exoclock

K2-121b (LOW)

Discovered by: Dressing et al. 2017

The Star
Simbad
GAIA
2MASS		 K2-121
DR2 662078902422542336
J08274481+1734457
RA 08:27:44.8140 DEC +17:34:45.804
Parallax
5.875 mas		 P.M. RA
-13.87 mas/y		 P.M. DEC
-14.712 mas/y
MagV
13.32		 MagR
12.98		 MagI*
12.121		 MagJ
11.309		 MagH
10.742		 MagK
10.616
MagG
12.925		 MagGBP
13.552		 MagGRP
12.189
*Calculated from GAIA magnitudes.

Ephemeris - Verified True
Kokori et al. 2025
Mid-time
2458139.225432 ± 6.9e-05 BJDTDB
Period
5.18575338 ± 5.3e-07 days
Transit Parameters
Dressing et al. 2017
Rp/Rs
0.109 ± 0.005		 a/Rs**
14.46 +0.16 -0.12
 i
87.2 +0.9 -0.5 deg
e
0.22 +0.19 -0.18
 ω
73.0 +64.9 -104.5 deg
DepthR*
14.93 mmag		 Duration*
2.12 hours
*Calculated from the other parameters, using PyLightcurve.
**Adjusted based on the space observations.

Limb Darkening Parameters
Dressing et al. 2017
Teff
4471.4 +111.6 -103.6 K
 Log(g)
4.52 +0.06 -0.06 cm/s2
 Fe/H
0.0 +0.0 -0.0 dex
ExoClock Status
Observing Priority LOW
Minimum aperture 7.85"
Total Observations (Recent) 78 (4)
O-C 1.15 ± 0.43 minutes
ExoClock Observations (Recent) 45 (4)
Space Observations (Recent) 33 (0)
ETD Observations (Recent) 0 (0)
Literature Mid-times (Recent) 0 (0)
Kepler Rp/Rs 0.10667 ± 0.00014
TESS Rp/Rs 0.10677 ± 0.00089

