20311+1548 A  1675

Coord 2000	20311+1548		Discov num	A  1675		Comp			Coord arcsec 2000	20 31 06.12 +15 48 27.5
Date first	1907		Date last	2018		Obs	84
Pa first	327		Pa last	301		P.A. Now (θ)	295.2°
Sep first	0.2		Sep last	0.1		Sep. Now (ρ)	0.14"
Mag pri	7.14		Mag sec	8.65		delta mag (ΔM)	1.51		Spectral class	A2V (white)
Pri motion ra	-003		Sec motion ra
Pri motion dec	-009		Sec motion dec
Notes	N O (See Notes, Orbital solution)

Visually invisible, K-band or other infrared star This double is physical.

Precise pa	301.3		Precise sep	0.139		Constellation	Delphinus		SAO	106194
HIP	101223		Tycho2	1632-01088-1		Gaia DR2	37932800896		HD	195481
ADS	13944		BD	BD+15 4181		Distance	168.92		Distance ly	551.02
last precise pa	301.3		last precise sep	0.139

Period (P)	49.62y		Periastron (T)	1947.75y		Semi-major axis (a)	0.145a
Eccentricity (e)	0.568		Inclination (i)	109.4°		Longitude of periastron (ω)	60.2°
Node (Ω)	142.6°		Note			Grade	2	(1=Definitive, 9=Indet.)
Equinox	2000		Last observation	1994

label rho theta 2000 0.056 344.4 2001 0.080 335.2 2002 0.100 330.1 2003 0.117 326.5 2004 0.131 323.8 2005 0.142 321.6 2006 0.151 319.6 2007 0.158 317.9 2008 0.163 316.3 2009 0.166 314.7 2010 0.169 313.2 2011 0.170 311.8 2012 0.170 310.4 2013 0.170 308.9 2014 0.168 307.4 2015 0.165 305.9 2016 0.162 304.4 2017 0.159 302.8 2018 0.154 301.1 2019 0.149 299.3 2020 0.144 297.3 2021 0.138 295.2 2022 0.132 292.9 2023 0.125 290.4 2024 0.118 287.6 2025 0.112 284.4 2026 0.104 280.9 2027 0.097 276.8 2028 0.091 272.0 2029 0.084 266.5 2030 0.078 260.1 Note: Theta is PA, Rho is Sep. For yearly orbits, data refer to Jan 1st.
		Measures: green=micrometric, blue=interferometric, purple=photographic

coord_2000	discov_num	comp	epoch	obs	pa	sep	mag_pri	mag_sec	spectr	notes	coord_arcsec_2000
20311+1548	A 1675		1994	80	148	0.1	7.14	8.65	A2V	NOD	203106.12+154827.5
20311+1548	A 1675		2006	81	323	0.1	7.14	8.65	A2V	NOD	203106.12+154827.5
20311+1548	A 1675		2015	83	306	0.2	7.14	8.65	A2V	NO	203106.12+154827.5
20311+1548	A 1675		2018	84	301	0.1	7.14	8.65	A2V	NO	203106.12+154827.5

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