Object name: HCG069

Designation(s): HCG069, IC4343, IC4344, IC4345, IC4346, IC4348, IC4349, FGC0195A,

HGC 69 is a group of 4 galaxies in western Bootes about 400 million light-years distant. Hickson groups, of which there are 100, must meet 4 requirements.

1. There must be 4 galaxies or more with a similar brightness that are brighter than 26.0 surface brightness per square second of arc.

2. The group must be isolated, not a small section of a larger group or cluster.

3. The group has to be so compact their relative sizes are similar to the distance between galaxies themselves.

Oddly, HCG 69 appears to break rule 2. There are a lot of galaxies, larger and smaller in angular size, in the image that are all (including HCG 69) part of a much larger group of galaxies. Note however Hickson doesn't say they all have to be at a similar distance. At the time of his listing, distances weren't all that well known. In fact, the first compact group known, Stephan's Quintet (HGC 92), has one member that's much closer than the others. All Hickson required was they visually appear likely to be at the same distance. In the case of HCG 69, they really are.

They are PGC 49499, 49502, 49505 and 59507. Hickson assumed many of his groups would show gravitational interaction when studied in detail. It's quite obvious from just my image that HCG 69A, PGC 49502, is highly distorted. It and HCG 69C, PGC 49505, are passive nucleus galaxies. A definition of them I found reads: "Passive nuclei (PAS) are typically red, contain exclusively old stars, with no star formation activity: their spectra show both H and [NII] in absorption. Thus the cores are red and dead though some I've found have jets so not totally dead. No jet is seen in these, however. Also, the entire galaxy need not be dead. HCG 69A has a blue star plume to the southwest indicating it is still forming new stars in that part while much of the rest is rather red. Thanks to this plume it is a huge galaxy which I measure at 194,000 light-years across. Note too that it has a very faint plume going north and a bit easy that goes past PGC 49499. This may indicate the path of yet a 5th galaxy it ate over hundreds of millions of years ago.

Many of the other galaxies associated with the same group as HGC 69 are also rather red and dead with a few exceptions such as ASK 538092.0 to the north of HGC 69 which is quite blue and very actively forming stars throughout as is LEDA 1723672 to the west.

There are 6 IC galaxies in the image 4343, 4344, 4345, 4346, 4348 and 4349. Redshift puts IC 4348 70 or so million light-years further away so it may not be related. The rest, however, are certainly members of the group that contains HCG 69. All 6 were discovered by Stephane Javelle on June 15, 1895.

There's an interesting pair of possibly interacting galaxies to the east-southeast of HCG 69. I found a redshift for only the southern galaxy. So are they interacting or is one well in front of the other so no interaction is possible? Wish I knew.

A quasar to the southeast is listed as having Damped Lyman Alpha emission. For what this means, see:

The stars are a bit flat on the bottom due to tube currents. Normally I let the scope cool to avoid these for an hour before imaging but this night was threatening rain so I didn't open the roof when suddenly the skies cleared with just enough time for one object. That left no time for cooling. I hoped the drizzle had helped cool the scope to ambient but this image showed that didn't happen.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designation(s):

2MASS J13545579+2507215, 2MASS J13551259+2501170, 2MASS J13551340+2503065, 2MASS J13554057+2509108, 2MASS J13554508+2512110, 2MASS J13554634+2509069, 2MASX J13545583+2507214, 2MASX J13551261+2501175, 2MASX J13551342+2503065, 2MASX J13554060+2509109, 2MASX J13554510+2512110, 2MASX J13554635+2509070, AGC 231563, AGC 231958, ASK 536042.0, ASK 538075.0, ASK 538083.0, ASK 538086.0, ASK 538214.0, ASK 538245.0, CAN 039 NED01, CAN 039 NED02, CAN 039 NED04, CGCG 132-044, CGCG 132-045, CGCG 132-046, CGCG 132-049, CGCG 132-050, CGCG 132-051, CGCG 1352.6+2521, CGCG 1352.9+2515, CGCG 1352.9+2517, CGCG 1353.3+2523, CGCG 1353.4+2526, CGCG 1353.5+2523, FBQS J135546.3+250907, FGC0195A, GALEXASC J135455.79+250722.6 , GALEXASC J135540.54+250909.8 , GALEXASC J135544.96+251212.4 , GALEXASC J135546.39+250906.9 , GASS 44846, GIN 318, GIN 319, GIN 321, HCG 069, HCG069, HDCE 0832 NED004, HDCE 0832 NED005, HDCE 0832 NED006, HDCE 0832 NED008, HOLM 556A, HOLM 556B, IC 4343, IC 4344, IC 4345, IC 4346, IC 4348, IC 4349, IC4343, IC4344, IC4345, IC4346, IC4348, IC4349, IRAS F13534+2523, LDCE 1013 NED004, LDCE 1013 NED005, LDCE 1013 NED006, LDCE 1013 NED008, LEDA 095536, LEDA 215031, MAPS-NGP O_381_0116799, MAPS-NGP O_381_0138786, MAPS-NGP O_381_0139167, MAPS-NGP O_381_0139205, MAPS-NGP O_381_0139920, MCG +04-33-024, MCG +04-33-025, MCG +04-33-026, MCG +04-33-029, MCG +04-33-030, MCG +04-33-032, NPM1G +25.0336, NSA 094489, NSA 094491, NSA 094494, NSA 094511, NSA 164225, NSA 164227, NVSS J135546+250905, PCC N79-297, PGC 049470, PGC 049492, PGC 049523, PGC 049530, PGC 049531, RASSCALS NRGs 272, SDSS J135455.79+250721.5, SDSS J135455.80+250721.5, SDSS J135512.58+250117.1, SDSS J135512.59+250117.2, SDSS J135513.38+250306.4, SDSS J135513.38+250306.5, SDSS J135513.39+250306.5, SDSS J135540.56+250910.9, SDSS J135540.57+250910.9, SDSS J135540.57+250911.0, SDSS J135545.08+251211.2, SDSS J135545.09+251211.2, SDSS J135546.33+250906.8, SDSS J135546.34+250906.8, SDSS J135546.34+250906.9, USGC U579 NED01, USGC U579 NED02, USGC U579 NED04, USGC U579 NED05, UZC J135512.5+250118, UZC J135513.3+250306, UZC J135540.6+250911, UZC J135546.4+250907, UZC-CG 205 NED01, UZC-CG 205 NED03, UZC-CG 205 NED04, WBL 477, WBL 477-002, WBL 477-003, WBL 477-004, WBL 477-007, WBL 477-008, WBL 477-009, [CBW93] J13 A, [CBW93] J13 B, [CBW93] J13 D, [DZ2015] 684-01, [DZ2015] 684-02, [DZ2015] 684-03, [DZ2015] 686-01, [DZ2015] 686-03, [PJY2015] 587739809948041324 , [PJY2015] 587739827662290959 , [SUV2010] 717, [TTL2012] 157115, [TTL2012] 164212, [TTL2012] 164219, [TTL2012] 164222, [TTL2012] 182719, [TTL2012] 182749,