Transit of Mercury 2016

On Monday, 09 May 2016, Mercury transited the Sun. The transit or passage of Mercury across the face of the Sun is a relatively rare occurrence and there are approximately 13 transits of Mercury each century. The next transit will be in 2019. If you missed this one, you don’t have to wait too long for the next one. But if you miss that one, you will have to wait until 2032 for another chance.

A typical transit lasts several hours. During a transit, Mercury can be seen as a very small black disk moving across the face of the Sun.

The transit was already in progress as the sun rose across the western states. This meant that I could capture an image of the sun with Mercury in transit and have some interesting foregrounds as a dark silhouette. I had hoped to capture images as the sun moved between the spires of Cathedral Rock but the geometry didn’t quite work out. The location with the best alignment also had obstacles in the way. So, on to a second choice. This option had the sun rising from the southern edge of Cathedral Rock.

The first image shows the rising sun with rocks and trees on Cathedral Rock forming a dark silhouette. Mercury can be seen as a faint dark spot just above the outline of the tree.

Mercury transiting the sun as it rises from behind Cathedral Rock.
Mercury transiting the sun as it rises from behind Cathedral Rock.

The second image is a composite of two images taken ~3 hours apart showing the movement of Mercury across the face of the sun. I took photos for about 15–20 minutes after sun rise then put the equipment away so that we could do a trail run in the area. When we returned, the transit was still in progress and I took a few more images — allowing me to create the composite.

Composite image showing the motion of Mercury.
Composite image showing the motion of Mercury.

These images were taken with a “consumer-type” zoom camera (Panasonic Lumix FZ150) which has a maximum zoom of 600 mm (equivalent) focal length. I used a 10-stop neutral density filter (ND3.0) which blocks ~99.9% of the light allowing a reasonable exposure (ISO 100; f/6.3, 1/2000 s).

Mercury is small. Even with the large (equivalent) focal length, the planet in transit makes only a very small dot in the image. Compare this with Venus, which transited the sun in 2012 and is more easily visible against the disk of the sun.

The next few transits of Mercury are in 2019, 2032, and 2039. The next transit of Venus is in 2117. Yes, 2117! So I’m happy to have seen the Venus transit in 2012 and the Mercury transit in 2016. They are more rare than total eclipses of the sun. The next total eclipse of the sun across North America is 2017.

Milky Way rises above a moonlit Cathedral Rock

The Milky Way rises above Cathedral Rock which is lit by the setting crescent moon. To the right, the triplet of Mars, Saturn, and Antares in the constellation Scorpius stand out as the brightest points of light. In the center of the triangle formed by these three objects lies the Rho Ophiuchi cloud complex, a nebula of gas and dust that appear in the image as dark bands.

Milky Way and Cathedral Rock.
Milky Way and Cathedral Rock.

This is a composite of two images. The first was taken of Cathedral Rock as the moon was setting in the west. An exposure of 120 seconds at ISO 400 and an aperture of f/4 was used. The second image was taken a short time later after the moon had set allowing the fainter stars in the night sky to appear. This image was 8 minutes at ISO 400 and an aperture of f/4. To prevent streaking of the stars an iOptron Sky Tracker was used. The two images were then blended together.

There will be several more opportunities during the spring and early summer for images like this as the moon sets in the west and the Milky Way rises in the east.

Rho Ophiuchi.
Rho Ophiuchi.

As twilight began in the east and the stars began to fade I switched lenses to a short telephoto to zoom in on Rho Ophiuchi to better show the dark dust present in this nebula. This is a 120-second exposure at f/2.8 and ISO 400 using an 85 mm lens.

Two views of Orion

Orion is one of the most conspicuous and recognizable constellations in the night sky. It was named after Orion, a hunter in Greek mythology. Its brightest stars are Rigel (Beta Orionis) and Betelgeuse (Alpha Orionis), a blue-white and a red supergiant, respectively.

Hanging from Orion’s belt is his sword which contains the Orion Nebula, also known as M42. This is a spectacular object that can be clearly identified with the naked eye as something other than a star. It is one of the most easily photographed Deep Sky Objects and can be captured by most modern digital cameras.

The first image of Orion was taken last winter on an evening with a very thin layer of high clouds. This cloudiness was enough to cause a beautiful glow around the brighter stars in the constellation. Some nebulosity is visible in both the belt and sword of Orion. (Nikon D700, ISO 1600, f/5.6, 120 seconds, 80mm).

Constellation Orion (February 2015)
Constellation Orion (February 2015)

The second image was taken this spring (Nikon D700, ISO 1600, f/4, 10x120s, 200mm) and is zoomed/cropped on the Orion Nebula (M42).

Orion Nebula —M42 (April 2016)
Orion Nebula—M42 (April 2016)

I recently heard someone say that a reasonable goal of astrophotography is not so much to produce the best image, but to produce a better image than your previous best. In this case, I can claim some success.