K2-121b


ExoClock Observations
Planet
Observation Date		 Observer
Observatory		 Telescope
Camera / Filter / Exp [s]		 O-C
minutes
K2-121b (LOW)
2026-01-18		Ed Mullen
Sycamore Canyon Observatory		Planewave CDK20
FLI ML4240BI / AstrodonExoPlanet-BB / 50.0		0.24 ± 0.6
K2-121b (LOW)
2026-01-07		Ivo Peretto
MarSEC Marana Space Explorer Center		R-C
Moravia G2-1600 MkII / R / 120.0		8.24 ± 1.87
K2-121b (LOW)
2025-12-12		Tommaso Dittadi
TD-TRO		Ritchey-Chretien
Moravian G2-1600 / R / 240.0		0.85 ± 2.3
K2-121b (LOW)
2025-03-28		Alexey Garmash
Lyceum 130		EdgeHD C11
ASI2600MM pro / rpr / 180.0		0.37 ± 1.58
K2-121b (LOW)
2025-02-04		Federico Palaia
Civico osservatorio astronomico di Rozzano		Meade ACF
SBIG ST10-XME / Clear / 120.0		0.13 ± 2.59
K2-121b (LOW)
2025-02-04		Francesco Scaggiante
Gruppo Astrofili Salese "GALILEO GALILEI"		NEWTON 410/1710
Player One Astronomy Poseidon-M Pro (IMX571) / rpr / 120.0		-0.73 ± 3.17
K2-121b (LOW)
2025-02-04		Riccardo Zancan
Riccardo		Celestron C11
ASI-1600-MM / R / 90.0		-3.61 ± 5.04
K2-121b (LOW)
2025-02-04		Christian Sartini
Chris31		C9 xlt
Asi533mc / R / 120.0		-4.33 ± 7.63
K2-121b (LOW)
2025-01-20		Yves Jongen
Deep Sky Chile		Plane Wave CDK 17"
Moravian 4G / Lum / 180.0		1.53 ± 1.15
K2-121b (LOW)
2024-12-09		Yen-Hsing Lin
Starry House Observatory		Mewlon 300 CRS
ASI 6200MM Pro / Lum / 60.0		2.99 ± 1.24
K2-121b (LOW)
2024-02-07		Carmelo Falco
Racalmuto - G. Lemaitre Observatory		Ritchey-Chrétien 16” F/8 + RM500 Mount
Andor Aspen CG16M / Lum / 60.0		3.21 ± 1.87
K2-121b (LOW)
2024-01-12		Ramon Naves
Montcabrer		Meade LX200 12" ACF
Moravian G4-9000 / rpr / 120.0		5.61 ± 2.74
K2-121b (LOW)
2024-01-12		Claudio Lopresti
Claudio Lopresti		Mak-Newton
CCD Sbig ST10xme / I / 240.0		2.15 ± 2.02
K2-121b (LOW)
2024-01-12		christian PANTACCHINI
Observatoire de BENAYES		Skywhatcher Newton
SBIG STF-8300M / Lum / 240.0		-3.18 ± 3.6
K2-121b (LOW)
2024-01-12		Patrick Farizy
BABOTE		schmit cassegrain
atik 314 l / Clear / 30.0		-5.77 ± 5.9
K2-121b (LOW)
2023-12-23		David Quiles
David Quiles Observatory		Celestron EDGEHD 800
Omegon veTEC 571M / R / 120.0		1.02 ± 2.88
K2-121b (LOW)
2023-12-17		Miguel Ángel Álava Amat
Sarriguren		Meade SC 8"
Asi 1600 MM / Lum / 240.0		-3.08 ± 2.74
K2-121b (LOW)
2023-04-07		David Quiles
David Quiles Observatory		Celestron EDGEHD 800
Omegon veTEC 571M / R / 120.0		3.71 ± 2.45
K2-121b (LOW)
2023-04-07		Eric Miny
BLOIS SOLOGNE ASTRONOMIE OBSERVATORY		Newton T305
QSI 683WS / Lum / 120.0		0.98 ± 1.73
K2-121b (LOW)
2023-04-07		Adrian Jones
Private Observatory (I64)		Meade ACF 30cm
QSI 583 / Lum / 200.0		-1.18 ± 3.02
K2-121b (LOW)
2023-04-07		David Molina
Anunaki Observatory Z51		Schmidt Cassegrain
SBIG ST-9xe / R / 120.0		-1.9 ± 1.73
K2-121b (LOW)
2023-04-07		Robert Roth
TURMX Observatory		Planewave CDK17
QHY600M / Lum / 120.0		-1.95 ± 1.08
K2-121b (LOW)
2023-03-18		Yves Jongen
Deep Sky Chile		Plane Wave CDK 17"
Moravian 4G / Lum / 180.0		-0.2 ± 1.27
K2-121b (LOW)
2023-02-15		David Bennett
Rickford Observatory		GSO RC
ZWO ASI2600MM Pro / Lum / 180.0		1.02 ± 1.73
K2-121b (LOW)
2023-02-15		Thomas Mollier
Tomastro		Newtonian
ZWO ASI1600MMC / rpr / 120.0		-1.42 ± 2.02
K2-121b (LOW)
2023-02-15		Pavel Pintr
Horní Halže		Celestron 235/1480
ASI ZWO 1600 MONO / Clear / 120.0		-1.71 ± 4.18
K2-121b (LOW)
2023-02-15		Marc Serrau
A77 Dauban		Celestron 11
QHY268 Mono / rpr / 180.0		-3.44 ± 1.87
K2-121b (LOW)
2023-02-09		Alessandro Marchini
Astronomical Observatory University of Siena		Mak-Cas 0.3m f/5.6
Sbig STL-6303 / R / 180.0		3.69 ± 1.73
K2-121b (LOW)
2023-02-09		Yves Jongen
Rasteau Observatory		Plane Wave CDK 17"
SBIG STXL 11002 / Lum / 120.0		0.81 ± 1.58
K2-121b (LOW)
2023-02-09		Francesco Scaggiante
Gruppo Astrofili Salese "GALILEO GALILEI"		NEWTON 410/1710
Custom made with KAF-1603ME CCD sensor / R / 90.0		-2.5 ± 2.45
K2-121b (LOW)
2023-02-09		Marco Stefanini
Osservatorio Aldebaran		Ritchey-Chretien Altair Astro
Atik 4000 LE / Lum / 250.0		-3.36 ± 2.88
K2-121b (LOW)
2023-02-09		Fabio Mortari
Hypatia Observatory		Ritchey Chretienne 250mm f/5.3
MORAVIAN C2-7000A / R / 250.0		-3.79 ± 2.45
K2-121b (LOW)
2022-02-11		Dominique DANIEL
La Montjoie		Celestron CGX C8 XLT
Camera CMOS ZWO ASI294MC pro (color) / Clear / 235.0		4.47 ± 4.32
K2-121b (LOW)
2022-02-11		Yves Jongen
Rasteau Observatory		Plane Wave CDK 17"
FLI Kepler CMOS 4040 / Lum / 120.0		0.29 ± 1.58
K2-121b (LOW)
2022-02-06		Taewoo Kim
Deokheung Optical Astronomy Observatory		NYSC 1m Telescope
FLI PL-16803 or PI SOPHIA-2048B / R / 120.0		0.45 ± 0.82
K2-121b (LOW)
2022-01-22		Yves Jongen
Rasteau Observatory		Plane Wave CDK 17"
FLI Kepler CMOS 4040 / Lum / 120.0		2.17 ± 1.08
K2-121b (LOW)
2022-01-22		Robert Roth
TURMX Observatory		Planewave CDK17
QHY600M / rpr / 120.0		-0.14 ± 1.31
K2-121b (LOW)
2022-01-22		Jean-Bernard Pioppa
La Roque-Esclapon		KEPLER
ATIK 383 L+ / R / 300.0		-3.0 ± 2.02
K2-121b (LOW)
2022-01-16		Cyrille Aumasson
observatory of Baronnies Provençales		ASTELCO 31.5"
FLI PL230 / R / 120.0		1.42 ± 1.31
K2-121b (LOW)
2022-01-16		Aziz Ettahar Kaeouach
High Atlas Observatory		PlaneWave CDK 12.5
Zwo asi 294 mm pro / R / 120.0		0.96 ± 3.74
K2-121b (LOW)
2022-01-16		Enrique Arce
Vallbona Observatory		Newton 10" f4
Sbig ST7-XME / Clear / 90.0		0.82 ± 2.3
K2-121b (LOW)
2022-01-16		Robert Roth
TURMX Observatory		Planewave CDK17
QHY600M / rpr / 60.0		-0.09 ± 1.37
K2-121b (LOW)
2021-03-16		John Savage
Z42 Rushay Farm Observatory		Celestron 14Edge FR
ZWO ASI6200MM / rpr / 120.0		3.91 ± 1.73
K2-121b (LOW)
2021-02-13		Manfred Raetz
privat observatory Herges-Hallenberg		SCT 280 /1790 (Celestron C11 with reducer)
Moravian Instruments G2-1600 / Clear / 120.0		0.2 ± 0.86
K2-121b (LOW)
2019-02-24		Lorenzo Betti
Osservatorio Polifunzionale del Chianti		RC-80cm
Moravian G2 - KAF1603ME / AstrodonExoPlanet-BB / 120.0		1.67 ± 1.73

