23/11/2023
Ales Stenar's journey in the galaxy
Background to the picture:
When the great pyramids in Giza had been standing for 3100-3300 years, this stone ship was raised during the younger iron age in Sweden, 500-700 years C.E. Swedish engineering was not as developed at that time in international comparison.
The purpose of the image is to show the night sky at the stone ship as it may have looked when it was first constructed prior to human-created light polluted skies.
Our galaxy was born 13.6 billion years ago and the solar system was born 4.5 billion years ago in the galaxy. Our solar systems rotates clockwise around the center of the galaxy and has made 19-20 revolutions in 4.5 billion years. 225-240 million years per revolution. This means we are rotating towards the upper left part of the Milky Way in the image.
One revolution ago i.e. last time the Earth looked at the galaxy from this view, the dinosaurs were born. They lived for two thirds to three quarters of the last revolution and went extinct some 70 million years ago. The modern humans were born 200 000 years ago, which is less than one thousands of a revolution around the galaxy center.
Our Sun is expected to live for another 4.5 billion years and 19-20 additional revolutions.
The strong yellow area at the horizon in the center of the image is light pollution from Rönne on Bornholm and the red area at the horizon to the right is light pollution from Swinoujscie in Poland across the Baltic sea.
How the picture was made (photo tech)
The picture can be taken during 1 week in April when the milky center is highest above the horizon without the moon above the horizon disturbing the dark night. Crisp clear atmosphere necessary without any clouds in the sky, which made it impossible during several years before the opportunity occurred. Cold weather during the night with 10 m/s steady wind.
Canon EOS R
16mm wide angle at f2.8, ISO6400, 13s exposure per light frame to avoid distorting stars due to earth rotation.
Deep sky astro photography technique
23 light frames of the galaxy, total of only 5 minutes exposure, regular tripod without star tracking, 5 kg hanging in the tripod to eliminate movement due to the wind.
40 bias frames to eliminate sensor noise
49 dark frames to eliminate long exposure noise
30 flat frames to correct for optical imperfections
25 dark flat frames to correct for long exposure noise in flat frames
3 frames with long exposure for the foreground with Ales Stenar
Bortle zone 4
Calibrated and processed as a linear 32-bit per channel floating point image in PixInsight
NoiseXterminator for removing luminance noise only.
GraXpert for light pollution gradient removals
Post-processed as a non-linear 16-bit per channel integer file in Photoshop
Processed both as an RGB and Lab image in PixInsight in various steps to enable extraction of the small signal levels from the galaxy
Stars and Milky way are color calibrated using a star atlas to ensure real color temperature of each star in the image.
The stretching process in careful small steps not to overexpose the nebulosity
Separate similar careful stretching process for the stars not to blow out highlights and colors of individual stars.
All relative sizes between the Milky Way and the foreground are intact and real. All taken with 16mm wide angle lens.
The images are calibrated to be viewed with 100Cd/m2 lightness on the screen, i.e. 15-20% lightness on a cell phone.