And, for comparisons sake, here is a richly detailed image of the Orion Nebula captured by the Hubble Telescope and posted on the Astronomy Photo of the Day (APOD) site.

Winter mountain biking in Sedona

Winter is fading away in the higher elevations of northern Arizona. Snow has melted across much of the area allowing the trails to be used again for walking, running, and, especially, mountain biking. While the trails were covered in snow this winter we did most of our mountain biking in Sedona. Although snow does fall there, it rarely lasts long. Here are a few photographs from Sedona mountain biking this winter.

Chuckwagon Trail in the Dry Creek area. Snow lingered in the shadows making for interesting travel.
Chuckwagon Trail in the Dry Creek area. Snow lingered in the shadows making for interesting travel.
Occasionally we had to walk around the ice. This is in a mostly dry wash near the Rabbit Ears.
Occasionally we had to walk around the ice. This is in a mostly dry wash near the Rabbit Ears.

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The Milky Way and Cathedral Rock

Winter is slowly coming to an end and we are about to transition into the warmer months of spring and summer. During these upcoming months, the center of our galaxy—known as The Milky Way—will be rising earlier each evening.

Milky Way rises above Cathedral Rock in Sedona, Arizona.
Milky Way rises above Cathedral Rock in Sedona, Arizona.

For photographers—and just about everyone else, too—staring up on a clear, moonless night with the Milky Way glowing above can be a magical experience. For those who live in brightly-lit cities, however, the Milky Way can be difficult or even impossible to see. From an article at PBS:

Light pollution — the needless shining of bright lights into the night sky — has robbed whole generations of the chance to see nature on its largest scale. It is estimated that as many as eighty percent of all the people alive today have never even glimpsed the Milky Way. (When a massive power outage struck southern California in the 1990s, Los Angeles residents reportedly called 911 to express alarm about strange clouds hovering overhead; they were seeing the Milky Way for the first time.)

With the rapid advancement of digital cameras in the past decade the ability to take images of the night sky has become remarkably easier. Not easy—just easier. Cameras can now take long exposures at high ISO settings to reveal details of the night sky not easily visible to the unaided eye. This has resulted in magnificent photographs of the Milky Way but also other objects such as comets and Deep Sky Objects (DSO).

Still, long exposures of the night sky can result in the stars leaving streaks (i.e., “star trails”) across the image. This is the result not of the stars moving, of course, but the earths’ rotation. Typical wide-angle lenses used for photographing the Milky Way are limited to about 15 to 30 seconds before trails become obvious. In order to capture enough night-sky light at these exposures requires high ISO settings which can add considerable noise to the image. Of course, sometimes star trails are desired as seen in the image below:

Star trails above Cathedral Rock in Sedona, Arizona.
Star trails above Cathedral Rock in Sedona, Arizona.

Another option is to use a tracking device that follows the motion of the stars (or, more correctly, counteracts the rotational motion of the earth) allowing the camera to take very long exposures without star trails. The downside of this technique is while the stars remain pin points of light, the ground is blurred as the camera slowly moves during the exposure.

Long exposure without tracking (left) and with tracking (right).
Long exposure without tracking (left) and with tracking (right).

The solution requires taking multiple images: one of the stars with the star tracker on and a second image of the ground with the tracker turned off.

The image shown at the top of this post is a composite to two images: one of the stars and one of the ground.

The star image was taken using the iOptron Skytracker, a relatively inexpensive tracker. The image was shot using a low sensitivity (ISO 400) to minimize sensor noise. The lens was an ultra-wide 16mm shot at f/4 and the duration of the exposure was 534 seconds (~9 minutes). The exposure for the foreground was shorter in duration (4 minutes) and at a higher sensitivity (ISO 1600).

The two images were combined as layers in Photoshop. Masks were applied to each of the images and then blended so that the pin-point stars on one image and the sharp foreground of the other image remained.

It turns out that taking the images was the easy and fun part. Standing around in the middle of the night watching stars, meteors, and satellites cross the sky can be very enjoyable. Not surprisingly, the blending of the images took many attempts and much time.

A visit to an archeological site in Sedona

The canyons that surround Sedona are known to contain many Native American dwellings and other artifacts. Visiting these sites can be an exciting adventure—especially if you don’t actually know where they are.

I suppose there are web sites and other sources of information that might show where these are and even include photographs and GPS coordinates. I’m less interested in visiting these web sites to get precise information than I am in exploring and finding them on my own. I certainly won’t find many this way—but that’s okay. It’s the adventure that provides the interest.

So we have been visiting and re-visiting some canyons in the area and trying to determine where dwellings might exist. There are several ways to do this. One is to look carefully at the cliff walls and decide if these might support a dwelling. The next is to look for faint paths created by others that lead to the hidden sites within the canyon. And the third is to listen for loud folks who’ve found something and follow them ;-)

Cliff dwelling in a canyon near Sedona.
Cliff dwelling in a canyon near Sedona.

