Dark Frames

The goal of this analysis was to examine the stability of dark frames and to compare using the slit mirror to the lens mirror.

Two different data sets were taken: One with the slit mirror in place and one with the lens mirror in place.  The data can be found in directory C:/data/CD016/cd016_2013oct/56.  The slit mirror frame numbers are 2165-2184 and the lens mirror frame numbers are 2145-2164.  The data was taken using a frame time of 0.5s and a 24 1 egos pattern (N6 S64 N5 D0) with 20 repeats.

The first read of an exposure was taken as a baseline and subtracted from all other reads.  A 3 sigma iterative rejection was used when calculating the statistics for each frame.  The results are shown below.

(Top Panel) All twenty frames are plotted with flux in DN versus integration time.  The blue triangles are the slit mirror data, while the black open circles are the lens mirror data.  The first frame has abnormally high flux compared to the rest of the images and so it is not included in the average polynomial fits shown in the bottom right.

(Bottom Panel) This plot shows the flux per time versus time.  These data points represent the average of all 19 frames (ignoring the first frame) for each integration time step.  The corresponding fits to the data are stated in the upper right-hand corner.  By the end of the frame time (~40s), the data points have flattened out at a value of ~3 DN/s.   The red circles were calculated from data that can be found in C:/data/CD016/cd016_2013oct/52, frames 1877-1896 (there were dropped reads in image 1889, so it was not used), frame time equal 0.5s with a 25 1 egos pattern (N2 S0 N3 S0 N3 S0 N1 D0) using the lens mirror.  This data is over plotted to show how well the fits work with data at integration times not present with a 24 1 egos pattern.  The error bars on all points represent the standard deviation from the mean.  The lens mirror and slit mirror data appear comparable with respect to each other.