November 2010

What is astrophotography...

Posted: November 20th, 2010

When I see people lecturing about little tidbits, or simply voicing their opinion about this or that, regarding what astrophotography is and what is not, often times I feel as if they forgot (or simply do not know), that astrophotography is a lot more than taking pictures of celestial objects, and certainly more than a set of rules, regulations or ethics that one must or must not follow. At least for me, it is. I've said before that in astrophotography there are as many schools of thought as there are astrophotographers. Leaving aside all those regulatory considerations, this is also what astrophotography is for me today - and hopefully for a long time...

Astrophotography for me is...

...knowing weeks ahead when the Moon won't be up and bright during the wee hours of the night.
...checking the weather days ahead during the 10-14 days of the month when there's no Moon.
...checking it (the weather) 3-4 times a day in the morning when I'm hoping to go out that evening.
...chatting with others online about what sites they (and I) will be going tonight, tomorrow, or the day after.
...the excitement that builds up as I start to load all my equipment in my car any day that I'm going out.
...the drive to a dark site, whether it takes me 50 or 300 miles to go there.
...arriving at the dark site, getting out of the car and stretching after the long drive. Yes, astrophotography is also that, for me.
...saying hello to other friends, when the night will be spent in good company, or just thinking "ok, another night alone" when I know nobody else will be coming.
...starting to set up all the gear, paying attention to all details.
...turning everything on - we are about to start!
...looking up. Enjoying the night sky in all its glory, feeling small, and getting ready to steal a bit of the Universe and take it home.
...sometimes (fortunately not too many), waiting for some high clouds to go away.
...slewing the scope to the target, framing, focusing, finding a guide star.
...of course, start capturing data.
...talking "shop" with other friends when there's company, during those long nights.
...sometimes, stealing a view here and there from someone doing visual, while my equipment is capturing photons.
...checking that first frame, and the one after, and maybe all of them, as they come.
...making adjustments during a session, refocusing, readjusting guiding... So many things, and so many can go wrong!
...maybe trying to take a short nap inside the car, especially if I'm very tired and I know I should rest a bit in order to get home back safely once I'm done.
...drinking a lot of coffee during a session. Or maybe hot cocoa during the winter nights.
...taking my flats at the end of the session, when all I really want at that time is to pack and go home.
...the tired drive back home, often around 4-5am.
...once at home, the next day, or a few days later, starting to calibrate, register and stack all the data.
...taking that first look at the data once it's been calibrated.
...thinking about the processing strategies to follow, in order to make the best out of the data.
...the entire "image processing" ordeal.
...hitting SAVE (and "Save as JPEG") that final image.
...sharing the image with other friends, listening to their feedback, appreciating their comments.
...doing the same with images from other friends.

All of that and a lot more is what astrophotography is for me today. Of course, I'm not implying that I don't consider astrophotography anything that happens to be less (or more) than that. This was my story, and everyone have theirs. Mine is just one more way to live astrophotography, not just doing it.

Polaris and the North Celestial Pole

Posted: November 10th, 2010

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Here's a 2x2 mosaic wide field of the North Celestial Pole, featuring one of the best friends of astrophotographers in the Northern Hemisphere: Polaris. In fact, for us nomadic imagers, Polaris is not only our friend, but at the beginning of each session, we get on our knees and what may seem as an imager doing polar alignment, we're in fact PRAYING to the Northern Star that the session goes well!

The image also features a copious amount of galactic cirrus (some of it displaying some very cool structures), one of the oldest known open clusters (NGC 188, at the bottom-middle), and Delta Um (middle right, the second star in Ursa Minor's tail)

If you'd like to see where the North Celestial Pole actually is, you can see it here:

The data was captured over the course of two nights next to the DARC Observatory under 21.3 mag skies (that's at the Zenith), average transparency and bad seeing, and the processing was roughly 75% PixInsight and 25% CS5. DARC is around 120 miles from my home, so that makes this a 480 miles image ;-) Not a lot of data (1h lum and 18m each color filter per frame) as I started the project when the Moon was already getting bit and setting late.

The image is also a testimony of how nice the polar scope of the EM400 mount is, as that's the only method I used both nights to polar align (no drift, etc) and as many of you know, imaging near the pole requires a good polar alignment, but of course, this image is not near the pole but on the pole itself! The forgiving resolution of the FSQ does help, but still, not bad at all.

As a friend said, in this image "north is not up", "north is IN"! :-)

As always, I identify a number of "I shouldn't have done that" or "I should have done this that other way" during the processing, but overall, and considering how seldom this area has been photographed, I think it does it justice somehow as a display of how the area looks like, and I'm happy with the results.

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Cassiopeia, The W

Posted: November 6th, 2010

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When I was a kid, the first constellation that called my attention wasn't Orion or the Big Dipper. It was Cassiopeia, the "W", and I would immediately go look for it and recognize it. Cassiopeia wasn't my early call into astronomy, but for a while it was the only reason for me to look up at the night sky from a light polluted city in southern Spain "Look, there's Cassiopeia!"... Well, maybe it was some sort of an early call...

This past week, during four different outings at three different sites and around 550 more miles in my SUV, I managed to capture this beautiful "starscape".

There's no better way to (hopefully) enjoy this image but at the largest resolution possible. And while the large image linked above is over 5600 pixels wide, it is still 1/2 of its original resolution, but I felt I had to reduce its size to avoid producing a JPEG over 12mb even at 55% quality (which is already quite degraded). The large image linked above weights almost 6mb (that's at 60% quality), so if you have a slow connection, be aware of that.

It's not a picture of some gorgeous and prominent celestial structures such as nebulae, galaxies, etc. but it's a very special image for me. I hope you enjoy it!

It may seem a simple image to capture and process, but processing was a bit challenging indeed. First, it's a 3x2 mosaic, so all the challenges associated with mosaics apply here - resolved with more or less fortune. Also, getting the subtle - but real - changes in background illumination took some work. Except for the darker areas, that are more prominent in part because of the "lack" of stars, you'll notice that areas with a brighter background don't really have more or less stars than other areas with a slight darker background, and pulling these background illumination differences with a swarm of stars in front can be tricky.

I find it's rather interesting to surf around the image looking for star clusters, and of course, there are plenty of them. Some people may feel that the Gamma Cas and Pacman nebulae could have been selectively processed to become more prominent, or perhaps more detailed, but although any field swarmed by stars can get in the way of other features and often times our goal is to give way to the dust or gas rather than the stars, I think it's obvious that the stars and nothing else are indeed the protagonist of this image.. Why let anything else steal the show?

Here's a small version showing the famous W asterism:

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