Felix does Fornax

by Jamie Dillon

Scotty Houston has enticing notes about this cluster in Deepsky Wonders, p 21 on. At one point he wrote,

But even so, a clear sky will show so many galaxies fainter than the 13th magnitude limit that identifications are almost impossible, and amateurs must satisfy themselves with the spectacle of unnamed wonders.

So having spent a chunk of the fall poring over the Perseus Cluster, Abell 426, this winter I've been hours playing around the Fornax Cluster. Interestingly, I started the exploration atypically, not being analytical with chart in hand, but working with the spectacle of unnamed wonders.

4 January

Dipped into the Fornax cluster for the first time at Mt Palomar, visiting and mooching views in Nilesh Shah's 12.5 Dobs, Papa Joe, made by Paul LeFevre. Fornax was way the hell up in the sky from those latitudes. First time I'd ever dipped into a galaxy cluster with no concern for who was who. No idea at this point what fancy galaxies we were seeing. There was one rectangle of galaxies, about a half degree across. Down to the SW about a degree, two more vertically stacked, then just down SW a bit more a fat bright number with a very bright core. It was fun picking out unknown galaxies like strange women on the beach.

9 January - homework:

Disclaimers aside, I had sketched that set of 7 galaxies and took note of relative positions as well as some sense of PA's. Sure enough, the set popped out of the finderchart for the Fornax Cluster in Luginbuhl and Skiff. NGC 1387, 1389, 1399 and 1404 form the rectangle. The smaller pair to the SW are 1386 and 1369. The fat bright number is 1365, a !! in the NGC and regarded in my books as a likely foreground object to the Cluster. A fine galaxy. The whole Fornax Cluster is some 40 mly away, probably somewhat closer than the main Virgo Cluster.

On 1365

Had this hunch somehow that 1365 was part of the cluster. Luginbuhl and Skiff mention that it was thought to be a foreground object to the Fornax Cluster. The new SkyAtlas Catalog and TNSOG cite the same info, though distance given in SAC for various identified members of the cluster vary widely. So I checked into NED, and there a whole set of citations up to 1999 discuss 1365 as a member of the Fornax Cluster. Sure enough, with help from Skiff himself, found that 1365 has been involved (without written consent) in the HST Key Project, using Cepheids, and is around 18.5 Mpc away, or some 58 mly. Repeatedly referred to in recent papers as a member of the Fornax Cluster. So correct your copies of SkyAtlas Catalog, TNSOG, and L&S.

TNSOG shows a cool sketch of 1365, showing big long arms and a bar, raves about the view in a 16-18" scope. It's a Seyfert galaxy, has several big OB associations in it (for bigger scopes than ours) and hosted a supernova in 1957. Must be an exciting place for astronomers to live!

12 January at Fremont Peak

(now with my own scope. Felix is a Celestron 11" f/4.5 Dobs with a primary made by Discovery. Was using a 22 Pan, 16mm UO Koenig, 10mm and 6mm Radians.)

Started right into Fornax. Landed right on a field with 8 galaxies in the 22, in a 1.2 deg field. Used the same rectangle of galaxies from before to orient: 1399, 1404, 1389 and 1387. 1399 stood out, bright, big, with lenticular shape and even brightness. 1380, off to the North, kept pulling me back, a pretty spiral with clear arms and a bright core. And 1365 toward the SW is remarkable. I have no idea how much time I spent in that field of 3 square degrees that Saturday night, couple of hours easy. Limiting magnitude that night was averaging 6.4. Seeing was at 5/5, excellent.

Sidenote on 1374: It is diffuse. That was my one-word description in my own notes. There are 3 galaxies stacked up on that spot, one of which I caught Saturday night. At least one more should show in Felix; all 3 were in Jim Everitt's 15. 1374 itself gets a surface brightness of 12.6 in Luginbuhl and Skiff, which sounded about right.

02/02/02 (cool date), in Pacheco Pass, 3rd Q

I was driven at dark, wanting to find more of the Fornax Cluster before it got too close to the hills. Did split 1374 from its close neighbors, 1373 and 1375. Also ran down 1382, a dim little thing in the middle of the cluster. 1365, the big guy in the main cluster, showed dark arcs across its arms. At one point I was working at 126x with the 10mm Radian, and found myself hypnotized, scanning from galaxy to galaxy, not really caring where I was. What a field!

This night limiting mag was around 6.2, doing the Finnish star count in Perseus. Seeing during the time I was exploring in Fornax was 4/5, good.

Made it the short way SW to 1316, Fornax A, the big radio galaxy, which showed a very bright core and oval-shaped arms. Has a close companion, 1317. 1326, just over a degree to North, was bright, but 1341 to the east was difficult. 1310 is on SkyAtlas just to E of 1316, and I could only find it by innuendo. Albert Highe looked in Felix, then in his 12.5, and thought he saw a dim splotch a few seconds south of where I thought the thing was. Hmmm, work for another night, like at Cone Peak. The thing is omitted in L&S and in Burnham's. Just the kind of object to obsess over.

9 February at Dinosaur Point:

Seeing was 4/5, good, with transparency around 6.5. Found one more of the main cluster, 1427, moder bright core, some swirls in the body. Albert found 1310 first in his 12.5, where it was cruel, that sufficed. Again spent a lost chunk of time at 126x scanning the main cluster, re-split 1374 from -73 and -75. Gorgeous field.

This is meant to serve as a backpocket guide for the Fornax Cluster in moderate apertures, also as a paean to an amazing part of the sky.