A typical procedure in astrophotography involves mounting a camera on a stable platform like a tripod so it doesn’t move during exposures. Some people have motorized platforms that allow the camera to move and track the subject for long exposures of several minutes. I was curious how an image would look for a camera mounted on strings that allowed it to swing forward-backward and left-right at the same time during an exposure. Years ago, this image appeared in a magazine. I kept it and thought of trying it someday.
Jupiter rose over the tree across the street a few minutes after 9 pm. With camera on a tripod and on full zoom, the intervalometer was set for 1 minute intervals of 10 exposures. The camera was set to ISO 800 and ¼ second. I hoped for just enough exposure to barely reveal the moons and not overexpose Jupiter too much. Europa was barely visible left of Jupiter. Ganymede and Callisto farther to the right. Smoke haze from western state forest fires dimmed the sky. After the exposures, Pixelmator Pro was used to layer them in this image.
I was inspired by a recent post in the blog Cosmic Focus by fellow amateur astronomy Ggreybeard in Australia. He put his DSLR camera on a tripod facing north and attached an intervalometer. The result was a series of 100 images each 45 sec long stitched together showing the star trails across the northern sky. I encourage you to go visit his blog to see the beautiful image.
I noticed Ursa Major and Minor, the Big and Little Dippers to most people, in the northwest sky in recent summer evenings when I was out with my telescope or binoculars. That post by Ggreybeard made me want to try the same thing. I decided to try to get the star trails using two different camera setups.
NightCap Camera
My iPad has the app NightCap Camera on it. It can capture many varied low-light scenes including one called Light Trails. I set the iPad on a stable base and started the exposure. It lasted for 1 h 7 m 46 s. Some scattered clouds glided in that were lit up by ground lighting. Airplanes flew over in various directions with blinking lights. The resulting image showed it all. I added some yellow lines highlighting Ursa Major and Ursa Minor as well as Polaris the North Star. It was a messy yet interesting image.
25 Aug 2022 | NightCap | Light Trails mode | ISO 3072 | 4066.23 sec | 0.5 sec per exposureContinue reading →
The James Webb Space Telescope provided the most detailed look to date of the Cartwheel Galaxy with the image release on 2 Aug 2022. The galaxy was first observed by the U.K. Schmidt telescope and then by the Anglo-Australian Telescope. It lies about 500 mega lt-yrs from us in the constellation of Sculptor. A much larger and high resolution image is available for you at this link. When there, scroll down and look for Download Options. I will use the detailed image to point out some highlights farther down in this post.
I enjoy making color composites from three grayscale images using the technique in this post. The colors assigned are not necessarily what the human eye would see, but are used to bring out details in structure and composition. Gallery of previous Astro-Images.
NGC 4845
This spiral galaxy is located in the constellation Virgo about 65 million light years away. Seen nearly edge-on, the bright core and the surrounding dust clouds are visible. The blue areas are artifacts of the original Hubble images used to make this composite.
Astronomers can observe the wavelengths of light from the galaxy to the left and right of the core. Rotation of the galaxy causes Doppler Shift of the wavelengths. The part of the galaxy moving away causes the wavelengths to be longer than normal. The part moving toward us causes the wavelengths to be shorter. The amount of shift in wavelengths indicates speed of rotation. A very massive central core of a galaxy results in fast rotation speeds.
Measurements of this galaxy allow astronomers to conclude a Black Hole resides in the core with a mass about 300,000 times the mass of our Sun. The galaxy was originally discovered by William Herschel in 1786.
How I See It 
