ExoClock

The Star
Simbad GAIA 2MASS	HAT-P-9 DR2 898130030131443584 J07204044+3708263
RA	07:20:40.4562		DEC	+37:08:26.342
Parallax 2.169 mas		P.M. RA -9.63 mas/y		P.M. DEC -13.043 mas/y
Mag_V 12.34	Mag_R 12.08	Mag_I^* 11.752	Mag_J 11.274	Mag_H 11.043	Mag_K 11.015
Mag_G 12.154		Mag_{G_BP} 12.422		Mag_{G_RP} 11.741
^*Calculated from GAIA magnitudes.

Ephemeris - Verified
Kokori et al. 2025
Mid-time 2457336.4804 ± 0.00014 BJD_TDB
Period 3.92281143 ± 2.6e-07 days
Transit Parameters
Wang et al. 2019
R_p/R_s 0.107 ± 0.0009	a/R_s 8.5 +0.3 -0.3		i 86.4 +0.4 -0.4 deg
R_p/R_s 0.107 ± 0.0009	e 0.08 +0.05 -0.05		ω 152.0 +42.0 -39.0 deg
Depth_R^* 14.08 mmag		Duration^* 3.34 hours
^Calculated from the other parameters, using PyLightcurve. ^*Adjusted based on the space observations.
Limb Darkening Parameters
Shporer et al. 2009
T_eff 6350.0 +150.0 -150.0 K	Log(g) 4.3 +0.06 -0.06 cm/s²		Fe/H 0.12 +0.2 -0.2 dex

ExoClock Status
Observing Priority		LOW
Minimum aperture		5.85"
Total Observations (Recent)		67 (12)
O-C		0.54 ± 0.5 minutes
ExoClock Observations (Recent)		40 (12)
Space Observations (Recent)		17 (0)
ETD Observations (Recent)		0 (0)
Literature Mid-times (Recent)		10 (0)
Kepler R_p/R_s		-
TESS R_p/R_s		0.10729 ± 0.00055

