Abell 21

Abell 21 (PK 205+14.1), Gem. February 3, 2021. Beaver Meadow [500 m a.s.l.]. 20" F/5. Clear, transp. 8/10, seeing > 4 arcsec, SQM 20.7 (snow). Not visible in 26 mm without a filter. Obvious with OIII. Crescent-shaped; extended overall NE-SW with enhanced ends, convex to the E. A star is embedded in the N part. A filament separates on the E side, running S to a star. In 13 mm with OIII, the SW end appears separated and has two extensions, to the W and E.

PANSTARRS g

Hickson 33

Elevation 550 m, telescope D = 0.5 m, F = 2.5 m. Sky 20.5 mag/sq arcsec, seeing > 4 arcsec. Hickson 33, galaxy group, Tau. February 3, 2021. Visible already in a 26 mm ocular as a mottled patch with some stars. In 5.5 mm, components A and B are readily seen, round, smoothly concentrated, with diffuse edges. Component D is a hazy companion of a star. C not visible. Unequal double star NE of D resolved, touching [Vm 16-17, 5" sep.].

Hickson 36

Elevation 550 m, telescope D = 508 mm, F = 2500 mm. Sky 20.8 mag/sq arcsec, seeing 4 arcsec. Hickson 36, galaxy group, Cnr. Component A (IC 528) is readily visible in a 13 mm ocular next to a bright star, elongated NNW-SSE. In 5.5 mm, component D is easily seen, elongated WNW-ESE. B and C are difficult but eventually can be seen simultaneously. The close companion of the star to the SW of the group and a similarly faint star to the NNW are seen [interpolated Vm 15.1, 15.2 by USNOA2].