O'Meara

Hidden Treasures (The "X" List)

This is O'Meara's personal pride and joy, often considered the most "fun" of his lists.

O'Meara's compilation endeavors to showcase the "best and brightest" objects overlooked by Messier and Moore in their respective catalogues. This comprehensive list underwent over two dozen revisions across a decade, resulting in the inclusion of 109 distinct objects. These comprise 38 Open Star Clusters, 35 Galaxies, 14 Planetary Nebulae, 8 Globular Star Clusters, 8 Bright Nebulae, 1 Dark Nebula, 1 Star with a substantial proper motion, and 4 Asterisms. Each entry in the "Hidden Treasure" list is prefixed with the letter 'X,' symbolizing 'X marks the spot.'

The aspiration is for the "X" list to achieve comparable popularity to the renowned catalogs of Messier, Caldwell, and the Herschel 400. This is not only justified by its inclusion of many overlooked "best and bright" DSOs but also by the incorporation of some of the most exquisite celestial wonders, exemplifying the true "Art de Ciel."

The "Hidden Treasures" compilation comprises 109 Deep Space Objects (DSO) meticulously curated by the renowned astronomer Stephen James O'Meara. Diverging from the contents of the Messier or Caldwell catalogues, this list was specifically designed to address gaps identified in both catalogs.

• History & Creator: Published in 2007 by O'Meara himself. He spent ten years and dozens of revisions refining this list.

• The Purpose: To find the "gaps" between the Messier and Caldwell lists. These are objects that are often bright enough to have been in Messier's catalog but were simply overlooked. He prefixes these with an "X" (as in "X marks the spot").

• Objects Found: 109 total.

  • 38 Open Clusters

  • 35 Galaxies

  • 14 Planetary Nebulae

  • 8 Globular Clusters

  • 14 Other (Including a star with large proper motion and 4 asterisms).

• The Gear: He famously observed all of these using a relatively small 4-inch Tele Vue refractor from the dark skies of Hawaii.

The Secret Deep

As the series progressed, the targets became more challenging and exotic.

• • History & Creator: Published in 2011. This list was born from O'Meara's "Secret Sky" column in Astronomy magazine.

  • The Purpose: To highlight "exceptional" objects that aren't just pretty to look at but have a fascinating scientific story—like the flattest known galaxy or the brightest quasar.

  • Objects Found: 109 total.

  • These are a mix of galaxies, clusters, and nebulae, but they include "extreme" targets: the largest edge-on galaxy, a piece of the only supernova remnant visible to the naked eye, and even a companion star to a black hole candidate.

Southern Gems

Finally, O'Meara turned his eyes toward the southern horizon to help those "below the equator."

• History & Creator: Published in 2013. O'Meara traveled to places like New Zealand and Botswana to finalize these observations.

• The Purpose: To honor the work of James Dunlop, the "Messier of the South," who surveyed the southern skies in the 1820s.

• Objects Found: 120 total.

• This list is a rich mix of bright and dark nebulae, globular clusters like Omega Centauri, and galaxies that Northern observers rarely get to see.

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credit Stephen James O’Meara