Space Observations
Planet
Observation Date		 Mission O-C
minutes
K2-121b (LOW)
2023-12-02		TESS0.03 ± 1.44
K2-121b (LOW)
2023-11-27		TESS1.69 ± 1.87
K2-121b (LOW)
2023-11-22		TESS1.41 ± 1.25
K2-121b (LOW)
2023-11-16		TESS1.13 ± 1.73
K2-121b (LOW)
2023-11-06		TESS0.13 ± 1.58
K2-121b (LOW)
2023-11-01		TESS-0.37 ± 1.87
K2-121b (LOW)
2023-10-27		TESS2.01 ± 1.58
K2-121b (LOW)
2023-10-21		TESS5.25 ± 2.3
K2-121b (LOW)
2021-12-27		TESS-0.17 ± 1.58
K2-121b (LOW)
2021-12-21		TESS-0.09 ± 1.58
K2-121b (LOW)
2021-12-11		TESS1.93 ± 2.16
K2-121b (LOW)
2021-12-06		TESS3.88 ± 1.58
K2-121b (LOW)
2021-12-01		TESS0.93 ± 1.44
K2-121b (LOW)
2021-11-26		TESS1.73 ± 2.02
K2-121b (LOW)
2021-11-15		TESS-1.86 ± 1.44
K2-121b (LOW)
2021-11-10		TESS1.96 ± 2.3
K2-121b (LOW)
2021-11-05		TESS2.43 ± 1.37
K2-121b (LOW)
2021-10-31		TESS-1.34 ± 1.58
K2-121b (LOW)
2021-10-20		TESS-0.48 ± 1.28
K2-121b (LOW)
2021-10-15		TESS-0.25 ± 1.58
K2-121b (LOW)
2018-06-25		K20.08 ± 0.2
K2-121b (LOW)
2018-06-20		K2-0.01 ± 0.29
K2-121b (LOW)
2018-06-14		K2-0.44 ± 0.24
K2-121b (LOW)
2018-06-09		K20.08 ± 0.24
K2-121b (LOW)
2018-05-19		K2-0.23 ± 0.13
K2-121b (LOW)
2018-05-14		K21.29 ± 2.02
K2-121b (LOW)
2015-07-07		K2-1.46 ± 0.73
K2-121b (LOW)
2015-06-27		K20.35 ± 0.24
K2-121b (LOW)
2015-06-16		K2-2.16 ± 0.66
K2-121b (LOW)
2015-06-11		K20.17 ± 0.35
K2-121b (LOW)
2015-06-06		K2-0.11 ± 0.55
K2-121b (LOW)
2015-05-26		K22.13 ± 0.42
K2-121b (LOW)
2015-05-11		K2-0.16 ± 0.35
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