Thursday, October 23, 2014

Solar Eclipse Sports a Great Sunspot

To see the eclipse today, Danielle and I set up on the roof of the parking garage of the North Austin office building at my place of work. All afternoon we had watched the weather forecast, hoping the the overcast skies would clear up before the eclipse began. Luckily we got a break in the clouds just in time for the show! Having seen a post on Bad Astronomy about the current huge sunspot AR-2192, we opted to bring a full set of equipment, not just the simple camera I had originally intended to use. In addition, we packed several "eclipse glasses" for my colleagues, who I encouraged to join us.

The equipment was very similar to that we had used on Haleakala for the Venus Transit. For white-light imaging, we setup a Canon 60Da with a Canon EF 100-400mm f/4L 4.5-5.6 IS lens. With a Kenko 1.4x tele-extender, this gave an effective focal length of 530mm. A Kendrick Visual Solar Filter mounted to the objective produced good images at ISO-100, f/8, and 1/250 sec. exposure. We used Astro Photography Tool to control the camera from the laptop and obtain better focus than we could manage by hand or autofocus. This setup was mounted on a tripod and had to be adjusted every few minutes.

For H-alpha imaging, we set up a Lunt 60T/PS pressure-tuned H-alpha telescope and captured short 250 frame AVI movies with an Imaging Systems DMK 41AU02 camera and an Antares 0.5x focal reducer. The latter required a shortened nose-piece to accommodate the limited back-focus of the telescope. These movie frames were later stacked using RegiStax 6. All of the H-alpha equipment was mounted on a GM-8 which we only roughly aligned to north. This was enough to prevent having to continuously find the sun in the small field of view of the telescope. We occasionally replaced the camera with a 15mm eyepiece to get the visual experience through the telescope.

The white light image below gives the best view of the photosphere showing the umbra and surrounding penumbra regions of the sun spot pairs. This view also shows some hints of granulation, evidence of surface convection cells. In contrast, the Hydrogen-alpha image gives a view of the hotter chromosphere. It shows lighter colored plages near the sun spots as well as filaments and prominences of plasma twisted by magnetic field lines. In addition to the AR 2192 region and several small spots, this image shows a large filament cutting across the top half of the solar disk. It looks like a Frankenstein scar. Though hard to see on the image below, several small solar prominences were also visible through the solar telescope.

Seeing the huge sunspot in conjunction with the eclipse was well worth the effort of setting up all of the equipment. I hope my colleagues were also impressed by the show that mother nature put on today, though I think they were more enthusiastic about the eclipse glasses than by the expensive imaging gear! There is certainly something cool about looking straight at the sun with these flimsy things on.

Update 10/24 - Phil Plait at Bad Astronomy was kind enough to link back to this blog page from his gallery of reader-contributed images of the eclipse. Take a look at some other creative shots he posted there. I have corrected the reversed time-stamps on my image above. The white-light image is the later shot. Since the moon has a faster retrograde motion, it should move across the solar disk from lower-right to upper-left as oriented in these images. My brother-in-law, Ross Cunniff, was clouded out part of the eclipse. See his YouTube video for a creative way of handling the disappointing conditions. As of 10/24, the AR 2192 region has thrown to X-class flares but no CME.

Update 10/26 - Had a look at AR 2192 this afternoon as it moved toward the edge of the solar limb. The sunspot is not as pronounced but there were a few more prominences.

Sunday, October 12, 2014

Afternoon at Berry Springs Park

On reports of a sighting of a Great Kiskadee at Berry Springs Park in Georgetown earlier in the week, we went today for a late morning of birding.  No luck seeing the Kiskadee, but saw a number of birds, including:
  • House Finch
  • Northern Cardinal
  • Black-crested Titmouse
  • Carolina Chickadee
  • Eastern Bluebird
  • Blue-headed Vireo
  • Scissor-tailed Flycatcher
  • Eastern Phoebe
  • Lesser Goldfinch
  • Orange-crowned Warbler
  • Nashville Warbler
  • Yellow Shafted Northern Flicker
  • Downy Woodpecker
  • Red-bellied Woodpecker
  • Red-shouldered Hawk
  • Great Blue Heron
  • Turkey Vulture
  • European Starling
  • Great-tailed Grackle
In addition, we saw several dozen Monarch Butterflies. The fall migration has apparently reached our area. We spotted a few on our nightly walk as well. None on our milkweed plants yet.

