lect17 - UCF Physics: AST 5765/4762: (Advanced)...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
UCF Physics: AST 5765/4762: (Advanced) Astronomical Data Analysis Fall 2009 Lecture Notes: 17. Making Flats, Coding, ND Gaussian 1 Check In: 10:30 — 10:35, 5 min Questions before we start? Do np.bitwise_and()? in ipython to get help on bitwise and logical operators. Note that plain help() will give the help for ufuncs. axis= keyword to np.median(), np.mean(), np.std(), etc. 2 Median Combination: 10:35 — 11:15, 40 min Can use median combination to make flats, darks, biases, skies Sigma-rejection technique from HW5 is even better, given enough images If sky varies and you are making skies, add indented normalized median combination steps Take many dithered images Subtract dark frame (cold shutter, “closed” filter) Divide each by its median (median is now 1, may use median region rather than full frame) Loop over pixel positions Find median of all images at each pixel position Astronomical sources, cosmic rays, bad pixels rejected! Noise reduced!
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

lect17 - UCF Physics: AST 5765/4762: (Advanced)...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online