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March 2013: Comet Panstarrs C/2011 L4 is here!

This is one of the most spectacular comets to visit us (and waiting for comet ISON at the end of this year).

Now, it is easily seen over the western horizon, soon after sunset.

I took these pictures from Falset’s castle, on March 15th, at around 19:50 local time (18:50 UT). I used an Olympus E450, with a 150mm zoom, at ISO 400, and exposures ranging from 4 up to 6 seconds. And no processing (only some cropping).

 

 

Go to this object description and this image technical detail.

Deconvolution with PixInsight, … or how to turn a humble image into a decent one

Of all the processing techniques, deconvolution is a real beast. It can work wonders, but it’s also very difficult to master. How many times I just gave up (using some unpolite words) trying to use it?

To my confort, I thought “well, calm down, … my images are noisy and of low quality, and deconvolution doesn’t like that, it only works fine with good images”. But, after some time I got to a conclusion: “If deconvolution ONLY works with good images, … what’s the point? Good images don’t really need deconvolution, do they?”

So, I decided to try again, and to devote time to apply deconvolution to my case. I chose a target which can benefit from deconvolution (the M101 galaxy), and I just took out the dust from the images I got a couple of years ago.

I’m glad to share with you my final result:

 

And with my conclusions, I wrote this article, hopping it can be helpful to other people out there.

Read the whole article about deconvolution…

January 2013: M33

M33 is a member of our local group of galaxies. The light of this beast came into my CCD after travelling for about 2,8 milion years.

This is a mosaic of two pieces, as M33 is a wide target. Each one of the pieces consists of LRGB subs of 5 minutes.

Processing has been difficult. As M33 lowered as the imaging session was ongoing, gradients appeared in the subs. Also, the B channel was affected by this lowering. All of this created uneven gradients between frames. As a result, the image appears noisy. Although I’ve tried to fix as much noise as I could, damaging the weakest parts of the galaxy was a potential damage, so I kept noise reduction in somehow a balance.

The core of the galaxy has been cleaned and exposed with wavelets processing. And the color saturation has been pushed to show the active regions in the galaxy. These regions appear as red knots.

M33 new processing

Go to this object description and this image technical detail.

October 2012: M2

Globular cluster M2 is not quite as spectacular as its big brother, M13. Nevertheless, this kind of objects are always worth a picture!

For this image I kept exposures to 400 seconds, to prevent burning out the center of the cluster. I used clear luminance, together with R, G and B exposures.

Processing was not easy. I tried to sharpen the core and the external stars, using wavelets techniques. Several attempts were needed to get a balance between sharpening and softness. For this, a mask was used which protected the background and the stars.

   Go to this object description and this image technical detail.

September 2012: Sharpless 2-115

This seems to be one of thousands out-of-the-circuit objects, not being part of the regular image catalog of the amateur. I saw a picture of it in a magazine, and I set it as my next target.

I imaged this nebula in two different nights (a week in between). I then carefully selected the best subs, as the Last-Quarter Moon was quite a problem with the R, G and B images.

I had an unexpected problem with field rotation. I noticed it in most of my subs those nights. My polar alignment is not perfect, I know, but having field rotation using the same exposures I usually use (700 and 400 seconds) was surprising. This was because this object has a higher declination than that of my “normal” targets.

The small cluster Berkeley 90 can be seen embeded in this huge nebula left off-center.

The image contains 7 700-second subs through the H-alfa filter, 7 400-second subs through the R filter, 8 400-second subs of G, and 6 400-second subs of B filter. Some gradients at the edges, due to the moonlight, were almost impossible to fix without damaging the nebula. 

  Go to this object description and this image technical detail.

August 2012: another mosaic, now with the Eastern Veil Nebula

The fact is that before I attempted the Western Veil with a challenging 6-piece mosaic, I tried the technique with a fragment of the Eastern Veil (a 3-pieces mosaic) I began processing it, but as I then imaged the Western Veil, all my time went to processing the big one, and my Eastern remained waiting.

After having finished its processing, I must say that this object is remarkably spectacular. I’m also very happy overall with it, and the contrast between the nebula and the background.

As with the big mosaic, each piece of it contains 3 700-second subs through the H-alfa filter, and 3 400-second subs through the R, G and B filters.

  Go to this object description and this image technical detail.

August 2012: a challenging mosaic, the Western Veil

My configuration (8″ LX200 with the Optec Focal Reducer and the QSI-583WSG) provides an effective FoV of about 40′ X 30′. This is a good field for many objects, but fails to cover big targets. One of these “big targets” is the Veil Nebula. So, I decided to go for my first mosaic!

This mosaic is a challenging one indeed. I needed 6 overlaping frames to cover almost all of it. As you can imagine, processing was critical, to get similar background brightnesses among the frames.

Each frame contains 3 subs through H-alpha, R, G and B filters. Exposures are 700 seconds for the H-alpha, and 400 seconds for RGB.

This is the result. I must say I am quite satisfied with it! This experience now encourages me to go for some “easier” mosaics (maybe 2 frames) to image objects too big for my regular configuration.

Go to this object description and this image technical detail.

July 2012: the Dumbbell

Encouraged with the pay-off of my primitive flat-frames technique, I now target one of the brightest deep sky object: M27, the Dumbbell, a magnificent planetary nebula in Vulpecula.

Due to its brightness, the 600-second exposures, and the extraordinary sensibility of the QSI, the central part of the nebula got over exposed, so the fine detail inside was burned. Fortunately, Pixinsight tools recover all this information which is hidden “below”.

The final image is the result of stacking and processing almost three hours total through RGB and H-alpha filters, in 600-second exposures.

Go to this object description and this image technical detail.