Virgo galaxies and Zwicky's Triplet - the other one

[Nyctimene]

Saturday morning, I was out with the 18" f/4.5 Obsession to get some more views of the Virgo galaxies and Markarian's Chain, before they will disappear in the brighter spring skies. Average conditions with NELM 5.7 (UMi), SQM-L 21.24, but very good seeing with pinpoint stars up to 250x mag. As usual, I started at the "entry -T"  (6 Com forming it's western end) and it's accompanying galaxies M98, 99, and 100. Down to M 84, M86 and the marvellous Chain - the most crowded group of brighter galaxies in the whole sky. M 87; followed by the "Siamese Twins" NGC  4567/4568; all of them "old friends" and wonderful sights at 85x mag and a TFoV of 1° (Maxvision 24mmf/82° eyepiece). SkySafari 6 Pro showed another fainter gx, 4528 (11,9 mag) 36' to the west. Observing it and comparing it to the star field around, SkySafari suddenly indicated "Zwicky's Triplet" 18' to the west. I was somewhat puzzled, as I had another location of this galaxy triplet in mind (checked it - in northern Hercules).  At 200-250x (Baader Hyperion zoom) I was able to make out the brightest member, IC 3481, 13.7 mag, rather easy with indirect vision, whereas the fainter IC 4381 A was invisible, as was the faintest, 3483 (14.4 mag), partly due to it's proximity to the 10 mag star BD +12 2486 only 45 arc sec N.The galaxy triple is also listed as "Arp 175", in contrast to the Zwicky triple in Hercules (Arp 103).  - I finished with the Coma Berenices galaxies 4494, 4565 (with the central dust line) and 4559 with three superimposed stars.

This morning, 01.30 CEST, I repeated the observation of the Triplet in Virgo, under worsened conditions (NELM 5.0). Again, 3481 was visible with averted vision with ease, for about 20-30% of observing time even directly. Sometimes I got the impression of a tiny stellar core region. 3481 A showed for seconds with AV. The toughest one remained 3483. Using all the DSO observer's tricks, as telescope tapping, breathing deeply, resting eyes for a few minutes etc., in about 30 min I got just three or four moments to glimpse it, using a 10 mmf Ortho giving 205x - but it was still too close to "averted imagination", so I don't count it as observed. Under slightly better skies, I'm sure, it will be doable. The close by galaxies 4528 and 4503 compensated, as did the bright edge-on gx 5746 close to 109 Vir.

As it seems, there are two "Zwicky triplets"(or divergent nominations). I observed the Hercules one years ago (cannot recall it exactly atm); the second one was new to me. I'll have to do some more research in the SIMBAD database.

Attached a picture, found in this excellent compilation: https://cseligman.com/text/atlas/ic34a.htm#ic3481

 

Thanks for reading

Stephan

[Martin Meredith]

Thanks for this very interesting report Stephan and I admire your patience. The image is intriguing and its got me thinking of trying to catch the plume/counter-tail next time I'm out (with my camera though, cheating!)

Martin

[niallk]

Great write up - nice report  i had that Zwicky triplet on my target list last week, but never tried due to poor transparency from the onset of thin fog - went for brighter objects.