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.

Astro-Image | Backward Galaxy NGC 4622

Spiral galaxies are common in the universe. This nearly face-on example from the Hubble Telescope is found 111 million light-years away in the constellation Centaurus. Most of them swirl in a direction one might intuitively assume. This one appears to go in a counter-clockwise direction. Analysis using images by the Hubble Telescope show the outer arms moving clockwise instead. Evidence suggests it consumed a smaller companion galaxy which disturbed its rotation.

Drs. Ron Buta and Gene Byrd from the University of Alabama, Tuscaloosa, and Tarsh Freeman of Bevill State Community College in Alabama, observed NGC 4622 in ultraviolet, infrared, and blue and green filters. Their findings were presented to the American Astronomical Society in January 2002.

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ISS Pass Segments

The International Space Station passed over my part of the world recently. I like to watch it when the conditions are right. Sometimes, I set up the iPad for a time exposure. This time I recorded the event with a different camera setup. My Canon was on a tripod pointed at the west-northwest sky. Six exposures were made. Each was 15 sec in duration. Each was started 40 sec after the start of the previous one. The first two images were combined with software into this one image. It was a little after 8:08 pm local time. Other objects of interest in the image are Taurus in upper left, Pleiades a little below right from Taurus, Perseus in top center, and Cassiopeia right center.

Looking west-northwest

During the intervening seconds before the third image, I turned the camera on the tripod to face northwest above Cassiopeia. I moved the camera and missed the fourth image.

Looking northwest

Images five and six were with the camera pointing north-northeast toward the Big Dipper. The dipper points to Polaris. The Little Dipper is barely visible.

Looking north-northeast

This was the first time I captured images from nearly horizon-to-horizon by moving the camera during the sequence. If you are viewing by phone or a tablet device, the details in the images might not show. A full-screen desktop view works best.

JWST Mirrors

The 18 mirror segments of the James Webb Space Telescope are currently being slowly moved from their safely stowed positions at launch to their fully deployed positions. They move about a millimeter per day. You can watch the progress here.

If you are interested in delving into the history and development of these mirrors, NASA has a lengthy and very complete web site explaining with text, diagrams, and short videos. I found it well-worth reading. Follow this link.

Photo: NASA/Chris Gunn

James Webb Telescope Deployment

The James Webb Space Telescope was successfully launched on Christmas morning from Kourou, French Guiana. It is coasting toward the location called LaGrange Point L2 where it is to be stationed for its scientific mission. Details of the mission and the telescope are described in this post by fellow blogger Steve Hurley in Explaining Science.

Where us JWST located at this time? NASA has a convenient website to answer that question.

The next month will be busy for the scientists and engineers as they carry out the multiple steps needed to deploy all the necessary parts of the JWST to make it fully functional. A timeline is available giving step by step descriptions of the deployments. Visit that deployment timeline here. Notice on that site that event times and descriptions are given. Short video links are available showing the deployments.

Another video is available showing the entire process that is planned over the month following launch. It last less than 2 minutes and is included here. If you are interesting in greater detail, explore the timeline. This is the nominal timeline. It will be altered if difficulties arise that need to be addressed.