The Fornax Globulars and M31 Globulars

[Preston Pendergraft]

I am sure most of you have seen the new article posted on CN about the Fornax Dwarf and its globular clusters. I had not heard of these globulars so I read the article with great interest.

One of the statements of the article that caught my eye was the comment that the Fornax globulars would be a good starting place for pratice before going after the globulars around M31, since they are brighter then G1.

I was wondering if anyone can give any commentary or insights about that.

I have observed G1 that orbits M31 last year, but being new to these globulars outside of the galaxy I probably didn't use enough power since I only used about 150X with my 10in SCT since the seeing was just okay. I could at times split the two stars from G1, but it took a little averted vision and could not be held steady. I did see G1 much better in a 18in nearby though!

[Clear Skies]

Below the horizon here, but high on the list for my next southern astrotrip.

Judging by the brightness of the objects on the blue DSS images I'd say four out of six (the article mentions five, but there is a Hodge 6) are bright enough for a 12" scope: Hodge 2, 3 (=NGC1049), 4 and 5. I expect all of them to, visually, be as bright as Mayall II in Andromeda, if not brighter. Hodge 1 & 6 are very faint and would require a much larger aperature.

[Marko]

Here are my observations of 2,3,4,5 and a very hard try to see 6 where I decided it would not claim it as it was just not sure enough.
These observations were in my 18" f/3.7dob with seeing 4/5 and trans 3/5 and SQM 21.4 (not an ideal sky for this sight called Willow Springs that can get 21.7 at the best nights.
As a side note my M31 glob count is 11 at this time with the same scope on a great night near zenith and I hope to continue that quest when it gets real high after summer.


con: For cmt: FornaxDwarfAndGlobs: fav: D3
ESO 356-4 MCG -6-7-1 PGC 10074 PGC 010093
Glxy 9.3 17.0x12.6' 60 dE0 NED 02 39 59.3 -34 26 57
1:00am 13mmNag 150x Estimate size at about 18' with extremely non-distinct edge and only a glow that fades to background at the limits. A large 'L' pattern is apparent made of about 6 stars with the top of the L being in the dwarf so a nice place to be our 'starting point' The Tall part of the L drops NW then cuts SW to hit tier 2 field star outside of fornax galaxy glow. The 16mm does not show the galaxy extent as well as the higher mag due to contrast.

Fornax 4
Glob 13.6 0.8' 18.6 21.3 --- --- BAA 02 40 07.7 -34 32 10
1:15am 7mmNag 278x 1/40fov [30"] size and appears as slight dim glow 1/4fov up and to right [7' E] of the bright FStar near middle of this dwarf. Also seen in 16mm Nag.

NGC 1049 Fornax 3
Glob 12.6 0.8' 18.4 21.3 --- --- BAA 02 39 48.0 -34 15 24
1:15am 7mmNag 278x 1/40fov [30"] Shows well, brighter than Fornax 4. 16mm shows this as not to be a star.

Fornax 2
Glob 13.5 0.8' 19.0 21.3 --- --- BAA 02 38 44.0 -34 48 36
1:20am 7mmNag 278x 1/30fov [40"] 100% with averted. Dimmer than 1049 and Fornax 4. Does not appear to be stellar concentrated core.

Fornax 5
Glob 13.4 1.7' 18.6 21.3 --- --- BAA 02 42 21.0 -34 06 12
1:30am 7mmNag 278x 1/40fov [30"] Seems perhaps stellar concentrated core. May be second easiest to spot or a tie with Fornax 4. Located well away from center of galaxy.

Fornax 6
Glob 0.6' --- --- --- --- BAA 02 40 06.8 -34 25 14
1:40am 7mmNag 278x Not a definite sighting. I don't think I will claim it. I 'thought' I detected it at times but it was fairly uncertain.

Also back to your question on M31 globs I would question how much time you want to put into M31 globs in a 10" but if you try be sure you collimation is spot on and seeing/transparency are amazing. They were mighty dim in 18" (except G1) and I had them very high and a very very good night with great seeing.

[Preston Pendergraft]

Victor,
I will get a look at those DSS plates one of these days to get an idea of what I would be looking for. Thanks for the response.

