Light Curves

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    Basic data
    Table & Plots
    Amateur Lransit LCs
    Professional Light Curves
    OOT LCs
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Comments on LCs on this web page:

Three LCs show brightenings either after egress, before ingress or both. This is not seen in the other LCs, so if there's forward scattering causing these occasional brightenings it couldn't be due to a simple ring system. Let's keep track of the egress and ingress shapes to see if more brightenings are present.

It has been suggested by Maciejewski et al, 2010 (http://arxiv.org/abs/1006.1348) that TTV exhibits a sinusoidal variation with a period of ~ 127.4 days, which can be produced by a second exoplanet in a close to 2:1 outer orbit resonance. Their best fit model has an amplitude (half of peak-to-peak) of ~ 2.0 minutes. The Maciejewski et al analysis uses the Baryccentric Julian Date reference frame (BJD) and Terrestrial Dynamic Time (TT) time standard, which is a practice all exoplanet observers should adhere to (see http://arxiv.org/abs/1005.4415 for more information about this). I have processed the data used in the Maciejewski et al analysis and arrive at a similar solution, given below (Fig. 1a). I have also converted all AXA amateur mid-transit times to the Barycentric Dynamical Time (TDB) time standard (the same as TT time to within ~ 50 ms) using the web site converter for JD_UTC to BJD_TDB (http://astroutils.astronomy.ohio-state.edu/time/utc2bjd.html). Adopting a 127.4-day periodicity does not show a similar TTV variation. It is probably premature to conclude that a second exoplanet near the 2:1 outer orbit is perturbing WASP-3b producing a ~ 127-day TTV. More observations are needed to resolve this intriguing possibility.

Note: On 2010.07.14 I sent an e-mail to many exoplanet observers calling for observations of WASP-3 to clarify the matter of a TTV caused by a second planet. I made a grievous mistake in thinking the TTV had a periodicity similar to the putative 2:1 outer orbit second planet, when in fact the suggestion by Maciejewski et al was for a 127.4 +/- 4.4 day periodicity caused by the 2:1 second planet. The following figures incorporate this correction (though one professional datum in my plots differ from that plotted in the Maciejewski et al paper). 

Figure 1a. Folded O-C for "professional" data using 127.8-day period (best chi-square). One measurement (Tripathi et al, 2454627.72098) has been deleted since it was a partial transit.

Figure 1b. Folded O-C for AXA amateur data using 127.4-day period. No support for the 127.8-day periodicity that appears to be present in the professional data set. 

Both plots use BJD (Baryccentric Julian Date) reference frame and TDB (Barycentric Dynamical Time) time standard.

Periodogram by Sigfried Vanaverbeke (2010.07.16). Note peaks at ~ 120 days and 91 days.

Basic Data - Updates After Each New LC Terminated 2009.07.20 (occasional updates will be made when I have time)

    RA = 18:34:31.6, Decl = +35:39:41
    Season = July 2
    V = 10.64
    HJDo = 4605.55915 (23) & P = 1.846834 (2) day (as listed on Schneider's Extrasolar Planets Encyclopaedia, from Gibson et al, 2008)
    BJD_TDBo = 4605.55995 (16) & P = 1.8468358 (6) day (fit using AXA data); or even better: BJD_TDBo = 4697.90174 (16) & P = 1.8468358 (6) day
    Depth = 12.8 ± 0.7 mmag (VRI-bands)
    Length = 2.70
± 0.05 hr
    Fp = 0.25
± 0.03, F2 = 0.89 ± 0.08

Table and Plots
TTV using BJD (Baryccentric Julian Date) reference frame and TDB (Barycentric Dynamical Time) time standard.              




Light curves not yet included in table & plots (above)




Light curves  - Updated 2009.08.25





Transit Light Curves - These Light Curves Have Been Included in Plots & Table in Above Section















Note the apparent "brightening" after egress. Such a feature could be produced by the hot Jupiter having a rings system (that forward scatters).


Out-of-Transit (OOT) Light Curves

Professional Light Curves

From Gibson, N. P., et al, 2008, using 2-m Liverpool Telescope (La Palma) with bandpass 0.5 - 0.7 micron, on dates 2008.05.18 (top) and 2008.09.04 (bottom). (Try to overlook the excessively conservative error bars, e.g., SE Sermon.)  


Maciejewski et al, 2010: http://arxiv.org/abs/1006.1348

Tribathi et al, 2010: http://iopscience.iop.org/0004-637X/715/1/421

Gibson, N. P., et al, 2008, "Updated parameters for the transiting exoplanet EASP-3b using RISE,..."   arXiv link

Finder Image

SkyMap image of WASP-3 star field (http://sky-map.org/).

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WebMaster: Bruce L. Gary. Nothing on this web page is copyrighted. This site opened:  November 06, 2007 Last Update:  2010.07.30