Seyfert’s Sextet
(NGC 6027 group, HCG 79, UGC 10116, VV115, VII Zw 631)

Galaxy Cluster
Serpens
RA 15h 59m 12s
DEC +20 45’ 31”

Magnitude: ~14.8 to ~16.5

HST_1024px-Seyfert_Sextet_ful_cropl.jpg

There are so many galaxy clusters in the August sky, but this is one of my favorites. One reason is that there are a couple of enjoyable observing challenges in this compact group, and another is that all the members are not actually galaxies. And a third supposed member is actually a line of sight object far in the background.

When I first started observing Seyfert’s Sextet, the first appeal was the name – named objects are usually interesting. This one was the tightest galaxy group when Carl Seyfert published his research about them in 1951. The group also has a distinctive flying wing shape that sets it off visually, with NGC’s 6027 c and e forming the wing tips.

The tidal tail, NGC 6027e, is the first observational challenge because it’s diffuse without a brighter core, and I’ve found it difficult to see unless conditions are quite good. 6027e shoots out to the upper left in my sketch (as seen through Jimi’s 48 inch) and the HST image in black and white. It’s listed as two magnitudes brighter than 6027c, the galaxy that’s aligned straight up and down in the bottom center of the images here. Oddly, I’ve found them to be more or less equally visible – if I can see one I can see both.

48inch_Seyfert's Sextet-N6027a-e.jpg HST_1024px-Seyfert_Sextet_ful_cropBWl.jpg 48inch_Seyfert's Sextet-N6027a-eInvert.jpg

The most difficult galaxy to see for me has always been 6027d, the background galaxy. I’ve seen it only once with my 28 inch, using averted vision and 700x on a great night, but it was easily and satisfyingly seen through Jimi’s 48 inch with direct vision at about half that magnification.

I didn’t think to try for the very thin dark lane is 6027a then, but that can be a challenge for another night.

Members of Seyfert's Sextet
Name Type Distance (million ly) ~ Magnitude
NGC 6027 S0 pec. ~190 +14.8
NGC 6027a Sa pec. ~190 +15.3
NGC 6027b S0 pec. ~190 +15.3
NGC 6027c SB(S)c ~190 +16.5
NGC 6027d SB(S)bc pec. ~877 (background galaxy) +16.5
NGC 6027e SB0 pec. ~190 (tidal tail) +14.4

HGC79_MegaStar.jpg

“GIVE IT A GO AND LET US KNOW"