HSC 691

0.15 UTI

0.0

C_N

0.23

C_dens

0.5

C_C3

0.0

C_lit

1.0

C_dup

N₅₀ (P>50% members) 21

Stellar density (N₅₀/rad) 1.1 [N/pc²]

C3 classification BB

C_N 0.0 Sparse
C_dens 0.23 Very loose
C_C3 0.5 Intermediate quality
C_lit 0.0 Rarely studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

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HSC 691 is a sparse, very loose object of intermediate 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, intermediate-age cluster, but with a large variance across recent sources for the metallicity parameter (see Parameters). It was recently reported in the literature.

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

⚠️ Warning: the low UTI value and no obvious signs of duplication (C_dup=1.0) indicate that this is quite probably an asterism, moving group, or artifact, and not a real open cluster.

Close Low extinction Near-solar metallicity Intermediate age

Palma et al. (2025)
Classified as optical pair P519, along with HSC_705.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as a moving group.

Data

🔍 Search references for HSC 691 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–	324.355	40.445	1.409	1.518	-2.374	-2.502
Zhang et al.	2024	324.407	40.395	–	–	–	–
Cavallo et al.	2024	324.29	40.556	1.406	–	–	–
Hunt & Reffert	2023	324.407	40.395	1.398	1.555	-2.383	-3.194

💡 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–	0.72	0.415	0.42	178	0.240	–	–	–
Zhang et al.	2024	–	–	–	–	0.031⁽¹⁾	–	–	–
Cavallo et al.	2024	0.75	0.49	–	214	0.450	–	–	–
Hunt & Reffert	2023	0.69	0.34	0.42	142	–	–	–	–

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

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
CWNU 3022	84.0	324.35	40.44	1.41	1.55	-2.37	-2.5	0.02

💡 Note: The % column shows the percentage of members that HSC 691 shares with each listed object.

Visualization

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