Sunday, December 31, 2017

Iridium Flares

Transient Events

There are 66 active Iridium satellites providing worldwide coverage for satellite phones. Each satellite has large flat surfaces that can reflect sunlight towards locations on Earth when everything is lined up properly. Some of these flat surfaces are antennas, and some are solar panels. The first picture below shows an Iridium satellite. The gold colored surfaces covered with squares are "door sized antennas" according to Wikipedia. You can also see one of the solar panels on the left.
When you are in the right observing location at the right time of day it's possible to see a temporary bright "flash", or flare, from one of these satellites when sunlight reflects from a flat surface towards you. Some of these flares are very bright. I've seen a particularly bright one appear in blue sky before sunset!

On the evening of November 19th I made the first attempt to capture an Iridium flare with my phone camera. Since flares usually last only a few seconds, and the maximum phone camera exposure time is 10 seconds, the shutter release needed careful timing. I tried to have the exposure begin 5 seconds before the predicted flare time. The timing was fairly good as you can see in the first image below which shows the flare as a short bright streak left of center.
This flare occurred against the background constellation Aquarius. Aquarius and Capricornus are most prominent in the image. Moonlight illuminated patchy clouds. The brightening appears asymmetrical. Either the exposure didn't include both the increase and decrease in brightness, or there was a particularly sudden increase of brightness. This flare was from Iridium satellite 64 and was predicted to be magnitude -7.4, brighter than everything normally in the sky except a full Moon and the Sun.

On December 10th another dimmer Iridium flare occurred near the same section of sky in the constellation Cetus. In this case it was Iridium satellite 47, and the flare magnitude was only 0.4. The next image shows the brightest part of the flare I was able to capture. You can see how dim it was compared to the Iridium 64 flare on November 19th.
This time I was able to get a sequence of three images over a span of 43 seconds showing the satellite's trail as it dimmed and moved from Cetus into Sculptor toward the southern horizon.
Iridium flares would look great in a continuous video. Unfortunately, as I mentioned in the last post, phone camera videos aren't sensitive enough to show stars. A phone video would show only a moving temporarily brightening and dimming light against a blank black background.  

Saturday, December 23, 2017

Space Station

Orbital Motion

I continued to experiment with my phone camera on November 28th as the International Space Station traveled through the constellations Draco and Ursa Minor in early evening. The Moon was quite bright that night, so my 10-second exposures at ISO 800 did not reveal a dark background sky. The bright streak in the center of the first picture below is the trail made by the Space Station during one 10-second exposure. You can also notice the dim trail of either an airplane or another satellite moving diagonally through the upper right of the picture.
Next is a 6-frame animation of the Space Station's motion covering approximately 2.25 minutes of elapsed time. Since the phone camera has a maximum exposure time of 10 seconds, there are missing gaps in the continuous Space Station path. I repeatedly pressed the shutter as fast as I could, but I included an automatic 2-second delay between pressing the shutter button and exposure initiation to let vibrations die down. Notice how the Space Station gradually fades away in the last frame. An unknown satellite or airplane streaks diagonally through the upper right.
The Space Station's altitude is approximately 260 miles, and it moves at roughly 17,130 mph! At this speed it can travel 1,000 miles in about 3.5 minutes!

My next attempt to capture the Space Station happened on December 15th. This evening the Moon was below the horizon, and the sky was dark when the Space Station passed nearly overhead. The next image shows 10 seconds worth of orbital motion as the station passed near the constellation Lacerta heading toward the Great Square of Pegasus. Cepheus, Cassiopeia, and Perseus are seen from left to right along the bottom of the picture. The Andromeda Galaxy is the tiny fuzzy smudge slightly to the right of center.
I misjudged the location of the Space Station's path as it passed near the zenith, so the previous picture shows the track off center. As the orbit continued I was able to get three consecutive images while the Space Station descended toward the southeast. The following 3-frame animation captures 40 seconds of motion and shows the path dropping through the constellations Pisces and Cetus toward the murky light polluted horizon.
I tried using the phone's video recording mode to capture continuous motion of the Space Station through the constellations. If the Space Station is bright enough, the phone camera detects it as a moving point of light, but the background stars do not show up during the short time exposures of each video frame. Thus, choppy animations like the two shown above are the best I can do with the phone to show orbital motion among the stars. 

