Category Archives: Pictures

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.

Go to this object description and this image technical detail.

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.

Go to this object description and this image technical detail.

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.

June 2011: Supernova SN2011dh in M51!

On June 3, astronomers discovered a brilliant supernova in M51. This is the kind of spectacular target to image, due to M51 extraordinary beauty. I must admit that I didn’t know about the supernova existence when I imaged M51 by routine. When I processed the images, I compared them with professional pictures, to identify some of the features of the galaxy. I was stuck when I “discovered” a new star, around magnitude 13. I run to my computer and connected to the internet! Yes! Got it!

This image is an LRGB one. As I was testing, unaware of the supernova, it only contains 2 ten-minute subs through each filter, so the result is noisy, despite the 80-minute total exposure, and has some disturbing gradients (well, it’s time for me to begin taking flats!). Imaged with the QSI583WSG, guided with the DSI.

Go to this object description and this image technical detail.

April 2011: testing with galaxies

I keep on working with balance issues. These seem critical for a good guiding, and right now they appear to be the main culprit for guiding errors. As I lack a comprehensive balancing system, with 3D weights, I get by using a somehow primitive approach: I balance the scope to the specific declination of the target to image. This approach forces me to balance again if I want to image a different target, but, anyway, with the “long” exposures I’m using this is not of main concern.

The results pay off, I think. The guiding goes on smooth, with only some problems in between exposures, as during the CCD download time the guiding system keeps in “latency” and after that the guide star may have moved much (sometimes even out of the small guiding window).

The picture shows the galaxy group knonw as NGC3190, some 60 million light years away, in Leo.NGC3193 is the huge elliptical near the center. NGC3190 is the beautiful spiral, near edge-on, showing the clear dust lane in its plane. NGC3187, to its right, is another spiral, with distorted arms due to the interaction with NGC3190. NGC3185 appears in the top right side of the picture, but it is not related with the group. Also, at least two other faint galaxies can be seen.

This picture was taken with a total exposure over two hours (40 min. luminance + 30 min. through each R, G and B), with 10-min subs. Processed with Pixinsight.

Go to this object description and this image technical detail.

February 2011: improved guiding with the new CCD

After much effort,  results seem to pay off. It’s been a lot of testing to realize that balancing the scope is one of the keys to guide smooth and consistently. 

This image of IC410, surrounded with a rich star field in Auriga, consists of 70 minutes of total exposure, with 10-minute subs, through H-alpha, R, G, and B filters. During the whole 70-minute period, the guiding was wonderful, when compared with my previous ones. Now, my goal is to be able to consistently achieve this guiding quality. The improvement allows for a image which is 1663 x 1252 pixels (even so, it’s only half the capability of the QSI583!). 

Go to this object description and this image technical detail.

November 2010: guiding with the new CCD

The new CCD is so powerful that all the defects of my setup have appeared! (collimation being one of them!). So, my current task is to fix all these defects, and also begin guiding. Yes, with guiding I should go up to 10 minutes (or more) of exposition with my subs. After working hard with guiding setup, I am now beginning to get my first outcome.

Here are two first examples. The Crescent Nebula and the Veil Nebula. It’s still a LONG way to go… but I know I’m going the right direction! Both of them consist of 10-minute subs.

October 2010: New CCD arrived!!! QSI-583WSG

After waiting for a long time, saving money for this beauty, it finally came to me! A wonderful CCD. But this baby has showed all the defects of my current setup! Now I have a LONG task list to improve everything and get the most out of my new CCD.

But, for now, some initial tests. Let’s give them a look. 

A section of the Moon, Jupiter with the shadow of one of its satellites, and M57 showing the wide field of the QSI583.