HSC 1721

0.08 UTI

0.0

C_N

0.11

C_dens

0.25

C_C3

0.06

C_lit

0.8

C_dup

N_m (P>50%) 22

Core radius and density 2.0 [pc], 0.5 [pc^-2]

C3 classification DB

C_N 0.0 Sparse
C_dens 0.11 Very loose
C_C3 0.25 Low quality
C_lit 0.06 Rarely studied
C_dup 0.8 Very likely unique

📥 Members 📊 Colab 🔬 Bayestar19

MOCA 🔍 CDS 🔍 Simbad 🔍 CDS (α, δ) 🔍 Simbad (α, δ)

Overview

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HSC 1721 is a sparse, very loose object of low C3 quality. Its parallax locates it at a moderate distance, near the mid-plane, affected by moderate extinction. It is catalogued as a near-solar metallicity, young cluster (see Parameters). It was recently reported in the literature.

Note: This is very likely a unique object, which shares a small percentage of members with at least one previously reported entry. See table with shared members information.

⚠️ Warning: the low UTI value and no obvious signs of duplication (C_dup=0.8) indicate that this is quite probably an asterism, moving group, or artifact, and not a real open cluster.

Relatively close Moderate extinction Near-solar metallicity Young

Liu et al. (2025)
Classified as primordial binary cluster 204 along with HSC_1723, and as tidal capture (resonant trapping binary) 282 along with NGC_2311, and of multiple system 58 along with HSC_1722, HSC_1723 and NGC_2311.

Palma et al. (2025)
Part of multiple system G128, along with HSC_1723 and HSC_1722.

Cavallo et al. (2024)
Silver sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.78 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.78 (50th percentile).

Data

🔍 Search references for HSC 1721 in: SciX Simbad

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Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	99999–	104.967	-4.518	0.446	-1.89	0.601	–
Liu et al.	2025	104.98	-4.5	0.44	-1.89	0.57	–
Hunt & Reffert	2024	104.983	-4.501	0.444	-1.886	0.568	–
Cavallo et al.	2024	104.995	-4.505	0.444	–	–	–
Hunt & Reffert	2023	104.983	-4.501	0.444	-1.886	0.568	–

💡 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]	B_frac	BSS
UCC	99999–	2.235	1.375	1.05	36	-0.210	117	–	–
Liu et al.	2025	3.89	0.48	–	13	–	–	–	–
Hunt & Reffert	2024	2.11	1.47	1.05	48	–	117⁽¹⁾	–	–
Cavallo et al.	2024	2.36	1.28	–	24	-0.210	–	–	–
Hunt & Reffert	2023	2.11	1.47	1.05	48	–	–	–	–

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

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
Sh2-287C	20.0	104.85	-4.7	0.45	-1.61	0.76	48.19	0.12

💡 Note: The % column shows the percentage of members that HSC 1721 shares with each listed object.

Visualization

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