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.

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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.

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June 2012: Trifid and NGC4565… now with FLATS

After some months with bad weather and/or other priorities, I’m back again with my QSI. Now aiming at two great targets, and testing, FINALLY, my first flats! I consider this my first attempt, to be largely imporved (I hope). I used the T-shirt method. As I couldn’t wait till the dawn, I imaged my flats at dusk. And, as the focus was not exactly teh same as used during the night, these flats were not 100% correct. Anyway, I think they did a good job. More to explore and improve.

First target is the famed Trifid Nebula. And I must say that I’m not totally happy with my results, as I think I can improve focus. Although tha nebulosity has been perfectly captured, the overall look of the image, with it’s rich star field, is a bit fuzy. Now that I have experience enough with my setup, and comparing with previous targets, I am sure this imaging session can be improved. Maybe I slightly missed the focus, maybe it slightly shifted during the session.

For this image, I didn’t use the H-alfa filter. It’s a composite of  15 minutes through clear Luminance, and 30 minutes each through R, G and B filters, for 1:45 hours of total exposure.

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The second target is NGC4565, one of the most spectacular edge-on galaxies. I must say that thanks to my much-to-be-improved flats I had little difficulties processing this baby. One thing is to image big ans bright objects, which fill the frame, and the other is aiming at little objects, in poorly iluminated fields. In this case, severe vignetting appears in my frames, as you must stretch the histogram to pull out the most of it.And flats come into rescue! Having processed this kind of images before without them, I tell you, flats make the difference.

Probably due to the focus issue I said before, and due to a poor guiding session, the galaxy details are not wery well defined. But being this object much more demanding than the Trifid, I consider myself satisfied with it.

For this image, I didn’t use the H-alfa filter. It’s a composite of  15 minutes through clear Luminance, and 30 minutes each through R, G and B filters, for 1:45 hours of total exposure.

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March 2012: IC405, the Flaming Star Nebula

This is a really spectacular object. The Flaming Star nebula is called after AE Aurigae, the powerfull star which dominates the field. This very hot, blue star ionizes the gas in the nebula, so it brights. Also, it casts its blue light on the dust inside the nebula, which gives these remarkable blue hues.

I’m quite happy with this baby, taking into account the almost full moon in that night. Processing has not been easy, as the image has a lot of different features which needed to be protected or highlighted. This image is a composite of  almost an hour through H-alfa filter, plus more than half hour through R, G and B each. Hope you like it!

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February 2012: Horsehead nebula and the Cone nebula

It’s been a long, inactive winter for me (in terms of astrophotography). After more than two months counting sheep, I finally saw the opportunity, in spite of the freezing temperatures, to keep on my astrophotography learning journey. Thanks God, my remote, wifi-based setup paid off, so I could face long exposures while warm inside the house and keeping tight control of the imaging session.

This is a composite of almost one hour of H-alpha exposures (5 frames, 700 seconds each), and about an hour and a half through RGB filters. The H-alpha filter was mandatory for trying to image the fine details and vertical filaments of the nebula. Even so, the noise in the image background is apparent, clear indication that, for this object and the used setup, more signal was needed.

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And this is the Cone Nebula, in the middle of the rich star field of the Christmas Tree Cluster. This is a composite of  almost 3.000 seconds thru an H-alpha filter, and one hour thru RGB. The nebulosity is everywhere in this frame, so that the processing was not straightforward.

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October 2011: Tulip Nebula

A battle against the full Moon, … and a win thanks to the H-alpha filter!

This is another try to image a deep sky object under a full Moon light. The narrowband component (almost an hour exposition), with an H-alpha filter, was gradient free and of great detail and beauty. Unfortunately, the RGB components (1500 second each) were seriosly damaged with the Moon gradient. 

To somehow overcome this, a “synthetic” R component was created with the H-alpha and the original R image. This synthetic R was also used as a Luminance component, with a 50% weight. The R, G and B were processed with agressive background neutralization tools in PixInsight, to remove as much gradient as possible.

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September 2011: … or one of the thousand things that can spoil an image

Every thing works quite fine during your imaging sesion. It seems you’ll get some wonderful images that night. Suddenly, the guide star seems to fade away, and guiding fails. No clouds in the sky, so? 