The Blue-headed Vireo was a new species for us. I thought I was seeing another White-eyed Vireo until I looked at the pictures and noted that the spectacles were white. Looking closely, the head is dusky blue rather than olive and there is no hint of a light iris. The very similar looking Plumbeous Vireo is out of range for this location and the Cassin's Vireo would be rare.This bird also has a rather sharp contrast between the throat and auriculars, consistent with the blue-headed.

ISO-800, 400mm, f/6.3, 1/3200 sec, FEC -1 2/3
In the same section of trail as the vireo, we saw a number of small warblers flitting along in the low brush. This one that Danielle managed to capture, we believe is a first winter Orange-crowned Warbler. It has a white split eyering with dark eyeline. It also has a yellow undertail coverts.  The Nashville Warbler we were less certain of and did not get a clear picture.

ISO-500, 215mm, f/6.5, 1/160 (Danielle)

There were many Scissor-tailed Flycatchers in the park, in greater concentration than we have seen before. Danielle was in a better spot to see them and got this nice photo showing the full extent of the tail. Amazing these birds can fly at all, never mind be agile enough to snatch airborne insects.

ISO-80, 215mm, f/6.5, 1/250 (Danielle)
Berry Springs is one of the few places I have seen Eastern Bluebirds - they seem to be a regular sight at the park and were again today. In the right image, a bluebird perches in a group of house finches.

ISO-800, 400mm, f/6.3, 1/250, EC +0.7, FEC -1 2/3

As usual in the park, we saw many Red-bellied Woodpeckers and a few Downy Woodpeckers. The Yellow-shafted Northern Flicker was more of a surprise. We saw both a male and female and Danielle took these images. The male on the right shows a red nape, which is only present in the yellow-shafted variety.

ISO-80, 215mm, f/6.5, 1/640 (Danielle)
Danielle also saw this Red-shouldered Hawk which I missed completely.

ISO-80, 215mm, f/6.5, 1/250 (Danielle)
I managed to get a nice pose of a Goldfinch taking flight. Cool how the feathers are translucent enough to see the shadow of the branch behind them.

ISO-800, 400mm, f/6.3, 1/5000, EC +0.1, FEC -1 2/3

Wednesday, October 8, 2014

Second Lunar Eclipse 2014

I did manage to observe the second lunar eclipse of this tetrad, vultures not withstanding. Hazy clouds in the west moved in before I could set up anything complicated but did get a couple of camera-tripod shots with a 400mm lens. The point in the eclipse progression was favorable as it showed the blue-edging on the ruddy lunar disk. The blue dot to the left is the planet Uranus, which I did not see with binoculars. This was a much closer conjunction than the Moon-Mars conjunction during the first eclipse of the tetrad. The focus on my images was, unfortunately, not very good since I relied on the camera's auto-focus. In post-processing, I had to tighten up the radius of Uranus and sharpen the lunar surface details. Colors are as-shot.

Canon 60Da, EF 100-400mm f/4.5-5.6L IS - ISO-400, f/5.6, 1"

Sunday, October 5, 2014

Vulture Eclipse

This week is the second lunar eclipse of a series of four this year. I don't think that I am going to make the observation this time. In lieu, here is a "vulture eclipse."

As the nearly full moon was rising this evening, I watched fifty or so Turkey Vultures gliding overhead making their way to their roosts nearby along the San Gabriel River. This one glows orange in the light of the setting sun. Image composed from two exposures with same exposure parameters but different focus points. Danielle quipped that most people try to pose Bald Eagles in front of the moon ... yeah, but we got vultures, lots of them!

Canon 60Da, EF 100-400mm f/4.5-5.6L IS, ISO-800, 400mm, f/5.6, 1/1000sec, EC +1.0