Friday, December 15, 2017

Nightscapes With a Phone Camera

Sky Scenes

I've been exploring the ability of my Samsung Galaxy 8 Plus phone to image constellations. The maximum exposure time in the "pro" setting is 10 seconds at ISO 800. Only limited faint detail can be captured, but I'm amazed at how well the tripod-mounted camera works at night.

For example, look at the next picture of Orion rising among moonlit clouds on November 27th. Auriga, Taurus, and the Pleiades are also visible.
The next night, November 28th, I captured the same scene when clouds were absent. Constellations are easier to see, but the Moon was one day closer to full. Consequently, the sky is bright.
On December 10th moonlight was absent in the evening. I walked away from neighborhood lights to take pictures in a nearby field. The next image shows a noticeably darker moonless sky as Orion, Taurus, and the Pleiades shine above bare trees.
Trees make a nice foreground in the previous picture, but the branches are very dark. It would be nicer if the branches were slightly illuminated. I next moved to a place where local lights were blocked by surrounding trees and got the following image of Auriga centered between the trees. Perseus, Taurus, and the Pleiades are also visible.
In the previous picture (and others) the image center is noticeably brighter than the upper edges. I wonder if the camera chip is more sensitive in the center, or if there is vignetting. This effect could be removed by flat fielding, but I didn't take a flat field image.

Finally, I walked further away from neighborhood lights to capture the following picture of Orion, Taurus, Auriga, and Gemini rising above pine trees in a nearby soybean field.
I've tried doing constellation photography with my Nikon DSLR, but have encountered several frustrating obstacles. The Nikon will not automatically focus on stars, so I need to manually focus. Unfortunately, the infinity setting for manual focus is not accurate. This means I need to rotate the focus ring back slightly away from infinity and then visually check to see if stars are focused. The visual checking requires several time exposures and subsequent magnifications of the viewing screen in order to see if stars appear as points. While this tedious exercise is going on my hands are getting numb and the camera lens is getting covered with dew. The Nikon DSLR can do long exposures on the "bulb" setting, and this reveals lots of dim stars and faint details. But these long exposures require a tracking mount to keep up with Earth's rotation. On many occasions I've spent the better part of a freezing, hand numbing hour setting up the tracking and focusing the camera only to find the lens covered with dew and useless.

In contrast, the phone camera quickly focuses automatically and does a good job showing the brighter constellation stars. The phone lens doesn't seem to get quickly covered with dew the way my DSLR lens does. Ten second exposures don't require guiding equipment to follow Earth's rotation. The phone/tripod combination is easy to carry from place to place and sets up quickly.

Images like the ones above can easily show satellite and meteor tracks among the constellations even if dim stars are missing. I hope to capture some of these events and display the results in the next few posts.

Thursday, December 7, 2017

Nutcrackers Galore!

Christmas Decorations

There's a nice little restaurant here in Williamsburg called, Victoria's. Near Christmas it's decorated with an astounding collection of nutcrackers! Here's what you see when you enter.
The entrance display is only the beginning. A table near the entrance has this view.
Tables on the right see this side of the central display.
Tables on the left see the other side of the central display.
And there's even more!
Where in the world did they get so many nutcrackers? Victoria's is a lovely place to get breakfast, especially near Christmas!

Wednesday, November 29, 2017

Sunset and Dawn

Atmospheric Beauty

Near sunset on October 29th, after a long day of rain and overcast, I noticed a strange orange light outside. Past experience made me think a rainbow might be visible opposite the nearly setting sun. Sure enough, when I rushed outside with my phone camera I saw the next two views. A bit of secondary rainbow is visible in the second picture. Click on these panoramic images to enlarge them.
Just a few days later, On November 3rd, I happened to look out the window near dawn and saw the following display of crepuscular rays. Click on the image to enlarge it.
The bright pink rays are sunlight passing through gaps in distant unseen clouds below the horizon. The darker blue rays are shadows cast by these same distant clouds. The dark and light rays are actually parallel to each other, but their source is so far away that they appear to converge just as parallel railroad tracks seem to converge in the distance. (Crepuscular means "relating to twilight".)

I continue to be surprised and astounded by the capability of my phone camera. In future posts I hope further explore how well the camera can capture sky scenes. 

