Southern Arp

Introduction & Overview to the Southern Arp

Galactic evolution may include interaction and disturbances between and among galaxies. The changes occurring are in slow motion by our time standards so when we view galaxies, we are witnessing a mere snapshot of the evolutionary process. Halton Arp documented 338 peculiar galaxies in his article Atlas of Peculiar Galaxies1 in 1966 and more recently Kanipe & Webb2 published a book with many images of peculiar galaxies.

Twenty years later Halton Arp and Barry Madore published a catalogue of southern peculiar galaxies3. This was done for several reasons: to document a larger sample of peculiar galaxies to investigate the nature of their redshifts and “to survey systematically the rich forms found among galaxies, from which new insights and, at the very least, a close familiarity would arise.”3

Purpose & Significance of the Southern Arp

The purpose of this program is to provide an auxiliary and unique challenge for visual and imaging observers of the Arp Peculiar galaxies. It complements and extends the existing Arp Peculiar Galaxy Program (Northern Arp) of the Astronomical League by providing additional peculiar Arp galaxies in the Southern celestial hemisphere. The objective is to provide additional observing material for any observer in the Northern or Southern hemisphere. This new addition is based on 498 objects selected from the catalogue published by Arp et al.3,4. The galaxies selected are brighter than 15th magnitude, with many of them falling within the range of moderately-sized amateur telescopes under dark, transparent skies.


  • Observers from either the Northern or Southern hemisphere will be required to observe any 100 of the Southern Arp galaxies. There are 122 galaxies higher than -30o declination.
  • Observations will be telescopic and can be recorded either visually (V) or electronically/photographically (E).
  • The galaxies can be located manually (M) or with digital setting circles (D; this includes GOTO capabilities).
  • For Visual observations, log sheets should contain:
  • Date and time.
  • Latitude and Longitude of observation.
  • Sky conditions: transparency, and seeing.
  • Telescope aperture and focal length.
  • Whether the object was found manually, with digital setting circles or a GOTO telescope.
  • Magnification
  • The Arp-Madore (AM) catalogue number of the Southern Arp galaxy observed.
  • Observing details and descriptions.
  • Photographic or digital imaging observations:
    • If multiple galaxies are in the field, the Southern Arp galaxy should be indicated clearly.
    • Field of view.
    • In addition, log sheets should contain:
    • Type of camera used.

Rules for Completing Program:

  • The log sheets with visual observations or electronic files containing digital images (which should be submitted on a CD-ROM) should be sent to the program administrator. The observations will be verified by the program coordinator. Separate awards will be issued for Visual and Imaging and observers are encouraged to apply for both!
  • Eligibility for the Award:  AL members in good standing only.
  • Appendices:
    • Appendix A: a list of Southern Arp galaxies by constellation (Spreadsheet) (PDF)
    • Appendix B:  a list of Southern Arp galaxies by Declination (Spreadsheet) (PDF)
    • Appendix C: a list of Southern Arp galaxies by Arp-Madore# (Spreadsheet)(PDF)


1Atlas of Peculiar Galaxies, Arp, H. Astrophysical Journal Supplement 14: 1-20, 1966

2The Arp Atlas of Peculiar Galaxies – A Chronicle and Observer’s Guide, Kanipe, J. and Webb, J. Willmann-Bell Publishers, 2007.

3A Catalogue of Southern Peculiar Galaxies and Associations, Arp, H. C. and Madore,  B.F., Vol. 1, Positions & Descriptions, Cambridge University Press, 1987.

4 A Catalogue of Southern Peculiar Galaxies and Associations, Arp, H. C., Madore, B.F. and Roberton, W.E., Vol. 2, Selected Photographs, Cambridge University Press, 1987.


Members of the Delaware Valley Amateur Astronomers: John Bajtelsmit, Mark Huss, Vince Scheetz of who assisted in the development of this program and     Frank Colosimo who imaged the galaxy used on the certificate. A special thanks to Barry Madore who advised how to navigate the NASA Extragalactic Database (which he helped develop) to retrieve the parameters of the Southern Arp galaxies needed.


Al Lamperti
505 Ramsey Road, Oreland, PA 19075