| The Star | |||||
|---|---|---|---|---|---|
| Simbad GAIA 2MASS |
HAT-P-21 DR2 770622651659107712 J11250598+4101406 |
||||
| RA | 11:25:05.9858 | DEC | +41:01:40.669 | ||
| Parallax 3.578 mas |
P.M. RA -1.088 mas/y |
P.M. DEC 13.243 mas/y |
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| MagV 11.46 |
MagR 11.71 |
MagI* 10.716 |
MagJ 10.503 |
MagH 10.154 |
MagK 10.111 |
| MagG 11.558 |
MagGBP 11.921 |
MagGRP 11.059 |
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| *Calculated from GAIA magnitudes. | |||||
Ephemeris
- Verified 
|
|||||
|---|---|---|---|---|---|
| Kokori et al. 2025 | |||||
| Mid-time 2458617.71445 ± 0.00029 BJDTDB |
|||||
| Period 4.12448935 ± 7.5e-07 days |
|||||
| Transit Parameters | |||||
| Bakos et al. 2011 | |||||
| Rp/Rs 0.095 ± 0.0022 |
a/Rs 9.6 +0.7 -0.7 |
i 87.2 +0.7 -0.7 deg |
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| e 0.228 +0.016 -0.016 |
ω 309.0 +3.0 -3.0 deg |
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| DepthR* 11.12 mmag |
Duration* 3.71 hours |
||||
|
*Calculated from the other parameters, using PyLightcurve.
**Adjusted based on the space observations. |
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| Limb Darkening Parameters | |||||
| Bakos et al. 2011 | |||||
| Teff 5588.0 +80.0 -80.0 K |
Log(g) 4.33 +0.06 -0.06 cm/s2 |
Fe/H 0.01 +0.08 -0.08 dex |
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| ExoClock Status | |||||
|---|---|---|---|---|---|
| Observing Priority | LOW | ||||
| Minimum aperture | 5.82" | ||||
| Total Observations (Recent) | 45 (6) | ||||
| O-C | -1.17 ± 0.84 minutes | ||||
| ExoClock Observations (Recent) | 31 (6) | ||||
| Space Observations (Recent) | 10 (0) | ||||
| ETD Observations (Recent) | 2 (0) | ||||
| Literature Mid-times (Recent) | 2 (0) | ||||
| Kepler Rp/Rs | - | ||||
| TESS Rp/Rs | 0.09049 ± 0.00052 | ||||
ExoClock Observations |
||||
| Planet Observation Date |
Observer Observatory |
Telescope Camera / Filter / Exp [s] |
O-C minutes |
|
|---|---|---|---|---|
| HAT-P-21b (LOW) 2026-01-23 | Michael Nezel Celle Observatory | CDK 14 QHY 268M / I / 180.0 | -3.79 ± 2.02 | |
| HAT-P-21b (LOW) 2025-03-27 | Vojtěch Školník Broumov NM Observatory | Meade LX90 ACF MI C2-7000A / Clear / 60.0 | 7.33 ± 2.59 | |
| HAT-P-21b (LOW) 2025-03-27 | Manfred Raetz privat observatory Herges-Hallenberg | SCT 280/1850 (C11 with Starizona reducer) Moravian Instruments G2-1600 / AstrodonExoPlanet-BB / 120.0 | 0.27 ± 1.87 | |
| HAT-P-21b (LOW) 2025-03-27 | Deborah Smith Complejo Astronomico Los Coloraos, Gorafe | C9.25 QHY9 / R / 90.0 | -6.07 ± 4.03 | |
| HAT-P-21b (LOW) 2025-03-03 | Darryl Madison Ajijic Observatory | Celestron CPC 800 Edge HD ZWO2400MC / Clear / 90.0 | -3.85 ± 3.74 | |
| HAT-P-21b (LOW) 2025-02-27 | Pierre Farissier Obesvatoire de Haute Provence OHP France | Celestron 9 Moravian G2-4000 / Clear / 120.0 | 1.32 ± 2.02 | |
| HAT-P-21b (LOW) 2025-01-16 | Lee YuHsien KMSH Observatory | C14HD QSI-660 / R / 40.0 | -7.91 ± 5.62 | |
| HAT-P-21b (LOW) 2024-04-11 | Bryan Martin Tiger Butte Observatory Remote | AG Optical IDK ZWO ASI 294 / R / 150.0 | 1.7 ± 3.6 | |
| HAT-P-21b (LOW) 2024-02-25 | Deborah Smith El Olivar, Gergal, Spain | William Optics GT81 QHY9 / Clear / 120.0 | -0.05 ± 3.6 | |
| HAT-P-21b (LOW) 2024-01-28 | Manfred Raetz privat observatory Herges-Hallenberg | SCT 280/1850 (C11 with Starizona reducer) Moravian Instruments G2-1600 / AstrodonExoPlanet-BB / 240.0 | -8.65 ± 2.45 | |
| HAT-P-21b (LOW) 2023-12-26 | Lluis Ribe Les Pedritxes | Celestron Moravian G3 16200 / R / 120.0 | 0.01 ± 3.02 | |
| HAT-P-21b (LOW) 2023-12-26 | Yves Jongen Rasteau Observatory | Plane Wave CDK 17" SBIG STXL 11002 / Lum / 120.0 | -4.74 ± 2.02 | |
