SIMBAD references

We report the discovery of four relatively massive (2-7 M_J) transiting extrasolar planets. HAT-P-20b orbits the moderately bright V = 11.339 K3 dwarf star GSC 1910-00239 on a circular orbit, with a period P = 2.875317 ±0.000004 days, transit epoch T_c= 2455080.92661±0.00021 (BJD_UTC), and transit duration 0.0770±0.0008 days. The host star has a mass of 0.76 ±0.03 M_☉, radius of 0.69±0.02 R_☉, effective temperature 4595±80 K, and metallicity [Fe/H] = +0.35±0.08. The planetary companion has a mass of 7.246±0.187 M_J and a radius of 0.867±0.033 R_Jyielding a mean density of 13.78±1.50 g/cm3. HAT-P-21b orbits the V = 11.685 G3 dwarf star GSC 3013-01229 on an eccentric (e = 0.228±0.016) orbit, with a period P = 4.124481±0.000007 days, transit epoch T_c= 2454996.41312 ±0.00069, and transit duration 0.1530±0.0027 days. The host star has a mass of 0.95±0.04 M_☉, radius of 1.10±0.08 R_☉, effective temperature 5588±80 K, and metallicity [Fe/H] = +0.01±0.08. The planetary companion has a mass of 4.063±0.161 M_J and a radius of 1.024±0.092 R _J yielding a mean density of 4.68^+1.59_- 0.99_g/cm3. HAT-P-21b is a borderline object between the pM and pL class planets, and the transits occur near apastron. HAT-P-22b orbits the bright V = 9.732 G5 dwarf star HD 233731 on a circular orbit, with a period P = 3.212220±0.000009 days, transit epoch T_c= 2454930.22001±0.00025, and transit duration 0.1196 ±0.0014 days. The host star has a mass of 0.92±0.03 M_☉, radius of 1.04±0.04 R_☉, effective temperature 5302±80 K, and metallicity [Fe/H] = +0.24±0.08. The planet has a mass of 2.147±0.061 M_J and a compact radius of 1.080±0.058 R_J yielding a mean density of 2.11^+0.40 _- 0.29_ g/cm3. The host star also harbors an M-dwarf companion at a wide separation. Finally, HAT-P-23b orbits the V = 12.432 G0 dwarf star GSC 1632-01396 on a close to circular orbit, with a period P = 1.212884±0.000002 days, transit epoch T_c= 2454852.26464±0.00018, and transit duration 0.0908 ±0.0007 days. The host star has a mass of 1.13±0.04 M_☉, radius of 1.20±0.07 R_☉, effective temperature 5905±80 K, and metallicity [Fe/H] = +0.15±0.04. The planetary companion has a mass of 2.090±0.111 M _J and a radius of 1.368±0.090 R_Jyielding a mean density of 1.01 ± 0.18 g/cm3. HAT-P-23b is an inflated and massive hot Jupiter on a very short period orbit, and has one of the shortest characteristic infall times (7.5^+2.9_- 1.8_Myr) before it gets engulfed by the star.