From the March 2012 issue

Follow an urban deep-sky catalog

The Baker Street Irregular Astronomers astronomical society in London, England, shares its “Holmes Catalog.”
By | Published: March 26, 2012
The Hub in London’s Regent Park is the observing spot for the Baker Street Irregular Astronomers. Tom Kerss
Central London can be a challenging location, but from the Baker Street Irregular Astronomers’ superb vista point at The Hub in Regent’s Park, the group has been extremely successful to date in tracking down some elusive deep-sky objects. Our “Holmes Catalog” to date, although not definitive, shows how much deep-sky astronomy is possible from city centers. As a guide, we have found the requirements to be as follows:

• Excellent-quality telescopes and eyepieces with high image contrast (refractors have proven to be the most powerful tool here)
• The usual “tricks of the trade,” including averted vision and filters to eke out the best views of each target object
• Dark adaption (as best as possible in our location), scope equilibration with the ambient temperature, and user comfort for extended “hunting” time eyepiece
• Holmsian-like doggedness and determination to get a result

The catalog so far
Object Type Constellation Magnitude
M3 Globular cluster Canes Venatici  6.3
M4 Globular cluster Scorpius  5.4
Butterfly Cluster (M6) Open cluster Scorpius  4.2
Ptolemy’s Cluster (M7) Open cluster Scorpius  3.3
Wild Duck Cluster (M11) Open cluster Scutum 5.8
Hercules Cluster (M13) Globular cluster Hercules 5.8
M15 Globular cluster Pegasus 6.3
M22 Globular cluster Sagittarius 5.2
Dumbbell Nebula (M27) Planetary nebula      Vulpecula 7.3
Andromeda Galaxy (M31)     Galaxy Andromeda 3.4
M32 Galaxy Andromeda 8.2
M35 Open cluster Gemini 5.1
M36 Open cluster Auriga 6.0
M37 Open cluster Auriga 5.6
Orion Nebula (M42)      Nebula Orion 3.7
M43 Nebula Orion 6.8
Beehive Cluster (M44)           Open cluster Cancer 3.1
Pleiades (M45) Open cluster Taurus 1.5
Whirlpool Galaxy (M51) Galaxy Canes Venatici 8.4
Ring Nebula (M57) Planetary nebula Lyra 8.8
M65 Galaxy Leo 8.8
M66 Galaxy Leo 9.0
Bode’s Galaxy (M81) Galaxy Ursa Major 6.9
Cigar Galaxy (M82) Galaxy Ursa Major 8.4
Owl Nebula (M97) Planetary nebula Ursa Major 9.6
M101 Galaxy Ursa Major 7.9
Sombrero Galaxy (M104) Galaxy Virgo 8.0
NGC 205 Galaxy Andromeda 8.0
NGC 3628 Galaxy Leo 9.5
Blinking Planetary (NGC 6826)   Planetary nebula Cygnus 8.8
Blue Snowball (NGC 7662) Planetary nebula Andromeda 8.3
Witch’s Broom (NGC 6960) Nebula Cygnus
Veil Nebula (NGC 6992/5) Nebula Cygnus
Targets for future meetings
Crab Nebula (M1) Supernova remnant Taurus 8.0
Lagoon Nebula (M8) Nebula Sagittarius 6.0
Trifid Nebula (M20) Nebula Sagittarius 9.0
(London’s very light summer evenings and the low elevation make such targets difficult at best)