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Final drawing:

IC 4499

IC 4499

Drawing data

IC 4499 Aps GC
Date(s) of observation:
2016.05.01/02. Hakos
2016.05.02/03. Hakos
Place(s) of observation:
Hakos Astrofarm, Namibia, 1835m amsl
Telescope(s) used:
4" f/4 Newtonian (Dobson)
Enlargement(s) used:
67x (6mm Planetary)
Field size:
Author / Observer:
Peter Kiss


IC 4499 drawing inverted into positive.
IC 4499 drawing inverted into positive. Peter Kiss

The 16" Dobson was not mine on the first many nights of our Namibian trip so I needed more targets for my little 4" telescope. I had already selected the globular cluster IC 4499 in the constellation Apus (Bird of Paradise) at home. Not because the object itself seemed to be so interesting but because I liked the name of the constellation and the name of the cluster. Both feel a little exotic to me. Its position on the sky is interesting as well: it can be found less than 8° from the Southern celestial pole. This makes it easy to observe all night from Hakos.

The object itself is rather obscure in the small telescope. It is a faint diffuse globular cluster showing no resolution. Two barely visible inhomogenities (brighter spots) can be discerned to the West and North of the core. It gets very slightly brighter towards the core. The central region is barely more prominent than the outer regions. A 12.3m star is visible in front of it. This is a foregroung star based on Gaia DR2 data (parallax). It is interesting that the star is offset from the center based on the photos though I observed it right in the middle. If I am right this is a trick of the eye and the brain. A desire for symmerty. These are two faint and therefore uncertain objects which might be needed for the trick. This is one of the possibly many artifacts that make visual observation more difficult. The brighter (10.3m) star next to the cluster makes the object more interesting.

From an astrophysical point of view IC 4499 is interesting because it was thought to be one of the youngest globular clusters of our Milky Way. More recent results suggest that its age doesn't differ so much from the rest of our globulars. Also, IC 4499 contains one of the greatest number of RR Lyrae variables. It belongs to the Oosterhoff I class - its RR Lyrae stars have a mean period around 0.55 days.

IC 4499 photo made with the Hubble Space Telescope (HST).
IC 4499 photo made with the Hubble Space Telescope (HST). The orientation of the photo any my drawing are different but directions can easily be identified using the two bright stars. Note that dozens of background galaxies are visible among the stars of the cluster. Credit: ESA/Hubble & NASA, Source:

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