Best Abell Planetaries: Winter

Observing Notes by Steve Gottlieb

Abell 02 in Cassiopeia

17.5: faint but visible without filter at 105x, estimate V = 14.0-14.3. Can hold with direct vision using an OIII filter. Appears as a fairly small, round, nice disc at 220x and UHC filter. Located 5.0' S of mag 8.4 SAO 21680. Two mag 10 stars are about 2' E and SE of this star.
13: at 79x and OIII filter appears very faint and can just hold steadily with averted vision, small, round. Located 5' S of a mag 8.5 star with two mag 9.5 stars near.

Abell 04 in Perseus

17.5: at 105x and OIII filter appears faint, small, round. Can hold steadily with averted vision, estimate V = 14.5-14.7. Nice view at 220x and UHC filter although visible without filter at this power. Smaller than most Abell planetaries. Located 40' ESE of M34.

Abell 10 in Orion

17.5: Easily picked up at 100x using an OIII filter as a fairly faint, round disc. There was a better view at 220x and a UHC filter with the 25"-30" disc having a crisp edge. No annularity or interior stars were visible. Also viewed unfiltered as a weak, round glow although filters provided a significant contrast gain. A mag 13.5 star lies 0.9' SSE of center. The PN is situated between two mag 12 stars oriented SW-NE [3.5' separation] and is 5' WSW of an unequal double [mag 10/13 at 11"].

Abell 12 in Orion

17.5: at 220x and UHC filter; moderately bright, round, moderately large. Difficult to view as overpowered by glow of mag 4.1 Mu Orionis 1.2' WNW! Easier at 294x which cleanly separates the pair, estimate V = 12. Takes 412x which puts more room between Mu and Abell 12.

Abell 20 in Canis Minor

17.5" (1/12/02): at 100x with an OIII filter this moderately large planetary appeared very faint, round, evenly lit, crisp-edged. With concentration I could almost hold it continuously. The magnitude must be fainter than Jack Marling's computed V = 14.0 (Owen Brazell gives V = 14.7). A mag 10 star lies 3.2' WSW.
13" (12/7/85): extremely faint at 79x and OIII filter, fairly small, round. Difficult to view and cannot hold steadily with averted, estimate V = 14.5-15. Located 3.3' ENE of a mag 10.5 star.

Abell 21 in Gemini

17.5: at 100x and OIII filter the "Medusa Nebula" appears moderately bright, very large with a distinctive thick "horseshoe" shape open to the W. The S and SW portion of the rim are brighter and the rim is incomplete on the W and NW side. A brighter star is embedded in the NE portion of the rim.
13: 79x with UHC filter; moderately bright, very large, thick partial annulus, incomplete on NW side, brightest on W and SW edge. Without filter this huge planetary appears faint, diffuse.
16x80:just visible with OIII filter!