NGC 3198
UGC5572
PGC 30197
Herschel 146

Galaxy

Constellation: Ursa Major

RA: 10 19 54.9

DEC: +45 33 09

Class: SB(rs)c
Mag: 10.3
Size: 8.6’x3.3’

Give or take 47,292,674.7 light years in the direction of the ‘Bears Toes’ in Ursa Major lies this weeks OOTW. NGC3198 is rather bright, elongated barred spiral visible in a wide range of telescope apertures. One account I found is that NGC3198 was discovered by Lord Rosse Williams Parsons in the mid-19th century. Another was that it was discovered by Sir William Herschel in 1788. Anyone?

Scientifically, NGC3198 has played a pivotal role in our understanding in the universe. In one paper published in 1999, researchers used the Wide Field and Planetary Camera 2 (WFPC2) on Hubble to locate and measure the distance to 52 different Cepheid Variables located in NGC3198. Using this data, astronomers were able to ascertain a rather accurate distance to our OOTW of 14.5±1.2 Mpc – giving us the number I sarcastically opened this post with. NGC3198’s distance is so well measured that is used as a ‘calibration’ galaxy for the Key Project. In short, the Key Project was a study using data obtained through Cepheid observations in ~25 ‘nearby’ (~65Mly) spiral galaxies from the HST to help measure and refine the Hubble Constant – one of the principle goals for which the HST was designed and built. These refined distances of nearby galaxies would then help to refine observations and distances to galaxies further away (65Mly to more than 325Mly distance). NGC3198 is now used to help refine these other observations.

Another interesting bit I learned about NGC3198 is that it’s considered the “flagship” galaxy for evidence of dark matter in galaxies. In a 2015 paper titled The dark matter distribution in the spiral NGC 3198 out to 0.22Rvir alludes to the amount of dark matter measured in NGC3198 may actually be at least 4 times larger than the amount of visible matter. NGC3198 is MUCH larger than it appears to the eye.

To an eye looking through a telescope, NGC3198 makes for a fine sight. Telescopes in the 10” range provide the observer with a rather large, faint smudge with the possibility of spotting some mottling. In scopes approached 18” to 20” from a dark sky, the galaxy appears elongated on a NE to SW position angle with a bright core and the makings of spirality.

So if you’re out late this dark moon or next, please point your scope towards the Great Bears Paws. I think you’ll be pleasantly surprised at this galaxy. Not just for its appearance in the eyepiece, but for its overall contributions to the advancement of our understanding of this awesome universe!

And as always,
Give it a go and let us know! Good luck and great viewing!

NGC3198_AdamBlock.png
©Adam Block