O-C diagram for Mira from derived elements

Dave McAdam

Maxima of Mira were found from BAAVSS observations by a computer program and method described previously. (see The Maxima of Chi Cygni)

The O-C values are plotted from the derived elements; 2412866.6 + 332.83E
Forthcoming maxima should occur within two or three weeks of; JD2451474 = 1999 Oct 22, JD2451807 = 2000 Sep 19, JD2452140 = 2001 Aug 18, JD2452473 = 2002 Jly 17, JD2452806 = 2003 Jun 15

Mira is difficult to observe in April and May (see Mira's 'closed season') hence maxima can be missed when they occur at this time of year. As can be seen in the long-term lightcurve, the brightness of maxima vary considerably. In the table below, the least-squares fits give values between 5.0m and 2.1m.

Table of maxima found for Omicron Ceti

-d and +d = days considered before and after the observed max.
obs = number of observations used in the fit.
ex = additional scattered observations excluded from the fit.
F = estimated worthiness of the fit;- Good, Average, Poor.
mag = maximum of the fitted parabola; mags from very poor fits are omitted.

JD  maxima   date    -d  +d obs ex F  mag
2412901=1894 Mar 13  23  27   9  1 P  3.5
2413258=1895 Mar 05  41  12  11  0 P  4.0
2413596=1896 Feb 06  34  12  14  0 P  3.9
2414913=1899 Sep 15  38  31  20  0 G  4.0
2415221=1900 Jly 20  35  69  14  0 A  3.5
2416549=1904 Mar 09  30  20  24  0 A  3.1
2416901=1905 Feb 24  34  36  51  0 G  3.8
2417221=1906 Jan 10  26  24  48  0 A  4.4
2417557=1906 Dec 12  20  20 112  0 G  2.1
2417886=1907 Nov 06  25  25  86  0 G  3.4
2418226=1908 Oct 11  25  33 125  0 G  3.6
2418553=1909 Sep 03  32  28  66  0 G  3.1
2418876=1910 Jly 23  34  26  18  1 G  3.3
2419209=1911 Jun 21  16  34  10  0 A  3.3
2419880=1913 Apr 22  33  40  10  0 A  2.9
2420214=1914 Mar 22  41  22  63  2 A  3.2
2420530=1915 Feb 01  23  27  65  0 G  3.7
2421191=1916 Nov 23  31  29  86  0 G  3.8
2421507=1917 Oct 05  32  28  80  0 G  3.6
2421857=1918 Sep 20  24  26  66  0 G  3.6
2422183=1919 Aug 12  22  28  46  0 G  3.0
2422867=1921 Jun 26  42  38   6  1 P  4.0
2423492=1923 Mar 13  29  21  53  0 A  3.0
2423828=1924 Feb 12  35  25 139  0 G  4.9
2424163=1925 Jan 12  27  23 160  0 G  3.8
2424489=1925 Dec 04  23  27 140  0 G  3.3
2424809=1926 Oct 20  21  19 126  0 G  3.2
2425151=1927 Sep 27  23  27  67  0 G  4.2
2425484=1928 Aug 25  21  29  74  0 G  2.9
2425810=1929 Jly 17  23  27  28  0 G  4.4
2426147=1930 Jun 19  27  33  10  0 A  3.6
2426824=1932 Apr 26  51  46  12  0 P   - 
2427156=1933 Mar 24  35  25  30  2 A  3.8
2427477=1934 Feb 08  29  21  76  0 G  4.0
2427805=1935 Jan 02  21  19  62  0 G  2.6
2428158=1935 Dec 21  32  18  34  0 G  4.5
2428491=1936 Nov 18  20  20  85  0 G  2.6
2428840=1937 Nov 02  25  25  54  1 G  4.7
2429166=1938 Sep 24  18  22  31  0 G  4.1
2429485=1939 Aug 09  20  30  19  3 A  3.1
2431488=1945 Feb 01  21  25  20  0 G  2.7
2431831=1946 Jan 10  27  23  30  0 A  4.3
2432161=1946 Dec 06  25  25  53  0 G  4.3
2432479=1947 Oct 20  25  25  34  1 G  3.0
2432817=1948 Sep 22  19  31  22  2 G  3.7
2433156=1949 Aug 27  26  24  21  0 G  2.8
2433490=1950 Jly 27  24  36   8  1 A  3.5
2435146=1955 Feb 07  30  25  23  0 G  4.0
2435490=1956 Jan 17  35  25  32  1 A  3.6
2435808=1956 Nov 30  28  32  20  0 G  4.0
2436150=1957 Nov 07  45  63  26  0 P  4.0
2436486=1958 Oct 09  21  29  25  0 A  3.2
2436798=1959 Aug 17  38  22  20  0 A  3.4
2437141=1960 Jly 25  31  29  13  0 A  3.4
2438466=1964 Mar 11  37  13  12  0 A  3.5
2438822=1965 Mar 02  43  34  25  0 A  3.3
2439138=1966 Jan 12  36  35  20  0 A  3.1
2439469=1966 Dec 09  34  26  31  0 G  3.6
2439824=1967 Nov 29  33  17  51  0 G  3.5
2440127=1968 Sep 27  30  40  26  0 G  4.0
2440463=1969 Aug 29  36  44  20  0 A  2.5
2440824=1970 Aug 25  33  27  21  0 G  4.0
2442484=1975 Mar 12  28  22  45  0 G  3.1
2442825=1976 Feb 16  23  27  46  0 G  5.0
2443169=1977 Jan 25  24  26  44  0 G  3.2
2443492=1977 Dec 14  26  34  60  0 G  2.9
2443842=1978 Nov 29  24  26  31  0 G  4.9
2444175=1979 Oct 28  27  23  39  0 G  3.9
2444510=1980 Sep 27  25  25  65  0 G  3.8
2444852=1981 Sep 04  25  25  40  0 G  3.9
2445185=1982 Aug 03  25  25  22  0 A  3.1
2446841=1987 Feb 14  24  22  69  0 G  3.0
2447176=1988 Jan 15  21  29 147  1 G  4.2
2447509=1988 Dec 13  35  25 122  1 G  3.7
2447820=1989 Oct 20  26  24  74  0 G  2.9
2448172=1990 Oct 07  39  41  57  0 A  3.9
2448500=1991 Aug 31  26  44  59  0 G  3.9
2450494=1997 Feb 14  24  21  57  1 G  2.5
2450817=1998 Jan 03  17  33  63  0 G  3.8
2451163=1998 Dec 15  33  27  69  0 G  4.9