Methods two and three above worked in our favor recently and we visited this dwelling. It was well preserved and there were some pottery sherds (also sometimes called “shards”) as well as corn cobs. As is often the case, visitors had picked up these artifacts and placed them on rocks or walls for easy viewing—although most archeologists suggest they be left where they were found.

Ancient rock art on canyon walls.
Ancient rock art on canyon walls.
Pottery sherds laid out on nearby rocks.
Pottery sherds laid out on nearby rocks.

Our appetites whetted, we plan to visit these canyons again and try to find more
sites.

Clear, Blue Skies and Deep Powder

We had a nice snow storm earlier this week that brought a bit less than a foot of new snow to Flagstaff—but more than two feet in the mountains. Time to get out and ski some deep powder!

Snow covered trees in the Kachina Peaks.
Snow covered trees in the Kachina Peaks.

So off we went to ski the backcountry. Our destination was the area known as “Allison Clay” on the west face of Humphreys Peak. Getting there is not straightforward as there is no trail. One has to bushwack their way from the lower sections of the Humphreys Peak trail around a portion of the mountain before reaching the open slopes. Nonetheless, the trek can be quite beautiful when there is a lot of fresh snow on the trees.

While bushwhacking through the forest we spotted this yin-yang symbol on a tree.
While bushwhacking through the forest we spotted this yin-yang symbol on a tree.

Along the way we stopped at “Flying Dutchman” to survey the conditions. The old snow had settled so much in the past few weeks that the new snow was insufficient to completely cover the rocks and many were poking through the powder. After a quick stop, it was time to continue to our main destination.

First, we must climb this...
First, we must climb this…

Normally setting a trail through the forest and finding Allison Clay is not that difficult—but on this outing I aimed too low and we ended up below the normal ski zone. Not a problem! As it turned out, we found another nice gully with deep, untracked powder. Up we climbed—determined that we would return through this gully on our way back. Higher up, we broke out into the open and began the moderately steep climb up the west face of the mountain. Then it was time to convert all that potential energy into kinetic energy—in other words, let gravity do its thing.

...so that we can do this!
…so that we can do this!
Tree skiing in a wide gully.
Tree skiing in a wide gully.

And, oh, it was GOOD—especially the powder-filled gully! By this time, however, we were getting tired since we had to break a lot of trail through deep snow just to get here.

Look at that happy smile!
Look at that happy smile!

Next morning—same thing. We did all the work yesterday breaking trail so today would be easier. Unfortunately, winds had increased overnight and the avalanche danger began to increase so we chose to ski through the trees and away from the open slope. That turned out to be even better because the powder in the trees was simply marvelous.

Clear, blue skies and deep powder. Wow!

Comet Catalina and its closest approach to Earth

Over the past few years I’ve been interested in capturing images of comets as they move through the inner solar system. Some have been easier than others primarily because of their brightness but also because of where they lie in the sky.

Comet Catalina (C/2013 US10), however, has been a challenge. When it first became visible in the northern hemisphere it was difficult to see in the early morning twilight. Later, it moved so that it was well up in the sky before twilight but then I was fighting both bright moonlight and cloudy weather.

Finally, clear skies have allowed me another chance to take images of the comet this week. It is quickly moving through the northern skies towards the constellation Ursa Major and made its closest approach to Earth (at a very safe distance of 110 million km) last night (17 January 2016).

The comet isn’t bright enough to be visible to the unaided eye but binoculars are sufficient to reveal it as a fuzzy spot in the sky. With a DSLR and long exposure it’s possible to get reasonable images.

C/2013 US10 (Catalina) showing its double tail structure (12 January 2016).
C/2013 US10 (Catalina) showing its double tail structure (12 January 2016).
C/2013 US10 (Catalina) long exposure showing motion in the comet (12 January 2016).
C/2013 US10 (Catalina) long exposure showing motion in the comet (12 January 2016).
C/2013 US10 (Catalina) moving past stars in the Big Dipper handle and a couple of galaxies (12 January 2016).
C/2013 US10 (Catalina) moving past stars in the Big Dipper handle and a couple of galaxies (12 January 2016).

The first set of images are from 12 January 2016. The comet is approaching the handle of the Big Dipper. One long-exposure image shows points of light for stars but a short streak for the comet as it moves through the sky.

C/2013 US10 (Catalina) as it continues on its journey (18 January 2016).
C/2013 US10 (Catalina) as it continues on its journey (18 January 2016).

The second set of images are from 18 January 2016. Occasional clouds and a quarter moon made it more challenging to get a great image but there will be more opportunities later this month.

Big snow on the peaks

Clouds swirl around the snow covered Kendrick Peak.
Clouds swirl around the snow covered Kendrick Peak.
Sunset colors illuminate the Kachina Peaks.
Sunset colors illuminate the Kachina Peaks.

After five days of snow the skies finally cleared showing several feet of new snow on the peaks of northern Arizona. Late afternoon shadows race across the meadows of Brannigan Park while sunlight continues to illuminate the high peaks.