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Goto Images from 2007-05-14

Further Base Line Observations of HAT-P-2 , Parent Star to Exosolar Planet

A further series of baseline images of HAT-P-2 (host star to exosolar planet HAT-P-2b) were acquired through R filters.

(Description of earlier baseline series of 2007-05-07) 

R Band images were acquired with 15s exposure at airmass values of 1.04. Analysis of S/N values show occasional reductions in S/N value due to passing cloud, and a S/N cutoff was applied to screen out, sub-standard images.   Of the remaining 31 images, it was found that the average S/N value for the 15s exposures was 212 (compared to average of 217 measured on 2007-05-07). 

The calculated R Band magnitude for HAT-P-2 was 8.36 +/-0.01 from an initial 15 minute run.. This is identical with a value of 8.36 +/- 0.01 calculated on 2007-05-07. (these values can be compared with an expected R Band magnitude of 8.47, based on Arne Equations & catalog Bt, Vt values). Plotting the difference between calculated HAT-P-2 magnitude of individual images and average HAT-P-2 magnitude shows a range from -0.016 to +0.014 (or a SD of 0.007).  

A further set of 15s exposures was taken 1h 20m later.  Although airmass was similar and S/N values were broadly similar the calculated magnitude of HAT-P-2 was a distinctly brighter by 0.06 mag brighter. No obvious reason for this discrepancy has been found.   It is conjectured that explaination lies with different pixel positions between the two image sets/ coupled with a deficiency with the Flat frame used to reduce the image.

HAT-P-2, Reference Stars

Annotated CCD Image  20s, 2x2 binning, R Filter 2007-05-07 23:31 hUT (#196065)

Analysis of HAT-P-2 Base Line Images (R Band)

HAT-P-2  - Comparison between datasets on 2007-05-07 and 2007-05-15

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