| HAT-P-21b (LOW) 2023-12-26 | Ramon Naves Montcabrer | Meade LX200 12" ACF Moravian G4-9000 / rpr / 60.0 | -8.06 ± 2.16 | |
| HAT-P-21b (LOW) 2023-03-28 | Claudio Lopresti Claudio Lopresti | Meade LX200 12" CCD Sbig ST9xe / I / 180.0 | 1.73 ± 1.87 | |
| HAT-P-21b (LOW) 2023-03-28 | Paolo Arcangelo Matassa P:M.P.H.R. Deep Sky (K81) | Ritchey Chretien 40cm-F5.3 CCD ICX453AQ / Lum / 60.0 | -2.3 ± 2.74 | |
| HAT-P-21b (LOW) 2023-03-28 | Emanuele Pavoni Leavitt Observatory | RC QHY268 / R / 140.0 | -5.04 ± 3.46 | |
| HAT-P-21b (LOW) 2023-02-28 | Stephen Mills OSO PIRATE | PlaneWave CDK24 FLI ProLine KAF-16803 / R / 120.0 | 5.79 ± 1.3 | |
| HAT-P-21b (LOW) 2023-02-28 | Eric Miny BLOIS SOLOGNE ASTRONOMIE OBSERVATORY | Newton T305 QSI 683WS / Lum / 60.0 | 2.92 ± 4.32 | |
| HAT-P-21b (LOW) 2022-05-02 | Mauro Caló Cavallino | RC SBIG ST10 / Lum / 60.0 | 5.55 ± 4.32 | |
| HAT-P-21b (LOW) 2022-05-02 | Antonio Ferretti Gruppo Astrofili Frentani - Anxanum Observatory | Meade LX200 ACF FLI MicroLine 11002 / Clear / 60.0 | 2.67 ± 4.32 | |
| HAT-P-21b (LOW) 2022-02-25 | Simon Dawes William James II Observatory | Skywatcher MN190 2 ZWO ASI 1600MM-PRO USB 3.0 Mono Camera / Lum / 120.0 | -8.67 ± 3.46 | |
| HAT-P-21b (LOW) 2022-01-28 | Tobias Gesser TURMX Observatory | CFF Telescopes 160mm APO ZWO ASI6200MM Pro / Lum / 120.0 | -1.58 ± 2.88 | |
| HAT-P-21b (LOW) 2021-04-01 | Anaël Wünsche Observatoire des Baronnies Provençales | CDK Planewave 2 ZWO ASI6200 / R / 120.0 | 1.91 ± 2.3 | |
| HAT-P-21b (LOW) 2021-03-28 | Carmelo Falco GALHassin Robotic Telescope 2 (GRT2) | Giacometti-Fogale RC16 Andor Apogee Aspen CG16M / Lum / 60.0 | -0.98 ± 2.02 | |
| HAT-P-21b (LOW) 2021-02-28 | Adrian Jones Private Observatory (I64) | Meade ACF 30cm QSI 583 / R / 99.0 | -1.52 ± 2.88 | |
| HAT-P-21b (LOW) 2021-02-28 | Lionel Rousselot Private observatory Vierzon | Newton ZWO 1600 monochrome / Clear / 180.0 | -2.39 ± 2.45 | |
| HAT-P-21b (LOW) 2021-01-26 | Yves Jongen Rasteau Observatory | Plane Wave CDK 17" SBIG STXL 11002 / Lum / 120.0 | 3.68 ± 2.45 | |
| HAT-P-21b (LOW) 2021-01-26 | Adrian Jones Private Observatory (I64) | Meade ACF 30cm QSI 583 / R / 100.0 | 0.23 ± 2.59 | |
| HAT-P-21b (LOW) 2021-01-21 | Vikrant Kumar Agnihotri Cepheid Observatory India | C11/f5.5 Schmidt-Cassegrain Atik383L+ mono / R / 90.0 | -2.67 ± 4.32 | |
| HAT-P-21b (LOW) 2020-05-07 | Manfred Raetz privat observatory Herges-Hallenberg | SCT 280 /1790 (Celestron C11 with reducer) Moravian Instruments G2-1600 / Clear / 120.0 | -5.79 ± 2.3 | |
| HAT-P-21b (LOW) 2020-01-24 | Nikolaos Paschalis Nunki Observatory | Officina Stellare RILA 400 SBIG STXL 11002 / R / 90.0 | 0.3 ± 2.16 | |
Space Observations |
||||
| Planet Observation Date |
Mission | O-C minutes |
||
| HAT-P-21b (LOW) 2022-02-21 | TESS | -1.3 ± 1.2 | ||
| HAT-P-21b (LOW) 2022-02-17 | TESS | -0.99 ± 1.22 | ||
| HAT-P-21b (LOW) 2022-02-09 | TESS | -0.72 ± 1.38 | ||
| HAT-P-21b (LOW) 2022-02-05 | TESS | -0.54 ± 1.35 | ||
| HAT-P-21b (LOW) 2022-02-01 | TESS | 1.25 ± 1.28 | ||
| HAT-P-21b (LOW) 2020-03-14 | TESS | -0.81 ± 1.44 | ||
| HAT-P-21b (LOW) 2020-03-10 | TESS | 2.08 ± 1.38 | ||
| HAT-P-21b (LOW) 2020-03-02 | TESS | -0.62 ± 1.24 | ||
| HAT-P-21b (LOW) 2020-02-26 | TESS | 2.23 ± 1.3 | ||
| HAT-P-21b (LOW) 2020-02-22 | TESS | -1.58 ± 1.37 | ||
ETD Observations |
||||
| Planet Observation Date |
Observer(s) | ETD link | O-C minutes |
|
| HAT-P-21b (LOW) 2017-04-02 | David Molina | 1491253702 | -1.36 ± 4.32 | |
| HAT-P-21b (LOW) 2014-02-11 | Paul Benni | 1392252814 | -1.44 ± 2.3 | |
Literature Mid-times |
||||
| Planet Observation Date |
Reference | O-C minutes |
||
| 2012-03-08 | Mancini et al. 2022 | -1.37 ± 0.91 | ||
| 2009-06-13 | Bakos et al. 2011 | 1.57 ± 0.99 | ||