Comments

Transit depths don't fit a pattern with wavelength, as earlier thought. This is compatible with compatible with the transit chord being close b ~0.73 (where b = impact parameter, ratio of transit chord's closest approach to star center divided by star radius). Holman et al (2006) claim it is close to a central transit (b=0.13), whereas the discovery paper (McCullough et al, 2006) reports b ~0.4. Transit depth measurements with B-band and I-band filters would help settle this since b = 0 will produce a deeper depth for B-band than I-band (and the reverse will be true for b >0.73).

Some of the observation session data sets will be represented by two light curve plots. This first one has the two systematic errors removed (temporal trend and air mass curvature) and the second one shows the same data before removing the systematics.

Basic data

    RA = 16:02:11.6, Decl = +28:10:11
    Season = May 26
    B = 11.85 ± 0.025, V = 11.19 ± 0.035, Rc = 10.81 ± 0.030, Ic = 10.43 ± 0.040, B-V = 0.66 ± 0.05 (B. Gary, all-sky)
    HJDo = 3808.91686 day (the discovery paper, McCullough et al, 2006, gives 3808.9170 days and is used for most of the following plots)
    P = 3.9414985 day (3.94151 is used in most of the following LC plots)
          3.941534 (discovery paper, McCullough et al, 2006) and 3.941634 days (Wilson et al, 2006) are based on less data
    Depth = 23.0 ± 0.5 mmag (mostly R-band)
    Length = 2.91 ± 0.05 hr (mostly R-band) 
    Fraction of time in partial transit = 0.26 ± 0.02 (R)
    Relative depth at contact #2 = 0.79 ± 0.03 (R)

Transit Paramters

Light Curves

High air mass ruined the early data and clouds affected the post-egress data.

Wind, clouds and lightning degraded data & forced early closure.

There must be an OOT slope; adding it won't affect egress solution but it would affect depth.

 
Good.

Depth deeper than expected (?).

Average of 2006.03.14 and 2006.06.01
 

Junk Bond Observatory 32-inch allowed B-band observing. Depth was greater, as expected.

Good.

Depth sortof deep. "Low frequency" variations.

 
 
This LC was used to establish HJDo for the discovery paper ephemeris.

2006.03.06. UT mid ~12.88 (i.e., 11.40 + 1.48).

2005.07.05. UT mid ~03.74 +/- 0.10.

2005.07.01. Mid UT = 05.125 +/- 0.015. Depth = 23 +/- 3 mag. Length = 3.15 +/- 0.15 hr.

Out-of-Transit (OOT) Light Curves
 

In spite of cirrus clouds, with losses up to ~1/2 magnitude, the LC is featureless at the 1 mmag level.

I have a couple dozen OOT observing sessions from May, 2006 that I'll add to this section when time permits.
 
 

All-Sky Photometry

Estimated SEs are 0.025, 0.035, 0.030, 0.040 magnitude, based on RMS residuals of fit to three Landolt star regions (N = 29, 35, 18, 14).

Finder Charts

Detailed description of Spring, 2006 observations of XO-1

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WebMaster: Bruce L. Gary.  Nothing on this web page is copyrighted. This site opened:  July 04, 2007.  Last Update:  May 12, 2008.