Mark,
Glad to hear someone has observed the globular clusters from both galaxies. I figured a few posters on this board had observed them. I think with the 10in SCT G1 is probably going to be the limit with M31 under the skies I observe under. I know that M33 has some globular clusters that are viewable, but I would assume those are for larger scopes then my 10in. So when I heard that this galaxy had some globular clusters viewable I was pretty excited since I had not heard of these globular clusters. It is hard observing globular clusters in the summer months here in the Deep South since we get pretty strong haziness and lots of rain in those months. I am optimistic that I will be able to finish the globular cluster pin this summer since I have 17 observed, I figure if I can get three good nights I might be able to close the gap on the 50 observations that are required for the pin. These globular clusters in the Fornax dwarf could really help since they would be best viewable after the summer months. Also doing the globular cluster pin, I am trying to do globular clusters I have not observed before.

[Marko]

Hello Preston,
I re-observed G1 for the AL Globular cluster pin award last year. The interesting thing about G1 is that is is deceptively far from the core of M31 in terms of apparent displacement, so much so that it was off my detailed charts I found. I actually started looking at M31 globs before I realized everyone looks for G1 first so I went back LATER to see it for the AL glob pin. G1 is a bit of an 'orphan' I used a set of charts that I had found that locates the globs and really had a great time on one night a day after our California centric 'CalStar' finished and it was a very fun project for that one night. I only did one of the charts so far. So besides the 10 globs from the southern regions of M31 I also logged A67, C205, C203 and C202 which are clusters and an association in that area. I missed getting back to it last year but mean to catch 10 more globs that are within 18" limits this next year for a total of 21 M31 centric globs. As I understand it G76 may also be within the grasp of a 10" but I am not certain.

As far as M33 I have at this time observed Ngc 604 (the most noted one), Ic143, A71, IC142, Ngc595, 592, 588 (also of common note), A127 (Ic136) I have at least 16 objects in M33 that are within 18" grasp to go for some later date.

I find it fun to look for objects on closeby other galaxies and when I had the chance to 'cruse' the LMC and SMC I was 'out of control' in tracking down numerous object. I so wish we had the LMC up here. The SMC (IMHO) is rather boring (except for closeby NGC104 and 362 of course) but the LMC is amazing and loaded with extra-galactic objects of detailed nature since it is so close. I certainly will go back but when is uncertain at this point. I would like to go back next time when LMC is very high as I went in March for my only observing session to date for 'down south'.

Also don't forget Barnards Galaxy (NGC6822) which is also low like Fornax dwarf and is now 'in season' but has a few H2 regions of note in it's northern region that are worth tracking down. Two of those regions on it's north end I suspect may be available in 10" on nights of great transparency in low altitudes (only just). I suspect mgc-2-50-2 and mgc-2-50-3 are likely too dim as I only just was able to detect them on a great night in the 18" using NPB filter and fairly high power. (Same night as I did the Fornax dwarf actually).

[Dave Tosteson]

Preston, A good resource is Hodge's Atlas of the Andromeda Galaxy, available online through Caltech. It lists over 300 globulars. Also the literature has many articles about globulars in M31. David Higgins wrote an excellent piece in the Autumn 1990 Deep Sky and Cramptom, et al has a nice, if older article in ApJ 288, p. 494, Jan 15, 1985, discussing over 400 globulars. Several should be accessible to a 10", and if you had access to an 18-20" instrument, many dozens would be visible.

Dave Tosteson

[Preston Pendergraft]

Preston, A good resource is Hodge's Atlas of the Andromeda Galaxy, available online through Caltech. It lists over 300 globulars. Also the literature has many articles about globulars in M31. David Higgins wrote an excellent piece in the Autumn 1990 Deep Sky and Cramptom, et al has a nice, if older article in ApJ 288, p. 494, Jan 15, 1985, discussing over 400 globulars. Several should be accessible to a 10", and if you had access to an 18-20" instrument, many dozens would be visible.

Dave Tosteson

Dave,

Thanks for the reply, I will see if I can find a copy of the article from Deep Sky and ApJ. I do see issues of Deep Sky magazine posted to astromart from time to time.