Planet Observation Date	Observer Observatory	Telescope Camera / Filter / Exp [s]	O-C minutes
ExoClock Observations
HAT-P-9b (LOW) 2026-03-02	Mark Salisbury POST	Orion Optics ODK SBIG ST-10 XME / Clear / 240.0	1.08 ± 0.89
HAT-P-9b (LOW) 2026-02-23	Alberto García Sánchez Observatorio Astronomico Rio Cofio	MEADE LX 200 Classic f6.3 CMOS ARESM-PRO / Clear / 120.0	-2.09 ± 2.59
HAT-P-9b (LOW) 2026-02-23	Alex Capdevila Corral Alba Ridge Observatory	Askar Apo Player One Poseidon-M Pro / R / 300.0	-2.81 ± 2.59
HAT-P-9b (LOW) 2026-01-10	Eric Miny BSA NEW	NEWTON T305 Player One Poseidon / Lum / 120.0	0.83 ± 1.73
HAT-P-9b (LOW) 2026-01-10	Claudio Lopresti Claudio Lopresti	Mak-Newton CCD Sbig ST10xme / I / 240.0	0.69 ± 1.87
HAT-P-9b (LOW) 2026-01-06	Enrique Arce Vallbona Observatory	Ritchey Chretien ZWO ASI 294 MM PRO / Lum / 300.0	3.58 ± 2.45
HAT-P-9b (LOW) 2026-01-06	Xesco Rubia Stupa Observatory	CDK14 QHY600PH M BSI / R / 120.0	3.58 ± 3.74
HAT-P-9b (LOW) 2026-01-06	Alex Capdevila Corral Observatorio de Albatàrrec	Celestron Evolution 6 Player One Poseidon-M Pro / Clear / 300.0	0.41 ± 2.74
HAT-P-9b (LOW) 2026-01-06	Yves Jongen Rasteau Observatory	Plane Wave CDK 17" SBIG STXL 11002 / Lum / 180.0	-3.91 ± 2.59
HAT-P-9b (LOW) 2025-12-30	Fabio Mortari Hypatia Observatory	Ritchey Chretienne 250mm f/5.3 MORAVIAN C2-7000A / R / 200.0	3.61 ± 2.74
HAT-P-9b (LOW) 2025-11-16	Alexey Garmash Lyceum 130	EdgeHD C11 ASI2600MM pro / ipr / 240.0	-1.96 ± 3.31
HAT-P-9b (LOW) 2025-11-09	Salvador Miquel Romero Vedat Observatory	Meade SN10 F/4.1 SBIG ST8XME / Lum / 300.0	2.39 ± 3.02
HAT-P-9b (LOW) 2025-01-14	Francesco Scaggiante Gruppo Astrofili Salese "GALILEO GALILEI"	NEWTON 410/1710 Player One Astronomy Poseidon-M Pro (IMX571) / rpr / 90.0	3.06 ± 3.02
HAT-P-9b (LOW) 2025-01-14	samuel Diaz Lopez Tomas Lopez (AstroCamp)	SCA260 Atik16200MM / V / 180.0	0.33 ± 2.45
HAT-P-9b (LOW) 2025-01-11	Simon Dawes William James II	Celestron Edge11 HD Risingcam Monochrome SONY imx571 / Lum / 217.0	0.4 ± 1.3
HAT-P-9b (LOW) 2024-11-28	Alexey Garmash Lyceum 130	SW Esprit 150ED ASI1600MM / V / 300.0	-2.93 ± 2.59
HAT-P-9b (LOW) 2024-02-08	Vikrant Kumar Agnihotri Cepheid Observatory India	GSO Ritchey–Chrétien Atik383L+ mono / Lum / 90.0	-1.55 ± 1.24
HAT-P-9b (LOW) 2024-01-31	Miguel Ángel Álava Amat Sarriguren	Meade SC 8" Asi 1600 MM / Lum / 240.0	-5.84 ± 2.45
HAT-P-9b (LOW) 2024-01-27	Eric Miny BLOIS SOLOGNE ASTRONOMIE OBSERVATORY	Newton T305 QSI 683WS / R / 120.0	2.82 ± 6.48
HAT-P-9b (LOW) 2024-01-27	Anaël Wünsche Observatoire des Baronnies Provençales	CDK Planewave 2 ZWO ASI6200 / R / 60.0	1.66 ± 1.44
HAT-P-9b (LOW) 2024-01-27	Attilio Bruzzone Anxanum Observatory	LX200 ACF 10" QHY 268M / Lum / 180.0	0.37 ± 1.58
HAT-P-9b (LOW) 2023-03-27	Eric Miny BLOIS SOLOGNE ASTRONOMIE OBSERVATORY	Newton T305 QSI 683WS / Lum / 120.0	-2.81 ± 2.16
HAT-P-9b (LOW) 2023-02-08	Pieter Vuylsteke TheGardenToTheSkyFacility	TS ONTC 25cm f4.7 QHY 268M / rpr / 120.0	0.84 ± 2.02
HAT-P-9b (LOW) 2023-02-01	Simon Dawes William James II Observatory	Skywatcher MN190 2 ZWO ASI 1600MM-PRO USB 3.0 Mono Camera / Lum / 180.0	2.31 ± 4.03
HAT-P-9b (LOW) 2023-02-01	Mark van der Grijp Trevinca Observatory	William Optics FLT132 ZWO ASI2600mm Pro / Lum / 110.0	2.03 ± 2.59
HAT-P-9b (LOW) 2022-12-15	Simon Dawes William James II Observatory	Skywatcher MN190 2 ZWO ASI 1600MM-PRO USB 3.0 Mono Camera / Lum / 180.0	-5.26 ± 3.02
