[vsnet-newvar 1816] Re: Some new eclipsing binaries

[Chris Lloyd <cl@ast.star.rl.ac.uk>]

A look at the Tycho data for these stars is not particularly revealing but
suggests that BD-2 2221 rather than BD-2 2220 is the more likely
candidate. The 1-day alias of the period found for HD 296761 may also be
present. Generally the Tycho data are doubtful, but do not provide clear
evidence of variability.

 RA       Dec     ID     Type Ampl   Epoch    Freq c/d  Note
104.575 -4.635  HD 51697  EA   0.2  2452640.75  1.798

TYC 4809-819-1 and TYC 4809-819-2; all the data are flagged and the errors
are typically 0.2-0.3 mag.

105.271 -3.967  HD 52433  EA   0.3  2451586.64  1.339

The Tycho epoch photometry of HD 52433 = TYC 4822-2853-1 does show
variation at this level, BUT the BT and VT periodograms are inconsistent.

108.783 -4.745  HD 296761  EW   0.7  2452233.88  1.722

TYC 4824-153-1; The Tycho data are mostly flagged and very noisy with a
large number of doubtful points. However, the two principal features in
the periodogram lie at 7.735 and 9.727 cycles/day and are possibly
consistent with an alias of the Stardial data. The amplitude is 0.5 mag.

114.767 -2.657  BD-2 2220 EW   0.4  2452323.65  1.440  BD-2 2221?

The Hipparcos photometry of BD-2 2220 = HIP 6833 shows no sign of
variation with <Hp>=8.733+/-0.011 (sd), ignoring one obviously discordant
point. However Tycho photometry of BD-2 2221 = TYC 4835-1947-1 shows a
sinusoidal variation with an amplitude of 0.4 mag at 3.01 or 3.11
cycles/day in both BT and VT. Having said that there are some very
suspicious points and most of the observations are flagged.

121.574 -4.447  HD 67093  EA   0.5  2452252.86  0.461

The Tycho photometry of TYC 4854-362-1 is mostly flagged and the maximum
amplitude of any sinusoidal variation is 0.2 mag.

Chris Lloyd

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