Alessi 33

(ASCC 32; MWSC 1069; FoF 2271)

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0.96 UTI
0.79
CN
1.0
Cdens
1.0
CC3
1.0
Clit
1.0
Cdup
N50 (P>50% members) 210
Stellar density (N50/rad) 11.1 [N/pc2]
C3 classification AA
  • CN 0.79 Rich
  • Cdens 1.0 Very dense
  • CC3 1.0 Very high quality
  • Clit 1.0 Very well-studied
  • Cdup 1.0 Unique
đŸ“Ĩ Members 📊 Colab đŸ”Ŧ Bayestar19 MOCAMOCA 🔍 CDS 🔍 Simbad 🔍 CDS (Îą, δ) 🔍 Simbad (Îą, δ)

Overview
ℹī¸
Alessi 33 is a rich, very dense object of very high C3 quality. Its parallax locates it at a close distance, below the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, young cluster, but with a large variance across recent sources for the age and mass parameters (see Parameters). It is very well-studied in the literature.

Note: This object shares a large percentage of members with 3 later reported entries. See table with shared members information.

Liu et al. (2025)
Classified as primordial binary cluster 20 along with HSC_1894, and as primordial binary cluster 214 along with HSC_1913, and of multiple system 10 along with HSC_1913 and HSC_1894.

Palma et al. (2025)
Part of multiple system G2, along with HSC_1894 and HSC_1913.

Almeida et al. (2025)
Mass determination: intermediate fit. Isochrone match: good fit. Silver sample.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD classes: 1.00 (50th percentile), true positive (human-assigned).

Hunt & Reffert (2023)
Classified as open cluster. CMD classes: 1.00 (50th percentile), true positive (human-assigned).

Bica et al. (2019)
Web updates in DAML02, some were later removed (2003 to 2010). List of clusters and alike reported by B. Alessi. The Preliminary Amateur Open Cluster Catalog, Version 08/03/2003.

Data
🔍 Search references for Alessi 33 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 105.744 -26.477 1.252 -3.228 3.502 33.096
Liu et al. 2025 105.71 -26.37 1.25 -3.22 3.49 34.11
Li et al. 2025 105.714 -26.512 1.23 -3.307 3.477 –
Almeida et al. 2025 105.711 -26.576 – – – –
Alfonso et al. 2024 105.768 -26.563 1.21 -3.201 3.484 –
Swiggum et al. 2024 105.71 -26.365 1.249 -3.218 3.488 33.293
Hunt & Reffert 2024 105.71 -26.365 1.249 -3.218 3.488 34.107
Celli et al. 2024 105.714 -26.512 – – – –
Cavallo et al. 2024 105.761 -26.431 1.246 – – –
Hunt & Reffert 2023 105.71 -26.365 1.249 -3.218 3.488 34.107
Cordoni et al. 2023 105.711 -26.576 1.24 -3.317 3.475 –
Just et al. 2023 105.52 -26.558 – – – –
He et al. 2022 105.703 -26.169 1.233 -3.218 3.456 –
Dias et al. 2021 105.711 -26.576 1.24 -3.317 3.475 34.607
Cantat-Gaudin et al. 2020 105.714 -26.512 1.23 -3.307 3.477 –
Cantat-Gaudin & Anders 2020 105.714 -26.512 1.23 -3.307 3.477 –
Liu & Pang 2019 105.742 -26.363 1.219 -3.264 3.461 –
Bossini et al. 2019 105.714 -26.512 – – – –
Soubiran et al. 2018 105.714 -26.512 – – – 35.05
Bica et al. 2019 105.499 -26.499 – – – –
Cantat-Gaudin et al. 2018 105.714 -26.512 1.23 -3.307 3.477 –
Dib et al. 2018 105.525 -26.56 – – – –
Loktin & Popova 2017 105.495 -26.503 – -0.768 0.813 –
Sampedro et al. 2017 105.496 -26.503 -1.41 2.29 – –
Joshi et al. 2016 105.525 -26.56 – – – –
Kharchenko et al. 2016 105.52 -26.558 – – – –
Dias et al. 2014 105.496 -26.503 – -1.47 2.32 –
Kharchenko et al. 2013 105.525 -26.56 – -2.33 4.25 –
Piskunov et al. 2008 105.489 -26.503 – – – –
Piskunov et al. 2007 105.489 -26.503 – – – –
Kharchenko et al. 2005 105.49 -26.5 – -3.39 1.97 –
Dias et al. 2002 105.496 -26.503 – -1.47 2.32 –

💡 Note: The UCC values are estimated from its identified members.

Reference Year Dist [kpc] Av [mag] DAv [mag] Age [Myr] [Fe/H] [dex] Mass [Msun] Bfrac BSS
UCC 99999– 0.78 0.25 0.73 27 -0.003 545 0.36 0
Liu et al. 2025 0.87 0.07 – 22 – – – –
Li et al. 2025 0.77 0.17 – 24 -0.043 – – –
Almeida et al. 2025 0.79 0.22 – 27 – 697 – –
Alfonso et al. 2024 0.81 0.26 – 24 -0.003 – – –
Swiggum et al. 2024 0.78 – – 16 – 545 – –
Hunt & Reffert 2024 – – – – – 272(1) – –
Celli et al. 2024 – – – 25 – 560 – –
Cavallo et al. 2024 0.84 0.44 – 6 -0.280 – – –
Hunt & Reffert 2023 0.78 0.14 0.73 16 – – – –
Cordoni et al. 2023 0.79 0.22 – 27 -0.003 2417 0.36 0(1)
Just et al. 2023 – – – 164 – 220 – –
He et al. 2022 – 0.10 – 18 – – – –
Dias et al. 2021 0.79 0.22 – 27 -0.003 – – –
Cantat-Gaudin et al. 2020 0.81 0.26 – 25 – – – –
Kounkel et al. 2020 0.77 0.29 – 29 – – – –
Cantat-Gaudin & Anders 2020 0.79 – – – – – – –
Liu & Pang 2019 – – – 19 -0.750 – – –
Bossini et al. 2019 0.73 0.22 – 25 0.000 – – –
Soubiran et al. 2018 0.79 – – – – – – –
Cantat-Gaudin et al. 2018 0.79 – – – – – – –
Dib et al. 2018 0.77 – – 164 – – – –
Loktin & Popova 2017 0.79 0.23 – 155 – – – –
Joshi et al. 2016 0.77 0.25 – 164 – 813 – –
Kharchenko et al. 2016 0.77 0.25 – 164 – – – –
Kharchenko et al. 2013 0.77 0.25 – 164 – – – –
Piskunov et al. 2008 0.75 0.25 – 151 – 380(1) – –
Piskunov et al. 2007 0.75 0.25 – 151 – 158 – –
Kharchenko et al. 2005 0.75 0.25 – 151 – – – –
Dias et al. 2002 0.75 0.25 – 151 – – – –

(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.

Cluster % RA DEC Plx pmRA pmDE Rv UTI
CWWDL 14294 94.8 105.75 -26.5 1.26 -3.22 3.51 32.7 0.06
OC 0408 6.2 105.12 -26.51 1.22 -3.22 3.55 34.95 0.09
OC 0410 3.3 105.73 -27.38 1.2 -3.1 3.48 35.18 0.13

💡 Note: The % column shows the percentage of members that Alessi 33 shares with each listed object.

Visualization
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Alessi 33 UCC
Alessi 33 HUNT23
Alessi 33 CANTAT20
Galactocentric position diagram