Constellations IV: Scorpius Rising

Click for larger image.

From my vault of unpublished astrophotography, today I bring you a rendition from earlier this year of the constellation Scorpius.  I had been meaning to process this one for a while.  Days turned into weeks which turned into months.  An eclipse got in the way somewhere along the journey.  So here we are, mid-October, discussing a constellation normally thought of in the Summer.

I recall that it was still very early evening when I took the photographs which comprise this stacked image.  As you can see, my view was a tad narrow, but you can easily make out the side of Scorpius anchored by Antares.  To the top-left are two moderately bright stars, part of the constellation Ophiuchus.  If you imagine a horizontal line from the bottom of those stars in Ophiuchus to the top stars in Scorpius, then you are envisioning the Sun’s elliptic path in the sky.

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Constellations III: Of the Summer Triangle

Click to see the full-sized hi-res image!

A few days after I searched for Pluto, I chose to forgo my telescopes for one clear evening and play with my digital camera.  The Summer Triangle is straight up in the evening sky right now for several hours after sunset.  As Jack Horkheimer used to say, “Keep looking up.”  This time, take his advice literally and you will see the magnificent asterism defined by the stars Altair, Deneb, and Vega.

This image was taken in a similar fashion to my prior wide-field constellation pictures, like Leo, where I took dozens of light, dark, and bias frames and then created a composite in DeepSkyStacker.  For this new image, though, I went a step further.  I have been searching for a way to accentuate the stars based on their brightness, short of manually blowing them up.  I believe I have uncovered a technique to get the desired effect.  You can easily make out the three main stars along with other stars/patterns in descending order from their apparent magnitudes.

I must admit that I was mildly shocked at how many stars are shown.  Are those really stars, or image noise?  As the images were taken straight up, to the darkest part of the sky, it seemed plausible.  Also, the Milky Way runs right through the Summer Triangle.  You cannot see the Milky Way in my picture, as I don’t think it is possible to capture in my light-polluted area without longer exposures and an equatorial mount.

In checking as many detailed online star charts as seemed reasonable, I do believe those dots are all stars!

Remember that an asterism is a pattern of stars, versus a constellation, which is a generally accepted “official” pattern.  The Summer Triangle is an asterism (a triangle, duh) but it has several constellations in and around it.  How many constellations can you see and name in this picture?

Constellations II: Leo the Lion

Click to enlarge and discover many stars!

Five weeks.  That is how long I had to wait from my first session photographing Leo the Lion to my second.  That is how long I had to wait for a mostly clear night, but even then, in the early evening of May 29th, I just finished my shots in time before large clouds rumbled in.

Five weeks prior, on April 22nd, the skies were much clearer and Leo was still directly overhead.  But as that was more of a test-shoot, compiling light, dark, and bias frames with my Canon EOS DSLR camera, I wanted to get a second set to see if there was any noticeable difference in the final imagining.  In particular, I wanted to shorten the focal length from f/22 to f/14, about mid-range.

I don’t think the focal setting change made much of a difference, but at least I did learn a few more things about the stacking software, DeepSkyStacker.  For example, the stacking “Intersection Mode” works wonders if you have to move the camera a bit and to ignore the stray wisps of clouds.  I know now for future reference that the sky does not have to be perfectly clear, just clear enough.  I can also take as many light/picture frames as I want, so long as I keep the object approximately centered.  DSS figures out the rest!

The one aspect of this technique I wish I could improve is to highlight better the apparent magnitudes.  Regulus is the brightest stars in my picture, but you cannot tell.  I don’t want to faux edit the image just to make the brighter magnitude stars bigger, but I do want to research possible PSP techniques to highlight the bigger stars.

I am also amazed at how accurate the picture is.  Compare the above image with this star chart and you can mentally plot the smaller stars.  Pretty cool!

Constellations I: Testing Ursa Minor, Snagging Draco

Do you see Polaris, Ursa Minor, and Draco?
Click to enlarge to full size.

