Observations were commenced at 02:01 local time 20060608 (06:01 UT  20060609) following an earlier XO-1b transit run. Atmospheric conditions were  hazy with occasional thin cirrus cloud. Observations occured while TrES-1b's parent star was at very low air mass  Lunar phase was 89% however the moon was very low in the sky at the time of observation and the observatory dome and telescope dewshield effectively eliminate stray lighting. Thin clouds passed through just before and during the predicted time of ingress @06:53 UT.  Eight data points were found to be > 5sigma from the rest of the population and were rejected.  The blue dots represent individual 20 sec exposures. The average standard deviation for the populations is 0.0046mag. Ten individual data points were averaged ( non-overlapping) to produce the larger solid red dots corresponding to a time interval of 5.9 min for each datum. Predicted mid-transit was at 08:11UT. My observations reveal maximum depth  near this time as well. I was unable to observe egress due to the arrival of dawn.Observations were terminated early at 04:26 local time to prevent the scope from striking the telescope pier. The observatory was operating autonomously under control of ACP ver 4.2
 
 
 

Details:
Observations were conducted from my suburban backyard observatory located in Knoxville, TN. Instrumentation used was a 0.36m Meade SCT with an Optec TCF-s focuser mounted on an Astrophysics AP1200 GTO mount with an SBIG ST10XME/CFW-8a CCD binned 2x2. An Agos universal focal reducer was used inline producing an effective focal length of 2261mm (f/6.37) with the current spacing. The resulting image scale is 1.24 arcsec/pixel with a fov of  15.2 x 22.5 arcmin. CCD operating temp was set to -20C, operating with water cooling assist. 20sec exposures were utilized with a Schuler Rs photometric filter. The scope was autofocused with Focusmax then the temperature compensation feature was enabled in Maxim, automatically maintaining correct focus position for the Optec TCF-s for the duration of the observing run. The exposures were autoguided with the ST10 camera's self guiding TC-237 ccd. This allowed the star centroids to be maintained to within 1.5 pixels over the length of the observing run. Calibration flats were acquired at dusk. Dark and Bias frames were acquired at a later time at the same operating temp and integration time as light frames. Master calibration frames consist of 10 flats median combined, 40 bias median combined, and 40 darks sigma clipped combined. Acquisition and calibpration performed  Maxim DL/CCD with AIP4Win v2 utiliized for the photometry analysis. Data manipulation and charting were performed with MS Excel 2003.

This is my first TrES-1b observation of the 2006 season

mlfleenor"at"charter.net

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