HD 189733
AXA Light Curves

Links internal to this web page

    Basic data
    Light Curves Only
    Table of Measurements & Plots of Transit Properties
    Amateur Transit LCs
    Professional Transit LCs
    OOT LC
    Finder image

Comments on LCs on this web page

    Period seems to be good. Length is stable.
    The z-band depth may be 25 mmag, but V, R, and C-band depths are 29 mmag.

Basic Data - Updated 2009.08.30
      RA = 20:00:43.7, Decl = +22:42:37
      Season = July 21
     HJDo = 3988.80336 (24) & P = 2.218573 (20) day (Schneider listing in Extrasolar Planets Encyclopaedia)
     HJDo = 3988.80319 (24) & P = 2.2185762 (3) day (AXA data fit, below); or better yet: HJDo = 4432.51844 (17) & P = 2.2185762 (3) day (another AXA data fit, below)
     Depth = 29.0 ± 0.4 mmag (VRC-band)
     Length = 1.70 ± 0.03 hr (VRC-band)
     Fp = 0.39 ± 0.02, F2 = 0.85 ± 0.05
     b = 0.66

Table of Measurements and Plots of Transit Properties - Updated 2009.08.30





Transit light curve

LCs below here have NOT been included in table & plots (above)

Notice the faded region indicated by double- arrow, which I can't explain. (The overall curvature of this LC is most likely due to "air mass curvature," produced by HD189733 being redder than the average of reference stars.) A sine-wave fit was used to represent whatever the systematic error produced the fade feature.

LC's below here HAVE been included in the above table & plots.



9919LCO3  Digital SLR camera used; only blue pixels used for this LC. Good work!

9919LCO2  Digital SLR camera used; only red pixels used for this LC. Good work!

9919LCO1  Digital SLR camera used; only green pixels used for this LC. Good work!




Light curves below here have been included in table & plots








9626SFI  (I subtracted one hour from JD time tags, & inverted mag's; I hope this was appropriate)










This light curve was made with a 1.33-inch aperture "telescope" (actually, a camera lens) by Petr Svoboda (Czech Republic). It illustrates that for bright exoplanet stars "aperture isn't everything." Observing technique and an understanding of observing and image analysis procedures can be crucial to extracting the information that is capable of being gleaned from an observing session. Congratulations to Petr Svoboda for demonstrating what can be done using a small aperture to obtain a scientifically useful exoplanet transit light curve. (He used a Sonnar 135/3.5 camera lens with a R-band filter attached to a ST7-XME CCD, defocused so that FWHM ~ 4 pixels; exposure times were 1 to 3 minutes to assure linearity. Individual images exhibited SE ~ 10 mmag.)







Thanks, Isaac Cruz, for creating this LC.


First attempt with a 8-inch telescope and V-band filter, by Steve Orlando (New York). Take note "beginners," you can do it too!

7728srdc  First submission for Gregor Srdoc! Good work! Same depth as measured by Ramon Naves in Spain for same transit.

Note the 2-second exposure time. Mid-transit "on schedule"!

Note the excellent 2-mnute RMS!

Looks like the observer's clock was set 1 hour off. If we subtract 1 hour from the observation times we'd be able to say that mid-transit was ~3 min late.


Professional LCs

Algol et al (2008) Switzer 8 micron LC (without and with limb darkening modeled). The ephemeris solution is HJDo = 2454279.436741± 0.000023 & P = 2.21857503 ± 0.00000037 days.

Out-of-Transit Light Curves

9722SG2  Notice the sinusoidal variation with a period of ~ 1.8 hrs, amplitude ~ 1.5 mmag. This might be real.

Just as ingress was expected a thunderstorm began! At least the 4.5 hours of OOT data is featureless.

Finder Image

Return to calling web page AXA


Bouchy, F. et al, 2005 (discovery paper) link
Algol, E. et al, 2008, Spitzer 8 micron LC link
Miller-Ricci, E. et al, 2008, ApJ, 682, 593 link 

WebMaster: Bruce L. GaryNothing on this web page is copyrighted. This site opened:  August 10, 2007 Last Update:  2012.09.30