exoclock

WASP-138b (MEDIUM)

Discovered by: Lam et al. 2017

The Star
Simbad
GAIA
2MASS		 WASP-138
DR2 2498515516990171392
J02463338-0027501
RA 02:46:33.3867 DEC -00:27:50.316
Parallax
2.386 mas		 P.M. RA
11.247 mas/y		 P.M. DEC
-34.464 mas/y
MagV
11.79		 MagR
11.74		 MagI*
11.182		 MagJ
10.782		 MagH
10.54		 MagK
10.494
MagG
11.687		 MagGBP
11.968		 MagGRP
11.263
*Calculated from GAIA magnitudes.

Ephemeris - Verified True
Kokori et al. 2025
Mid-time
2458311.55351 ± 0.00034 BJDTDB
Period
3.6344332 ± 1.5e-06 days
Transit Parameters
Lam et al. 2017
Rp/Rs
0.0826 ± 0.0008		 a/Rs**
7.39 +0.15 -0.15
 i
88.5 +0.9 -1.2 deg
e
-		 ω
- deg
DepthR*
8.91 mmag		 Duration*
4.02 hours
*Calculated from the other parameters, using PyLightcurve.
**Adjusted based on the space observations.

Limb Darkening Parameters
Lam et al. 2017
Teff
6272.0 +96.0 -96.0 K
 Log(g)
4.25 +0.02 -0.02 cm/s2
 Fe/H
-0.09 +0.1 -0.1 dex
ExoClock Status
Observing Priority MEDIUM
Minimum aperture 7.22"
Total Observations (Recent) 24 (0)
O-C 0.54 ± 1.46 minutes
ExoClock Observations (Recent) 11 (0)
Space Observations (Recent) 11 (0)
ETD Observations (Recent) 1 (0)
Literature Mid-times (Recent) 1 (0)
Kepler Rp/Rs -
TESS Rp/Rs 0.08728 ± 0.00053

WASP-138b


ExoClock Observations
Planet
Observation Date		 Observer
Observatory		 Telescope
Camera / Filter / Exp [s]		 O-C
minutes
WASP-138b (MEDIUM)
2024-12-22		Yves Jongen
Deep Sky Chile		Plane Wave CDK 17"
Moravian 4G / R / 180.0		2.99 ± 2.45
WASP-138b (MEDIUM)
2024-12-03		Gustavo Muler
Obs. Nazaret J47		lx 200
ST8 XME AO8 / R / 90.0		-2.82 ± 2.3
WASP-138b (MEDIUM)
2024-11-04		Francesco Scaggiante
Gruppo Astrofili Salese "GALILEO GALILEI"		NEWTON 410/1710
Player One Astronomy Poseidon-M Pro (IMX571) / rpr / 60.0		3.32 ± 3.46
WASP-138b (MEDIUM)
2024-11-04		Matthieu Bachschmidt
Gonachon		Celestron C11
SBIG ST8XME / AstrodonExoPlanet-BB / 120.0		0.3 ± 5.76
WASP-138b (MEDIUM)
2023-10-13		Marc Serrau
A77 - Dauban		Meade SC 12"
QHY260MM / rpr / 300.0		5.99 ± 3.6
WASP-138b (MEDIUM)
2023-10-02		David Quiles
David Quiles Observatory		Celestron EDGEHD 800
Omegon veTEC 571M / R / 120.0		7.57 ± 2.74
WASP-138b (MEDIUM)
2023-01-09		Martin Crow
Burnham Observatory		Celestron C9.25
SX694 mono / R / 150.0		-1.32 ± 2.88
WASP-138b (MEDIUM)
2021-11-06		Robert Roth
TURMX Observatory		Planewave CDK17
QHY600M / rpr / 60.0		0.87 ± 1.73
WASP-138b (MEDIUM)
2021-11-03		Steven Peterson
Vail View Observatory H18		GSO 10" RC f/8.0
SBIG STL6303E / I / 120.0		-6.29 ± 2.74
WASP-138b (MEDIUM)
2020-12-14		Carmelo Falco
GALHassin Robotic Telescope 2 (GRT2)		Giacometti-Fogale RC16
Andor Apogee Aspen CG16M / rpr / 60.0		3.01 ± 2.3
WASP-138b (MEDIUM)
2020-12-14		Carmelo Falco
GAL Hassin Robotic Telescope 2 (GRT2) - Multiband		Giacometti-Fogale RC16 - 2
Andor Apogee Aspen CG16M / gpr / 60.0		-1.02 ± 3.02

Space Observations
Planet
Observation Date		 Mission O-C
minutes
WASP-138b (MEDIUM)
2020-11-15		TESS1.91 ± 1.17
WASP-138b (MEDIUM)
2020-11-12		TESS0.47 ± 1.25
WASP-138b (MEDIUM)
2020-11-08		TESS0.49 ± 1.28
WASP-138b (MEDIUM)
2020-11-01		TESS-0.45 ± 1.58
WASP-138b (MEDIUM)
2020-10-28		TESS0.33 ± 1.18
WASP-138b (MEDIUM)
2020-10-24		TESS1.23 ± 1.58
WASP-138b (MEDIUM)
2018-11-12		TESS-1.11 ± 1.41
WASP-138b (MEDIUM)
2018-11-08		TESS-4.33 ± 1.44
WASP-138b (MEDIUM)
2018-11-05		TESS-4.28 ± 1.58
WASP-138b (MEDIUM)
2018-10-25		TESS-0.97 ± 2.16
WASP-138b (MEDIUM)
2018-10-21		TESS-4.29 ± 1.2

ETD Observations
Planet
Observation Date		 Observer(s) ETD link O-C
minutes
WASP-138b (MEDIUM)
2020-10-24		F. Lomoz16036077032.53 ± 5.33

Literature Mid-times
Planet
Observation Date		 Reference O-C
minutes
2015-10-31 Lam et al. 2017 0.73 ± 0.46
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