David's Astronomy Pages CCD Image Notes - Session 102 (2005-10-30) Notes (S101)   Notes (Main)   Home Page   Notes (S104)

Goto Images from 2005-10-30

Sky Condition Graph

Sky Conditions Chart (S102)

Notice  1)  Analysis of previous session (S98) shown that poor attempts at refocussing had in in  certain cases caused a backward step in focussing quality. During session S99 the initial  focus position was retained for the entire session.

See explanation of these graphs

Back to Top

RR Lyrae Photometric Analysis (2005-10-30)

73 images of RR Lyrae were taken in each of B and V filters over a 1.1 hour period.  The comparison star method was used to produce calibrated magnitude estimates for the variable.   An unexpected rain shower occurred part way through the period, causing loss of data from cloud cover and lightly coating the telescope with raindrops.  

The dataset records fairly constant brightness of RR Lyrae over the 1.1 hour interval. The brightness was dimmer than expected based on previous sessions, raising the possibility that either the star's cycle differs from the 'standard' period length (0.56686776 days), the star has a longer length variability or that my magnitude estimates are in error.

Data / Data QC

Calibrated V mag and B Mag data are plotted against time in the graphs below, along with control star magnitude (shifted to fit on graph). Zero Point values determined from reference star measurements that lie above a threshold level are used to distinguish higher quality data. Quality of magnitude data is slightly compromised on occasions by cloud,  including complete loss of data for for an interval of around 10 minutes.

Magnitude Data (B & V Filters)

V mag, B mag and B-V data is plotted here against time.  The high quality data points (passing QC) are highlighted.

Magnitude / Colour Analysis including comparison with previous sessions

V mag and B-V data was combined with data from previous sessions & plotted against phase, assuming the catalog period length for RR Lyr.

[Prior Sessions :  Data/Analysis from 2005-10-08 ] [Prior Sessions :  Data/Analysis from 2005-10-13 ]

Back to Top

Sky Brightness Survey

Back to Top