Challenge Object - April 2021

Original article appears in GuideStar April, 2021.

by Stephen Jones

Hickson 44.png

Hickson 44 – Compact Galaxy Group in Leo

RA 10h18m05.7s Dec +21deg 49’57” (position is for NGC 3190)

NGC 3190: Size 4.4’x1.2’ Vmag 12.1

NGC 3193: Size 2.0’x2.0’ Vmag 11.8

NGC 3187: Size 3.6’x1.6’ Vmag 13.4

NGC 3185: Size 2.3’x1.5’ Vmag 13.0

Galaxy season is upon us, so this month we will look at a small but interesting group of galaxies in Leo.  These 4 galaxies form the 44th galaxy group in Paul Hickson’s 1982 catalog of compact galaxy groups.  The individual galaxies themselves were discovered much earlier, however.  The two brighter galaxies were both discovered by William Herschel on March 12, 1784.  The fainter two galaxies were discovered by Lord Rosse’s assistant Johnstone Stoney with Lord Rosse’s telescope in January 1850.  A portion of the cluster (particulary 3190 and 3187) was also included in Halton Arp’s catalog of peculiar galaxies as Arp 316. 

The two Herschel-discovered galaxies 3193 and 3190 are bright and should be visible easily in medium-sized scopes.  3187 is easily the most difficult to observe of the 4 galaxies; while 3185’s listed magnitude is almost as faint, its higher surface brightness makes it a good bit easier to observe. Interesting note on 3187: charts show the galaxy’s direction of elongation as perpendicular to that of 3190, but when you observe it you may perceive it to be parallel! The reason for this is that 3187 is a barred spiral, with the bar significantly brighter than the heavily disrupted arms.  The elongation noted on the maps takes the full shape of the galaxy into account; the bar itself is indeed parallel in PA to 3190, and you, like me, may only be seeing the bar.  My log entry is as follows:

4/15/2018 9:57 pm – 16” f/4.5 SCT 131x

NGC 3190 is very bright, elongated; definitely presents as edge-on; NGC 3193 is slightly brighter; more compact, round with stellarish nucleus; NGC 3185 is visible with direct vision, but amorphous; some detail visible with averted; hard to tell what it is, just distorted; NGC 3187 is faintest; requires averted vision to see at all; then only central bar is visible; arms not visible at all

If you’re feeling challenged reading this so far, I do have a bit of good news for you… it’s not particularly difficult to find.  Hickson 44 is located almost exactly in between ζ and γ Leonis in the neck of the Lion (very slightly closer to ζ).  The charts below should get you right there.

Hickson_44_b.pngHickson_44_c.png

The HAS VSIG would love to hear about your own visual observations of Hickson 44.  Send them to the VSIG list server.  To get on the VSIG email list server, contact me at [email protected].

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