Tuesday, November 21, 2017

Norway - Part 9

Alta to Home

The last official day of our tour began with a morning visit to the Alta Museum where ancient rock carvings made by Sami people as much as 7,000 years ago can be seen. It was raining, chilly, and sometimes windy as we hiked on wooden walkways to the site of the carvings.
The carvings were made on gray, flat, smooth-surfaced sandstone scoured by past glaciers. The stone surfaces reminded me of blackboards, and blank blackboards invite doodling. Perhaps ancient Sami carvers were similarly tempted to doodle.
Red coloring has been added by the museum to make carvings easily visible to visitors. The original carvings were not colored. You can see an uncolored carving in the next picture. Look closely just above the symbol commanding no shoes off the walkway and to the right of the crack in the rock. Can you see the uncolored shape of an animal? Click on the image to enlarge it.
Our guide thought the next carving showed elk and reindeer enclosed by a fence.
Archeologists have been carefully studying and dating the carvings for years. Wall displays within the museum show some results of their work. The first panel below shows the way animals, people, and boats were depicted over thousands of years. Click on the image to enlarge it.
The next panel shows how elk (moose) and reindeer were depicted. Click on the image to enlarge it.
There were many carvings of boats with elk figureheads and the museum displayed how a real boat would have looked.
I thought the wooden walkways around the rock carvings were beautiful. Click on the next two panoramic images to enlarge them.
Imagine how glorious the next two images would have been a few weeks earlier on a sunny day when the birch trees were clothed in yellow fall leaves.
Our trip was now winding down. After the Alta Museum we drove to the sleepy Alta Airport, the least busy airport I've ever seen. It seemed they had to wake up some reluctant security personnel to screen our bags. All the snack bars were closed, and there were no planes parked at gates. Nevertheless, our plane eventually arrived on time. We boarded the two-engine propeller plane and began our journey home with a short, surprisingly smooth 30-minute flight south to Tromso.

The next step was a 2-hour flight from Tromso to Oslo. After an invigorating long walk from the Oslo Airport to our hotel we had our last dinner with the tour group and gladly went to bed.

I like window seats on long flights because sometimes spectacular views appear instead of uniform clouds. On our flights home to Virginia three beautiful sights occurred. First, was a glory seen against background clouds on the way to Iceland.
Second, over Iceland, the clouds parted long enough to unveil five glaciers in Vatnajokull, Iceland's largest ice cap.
Finally, while flying over southern Greenland I could see massive glaciers, glaciers ending in water where icebergs had broken off, and sea ice.
Weather on this Norway trip was a complete reversal from weather on last year's trip to Spain and Portugal. Last year every day was warm and sunny except for one single evening rain shower. In Norway every day was cold and rainy except for one single midday stretch of sunshine in Finnmark.

We had a wonderful trip to Norway, but I was very happy to be home in Virginia again. The contrast in weather conditions was immediately apparent. Norway was drizzly, dark and overcast with temperatures in the 40's. Norwegian trees had lost most of their leaves. Near home in Williamsburg the trees were full of green leaves, the sun was shining, and the temperature was in the 80's! It was time to shed clothing and feel warm sun on bare skin. Although Virginia is warmer, Norway has auroras! I was thrilled to see two dramatic auroral displays whose fantastic beauty made our entire trip worthwhile.

Saturday, November 18, 2017

Norway - Part 8

Karasjok to Alta

We left Karasjok on yet another cloudy morning and drove southwestward across northern Norway through the region called Finnmark. For the first time conditions matched what I thought we would find above the arctic circle. It was a cold morning with temperature at about 21 degrees F. Soon the surrounding landscape was completely snow covered. We traveled through very sparsely populated country containing only thin forests of dwarf birch trees. Click on the following panoramic image to enlarge it.
Hints of blue sky began to appear in the cloud deck. We rolled along on a well maintained two lane road when, suddenly, the bus driver jammed on the brakes causing our guide to stumble up the center aisle of the bus. Reindeer were crossing the road just ahead of us and running through the woods beside us! We would see many more reindeer before the day was over.

