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[vsnet 601] Comparison sequence for R Leonis
- Date: Sun, 14 Apr 96 20:25:15 MST
- To: macrobert@skypub.com, vsnet@kusastro.kyoto-u.ac.jp
- From: bas@lowell.edu (Brian Skiff)
- Subject: [vsnet 601] Comparison sequence for R Leonis
- Sender: owner-vsnet@kusastro.kyoto-u.ac.jp
I have measured all the stars on the AAVSO (b)-scale chart for R Leonis
that do not have previously-published photometry. The stars were measured as
before on two nights each using the Lowell 53cm photometric telescope,
Stromgren b and y filters, and 29-arcsec diaphragm. The results for the
standards observed were listed in the report for W Sextantis [vsnet 600].
In the middle range of magnitudes, the AAVSO chart has a fairly
consistent zero-point error averaging about -0.3 mag. (chart magnitudes too
bright), while at the bright and faint extremes they are mixed; the faintest
chart star ("104") is rated 0.9 mag. too bright. The funky magnitudes are
faithfully recorded on the charts accompanying Alan MacRobert's otherwise very
nice article about variable-star observing (which features R Leonis) starting
on page 48 of the March 1996 issue of Sky & Telescope.
Because of the mess, I give below a complete summary of photometry for
the field, including previously published results. The stars are listed in
order of AAVSO magnitude (first column), which is nearly their order by V as
well. My new measurements are those having errors listed on the second line
of an entry; the remainder are from the literature, as specified in the
remarks. All the stars as faint as V=7.6 (AAVSO "72") have been measured by
others, and many of the fainter ones have been observed previously for various
purposes as well. In all cases these confirm the present observations (or
mine confirm theirs!) to within a percent or so.
R Leonis has one of the longest observational histories of any variable.
The first maximum was observed in 1757, and it has been under steady
observation since 1782. Collecting the entire 240-year series of data and
placing it onto a uniform system (which can now be done) would be a tremendous
task, but might yield some interesting astrophysical results in terms of
cycle-length variations and searches for very-long-period oscillations.
Summary of photometry for stars in the field of R Leonis
AAVSO Name RA (2000) Dec V b-y spec remarks
var R Leonis 9 47 33.5 +11 25 44 7.172 1.970 M8IIIe (1)
38 omicron Leo 9 41 09.0 +9 53 32 3.52 0.306 F6II+A1/5V (2)
58 18 Leo 9 46 23.4 +11 48 35 5.63 0.917 K4III (3)
64 19 Leo 9 47 26.0 +11 34 05 6.45 0.152 A7Vn (4)
66 21 Leo 9 50 49.3 +11 50 32 6.865 -0.018 A0 (5)
67 23 Leo 9 51 02.0 +13 03 58 6.461 1.031 M0III (6)
.006 .005
69 HD 84183 9 43 35.3 +10 31 08 7.010 0.359 F8V (7)
72 HD 85091 9 49 48.5 +11 06 23 7.613 0.398 F8 (8)
75 HD 84740 9 47 29.3 +10 50 39 7.705 1.038 K0 (9)
.000 .001
77 HD 84764 9 47 41.3 +10 23 06 7.823 0.136 A5 (10)
80 HD 85269 9 50 56.8 +10 52 57 8.312 0.064 A0
.013 .020
82 HD 84951 9 49 00.0 +12 05 47 8.428 0.301 F2 (11)
84 HD 84915 9 48 51.6 +12 31 20 8.693 0.674 G5
.004 .001
86 HD 84348 9 45 00.4 +10 48 08 8.832 1.112 M1(iii) (12)
.024 .003
88 HD 85041 9 49 35.9 +12 05 49 9.010 0.617 G5 (13)
.001 .003
90 BD+12 2093 9 47 15.6 +11 25 41 9.19 K2 (14)
91 HD 84938 9 48 50.4 +10 33 32 9.469 0.301 F5
.001 .008
96 BD+12 2094 9 47 19.7 +11 22 35 9.843 0.405 (g2v) (15)
.011 .015
97 BD+11 2105 9 48 21.1 +11 18 13 10.00 (d)G5 (16)
101 BD+12 2089 9 45 58.5 +11 30 27 10.502 0.450 (g5v)
.012 .007
104 BD+11 2098 9 46 30.2 +11 18 49 11.333 0.385 (d)G5 (17)
.019 .021
(115) GSC 0831-0371 9 48 11.1 +11 28 21 11.50 (g2v) (18)
remarks:
(1) HR 3882 = HD 84748, observed 9 Apr 1996 UT.
(2) HR 3852 = HD 83808. V from J66 "prime list". also V=3.519 (K91). b-y
from CB70.
(3) HR 3877 = HD 84561. V from HO87. also V=5.665 (K91). b-y from Eggen.
(4) HR 3880 = HD 84722. V from J66 "prime list", b-y from SP65. Also V=6.447
(K91); V=6.452/b-y=0.163 (Sowell), V=6.456/b-y=0.166 (BSkiff), and
b-y=0.157 (PC90).
(5) HD 85259. near X Leonis. V from K91. also V=6.857 in Geneva seven-color
photometry catalogue. b-y from Eggen.
(6) HR 3896 = HD 85268. Also V=6.45 (Oja), 6.462 (K91). Not variable over
a few months timescale (sigma = 0.013) wrt 18 Leo (Percy et al. 1994,
PASP 106, 611).
(7) V/b-y from O83+O94b. Also V=7.017 (K91), 7.00 (Oja).
(8) V/b-y from O83. Also V=7.64 (SK), 7.61 (CL); V=7.625, b-y=0.402
(Schuster).
(9) b-y color indicates spectral type is probably an M0-giant.
(10) V/b-y from O83. Also V=7.823 (K91), 7.81 (Oja).
(11) V/b-y from O83.
(12) probably slightly variable.
(13) not variable, see Ashbrook 1951, AJ 56, 87.
(14) V from PC90.
(15) GSC 0831-1223.
(16) V from PC.
(17) also V=11.334 (PC90).
(18) V from PC90.
CL - Carney & Latham 1986, AJ 92, 116.
CB70 - Crawfrod & Barnes 1970, AJ 78, 978.
Eggen - Eggen 1986, PASP 98, 423, or 1989, PASP 101, 45.
HO87 - Haggkvist & Oja 1987, A&ASuppl 68, 259.
J66 - Johnson et al. 1996, Comm. LPL 4, 99.
K91 - Kornilov et al. 1991, Trudy Gosh. Astron. Inst. Sternberg, 63, 1.
Oja - Oja 1987, A&ASuppl 71, 561 or 1991, A&ASuppl 89, 415.
O83 - Olsen 1983, A&ASuppl 54, 55.
O94b - Olsen 1994, A&ASuppl 106, 257.
PC90 - Persinger & Castelaz 1990, AJ 100, 1621.
SK - Sandage & Kowal 1986, AJ 91, 1140.
Schuster - Schuster et al. 1993, A&ASuppl 97, 951.
Sowell - Sowell & Wilson 1993, PASP 105, 36.
SP65 - Stromgren & Perry 1965, Report Inst. Advanced Study, Princeton.
\Brian Skiff (bas@lowell.edu)
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