Astro-Image | NGC 4845

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.


Night and Morning Sky Shows

Recent good weather provided two viewing opportunities about 8 hours apart. The first was an International Space Station pass over our area on 30 July 2022. The ISS was to appear low in the NW sky at about 9:41 pm, pass overhead at about 65˚ elevation, then disappear into Earth’s shadow low in the SE at about 9:47 pm. I programmed my camera to take a series of images to record the progress across the sky. It was set to record 1-second images of ISO 3200 about 10 seconds apart. I pressed start and the program didn’t do what I expected. So, I did it manually.

The images were placed into iMovie for this video of ISS playing peek-a-boo with some clouds.

The second sky views came at around 5:25 am the next morning on 31 July. I planned to view 5 of the planets. I looked south to easily find Jupiter high in the sky. The Galilean moons were arranged left to right Callisto, Ganymede, Io, and Europa.

Callisto, Ganymede, Jupiter, Io, Europa

Looking east revealed Venus rising well before the Sun.

The prize for the morning included Mars and Uranus in the same field of view.

Finally, I looked around me to see Earth cast in the morning light to top off the 5 planets.

JWST | Alignment Complete

Webb’s mirrors now direct fully focused light from space down into each instrument. This alignment allows each instrument is capture images. For the next two months, work will be done to commission each of the four scientific instruments. Performance appears better than the engineering team’s most optimistic predictions.

The NASA blog posted 28 April 2022 by Thaddeus Cesari describes the significance of this milestone in greater detail. Images in the post can be enlarged to show the great detail achieved by each instrument as well as the Fine Guidance Sensor. They are impressive. In addition, this one minute video from the blog summarizes the accomplishments.

GOES-T Launch | 1 March 2022

There are 4 satellites in the GOES-R series. Initially named R, S, T, and U, their names are changed once checked out and in position 22,300 miles above the equator. The first in the series GOES-R was re-named GOES-16. It maintains a position above the equator at 75.2˚ west longitude and keeps watch on the Atlantic Ocean basin. The second in the series GOES-S was re-named GOES-17. It maintains a position above the equator at 137.2˚ west longitude and keeps watch on the Pacific Ocean basin. GOES-T is scheduled to replace GOES-S which has a malfunctioning system limiting its performance.

Our son-in-law works for a company that provides important support for the GOES satellites. He extended an invitation to us to attend the March 2018 launch of GOES-S at the Cape in Florida. We posted about that day in this blog entry. We were invited to attend the launch of GOES-T but COVID restrictions cancelled those plans for everyone. Online coverage let us watch the successful launch.

Launches are normally viewed from ground locations. Camera placements can provide dramatic views up close, through telephoto lenses miles away, and with on-board cameras. Our SIL sent a link to us from two camera views in space. The views were from GOES-16 and GOES-17. The images were captured by the two GOES spacecraft at 30 sec intervals. The video lasts 14 seconds and repeats the launch once.