M93 (1-19-09)

I discovered this previously unfinished bit from the January run. This is not a deep image at all, but it is remaniscent of what one would see in a small telescope. M93 is an open cluster in the constellation Puppis.

M57 & IC 1296

I am constantly amazed at how the ccd camera has enhanced my ability to see. M57 is a very bright nebula. It is 2,000 light years away. I have seen it in very small scopes. I have never observed IC 1296 before now. The spiral galaxy is 200 million light years distant and shines at a dim magnitude 15 or thereabouts. For a very cool, color view of the same object, see the APOD here. My image is 83x30" with the Atik 16 through the Vixen R135S.

NGC 5490, 5490C (Arp 79), & Arp 117 (IC 0983 &0982)

This intriguing bunch of galaxies can be found just southwest of Arcturus. The image needs more time, which I hope to get soon before I lose Arcturus in the trees. NGC 5490 is the bright elliptical, somewhere around 230 million light years away. NGC 5490C is the smaller spiral galaxy just above it, also known as Arp 79. IC 0983 is the large spiral near the brightest star, and the smaller galaxy interacting with it is IC 0982. The two Arp entries are 260 million light years away. Check out this fantastic image of the same set of galaxies by Don Goldman. This one by another astrophotographer is also excellent but omits NGC 5490.

M5 (5-28-09)

M94 (5-28-09)

Last night the skies were a bit soupy. I was only able to collect for this image of M94 about 25 minutes of data worth keeping before clouds convinced me to switch targets to something brighter. Some of the sub-frames are pretty hazy, taken through light clouds. It could be worse, though.

M94 is about 16 million light years away, halfway to M63, though from our line of sight they are practically next to each other in the sky near the handle of the Big Dipper. This image is 49x30" through the R135S with the Atik 16, unguided on the EM-10.

Thoughts on Color in Astrophotography

The Atik 16 is a monochrome camera. It records all of the visible spectrum and some beyond it, especially into the infrared. I like that about the camera, but only one familiar with the camera's range knows what light I am capturing, actually. I have been trying to decided what to do about color. I want to do some experimenting soon. In response to a great suggestion by Anjal Sharma that I start with simple color filters for visual observing (of which I have a few), I responded as follows:

I still haven't decided what to do with color. Don [Taylor, also a member of the Huntsville club,] uses an interesting palette with narrowband filters. I understand why folks would do that. Knowing where the hydrogen, oxygen, and sulphur are allows one to pinpoint where the radiation is that is exciting the gas. The detail possible in a narrow wavelength is also interesting. I can also understand colors for reflection nebulae, in part because dust is a different color than the gas. Where there is information in the color, I can learn something from it. H2 regions in M33, for instance, will be a different color than the young stars in M33's arms.

When it comes to regular old RGB, I'm not sure. Aesthetically, sometimes the colors look very nice, but so does an impressionist painting. Why not red, yellow, and blue? Why not orange, green, and purple? Is it because RGB roughly corresponds to Ha, Oiii, and some other things? So it's sort of broad narrowband? What about Hb and other less prominent lines? In fact, many cameras pick up in the infrared as well, and that records in luminance and perhaps in some red filters, but that isn't even visible light to our eyes. It has no color. Our eyes respond only weakly to Ha, too, so what does a bright red Ha coloration mean? One thing I like about the Atik 16 is its response in Ha and its strength in infrared. It's significantly more than Oiii, for instance, so I am getting a very different view than I would with filters. I am also getting a different view with a reflector than I would with a refractor, which would probably not focus the infrared. I'd have to cut it off.

Anyway, it seems to me that each camera, scope, and filter set are different enough that no one but the photographer really knows what we are looking at---unless there is some attempt to correlate everything, ... everything! But then we would have to justify why we are correlating it the way we are, and I'm not sure I've ever heard anyone justify that persuasively, particularly when our eyes cannot see the kinds of colors in the individual spectra of deep sky objects and our cameras record wavelengths beyond what our eyes can see.

Also, aesthetically, I like black and white about as much as color. Color strength is such a subjective thing, and everyone's monitor is different, anyway, so even the displays of the images will be different. Color seems like more or less a dice roll to me, in the final analysis---too random to matter much.

Actually, my bride would like my images better if they were in color. I may add color that she likes and be quite satisfied with that.

I'd be very interested in others' thoughts on this.

And in response, Don Taylor, whose excellent work can be seen at http://www.theatomiccafe.com/, responded as follows:

There are definitely (at least) two schools of thought on the topic of color.

There are, shall we say, the conservatives.

Those who would only ever use broadband.

