera and Siebert Barlow 2x

Seeing: 6/10

Image Processing: Frame stacking: AVI Stack, Image composition: Photoshop CS4, Astra Image Wavelet plug-in, Noise Ninja

This is one of the first pictures taken with my new Celestron EdgeHD 11″.  The seeing was  above average – but not excellent. Visually at x450, Saturn was impressive, with a great contrast on the Cassini division, and details easily visible on the north band (the great north band disturbance famously called “serpent storm”).

The 11″ of aperture here made a huge difference with previous images taken with my Mak Cassegrain 7″, not so much in terms of pure resolution (limited by seeing) – but in terms of image brightness. I imaged at f/d 25 – I should have imaged at f/d 37 with the Mak Cassegrain to achieve the same image scale. I was able to take most of the frames at 1/10 sec. or below, to capture moments of best seeing. This is a composite image made of roughly 2,500 frames shot in about 6 minutes.  Capturing Saturn’s satellites up to magnitude 12 on the luminance frame was fairly easy – even though each frame was 1/20sec of exposure for the luminance layer.

Saturn satellites from left to right:

  • Dione : magnitude 10.5
  • Enceladus: magnitude 11.9
  • Rhea: magnitude 9.9
  • Thetys: magnitude 10.4

This is a set of three images taken during this imaging session  showing Saturn’s rotation…

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Jupiter SEB revival in November 2010

Orion 180 Mak Cassegrain with DMK Camera on Takahashi NJP-Z mount.

Seeing: 4/10

I captured these pictures on a night of average seeing.

It is possible to notice a quite visible revival of the South Equatorial belt on this picture, that was not visible in pictures taken earlier in November.

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Jupiter – November 2010

Seeing condition was pretty good (Alpo seeing 6/10)  when I took this picture with my 7″ Orion Maksutov Cassegrain.

I spent 30min collimating the telescope before shooting Jupiter. I used a quality eyepiece at x350 to get pretty symmetric diffraction rings on a 2nd magnitude star.  It was I think time well spent.

This is the first time I collimated this telescope since I bought it – the scope  keeps collimation pretty well – but still it was time to tweak it.

And it paid off  – seeing was pretty good and with better collimation the telescope really showed its potential.

I am still very surprised by what this small telescope is capable of !

Image processing:

– Registax v5
– Photoshop CS4
– Astra Image wavelet plug in

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Jupiter opposition – October 2010

I took these shots of Jupiter with my 7″ Maksutov Cassegrain.

Seeing what good but not at the best this night. Seeing was below average first (first shot) and then turned better progressively at the same time Jupiter raised in the Sky.

However the LRGB technique I have been using lately allows to have quite good  resolution planetary imaging with average seeing, by extracting the best frames out of the large frame number / high speed luminance AVI.

For the first time I used the  Astra Image photoshop plug in for deconvolution (maximum entropy deconvolution) and wavelet sharpening.  I got this time better results compared to the deconvolution software “Focus Magic” I have been using so far.

I would recommend this software for planetary image processing.

 

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Jupiter is back: LRGB and Infrared Imaging

Jupiter is back in the late summer sky…

I tried out some new planetary imaging techniques compared to RGB imaging I did so far:  LRGB and Infrared imaging of Jupiter. The pictures were taken at approximatively f/d 25 and I found this is a f/d ratio working pretty well in average condition, optimizing the balance between exposure time, and magnification (1 pixel = 0.25 second of arc) for a planet like Jupiter.

I worked also hard on my Photoshop skills – and try to do less aggressive sharpening in order to produce planetary images with a more “natural” aspect and a better color balance. I found the overall aesthetic aspect of the picture is improved when doing so.

I’ll post other pictures but here are two  I took this week,

First –  LRGB imaging:

Since Jupiter’s rotation is very fast, the LRGB pictures have to be taken in a short period of time, definitely less than 4 minutes. I took more frames at high speed for the luminance with an IR/UV filter. The fast exposure time (about 1/30 sec) allows to take many pictures but also to find the right window where the turbulence is minimal. Visually, seeing was at 4/10 which is far from ideal – but by taking many frames, the signal/noise ratio is improved. Then I took less exposures for RGB frames – to make sure all the frames are taken in a window of 3/4 minutes. But since RGB frames are used for color – the slight time delay of 2/3 minutes they have with the Luminance layer is not that critical and not really visible on the final picture.

As a summary – I think the LRGB technique I have been using provides superior results compared to my previous RGB technique.  I don’t know if it is a valid /  general statement – but at least in my case it seems to work better.  I think it is because of the advantage of taking many frames at high speed for the luminance layer.

– Luminance exposure: 635 frames at 1/30 sec

– Red exposure: 203  frames at 1/5 sec
– Green exposure: 177 frames at 1/11 sec
– Blue exposure: 202 frames at 1/11 sec

The result is pretty good for a mass-produced telescope at a price tag of less than $1300 in average seeing condition … What do you think?

 

Second,  Infrared imaging:

The camera I use has no IR filter. It allows infrared imaging with the right blocking filter…

For infrared imaging I used the Astronomik IR 742 pro filter – it lets the light pass above 742nm and blocks the light below 742nm.

I was able to verify, as explained on the astronomik site, that the seeing is much better in the infrared – even if the turbulence is quite high – and Jupiter is low on the horizon.

However two factors are reducing the overall resolution

a) At + 742nm the resolution of the instrument is lower than at 500nm …by +50% – given the longer wavelength…  The aperture I used is pretty small so it really affects the resolution I can get in imaging.

b) Worse, the integration time has to be raised at +1/4 sec. so the longer exposure time does not allow to take shots so easily in a “low turbulence” window.

The IR Pro planet is not a miracle filter. Still, I found this technique quite interesting – as it certainly provides better quality pictures in a bad seeing environment, and highlights different features compared to the visible wavelength.

 

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Mars in early March 2010

This is probably my best photography of Mars even though it does not exhibit the side of mars with the most features.  The seeing was great for my location (Alpo seeing 6/10). Mars was quite high in the sky. The conditions were as good as for the shot I took in November.  Orographic clouds over  Olympus Mons can be seen, and as well as albedo features such as  Phlegra Montes, Phlegethon Catena and Amazonis Planitia. Picture taken at roughly f/d 40 using a 2.5x Siebert optics barlow with DMK B&K Camera – about 1,500 rgb frames  – each frane between 1/10 and 1/15 sec of exposure.

For those who are wondering why it is possible to capture (when the seeing is great…) details that are at or sometime far below Dawe’s limit – look at the excellent article from Damien Peach on this topic, explaining why Dawe’s limit is not really applicable to extended objects (planetary disk) with high contrast features.

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Saturn, Rhea and Tethys – February 2010

Between two rainfalls – I was able to take this picture of Saturn with my Maksutov Cassegrain 7″ at focal plane f/d 15 with my DMK B&W camera.  This is a composite picture from about 1100 RGB frames.

Notice from left to right two of Saturn’s satellites:  Rhea (mag 9.9)  and Tethys (mag 10.3).  Cassini’s division is guessed but not very obvious since the rings have a low inclination.  – The  C ring is hinted on the left and right portion of the disk. Disk diameter is 19″.

Saturn is more challenging to image because of its low surface magnitude. On the Red channel I had to shot at a speed as low as 1/9 sec by image.  Just finishing up shooting the blue channel, and clouds came over!  Next time I’ll try to image at f/d 22 using a 1/5x barlow to bring more details.

Seeing: 4/10
Transparency: 2/6 (Full moon)

Shot on 2/28/2010 at 1.10am PST

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