[TrevorW]

NGC4103 (Open cluster) The Longtail
From Perth, NGC4103 is visible all night. It will become visible around 19:05 (AWST), 39° above your south-eastern horizon, as dusk fades to darkness. It will be lost to dawn twilight around 05:30, 27° above your south-western horizon. NGC 4103 has been studied photometrically. for 512 stars brighter than V = 17m magnitudes and colours are given.
It was discovered by James Dunlop in 1826. It is located approximately 5,000 light years away from Earth, in the Carina-Sagittarius arm

Other names
Cr 252[3]
Mel 109[4]
Position
Constellation: Crux
Magnitude: 7.40 (V) [4]
Right ascension: 12h06m [2]
Declination: -61°15' [2]
Distance: 1.6 kpc
5.3 klyr [1]
Derived quantities
Absolute mag (V): -3.66
Equipment: GSO 10" f/8 Truss RC Losmandy G11 Mount guided PHD2, Orion Starshoot on 60mm guide scope. QHY 268c one shot colour camera, -10c, Gain 57 Offset 30 NINA capture software, with Optonlong L Extreme filter
Time/Locale: 120frames 2hrs captured 04/04/2023 Bortle 6, Najm Nazm Observatory Kelmscott WA, 94% moon
Processing: Stacked DSS, then P2, PS6