They will weight their colors to precisely match an analog star.

Then there are the color liberals.

Those who know humans can never get their natural eyes to ever see such deep sky object in color.

So they reassign certain wavelengths to one of the human eye perceptible frequencies.

I suppose a third school might be the monochromatic enthusiasts.

But even they must break into either the camp that uses the spectrum from 400nm to 700nm or the camp that selects a narrow slice of the magnetic spectrum.

Perhaps even a slice above or below the spectrum visible to the human eye.

In my mind it comes down to one’s personal goals in astro-imaging.

I feel that no method is either right or wrong, better or worse than any other method.

Each has its challenges and rewards.

For me, as long as my images depict the form and natural processes happening in nature, I’m satisfied.

I will correct a fault in the equipment; remove the bloom from a star.

I will readjust the weight of a color channel to emphasize an area of interest.

That’s the extent of the artistic license I’ll take.

I won’t “paint” in features I wish I had been able to capture.

But that’s my self imposed limit.

It doesn’t make my image any better or worse than an image which has undergone more aggressive processing.

Astro-imaging can certainly enter into the scientific arena if that is the direction one wants to go.

However, for me, astro-imaging is an art form, albeit a highly technical art form.

There are vast quantities of information on the many disciplines of astronomy, and I enjoy studying much of it.

Astro-imaging is simply my way to actually be able to go out and touch the universe that I would otherwise feel detached from.

-Don

PS: The technical reason for using RGB is because the color receptors in our eyes (presuming one has “normal” color vision) are tuned to accept red, green and blue light frequencies. As you know any (human eye perceivable) color can be synthesized by combining these 3 colors in varying intensities. (This is the same reason all of the pixels in our monitors are either red, green or blue.) I would love to be able to use one of the pallets you mentioned like orange, green, purple, but my software only allows for RGB or CMYK. At least if I expect to get a “color” image out of it. I have tried using the CMYK pallet with mixed results. I’ve also used the HFC pallet. But Hubble popularized the RGB=Sii, Ha, Oiii pallet and people are used to seeing it. When I first started using it, I got a lot of negative comments about my stars all having a pink glow around them. Funny thing is, I’ve never heard anyone criticize a Hubble image for that, and all narrowband Hubble images have pink halo stars.

Anjal Sharma also commented:

I agree with yours and Don's comments. Here's my take on color; although we do not see color visually in the faint fuzzies, that does not mean that there is no color in them. The issue of color is a very subjective one, but there is some consensus amongst users as to what information color adds to a monochrome image - namely what type of stars comprise that cluster or galaxy, or what type of molecules comprise a nebula. So, I myself cannot be satisfied with just monochrome images and want color in them to see a more interesting view of these objects. That being said, I would like to point out that in the end what we're doing is an art form, not a science. So, the colors depicted in my images are purely an artistic expression of what I think the color of these objects should be. I take a lot of liberties then in the way I depict color in my images. There are certain things I will not do such as add stars or remove stars or take the paintbrush tool and add in a patch of nebulosity if it does not exist or use the clone tool to remove an existing patch of nebulosity. What I will do however is emphasize certain aspects of the object by using layer masks, star masks or selective curving of the histogram in those areas. In my mind this is no different than when a photographer uses a different f-ratio in the camera lens or a selective physical lens filter for example to de-emphasize the background while drawing attention to the subject. So the point I'm trying to make is this - almost all aspects of image processing are quite subjective in my opinion and as the imager all you're trying to do is present YOUR view of the object to us, the audience.

I find much to agree with in both Don's and Anjal's comments. Any others?

M13 (5-19-09)

On the night of the 19th, after I had finished collecting images of M109 and M63, I turned the scope on M13 and then began processing M109. I figured I just as well collect images of something as long as I am out. This is the result. Compare M13 to M3 taken just a few days before. M13 appears to have more stars and is larger. Actually, I can see M13 clearly in my 6x30 finder scope. It's a showpiece of the northern sky and something I often find when I am out and it is up.

This images is just 46x30" with the Atik 16 through the Vixen R135S, unguided on the Tak EM-10, processed in Nebulosity and PS Elements 7.

This image, notwithstanding its casual creation, sure beats the one I took two years ago of the same cluster:

M63, the Sunflower Galaxy (5-19-09)

This was the other target on 5-19 besides M109. M63 is between 20 and 37 million light years away and is in the same group as M51. The two are fairly close together in the sky.

