Comments

The TTV plot for this amateur data appears to be plagued by systematic errors, which is a more credible interpretation than the one requiring another planet in a resonant orbit. An investigation by Alonso et al (link) of precision measurements of 80 consecutive transits (139 days) by CoRoT showed no evidence for TTV greater than ~10 seconds. This result was obtained by analyzing LC data in a way that minimized stellar activity effects; when the data were processed using a simple LC fitting procedure the greatest TTV anomaly was ~20 seconds. Therefore it is unlikely that the TTV of this amateur data is real, but it does illustrate one of the things we're looking for.

Basic data

    RA = 19:27:06.5, DE = +01:23:02
    Season = July 14
    V = 12.57
    HJDo = 4237.53562 ± 0.00014
    P = 1.7429964 ± 0.0000017 days (1.742988(10) according to data on this web page)
    Depth = 35.2 ± 0.3 mmag
    Length = 2.266 ± 0.013 hr
    Fp = 0.31 ± 0.05, F2 = 0.82 ± 0.08

Table of amateur observations

             
Let's not take the slope seriously until there's more data.

Light Curves - Amateur

Normally I don't accept observations with a span of less than 2 hours but this one spanned a predicted egress and the depth is large and with well-established length and shape it's possible to objectively constrain all parameters but mid-transit time and extract something useful. To judge whether the result is useful I note that its contribution to the TTV plot is eminently believable.


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Light Curves - Professional


Copied from discovery paper: Alonso et al, 2008

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Finder Charts

References

Discovery paper: Alonso et al, 2008a
TTV & Secondary Transit Search: Alonso et al, 2008b

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WebMaster: Bruce L. Gary.  Nothing on this web page is copyrighted. This site opened:  May 08, 2008.  Last Update:  2008.11.02