The XP4 is based on the original Sky Commander DSC design but with the following important hardware upgrades:

At this time the XP4 Boot-Flash Utility is available for download. With it you will be able to upgrade to the most recent version (5.02 SP05). With this version you will be able to select from a number of astronomical catalogs.

Abell_Planetary_Neb*- A list (82 objects) of old and ancient plantetary nebulae research by a well known astronomer, George Abell. As these planetaries are ancient, they provide a nice challenge as most are extended and of low surface brightness.

Arp_Galaxies- A list of 338 galaxies showing different aspects of peculairity studied by Halton Arp.

Bayer_Stars- About 1500 stars cataloged by Greek letter and constellation.

Double_Stars- A collection of 600 fine double stars provided with permision from the Saguaro Astonomy Club.

Hickson*- A list of small compact galaxy groups, which presents a challenge for the observer. This list, 100 groups, was compiled by a Canadian professional astronomer, Paul Hickson, for research on discordant redshifts.

Messier- The famous catalog of Charles Messier. 110 bright deep sky objects.

Named_Deep_Sky- 135 deep sky objects by common name.

Named_Stars- 142 stars by common name.

NGC- Entire NGC catalog, about 7800 deep sky objects.

Herschel 400- The 400 most impressive deep sky objects in William Herschel's catalog of over 2500. Cataloged by NGC number.

IC- Index Catalog of 5250 deepsky objects.

Barnard- 159 Dark Nebula

Berkley- 86 Open Clusters

Collinder- 71 Open Clusters

Trumpler- 34 Open Clusters

* Well written Observing Guides for the Hickson and Abell Planetary Nebulae, including finder charts, sketch and observing notes are available at The Arp Observer's Guide is due for release in mid-2007.