What impressed me about M63 is the long cloud of dust across the lower left. The dust does not appear to be following the same circular pattern around the center of the galaxy but rather lies in a straight line tangent to it. The dust lane is just visible in this image as a wide, jagged, dark line running diagonally along the left side of the galaxy. It seems odd to me that it appears to run diagonally and straight. The direction makes it seem that the dust lane is not part of the galaxy but merely crossing by it. In very deep images, such as this one from Tony Hallas, one can see stars forming at the right end of the dust lane on what would be near the outer edge of the galaxy. What's going on here? I am not sure, but notice that Hallas's image also shows loops and filaments of star formation all around the edge of the galaxy and not all of them are in the galaxy's plane. I suppose that M63 is still growing, and as it takes in matter from surrounding directions, not all of it flows evenly and directly into the galaxy's plane. Some of it is still being integrated. This would explain the large and relatively straight dustlane.

I imaged M51 and M63 on consecutive nights partly because each passes the meridian at about the same time. I could not image both in the same night, but both really ought to be done around the same time of year. This image is 148x30" through the Vixen R135S with the Atik 16, unguided. Processed almost entirely in Nebulosity, with a few touchups in PSE7.

M109 (5-19-09)

Here is M109, a galaxy said to be 55 million light years away in the direction of the Big Dipper or Ursa Major. In fact, M109 from our line of sight sits right next to one of the stars in the bottom of the dipper. This image is 69x30" with the Atik 16 through the Vixen R135S, unguided on the Tak EM-10, processed in Nebulosity and PS Elements 7. The sky was not quite as good as the night before, but it's always great to be under the stars.

Abell 39 (5-18-09)

This planetary nebula is a stretch for my equipment (well, especially without guiding). Abell 39 is a rather dim planetary nebula discovered in 1966. A planetary nebula forms when an aging star expels its outer layers. The nebula has a diameter of about 5 light years and is 7,000 light years away. Can you see it? It is near the top of the frame. It is very dim. You may have to turn the lights off to see it. What I like most about this nebula is that it is nearly round. How amazing to look out in the sky and see this ball of light, faint as it is. Several background galaxies can also be seen.

For a really amazing image of this same nebula, see here. Notice in the linked image that one background galaxy is visible right through the nebula itself! You can see that galaxy in my image, too, but it's just a smudge, not as obvious.

This image is 173x30" with the Atik 16 through the Vixen R135S, unguided on the Tak EM-10.

M51 (5-18-09)

So I have some success autoguiding and then the next night out the computer refuses to talk to the mount. It's a cable problem, I believe. So this is M51, unguided.

The image is 115x30" unguided on the EM-10, taken with the Atik 16 through the Vixen R135S, processed in Nebulosity 1 and Photoshop Elements 7.

M3 (5-14-09)

This is it: first real light for the new mount and first real autoguided image (well, worth publishing). M3 is a globular cluster in the constellation Canes Venatici, which last night passed directly overhead between 11 and 1. M3 is 33,900 light years from us and has perhaps half a million stars. This image is 48x2' through the Vixen R135S with the Atik 16, darks subtracted, autoguided on the Takahashi EM-10 with PHD through the DSI Pro. Wow! Processing was done in Nebulosity 1, Photoshop Elements 7, and Canon's Digital Photo Professional.

A New Mount and Autoguiding

I am happy to report the acquisition of a new mount, a Takahashi EM-10. This mount is used, about 9 years old, but its previous owner took great care of it, and it is built to last. Compared with other mounts I have used, it seems like a work of art. Everything fits so well and is finely finished. The hardwood tripod is beautiful.

Ever since the mount arrived a few weeks ago, we have had soupy weather. Every night has been cloudy, and if the clouds cleared off for a few hours at night the skies were hazy with water vapor. I took the mount out twice last week hoping to get the mount to autoguide, but just as I really came close to figuring out what was going on, the sky clouded over! So, finally, last night the sky cleared--not well, it's still pretty hazy, but clear enough to set up the mount, start Stark Labs' PHD autoguiding software, and figure out how to autoguide this mount. Success!

Autoguiding is basically the use of a second camera to create a feedback loop with the mount and a computer. The mount is already tracking the stars by motor pretty well. The guiding camera takes an image of the stars, sends it to a computer, and the computer sends commands to the mount. If the mount does not track the star exactly, the computer sends a correcting command to the mount to get it back on course. The guide camera tonight, a DSI Pro, was taking consecutive 3.5 second images through a 60mm f/5 achromat refractor mounted sturdily on the back of my Vixen R135S. The image from the guide camera was monitored by PHD, which sent correcting commands to the EM-10. I've had glitches before tonight (all of them generated by my own ignorance or carelessness), but finally everything came together.

Hooray! Let the fun begin! First target: M3 (which was approaching the zenith).