On Monday, the same night I photographed Jupiter and Io, I also set up my tripod and new digital camera.  I want to start taking wide-field pictures of the night sky.

As a test subject, I pointed at the Little Dipper.  On the digital camera, everything has to be set to manual.  The longest setup time was in getting the focus just right.  For this, I used the brightest “star” available, Jupiter.

I took 17 images at ISO 3200, 18mm, and 10 second exposures.  I then took eleven dark frames – same camera settings but with the lens cap on.  This is to ascertain camera noise.  Finally I took 14 bias frames.  These are dark as well – lens cap on – but very fast shots.  In reading up on this, it’s possible I did not need bias frames, but I used them anyway.

I put all these images into DeepSkyStacker, and the above is what I got.  This is not a very interesting part of the sky, and my light pollution does not help.  In Ursa Minor I can see Polaris and the two bright end stars, but the middle ones are more difficult.  Something like Draco I cannot see at all.  So it is remarkable what the camera can pull out!

I am pleased with the amount of stars I captured.  Can you see Polaris and Ursa Minor?  I also got all of Draco in this picture, which surprised me.  Do you see it?

If you are having trouble (like so many of my co-workers did), please see this cheat image I created.  I purposefully am not showing the image directly in the blog post, to give you time to first study the raw picture before looking at the “answers.”

Finally Found The Little Dipper

little-dipper-01

Earlier this week I wrote about my problems finding The Little Dipper (a.k.a. Ursa Minor, The Little Bear).  The past few nights have offered good views of the sky, so I went outside and, sure enough, I finally managed to “size” The Little Dipper properly.  Polaris is easy to find.  In hindsight, my main issue was that I always thought this constellation was much smaller than it really is (being “little”).  But by using the asterism The Big Dipper (part of Ursa Major) as a guide, it became fairly obvious where the two end stars Kochab and Pherkad were.  They are easily visible to me without an optical aid.

So in between Polaris and the Kochab/Pherkad set are the other four points of The Little Dipper.  They are much fainter and I could not obviously see them at early night with a big Moon, though I suspect I saw at least one.  I will wait for a dark (no Moon) night with my eyes properly adjusted to seek the rest of this constellation.  The great news is, from my location in the U.S.A, The Little Dipper is visible all year, every day, clouds permitting.

My Vexations in Finding The Little Dipper

little-dipper-01

One of my most obvious “misses” in observing the sky this past year has been The Little Dipper, a.k.a. Ursa Minor.  Whenever I say to myself I will focus on it on clear nights, I get distracted by some other, more interesting part of sky.

Why is The Little Dipper so hard to find?  I think it’s a combination of factors:

  • Since most of its stars are well above 2 magnitude, the excessive light polution in my area masks most of it
  • Difficult to judge its size relative to The Big Dipper, which is very bright
  • Finding Polaris is an easy nightly win that usually does not go much further
  • Generally boring part of the sky, party due to light pollution – Zenith and towards South are far more interesting (think Orion and planets)

I frequently spot Polaris, which at least is a good start.  My difficulty starts in that the rest of that area of sky appears blank, especially right after nightfall.

Reviewing the constellation and the brightness of each star, I now have a strategy to find it:

  1. Wait for a clear sky with no or little Moon
  2. Wait until the sky is sufficiently dark for the evening
  3. Locate Polaris, which is always easy
  4. Next, and here is the key, is to determine the approximate location of The Little Dipper’s next brightest star, Kochab.  It is supposed to be only slightly less bright than Polaris.  My guess, now that I think about it, is that I simply miss or ignore Kochab.

Since Polaris and The Little Dipper are effectively at the center of our cosmic wheel, it should just be a matter of gauging which position on the “clock” Kochab is to Polaris.  And for added perspective, I need to study the relative size differences of the two dippers, and use it as a marker as well in finding Kochab.  In hindsight, I think one of my bad assumptions is that Ursa Minor is far smaller than it really is.

So once I have Polaris coupled with Kochab, I can use either my telescopes of binoculars to trace out the rest of the constellation.  We’ll see how this strategy works on my next clear, dark night!