NGC 657

(MWSC 135)

0.24 UTI

0.0

C_N

0.07

C_dens

0.25

C_C3

0.44

C_lit

1.0

C_dup

C3 classification CC

Number of members (P>50%) 17

Radius (P>50% members) 8.2 [arcmin]

C_N 0.0 Sparse
C_dens 0.07 Very loose
C_C3 0.25 Low quality
C_lit 0.44 Poorly studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19 🔍 CDS 🔍 Simbad 🔍 CDS (α, δ) 🔍 Simbad (α, δ)

Overview

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NGC 657 is a sparse, very loose object of low C3 quality. Its parallax locates it at a moderate^* distance, below the mid-plane, affected by moderate extinction. It is catalogued as a low-mass, old cluster (see Parameters). It is poorly studied in the literature.

(*): The parallax distance estimate (~2.97 kpc) differs significantly from the median photometric distance (~1.93 kpc).

⚠️ 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.

Relatively close Moderate extinction Low mass Old

Data

🔍 Search references for NGC 657 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	–	25.796	55.905	0.336	-1.998	0.324	-85.774
Just et al.	2023	25.839	55.837	–	–	–	–
Loktin & Popova	2017	25.845	55.837	–	-0.366	-0.859	–
Kharchenko et al.	2016	25.839	55.837	–	–	–	–
Dias et al.	2014	25.837	55.836	–	1.14	-3.95	–
Kharchenko et al.	2013	25.849	55.84	–	-1.07	-1.53	–
Kharchenko et al.	2012	25.849	55.84	–	-1.07	-1.53	–
Dias et al.	2002	25.837	55.836	–	1.14	-3.95	–

💡 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]	Bfr	BSS
Just et al.	2023	–	–	–	1000	–	14	–	–
Loktin & Popova	2017	2.39	1.21	–	794	–	–	–	–
Kharchenko et al.	2016	1.93	1.62	–	1000	–	–	–	–
Kharchenko et al.	2013	1.93	1.62	–	1000	–	–	–	–
Kharchenko et al.	2012	1.93	1.62	–	1000	–	–	–	–
Dias et al.	2002	1.37	1.05	–	1585	–	–	–	–

Visualization

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