If you subscribe to Sky and Telescope, keep your eyes open for the article More of My Favorite Double Stars by James Mullaney in the September 2006 issue. I was invited to submit a few double star sketches to help illustrate the article. The author lists a couple dozen autumn doubles for your viewing enjoyment. Eight in that list are discussed in greater detail in the article. It just so happened that I had already sketched 5 of those, and I had enough time to observe and sketch 2 more of them. The only one I couldn't submit was Delta Cephei which was still simmering in the dawn twilight at the time.
As you might have guessed, I'm pretty excited that the author and/or editor chose to use sketches to supplement the article. I imagine part of that choice was due to the fact that it is just plain hard to find photography of specific doubles. They are out there; just not in the same abundance as other deep sky objects.
Following are the sketches that appear in the article:
Personally, I'd love to see sketches used more often to illustrate articles about visual astronomy. Not to the exclusion of astro photography of course. Because visual observers benefit from knowing more objectively what features to search for in an object. But I really value a sketch of an object for showing what a human eyeball and the not-quite-perfect human brain behind it are capable of discerning.
With double star sketches, that eye-brain interaction yields some interesting results when it comes to color assessment. Not only will optics, atmospheric conditions and local light pollution have an effect on color impressions in a double, but so will the physiology of an individual observer's eyes, and the psychological effects of their mind interpreting those little pinpricks of subtle color in close proximity.
I had some anxiety about how my personal interpretation of those colors would be received. Before submitting the sketches, I searched the web for other observers impressions of each double to see if I could soothe my nerves. I found that my assessment was in the norm for several of them. But there were a couple that definitely hit the fringe...such as Eta Cassiopeiae and Gamma Arietis. Eta Cass is described by most observers as a yellow primary and a purple/orange/red secondary. But I saw key-lime-pie green and orange. I remember that double vividly, because as I was observing it, I was fascinated that the primary exhibited such an unusual and obviously impossible color. But I couldn't shake the impression each time I returned to the eyepiece. So that's how I colored the sketch.
For a hobby that is built on a foundation of scientific interest, I'm sure the vagaries of visual observations are vexing to some amateur astronomers. But that same variation from observer to observer and even from observation to observation for the same observer, is a facet of the hobby that I find very enjoyable.
If you have any comments or criticisms about the sketches, I would love to hear them. You can post them here, or email me at the address shown at the top of the page.
Those are really tremendous! How did you apply the color to the sketches? Afterwards in photoshop? Seriously, it's like looking through the eyepiece.
I'm a big fan of doubles, too, since it's hard to see much color elsewhere in the night sky. The dramatic doubles like Albireo and Cor Caroli are quite popular with the folks who happen by on public nights.
Hi Kim,
Thank you!
After scanning the sketches, I invert them in Photoshop to appear as positive white on black images. Then I add the color using a paintbrush set to 'color' mode. This alters the color without changing brightness (any part of the star that is pure white will show as pure white with no color). With the brighter stars, I leave this central area white to give it a brighter appearance. For fainter stars, I'll darken the center a bit, which causes it to pick up more color in the middle and appear darker as well.
For the brighter stars, I'll sometimes use a white paintbrush in 'normal' mode with an 'opacity' of 10% or so, to very very lightly apply a slight glowing halo around the star. This helps convey some of the flaring that occurs in the eyepiece, and gives a feel for how bright it is.
If you are interested, I've got some additional info at this link: Digitizing Tutorial
I've been on a DSO binge lately, but I'm looking forward to diving back into more double star observations. I hope you get a chance to do the same soon.
Jeremy
Jeremy,
Great sketches, and your comments about illustrating material meant for visual observers with sketches is a point that cannot be made too often. Other forms of image certainly have their places, but too heavy a reliance on photos contributes to the disappointment beginners experience when first peering into an eyepiece.
Nice work, and hope to see you on the forum in the near future!
Tom
Hi Tom! Thanks, and I hope to contribute again soon. As they say, the candle has been burning at both ends...except that some joker also taped a bunch of sparklers to the middle. What a mess.
Tom, you didn't include your web address in your post, so I'm going to put it here: Under The Desert Stars. Tom's amateur astronomy writings from Tucson, Arizona are always a pleasure to read. Stop by if you get a chance.
Hi Jeremy,
Wonderful sketches, as usual, though I have to add this time that these ones are lively beautiful! I'm kind of color blind at night, so it's difficult for me to detect star colors in the telescope as most amateurs do. I know I miss a lot, but sketches like these ones help me "recoup" those fabulous hues. Thanks a lot!!! -JL
Congrats on the S&T invitation.I will be sure to look for it!!.
Juan and Andrew, thanks!