Registry · exoplanet

TRAPPIST-1 c

Exoplanet 295 papers

harvesting The full record is being pulled from the archives right now — measurement tables, the Gaia row, catalogue photometry. This page will fill itself in.

Right ascension: 23h 06m 30.33s
Declination: −05° 02′ 36.5″
Galactic l, b: 69.715, -56.65
Magnitude V: 17.02
Distance: 12.43 pc

Also known as

1 identifiers

TRAPPIST-1c

Planet

NASA Exoplanet Archive, composite parameters

Host star	TRAPPIST-1 · M7.5e
Discovery	Transit, 2016 · La Silla Observatory
Orbital period	2.42194 d
Semi-major axis	0.0158 au
Eccentricity	0.00654
Radius	1.097 R⊕ · 0.09787 R♃
Mass	1.308 M⊕ · 0.004115 M♃
Density	5.464 g/cm³
Equilibrium temperature	339.7 K
System distance	12.43 pc

Published measurements

6 quantities measured more than once

One object can carry a dozen published estimates of the same quantity. The register keeps them side by side rather than picking a winner — the citation is part of the value.

Mass 3 values

Value	Unit	Uncertainty	Band / method	Source	Reference	Year
1.308	M_earth	± 0.056	Transit	NASA Exoplanet Archive	Agol et al. 2021	2021
1.156	M_earth	± 0.142	Transit	NASA Exoplanet Archive	Grimm et al. 2018	2018
1.38	M_earth	± 0.61	Transit	NASA Exoplanet Archive	Gillon et al. 2017	2017

Radius 4 values

Value	Unit	Uncertainty	Band / method	Source	Reference	Year
1.097	R_earth	± 0.014	Transit	NASA Exoplanet Archive	Agol et al. 2021	2021
1.095	R_earth	± 0.03	Transit	NASA Exoplanet Archive	Grimm et al. 2018	2018
1.056	R_earth	± 0.035	Transit	NASA Exoplanet Archive	Gillon et al. 2017	2017
1.049	R_earth	± 0.05	Transit	NASA Exoplanet Archive	Gillon et al. 2016	2016

Orbital period 5 values

Value	Unit	Uncertainty	Band / method	Source	Reference	Year
2.421937	d	± 1.80e-05	Transit	NASA Exoplanet Archive	Rathcke et al. 2025	2025
2.421937	d	± 1.80e-05	Transit	NASA Exoplanet Archive	Agol et al. 2021	2021
2.421793	d	± 2.30e-07	Transit	NASA Exoplanet Archive	Ducrot et al. 2020	2020
2.421823	d	± 1.70e-06	Transit	NASA Exoplanet Archive	Gillon et al. 2017	2017
2.421848	d	± 2.80e-05	Transit	NASA Exoplanet Archive	Gillon et al. 2016	2016

Semi-major axis 5 values

Value	Unit	Uncertainty	Band / method	Source	Reference	Year
0.0158	au	± 0.00013	Transit	NASA Exoplanet Archive	Agol et al. 2021	2021
0.01579	au	± 0.00014	Transit	NASA Exoplanet Archive	Ducrot et al. 2020	2020
0.01581512	au	± 1.50e-07	Transit	NASA Exoplanet Archive	Grimm et al. 2018	2018
0.01521	au	± 0.00047	Transit	NASA Exoplanet Archive	Gillon et al. 2017	2017
0.01522	au	± 0.00055	Transit	NASA Exoplanet Archive	Gillon et al. 2016	2016

Eccentricity 4 values

Value	Uncertainty	Band / method	Source	Reference	Year
0		Transit	NASA Exoplanet Archive	Rathcke et al. 2025	2025
0.00654	± 0.00188	Transit	NASA Exoplanet Archive	Grimm et al. 2018	2018
0.083		Transit	NASA Exoplanet Archive	Gillon et al. 2017	2017
0		Transit	NASA Exoplanet Archive	Gillon et al. 2016	2016

Equilibrium temperature 4 values

Value	Unit	Uncertainty	Band / method	Source	Reference	Year
339.7	K	± 3.3	Transit	NASA Exoplanet Archive	Ducrot et al. 2020	2020
341.9	K	± 6.6	Transit	NASA Exoplanet Archive	Gillon et al. 2017	2017
342	K	± 8	Transit	NASA Exoplanet Archive	Gillon et al. 2016	2016
315	K		Transit	NASA Exoplanet Archive	de Wit et al. 2016	2016

In the same field

within 9 arcmin · wider search

Object	Type	Separation	V
TRAPPIST-1 e	Exoplanet	0.003074″	17.02
TRAPPIST-1 b	Exoplanet	0.003074″	17.02
TRAPPIST-1 d	Exoplanet	0.003074″	17.02
TRAPPIST-1 f	Exoplanet	0.003074″	17.02
TRAPPIST-1 g	Exoplanet	0.003074″	17.02
TRAPPIST-1 h	Exoplanet	0.003074″	17.02
TRAPPIST-1	Low-Mass*	16.23″	18.8
4C -05.95	Blazar	280.4″	19.5

Provenance

where this card came from

Archive	Read at (UTC)	Record
Seeded from the bulk archive load; no per-object fetch yet.

Machine-readable: /api/v1/object/trappist-1-c · Registry entry updated 2026-08-14.