Wednesday, March 21, 2018

Living History

Fun Afternoon

The afternoon of March 18th was relatively mild and sunny here in Williamsburg. It was a good day to attend an exhibition at the nearby Jamestown Settlement Museum called Military Through the Ages. Dedicated re-enactors displayed the clothing, equipment, food, weapons, and campsites of soldiers through history from the time of ancient Greece up to the modern Vietnam War. The re-enactors were wonderful! They easily stayed in character and spoke convincingly about details of life during their selected historical time period.

For example, the next picture shows a re-enactor portraying a surgeon with the American Revolutionary War army. He patiently explained the uses of medical instruments and medicines displayed on the table before him.
Directly opposite the surgeon's table was a British Royal artillery unit from the same Revolutionary War time period.
One artillery unit member was casting musket balls from molten lead. The silvery molten lead can be seen below in a small metal cup sitting in the fire near the left end of a piece of firewood.
The molten lead was scooped from the cup and poured into several molds to make musket balls. The re-enactors gave musket balls to visitors, but, even when solidified, the balls were often still too hot to handle.
Another 18th century display featured engraved powder horns.
Going back further in time, a group called La Belle Compagnie portrayed the time of the Hundred Years War between England and France 1337-1453.
Exhibits were not always about weapons. Food preparation, sewing, games, and crafts were also prominently displayed.
Another group, Lord Grey's Retinue, portrayed life in the medieval household of Lord Henry Grey of Codnor, England in 1471. One member displayed armor in use at the time and helped visitors try on various pieces.
Near the armor exhibit an archer explained the use of a longbow.
His supply of arrows was impressive. Also impressive was the hundreds of pounds of strength needed to operate the bow and the incredible range of the arrows. They could travel 100 to 200 meters or more!
The archer also displayed different types of arrowheads. Some were meant to penetrate armor. Some were meant to penetrate chain mail. They all look deadly.
Another interesting group was Das Teufels Alpdrucken Fahnlein (The Devil's Nightmare Regiment), German mercenaries of the Holy Roman Empire in 1529. They featured colorful uniforms and fearsome swords.
Here they march as a group.
Ancient Greek warriors represented the 5th century BCE. The crested Greek helmets look particularly fearsome.
Who are the people who become so dedicated to this role playing? How do they get interested in one particular historical time period rather than another?
This enjoyable exhibit returns each year. I hope to attend next year and learn more.

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.

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