HAT-P-9b (LOW) 2022-12-08	Martin Crow Burnham Observatory	Celestron C9.25 SX694 mono / R / 120.0	1.54 ± 2.16
HAT-P-9b (LOW) 2022-12-08	Simon Dawes William James II Observatory	Skywatcher MN190 2 ZWO ASI 1600MM-PRO USB 3.0 Mono Camera / Lum / 180.0	-3.5 ± 3.02
HAT-P-9b (LOW) 2022-12-04	Mark van der Grijp Trevinca Observatory	William Optics FLT132 ZWO ASI2600mm Pro / Lum / 45.0	-6.08 ± 2.74
HAT-P-9b (LOW) 2021-12-20	Andras Dan Rocca1	Celestron C8 QHY 183 M / AstrodonExoPlanet-BB / 60.0	-3.03 ± 1.58
HAT-P-9b (LOW) 2021-12-16	David Arnot OSO PIRATE	PlaneWave Instruments CDK24 24 inch (610 mm) f/6.5 Corrected Dall-Kirkham Astrograph FLI ProLine KAF-16803 / R / 45.0	1.02 ± 0.72
HAT-P-9b (LOW) 2021-12-16	Ulrich Kolb OSO PIRATE	PlaneWave Instruments CDK24 24 inch (610 mm) f/6.5 Corrected Dall-Kirkham Astrograph FLI ProLine KAF-16803 / R / 45.0	0.59 ± 1.01
HAT-P-9b (LOW) 2021-02-28	Manfred Raetz privat observatory Herges-Hallenberg	SCT 280 /1790 (Celestron C11 with reducer) Moravian Instruments G2-1600 / Clear / 120.0	0.94 ± 1.3
HAT-P-9b (LOW) 2021-02-28	Fabio Mortari Hypatia Observatory	Ritchey Chretienne 250mm f/5.3 Sbig ST8-XE / R / 200.0	-1.22 ± 1.01
HAT-P-9b (LOW) 2021-02-24	Manfred Raetz privat observatory Herges-Hallenberg	SCT 280 /1790 (Celestron C11 with reducer) Moravian Instruments G2-1600 / Clear / 120.0	-1.35 ± 1.87
HAT-P-9b (LOW) 2021-02-24	Francesco Scaggiante Gruppo Astrofili Salese "GALILEO GALILEI"	NEWTON 410/1710 Custom made with KAF-1603ME CCD sensor / R / 60.0	-4.37 ± 4.46
HAT-P-9b (LOW) 2021-02-24	Fabio Mortari Hypatia Observatory	Ritchey Chretienne 250mm f/5.3 Sbig ST8-XE / R / 120.0	-6.39 ± 4.32
HAT-P-9b (LOW) 2021-01-08	Francesco Scaggiante Gruppo Astrofili Salese "GALILEO GALILEI"	NEWTON 410/1710 Custom made with KAF-1603ME CCD sensor / R / 70.0	0.87 ± 2.45
HAT-P-9b (LOW) 2018-03-25	Anaël Wünsche Observatoire des Baronnies Provençales	Astelco FLIPL230 / Lum / 60.0	-0.47 ± 1.58
HAT-P-9b (LOW) 2016-02-19	Anaël Wünsche Observatoire des Baronnies Provençales	CDK Planewave SBIG STL11K / Clear / 120.0	-2.01 ± 2.02
Space Observations
Planet Observation Date	Mission		O-C minutes
HAT-P-9b (LOW) 2023-01-16	TESS		-0.36 ± 1.44
HAT-P-9b (LOW) 2023-01-12	TESS		-0.58 ± 1.3
HAT-P-9b (LOW) 2023-01-04	TESS		2.0 ± 1.58
HAT-P-9b (LOW) 2022-12-31	TESS		0.52 ± 1.37
HAT-P-9b (LOW) 2022-12-27	TESS		0.39 ± 1.43
HAT-P-9b (LOW) 2022-01-24	TESS		0.85 ± 1.2
HAT-P-9b (LOW) 2022-01-20	TESS		0.61 ± 1.41
HAT-P-9b (LOW) 2022-01-12	TESS		-1.14 ± 1.35
HAT-P-9b (LOW) 2022-01-08	TESS		0.11 ± 1.35
HAT-P-9b (LOW) 2022-01-04	TESS		-1.37 ± 1.4
HAT-P-9b (LOW) 2020-01-17	TESS		2.47 ± 1.4
HAT-P-9b (LOW) 2020-01-13	TESS		0.8 ± 1.44
HAT-P-9b (LOW) 2020-01-10	TESS		-2.21 ± 1.58
HAT-P-9b (LOW) 2020-01-06	TESS		-0.12 ± 1.14
HAT-P-9b (LOW) 2020-01-02	TESS		1.01 ± 1.11
HAT-P-9b (LOW) 2019-12-29	TESS		-0.86 ± 1.44
HAT-P-9b (LOW) 2019-12-25	TESS		0.65 ± 1.35
Literature Mid-times
Planet Observation Date	Reference		O-C minutes
2017-02-26	Wang et al. 2019		1.13 ± 1.43
2017-01-06	Wang et al. 2019		-4.97 ± 1.2
2016-12-29	Wang et al. 2019		-1.28 ± 1.66
2016-11-08	Wang et al. 2019		2.17 ± 1.34
2016-03-10	Wang et al. 2019		-2.97 ± 1.74
2016-01-11	Wang et al. 2019		0.63 ± 2.0
2010-04-06	Dittmann et al. 2012		0.97 ± 0.52
2010-02-18	Dittmann et al. 2012		0.13 ± 1.44
2010-02-14	Dittmann et al. 2012		-0.02 ± 0.46
2007-11-13	Shporer et al. 2009		-0.28 ± 0.43

HAT-P-9b (LOW)

Discovered by: Shporer et al. 2009

ExoClock Observations

Space Observations

Literature Mid-times