LH 25 + N23

A lovely association and a large, extremely faint SNR

Image credit Robert Gendler

RA 05 06 05 Dec: -68 05 54

Diameter: 3′

OB Associations: LH 25

Henize: N23, 23A

NGC Objects: NGC 1829

LH 25 is a beautifully obvious association, but the large SNR, N23, appears to be the realm for large telescopes, dark skies and superb transparency.

SNR N23: RA 05 05 55.0 Dec -68 01 54 Size 1.6′ x 1.5′ Age 11,000 ± 4,000 years

N23A = NGC 1829: RA 05 04 57.4 Dec -68 03 20 Mag 12.1 Size –

16″ at 228x: LH 25 is a pretty, little association with six mag 13 stars arranged in a small, crooked arc to the north of mag 12 SK -68°45, with a couple of tiny patches of hazy unresolved stars – one directly north of the star, the other to the east.

The only visible debris of the star that died is its southeastern rim, N23. Alas, although relatively large, N23’s nebulosity wasn’t visible in my scope either with or without a filter. I wonder if observers with big Dobs can see it? However, N23A = NGC 1829 is prominent at 228x without a filter. It appears fairly bright, irregularly round, ~1.0′ in diameter. Four stars (a mag 13.5 star, two mag 14 stars and a mag 15 star) are resolved in the soft nebulous glow. The edges of the glow are fairly well defined and fade rapidly into the surrounding sky. It has a good response to the UHC filter – round, somewhat brighter to the east, and with edges that fade very rapidly. Lovely bright mag 7.9 HD 33486 shines like a stellar beacon 1.8′ SE. HS 114, close to the site of the supernova, appears as a faint, round glow, ~20″ in diameter.