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Observations of the Local Group of Galaxies

FORNAX DWARF

Andrew Murrell observing from Australia using a 20" ƒ/5.

The Fornax dwarf is a very good challenge object for any observer. For the novice wanting to develop their skills the trick is to see the galaxy, and for the experienced observer is to track down its collection of globular clusters.

I was able to locate the galaxy through my 20" scope (Hector) at 100x. It appeared as a faint glow just above the sky background covering an area of more than 50'. A 9th magnitude star almost marks the middle of the galaxy. This star is missing for the Megastar database. There were many 13th magnitude and fainter stars scattered throughout the field. The finder on Hector is a 90mm f5.6 and I believed that I could see the galaxy through the small instrument. One of my observing companions had a Televue Traveler scope with him and we tracked the galaxy down with this RFT. It was visible as a faint haze about the 9th magnitude star.

The view through hector immediately showed 3 globular clusters without any trouble. Using the Megastar charts and a series of photos taken from the ESO plates I started to look for the globulars. Using the listings in Megastar:

  1. Has a very low surface brightness and was the most challenging of the 5 main clusters. The cluster had a diameter of about 1' and had no central brightening. The low surface brightness made this a difficult cluster to locate without a chart. It was best viewed at 300x, where it could be seen easily with direct vision. This cluster lies to the NNW of the Fornax Dwarf

  2. Is a 1' haze of even surface brightness much brighter than cluster 1. It was easily visible and well defined against the background sky. The cluster was seen through a 12" scope with direct vision and could be seen with averted vision in a 10". A 15th magnitude star lies just off the SW edge of the cluster. Cluster 2 lies to the SW of the dwarf.

  3. Appears as a 40" patch with a bright almost stellar nucleus. The main body of the cluster has an even surface brightness. This is NGC1049 the brightest of the clusters associated with the Fornax galaxy. The cluster was well detached from the background sky. It was best viewed at 300x where it even looked like a faint globular when viewed through a small telescope.

  4. Lies just a few arc minutes SW of the 9th magnitude star. This cluster appears very similar to NGC1049 in appearance with the bright nucleus surrounded by an even surface brightness halo. This cluster is fainter than NGC1049. It also has a 15th magnitude star just of the northern edge of the cluster.

  5. Appears as the smallest of the clusters at an apparent diameter of just 30". It to appears like a smaller version of NGC 1049 with the nucleus and halo. This cluster is located away from the main body of the galaxy toward the Northeast.

Megastar does not show the next object that I observed but it has been catalogued by Paul Hodge using the prefix C. This cluster was the most challenging of the clusters originally marked as being members of the galaxy. It appeared as a 30" patch of sky just visible with averted vision at 300x. Using about 400x I was able to see the cluster periodically with direct vision. This object lies to the Northwest of the 9th magnitude star.

The following evening I was able to re-observe the galaxy and look for some of the MAC clusters that have been included in the Megastar database:

  • MAC 0240-3437 - visible as a very small (15") very faint haze. I found the object with averted vision first at 160x but was able to hold it with direct at 300x. The cluster was to faint to see any detail. I was able to locate the exact position of the cluster using a copy of the ESO plate.

  • MAC 0240-3418 - a possible observation only as I observed it on the last nights observing. It was only visible using averted vision at 300x and was lost completely at 700x. The cluster was extremely faint and small. None of the other clusters were visible at this time.