David's Astronomy Pages CCD Image Notes - Session 112 (2006-01-31) Notes (S111)   Notes (Main)   Home Page   Notes (S113)

Goto Images from 2006-01-31

Sky Condition Graph

Sky Conditions Chart (S112)

Notice  1)

See explanation of these graphs

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Delta Cepheid - Variable Star (Cepheid)

As part of an ongoing project examining the variability in Delta Cepheid, further image sets of the variable star Delta Cepheid were recording during the observing sessions on 2006-01-30 and 2006-01-31. A revised quality control step was applied to Oct 2005-  Jan 2006 dataset in order to reject less reliable measurements.  Previously rejection was based on dropping points were applied Zero Point offset of Reference Star exceeded a specific amount. The new rejection method is based on dropping points where the control magnitude falls outside of a specified tolerance ( +/- 0.05).   

The first two figures below show the full datasets in B & V bands are shown in first two figures below (best data highlighted). Three further figures show just validated V, B & B-V data plotted against phase assuming a period of 5.366341 days.

V Band Magnitude estimates for Delta Cepheid  (Reference Star SAO 34542)

B Band Magnitude estimates for Delta Cepheid  (Reference Star SAO 34542)

V Band Magnitude estimates for Delta Cepheid  (Reference Star SAO 34542)

B Band Magnitude estimates for Delta Cepheid  (Reference Star SAO 34542)

Magnitude and colour variation in Delta Cepheid based on observations  on 13 observing sessions between 2005-10-02 and 2006-01-31.

Further observations will be made during future sessions  in order to fully refine the light curve

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Frost Slugs

Frost slugs appeared during the previous session (2006-01-30) and whilst the dessicator was renewed and reinserted in the ST7 camera before the session of 2006-01-31,, the moisture has still not fully been absorbed and further frost slugs showed during the session  (through noted to gradually shrink through the session).   By the next session (2006-02-02) the moisture had all been absorbed and no frost/ice problems occurred.

(Previous problems with frost slugs or ice effects occurred 2005-08-05,  2003-11-21

Frost slugs at CCD temperature of -30 degC
		Frost slugs and adjacent icy light reflections are  visible in this image. Black/white range set to highlight  the light reflections from icy frost slug patches.
		Frost slugs and icy light reflections still  visible with 'Normal' black-white range
		Adjusting black-white range removes the majority  of frost slugs/light reflections, but at the expense  of reducing the visibility of dimmest stars.
		Adjusting black-white range allows dim stars to be seen,  but at the expense of showing frost slug outlines.

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