Soon clouds were gone and we had a rare sunny day! Eventually, we arrived in the city of Kautokeino where a visit to Juhl's Silver Gallery was scheduled. I didn't know what to expect as we got off the bus and carefully walked down a hilly, slippery driveway to the gallery. The top of the driveway is on the left by the signs in the next picture.
At the bottom of the driveway we came upon the following interesting building. Click on the panoramic image to enlarge it.
Once inside we passed through an area where workers/artists were making jewelry. Examples of their beautiful work were displayed in the next room.
At this point I thought we were visiting just another gift shop/museum, although a very nice one. Then I noticed the following little side room with a cozy fire burning.
Perhaps you notice some stairs going down to left in the previous picture. I went over to explore and saw this inviting scene.
Huh? What's this? Of course, I had to go down! At the bottom of the stairs I turned left and saw a fantastic room.
Then I turned to the right and saw more surprises.
What in the world is going on here in the middle of arctic Norway? It turns out the founders and creators of the gallery had traveled to Afghanistan years ago and fell in love with the art and culture there.

The magical corridor pictured above led to another amazing room containing more eye popping sights. Click on the first panorama to enlarge it.
Walking around the room eventually brought me to this pretty view through decorated windows.
The sunlit view of snowy Kautokeino below the gallery was nice.
Juhl's Silver Gallery was incredibly original, interesting and beautiful. It was a completely unexpected pleasant surprise, one of the best of the trip!

After the silver gallery we stopped at a local hotel for a lunch of "game stew" very similar to the delicious "elk stew" we had in Karasjok. Then we boarded the bus and headed to our next adventure at a Sami reindeer herding camp. We were met at a remote roadside location in "the middle of nowhere" by a cheerful teenage Sami girl who took us walking about one kilometer on a slippery, snow covered dirt road to the camp which you can see in the next picture. Click on the panorama to enlarge it.
The teenage girl's older cousin operates the camp. The pair greeted us in their brightly colored Sami clothing in front of the lavvu we would soon enter in the background. Notice how long the shadows are in all the pictures. Here, at midday, above the arctic circle, the Sun was only 9 degrees above the horizon!
The camp operator took some of our group into the reindeer corral to give them each an individual reindeer to lead by rope. Then he went to capture a particular blue eyed reindeer at the back of the pen. He lassoed the beast, but, somehow, this feisty reindeer got away and took off running through the trees. A moment later the Sami guy was flying after the fleeing reindeer on an ATV, both of them moving at high speed through the dwarf birch trees. This was quite an entertaining dramatic scene! The fleeing reindeer was at least temporarily victorious because his pursuer eventually gave up and returned to our group. He told us not to worry. He would catch the runaway later.

Animal lover C soon had her own personal reindeer under control. At first, it resisted being led, but a few soft words and gentle tugs from C convinced it to go along.
After reindeer playtime was over we were invited into the camp lavvu to sit around a warm central fire where pots of coffee were kept hot. The burning wood was fragrant, but, in spite of the smoke hole above, it was slightly smoky inside. We were offered coffee and cookies as the Sami guy explained the rules of the lavvu. His 10-year old nephew, taking his work very seriously, carefully maintained the fire all the while by adding birch twigs.
Then it was time for the Sami girl to sing a joik, (pronounced like, yoik). As I understand it, a joik is not a song about something, and it isn't sung to anyone in particular like a loved one, or a baby. Instead, it is meant to evoke the spirit or essence of something. In the picture below our singer shyly sung a reindeer joik. You can hear a beautiful example of a Sami joik at this link.
After leaving the  reindeer camp we resumed our long drive northwest to Alta. Traffic frequently needed to stop or slow to avoid reindeer crossing the road or running along the roadside. At one point our guide announced, "These reindeer belong to my relative." We wondered how she could know this. She told us her relative owned all the reindeer in this particular area!
We arrived, tired, in Alta near sunset. After checking into our hotel room we returned to the bus for a drive to dinner at a remote restaurant some distance from the city. The halibut dinner was very good. After dinner clear dark sky outside tempted some of us to look for auroras, but no worthwhile aurora was seen. Then it was back to the hotel for our final night above the arctic circle.

People say I'm crazy doing what I'm doing
Well they give me all kinds of warnings to save me from ruin
When I say that I'm o.k. well they look at me kind of strange
Surely you're not happy now you no longer play the game

People say I'm lazy dreaming my life away
Well they give me all kinds of advice designed to enlighten me
When I tell them that I'm doing fine watching shadows on the wall
Don't you miss the big time boy you're no longer on the ball

I'm just sitting here watching the wheels go round and round
I really love to watch them roll
No longer riding on the merry-go-round
I just had to let it go

John Lennon