Iota Cassiopeiae: An Unforgettable Triple

Iota Cassiopeiae (also known as Iota Cass) is a beautiful triple star system in the constellation Cassiopeia. According to astronomer Jim Kaler, the two brightest stars (referred to as A & B) are white and fairly colorless, while the third is an orangish-yellow color.

My Observations

Patches of haze come and go from the west while I wait for small patches of sky to clear so I can observe. It appears Iota Cass will be the only object I’ll view tonight, but it is worth it!

The star system appears directly overhead. I have landed on the area using my wider (25 mm) eyepiece, but I can’t make out the three stars. With the winds picking up and fog blowing in, I’ve moved to my 12mm eyepiece with the Barlow.

I can make out the stars now, and it appears a larger cloud will hide by view within minutes. It’s true: the primary star is white, while the farther one away is yellowish and the third star nestled nearby the primary appears bluish. It takes a fairly high magnitude to see the blue star right by the primary.

Key Stats

Constellation	Cassiopeia
Best Viewing	Late Fall / Winter
Visual Magnitude	+5, +7, +9
Absolute Visual Magnitude	+3.66
Separation	Between AB 2.6″ | 198AU Between AC 6.7″
Position Angle	Between AB: 228° Between AC: 117°
Distance from Earth	133 ly
Orbital Period	620 years
Milky Way Location	Orion Spur
My Viewing Grade	B
Designations	SAO 12298, Struve / STF 262, Iota Cas

Sources and Notes

The banner image is of the constellation Cassiopeia by pithecanthropus4152 and is shared under the Creative Commons Attribution-Share Alike 4.0 International license.

Sketch by Wayne McGraw