Lacerta (The Lizard) & BL Lacertae Guide
Lacerta IAU constellation (201 sq deg, rank 68): October northern Milky Way zigzag between Cygnus and Cassiopeia, led by +3.77 Alpha Lacertae and BL Lac.
Sky Navigation & Astrophysical Context
Sandwiched into a 201-square-degree corridor between the Swan of Cygnus, the Great Square of Pegasus, Andromeda, and Cassiopeia, Lacerta was introduced in 1687 by the Polish astronomer Johannes Hevelius under the dual name 'Lacerta sive Stellio' (the Lizard or Newt). Its six brightest fourth-magnitude stars—led by the A1 V main-sequence star Alpha Lacertae (+3.77) and the K4 III giant 1 Lacertae (+4.14)—trace a miniature W- or lightning-bolt zigzag that earned Lacerta the nickname 'Little Cassiopeia.'
Because the northern half of Lacerta dips into the rich star clouds of the Cygnus-Cassiopeia Milky Way, sweeping the zigzag with binoculars reveals the scattered open clusters NGC 7243 (Caldwell 16, spanning 21 arcminutes near Alpha Lacertae) and NGC 7209, as well as the Lacerta OB1 stellar association, one of the nearest young OB associations to the Sun.
In high-energy astrophysics, Lacerta is immortalized by BL Lacertae: originally cataloged in 1929 by Cuno Hoffmeister as an irregular variable star in our own galaxy because of its rapid optical flickering and featureless continuum spectrum, BL Lacertae was proven at Palomar Observatory in 1968–1974 to be an active supermassive black hole (blazar) inside a giant elliptical galaxy at redshift z = 0.0686, with a relativistic jet pointed directly down Earth's line of sight.
Equatorial Center Position & Transit Altitude
Lacerta is centered near Right Ascension 22h 27m 36s, Declination +46° 02′ 24″ (The Lizard).
Practical Star-Hopping & Observing Tips
- Look midway between Deneb (in Cygnus) and the W of Cassiopeia to trace the 6°-long fourth-magnitude zigzag of Alpha, Beta, 4, 5, 2, and 6 Lacertae.
- Sweep 2.5° west of Alpha Lacertae with binoculars or a rich-field telescope to resolve the elongated star chains of open cluster NGC 7243 (Caldwell 16).
- In a 100 mm telescope, split the multi-star group 8 Lacertae (four B-type stars between magnitudes +5.7 and +6.5 packed within 82 arcseconds).
Notable Celestial Objects in & Near Lacerta
| Object | Family | Classification | RA (J2000) | Dec (J2000) | Min. Instrument |
|---|---|---|---|---|---|
| Andromeda Galaxy (Messier 31 / NGC 224) | galaxies | Barred spiral galaxy (Local Group largest spiral) | 00h 42m 44.33s | +41° 16′ 07.5″ | Naked eye; best framed in 10×50 binoculars and wide-field telescopes |
| Delta Cephei (Cepheid Distance Ladder Anchor) | variable-stars | Prototype Classical Cepheid pulsating supergiant variable | 22h 29m 10.27s | +58° 24′ 54.7″ | Naked eye for variable light curve; 50 mm telescope for 41″ companion |
Scientific Sources Cited
- IAU Official Constellation Boundaries & Designations (IAU 88 Recognized Constellations): Delporte, E. 1930, Délimitation scientifique des constellations (IAU / Cambridge University Press) — International Astronomical Union (IAU)
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg