RBA & AF Astrophotography

November 2011

The Great Square of Pegasus

Posted: November 10th, 2011

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Earlier this year, when I was done with one of my projects (I think it was the teapot), I told Eric Zbinden "I'm not sure what to go for next"...With a mysterious voice he said "I have a suggestion for you" ... "Yeah, what?" ... "The square in Pegasus".

We both laughed. Yeah... sure!

But despite I didn't even consider for a second to go for Eric's "suggestion" at that moment, I did a bit of study on the area that revealed that there are indeed some high latitude molecular clouds floating around that area, and that was enough for me to start planning a macro-mosaic on the not-so-small square... With my current equipment, that meant a 20 pane mosaic of an area of the sky presumably unexciting from an aesthetic point of view, but hopefully interesting from a documentary standpoint. I tell you, mosaics aren't easy, but large ones are a pain in the butt. When you plan a mosaic this large - and remember, this is still a hobby - you hope to be somewhat rewarded, but in this case I really wasn't sure what I was going to get. Of course, there's only one way to find out.

Many miles of driving to dark sites, and hours of sleep lost, here's the results.

The data for this image was so scarce (75 minutes total LRGB per pane with just a few exceptions) that I was on the verge to put the project to sleep and get more data some other time.

Still, after some post-processing, and presented at the "right" scale, I felt the image met the criteria of at least visually documenting some of the clouds that populate the Great Square, and that's all the image aims to achieve: nothing but "there is a lot of stuff there and the image hints you about the position, shape and brightness of these clouds", and have it rest until someone else comes along and either does the whole area again but in great detail and depth, or produces imagery of smaller areas in this field.

You all know how big this area is, but we're so used to see deep sky images covering much less sky, that the sense of scale may be hard to grasp at first. The FOV is about 18.3 x 15.3 degrees.

A side note: This was the first time I attacked two mosaics almost simultaneously. During the month of October, my main project was the From Pleiades to Hyades mosaic, but I was splitting my time to capture this mosaic in Pegasus during the first hours of darkness, then switch to the (more visually rewarding) Pleiades/Hyades mosaic. This, perhaps extreme, ambition of capturing and finishing both mosaics in a one month time is what resulted in both mosaics - particularly this one - having less than ideal data. Lesson learned: just don't do that again! :-)

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From the Pleiades to the Hyades

Posted: November 6th, 2011

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Here's one of the projects that kept me busy the month of October.

It's a 12 pane mosaic of the area that goes from the Pleiades (M45) all the way to the Hyades. An area that we know well it's quite "dusty" around M45, in part contributed by the Taurus molecular cloud, but that as this image shows, and as expected although not commonly imaged, it really extends all the way to the famous V-shaped open cluster that lies behind the red giant Aldebaran.

I wasn't quite sure in which section I should post it: Star clusters or nebulae. Clearly the reference objects are two open clusters - M45 and the Hyades - both of which are in fact visible naked eye even from moderately light polluted skies. Yet, the predominant structures in the image are the dusty clouds that swirl across the entire field of view. I guess that's the problem with very wide field views: they get a bit of everything!

My favorite presentation is vertical (portrait), as this is how I get to see this part of the sky as it comes from the eastern horizon, although for presentation purposes, the smaller version up there is shown in landscape orientation.

As usual, capturing this data required me some "unusual" amount of driving to dark sites, this time reaching over 1,650 miles.

Data was rather minimal almost by design (click on the "Show image details" below to see the number of subexposures, etc). On top of that, transparency was quite poor during the whole month, and I was getting barely 21.1 ~ 21.2 SQM readings every night at the dark site I usually go to capture the data, while the average at the site is around 21.5, and all the way to up to 21.8 on exceptional nights. Still, despite all that, I think the image came out okay in general, and pretty good considering the amount of data and transparency conditions. More data wouldn't have hurt, particularly color data, but what's new? :-)

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Overcast in the Constellation of Aries

Posted: November 1st, 2011

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The constellation Aries is bathed with numerous dust clouds. This image shows a small region - small in comparison to the constellation - near the also dusty constellations of Taurus and Perseus.

The dusty clouds you see in the image may feel a bit soft, prompting the trained observer to think that noise reduction was heavily applied. However, that's not the case in this image. Although I did apply a bit of noise reduction during the post-processing, it was in fact very mild, and the reason for the clouds having that soft appearance is because in the original data these structures were already lacking the tri-dimensionality and wispy appearance one would usually expect.

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