David's Astronomy Pages CCD Images - Session 51 (2003-08-12 / 2003-08-13) Images (S50)   Images (Main)   Home Page   Images (S52)

Notes (S00051)

Sky transparency was fairly poor and heavily effected by moonlight from near full moon. Session continued the current light survey project and tracked a couple of minor planets. 267 CCD frames were taken over a period of 5.9 hours, including a sequence of 107 images (20 sec exposures) of Kleopatra(216) and 105 images (60 sec exposures) of Illapa(37655).

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Kleopatra (216) - Minor planet

216 Kleopatra

Annotated CCD Image 20s, 2x2 binning, Unfiltered  2003-08-12  22:56h  UT (#51041)

CCD Image,  105 x 20s exposures (summed) Exposures at approximately 1min 7sec intervals.  The white steak records 58 arc sec motion of the  minor planet over a period of 1 hr 56 min (= 30 arc sec/hour) The image records stars down to Mag +16 (2003-08-12  22:56h to 2003-08-13 00:52h UT (#51041- 45147) (See Animated Sequence of CCD Images - 10 minute intervals, 0.4 MB)

Light Curve for 216 Kleopatra, generated from 101 CCD Image   taken over a period of 2 hours (Light Curve display in Excel). The light curve records a 0.5 mag variation (unfiltered mag range of +11.0 to +11.5),  with peak to tough time of 1 hr 11 min. Whilst this suggest a possible rotational period  of around 2 hr 22m, web based resources on the www indicate a rotational period of around 5.3 hours.  (2003-08-12  22:52h to 2003-08-13 00:52h UT (#51039- 45147)

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Illapa (37655) - Minor Planet

Illapa (37655) marked by cross-hairs. Note how its image is streaked, due to its movement  during the 60 sec CCD exposure.  (minor planet moving at 15.4 arc sec/minute)

CCD image,  60 sec exposures (unfiltered) 2003-08-13  02:35h UT (#51234) 11.4 x 5.9 arc mins

Composite montage, showing rapid (15.4 arc min/hour) movement of Illapa  through starfield in Aquarius over 2 hours (click on image to see at full size 0.4 MB)

CCD images,  60 sec exposures (unfiltered) 2003-08-13  01:02 to 03:04h UT (#51152, 173, 199, 224, 242, 260) 11.4 x 7.6 arc mins

Light Curve for 37655 Illapa, generated from 104 CCD Images   taken over a period of 2 hours ( Light Curve display in Excel). The light curve records an apparent 0.3 - 0.4  mag variation  (unfiltered mag range of +13.3 to +13.7),  Data quality isn't sufficient to be confident in  assessing a rotational period for the minor planet.  This was mainly due  to the object's comparatively low S/N ratio associated with its low magnitude  in comparison with a bright moonlight background sky. (2003-08-13  01:01 to  03:03h UT (#51122- 51260)

See earlier images of Illapa on 2003-08-08 when movement was recorded at 3.87 arc min per hour and Illapa on 2003-08-03 when movement was recorded as 1.25 arc min per hour and 

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Sky Brightness Survey

A sky brightness survey was conducted during this and the previous 4 sessions. This was performed as a baseline survey to compare against a new observing site at new home in Scotland in Q4 2003.

The survey confirmed the higher amount of light pollution to the south (towards city of Poole). The survey also confirmed the visual observation of deteriorating sky conditions associated with increased low haze (from August 2003 heat wave), together with increasing moon phase toward near full moon on 2003-08-12.

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