XO-4
AXA Light Curves, Finder Chart & All-Sky Photometry Results

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    Basic data
    Comments
    Summary of transit solutions
    Transit LCs
    Out-of-transit LCs
    All-sky photometry
    Finder Image

Basic data

    RA = 07:21:33.6, DE = +58:16:02
    Season = Jan 15
    B = 11.240 ± 0.030, V = 10.674 ± 0.030, Rc = 10.324 ± 0.030, Ic = 10.057 ± 0.05, B-V = 0.566 ± 0.05 (all-sky, all SE are total SE, orhtogonal sum of formal statistical and estiamted systematic SEs)
    HJDo = 4485.9322 (4)   & P = 4.12502 (2) day (Schneider listing)
     HJDo = 4485.9319 (6) & P = 4.125115 (4) day (AXA fit, below)
    Depth = 9.8 ± 1.0 mmag (R-band)
    Length = 4.58 ± 0.10 hr
    Fp = 0.18 ± 0.10, F2 = 0.74 ± 0.10 (fraction of transit that's partial and ratio of depth at contact #2 to mid-transit)
    Impact parameter, b = 0.18 ± 0.14

Comments

A period change might be required, but we need more data to be sure.

Summary of Transit Solutions

   

 

 

       

     

Light Curves



9311MQZ1


8c11FC21


8b28NR21


8a26SG21 






 

Out-of-Transit (OOT)

 
Excellent data quality!


All-Sky Photometry

Here's an image showing XO-4 (formerly referred to as "0607") and nearby stars.

 
Figure 1. XO-4 (formerly reffered to as "0607"), FOV = 16 x 11 'arc, north up, east left. Star numbers are shown for the table in the next figure.

 
Figure 2. Weighted average magnitudes of XO-4 ("x0607") and nearby stars using all-sky measurements from all (3) all-sky observing dates.

Here's a summary of XO-4 all-sky magnitude measurements:     

XO-4
    B-mag = 11.240 ± 0.029 (formal SE)
    V-mag = 10.674 ± 0.019 (formal SE)
    R-mag = 10.324 ± 0.008 (formal SE)
    I-mag  = 10.057 ± 0.018 (formal SE)
               
 
 Figure 3. Summary of various V-mag & R-mag estimates for XO-4 (formerly known as "0607").

To see a large-format LRGB image of "0607" for the purpose of verifying that stars that should be blue and red according to the above table are in fact blue and red, click LRGB_0607.

Table I: Number of Landolt Star Fields and Number of Landolt Stars Used in All-Sky Solutions
Observing Date
 Landolt
Fields
 BLU
 VIS
 RED
 INF
2008.01.10
 6
 36
 37
 19
 19
2008.01.19
 5
 29
 48
 39
 37
2008.01.20
 2
 0
 10
 8
 0

Estimated total SE values (orthogonal sum of statitical and systematic SEs) are 0.03, 0.03, 0.03 and 0.05 mag. The B-V SE is 0.05 mag.

     
Figure 4. Color-color scatter diagrams showing that the XO-4 star field has similar color relationships to those in the set of Landolt stars, thus validating the quality of the all-sky observations reported here.

These are "internal consistency checks." It passes!

 

I conclude that interstellar reddening biases the Tycho V-mag value, and might also influence the conversion from J and K to V. The two all-sky measurements provide a consistent result that is free of the interestellar reddening biases. which argues for V-mag = 9.80 ± 0.03.


Finder Image

 
Figure 5. XO-4 {"0607"), FOV = 16 x 11 'arc, north up, east left.
 
Here's a reference to the "discovery paper" for XO-4:

"XO-4b: An Extrasolar Planet Transiting an F5V Star" P. R. McCullough, Christopher J. Burke, Jeff A. Valenti, Doug Long, Christopher M. Johns-Krull, P. Machalek, K. A. Janes, B. Taylor, J. Gregorio, C. N. Foote, Bruce L. Gary, M. Fleenor, Enrique García-Melendo, T. Vanmunster, http://fr.arxiv.org/abs/0805.2921 

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WebMaster: Bruce L. Gary.  Nothing on this web page is copyrighted. This site opened:  May 21, 2008.  Last Update:  2009.03.12