Saturday, January 16, 2021

The Andromeda Strain

The inexpensive star tracker I bought last month continues to amaze me. And so do the capabilities of an ordinary camera with telephoto lens when used with it.

A cool front passed through south Texas yesterday, removing all traces of haze & humidity, leaving us with uncommon transparency of atmosphere. I took advantage of the opportunity to set up the items - once a 30 minute process, now honed down to a third of that time.

I wasted valuable time photographing the Pleiades, which were high overhead and therefore available for photography for hours. Meanwhile, Andromeda was low and setting. By the time I realized this, the galaxy was only 40 degrees up and trees took up a good portion of the horizon.

The next opportunity to photograph Andromeda with multiple long exposures won't come until October when it will once again be high overhead and visible for hours.

But for now, I managed to shoot thirty 30-second exposures (Nikon Z6, 300mm/f4 lens at f4, ISO 2500, stacked in Sequator. And twenty 30-sec dark frames for noise elimination suppression) before both galaxy and camera were down at treeline:

M31 with its companion galaxies (M32, fuzzy blob to the left. M110 lower right).


Fun Andromeda facts:

  • It is 2,500,000 light years away.
  • M110 and M32 are in orbit around Andromeda (M31)
  • Like our Milky Way, it is a spiral galaxy.
  • Contains 1 trillion stars, twice that of the Milky Way.
  • Until the 1930's Andromeda was thought to be a nebula within our own galaxy.
  • It is the only naked-eye non-Milky Way object we can see. All else is merely foreground.
  • We are approaching the Andromeda at the rate of 50 miles (80 km) per second.
  • The Milky Way and Andromeda will collide in 4.5 billion years. Stock up on canned goods.



A mesa blocked my view of Andromeda while I was in west Texas last week; trees and light pollution obscure it from home. For this image I drove to a location an hour north of home that was indicated on this map to be significantly darker. It was. My specific QTH was in the parking lot of a cemetery at the end of a dirt road in the Davy Crockett National Forest. Spooky, eh!



  1. Replies
    1. I regret not having more time to make exposures to get more detail - this pic will now tease me until October.