Last wednesday night while observing galaxies near Centaurus A (
NGC 5128) I came upon a galaxy with a peculiar name on my Uranometria finder chart 184, the Fourcade -Figueroa galaxy (ESO 270-17) a few degrees from omega centauri (
NGC 5139). So, out of curiosity decided to see what was there, and after a few minutes star hopping, found the location, but I couldn't see anything, so went back over the star hop procedure and ended back in the same location and nothing. Upping the magnification didn't help, so gave up on it for the moment, and continued with my planned observing list for the night.
The next morning, reading up on it, I learned that this object plus
NGC 5237 could possibly be the remnants of a spiral galaxy that had a close encounter (galaxy shredding event) with Centaurus A some 500 million years ago.
NGC 5237, a dwarf elliptical galaxy, is believed to be the central core/ bulge which remained relatively unscathed, and ESO 270-17, the Fourcade- Figueroa shred is a remnant of the outer portions, possibly a spiral arm, which is shown to be a non rotating, starburst galaxy remnant. The rest of the galaxy can now be seen as the ring of dust, gas and stars encircling Centaurus A.
Here is an article with more information about this object.
https://sandandstars.co.za/2019/05/05/c ... roa-shred/
Last night Saturday 18th April, was supposed to be overcast so I was surprised when I looked out the window to see a perfectly clear sky. After setting up the 18 inch scope and letting it acclimatise, I started the search with a 12mm (167x) wide field eyepiece. I began with
NGC 5237. Starting at Centaurus A, I was able to quickly star hop to the field of this object and spotted it immediately , forming the apex of a triangle with two 7th magnitude stars. The object was visible with direct vision, and was a diffuse blob with a very slight brightening of the central area. The search went quickly only because I was in the same area wednesday night searching for other galaxies.
Next up was the Fourcade-Figueroa object. This one was very difficult. Transparency last night was very average, but I wanted to try for it before the moon starts interfering with
DSO observing over the next week. Starting at omega centauri, I quickly manoeuvred to the field I had acquainted myself with on the previous session and once again, saw nothing. I retraced the steps again, and still nothing. I was certain I was looking at the right area. Accessing the site I linked above on my phone (keeping my viewing eye covered so as to retain my dark adaption) , and carefully matching the star patterns, confirmed I was in the right area, so why couldn't I see it? Increasing the magnification ( 9mm
ep, 220x) and removing the
coma corrector, I was finally able to see a very, very faint streak of light with averted vision. Tapping the scope confirmed it's location. There is a star superimposed on the Shred, which makes the sighting even more difficult, but I definitely saw it and was able to return latter when it was at higher elevation and confirm it. This is one of the more difficult objects I've tracked down, hopefully on a better night I'll be able to see more , as some observers have claimed seeing it in a 10 inch scope, so seeing and better transparency might improve prospects. Even though last night was clear, humidity was near 100 percent and after 3 hours outside and constantly wiping the scope down, I called it a night as the damp and cold conditions were getting worse.
Seeing these two objects, in conjunction with Centaurus A, and knowing how they might be related, puts the observation in perspective, as the shred and
ngc 5237 are not exciting objects to view on their own, but associating them with what you are seeing at Centaurus A and understanding that the ring of material around it probably came from them in a distant event, is something to ponder.
Finder chart to help locate the objects for anyone interested-
Some specs for the objects
ESO 270-17 Fourcade-Figueroa shred. (PGC 47847)
Dist-approx 24 MLys
mag 11.4
size 11.5'x 1.4'
RA 13 34 47
Dec -45 32 51
NGC 5237 The core (ESO 270-22)
Dwarf elliptical Gx
Dist approx 9 MLys
mag 12.5 SB 13.6
size 1.9'x 1.6'
RA 13 37 38
Dec -42 50 51
NGC 5128 Centaurus A
Dist Approx 13 MLys
mag 6.8
size 25.7'x 20'
RA 13 25 27
Dec -43 01 09
Thanks for reading.