From the thousand things which can go wrong and spoil an image, I discovered one of these last night. My anti-dew system failed, and the dew quicky landed on my corrector lens. I wasn’t able to see this until it was too late in the night, as I simply didn’t get suspicios about this failure.

I was imaging the Cocoon Nebula, a fine object indeed. I was able to take my H-alpha, narrowband images (with 700-second subs), but my R, G and B images (at 500 seconds) got almost all of them spoiled. I could only use one sub per each channel! The result: a noise image. I have had to apply a quite aggressive noise reduction process, and this can be seen in the background. 

On the other hand, it’s impressive how a narrowband image can work with not-so-good RGB ones. Taking into account the problems, I can be satisfied with the result. And with the lesson learnt!

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July 2011: Narrowband against full-Moon light

More of narrowband. This time, I tested the H-alpha filter on a delicate object in a full-Moon night. Of course, the light of the Moon washed out almost any signal from the R, G and B filters (the R one did capture some). But, as expected, the H-alpha subs were perfect, with no trace of light from the Moon. I even increased exposure time to 700 seconds in the subs. 

The target was the North America Nebula (NGC7000). Well, a small fraction of it, because it’s a quite wide object. In this case, I targeted the “central america” portion of it.

I’ll have to come to it again without Moon!

(H-Alpha + R)GB, with 700-second and binned 2X2 for H-alpha, and 300-second and binned 3X3 for RGB: 5 subs for H-Alpha, and 3 subs for R, G and B. Imaged with the QSI583WSG, guided with the DSI (and re-processed from the previous version after six months, trying to apply my improvements in processing!!!)

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July 2011: The challenge of processing narrowband with broadband

Well, nobody said that this was going to be easy! Using narrowband filters (here I’m using an H-alpha one) gives you a lot of flexibility in astrophotography. Specially, with nebulae, in which strong H-alpha emissions exist, this type of filters can get really deep inside details, and they also filter out undesired light (as, for example, polution light).

But, achieving a good balance while processing narrowband images together with “normal”, broadband RGB frames, has proven to be a real challenge for me. A lot of things have to be taken into account. To begin with, the size of the stars in the pictures are smaller in the narrowband images. Also, using H-alpha as a Luminance layer brings in new problems, as a lack of colour in the final image. And, if we try to weight it down, we lose the incredible detail it contains!

I’m NOT happy with my processing of the Crescent Nebula. But I’m not sure if I’ll be able to improve it in the short term. For this image, I’ve finally blended the R and H-alpha channels, but before that I’ve processed the narrowband component alone to allow for maximum detail and, at the same time, reduce noise in the background. Deconvolution, with the help of masks, has worked some “miracles” with the fine details and tendrils of the Crescent. The global colour balance has been achieved working with the R, B and G components histograms.

(H-Alpha + R)GB, with 600-second, binned 2X2 frames: 5 subs for H-Alpha, and 3 subs for R, G and B. Imaged with the QSI583WSG, guided with the DSI.

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June 2011: Another try on galaxies, … and the QSI against M13!

I keep on working (hard!) on improving the guidind and also the post-processing. To trhis, galaxies pose a great challenge to me. So, I tried on M101, and here is the result. Not so bad, although I should have got more signal! And the gradient problem is still there (until I take flats!), and oblige me to apply some severe corrections with PixInsight, which, I’m sure, spoil somehow the whole thing.

LRGB, with 4 600-second, binned 2X2, L frames, and 3 600-second, binned 3X3, throu RGB filters. Imaged with the QSI583WSG, guided with the DSI.

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Well, I thought it was time to test the QSI with a “big” one. I considered that my guiding techniques had improved enough to try. M13 is ALWAYS spectacular. Although it’s a bright and “easy” target, I find it challenging to properly image: smothly resolving the outskirts of it it’s something which is not simple.

RGB, with 180-second, binned 2X2, frames: 10XR, 8XG and 9XB. Imaged with the QSI583WSG, guided with the DSI.

 Go to this object description and this image technical detail.