New version page

SBU AST 443 - Exercise Lab 1

This preview shows page 1-2-3-4-5-6 out of 17 pages.

View Full Document
View Full Document

End of preview. Want to read all 17 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

Exercise Lab 1AST443, Lecture 6Stanimir Metchev2Administrative• Project 1:– code IDL algorithms to• generate a master dark and bias frame from a series of darks of a range ofexposures• generate a master flat field frame from a series of flats with a range of exposureintensities• generate a master bad-pixel mask (1 = bad, 0 = good) based on the above– problem 2.2 in Wall & Jenkins, including the “extra challenge”– one-paragraph description of an idea for observational project– due in class on Wednesday, Sep 23• Reading:– chapters 4–5 of Howell: CCD data reduction and photometry– chapters 3–5 of Wall & Jenkins: statistics, correlations, hypothesis testing– overview paper on IR arrays (Rieke, G. 2007, ARA&A, 45, 77)• http://arjournals.annualreviews.org/doi/full/10.1146/annurev.astro.44.051905.0924363Administrative (cont.)• Think of observing proposals– 10 hours on Tenagra Observatories 32”– http://www.tenagraobservatories.com/• Possible directions:– detecting the eclipse signal of transiting hot Jupiters• determine orbital period and size of planet• determine surface temperature– a color-magnitude diagram and age estimation of a globular oropen cluster– astrometric monitoring of a binary object• nearby fast-moving star• binary asteroid in the solar system– etc.4Outline• Overview of previous lecture– CCDs• Basic imaging data reduction5Context: Plates, PMTs, CCDs6Basic Concept• electron-hole pair generation• doping:– n-type (electrons)– p-type (holes)– creates additional energy levelswithin band gap– increases conductivity• silicon– band gap: 1.12 eV (11 300Å)– free-electron energy: 4 eV (3000Å)– 1 photon -> 1 electron7Basic Concept• electron-hole pair generation• doping:– n-type (electrons)– p-type (holes)– creates additional energy levelswithin band gap– increases conductivity• silicon– band gap: 1.12 eV (11 300Å)– free-electron energy: 4 eV (3000Å)– 1 photon -> 1 electron8Basic Concept:A P-N Photo Diode• depleted region– low conductivity– can support an E field• net positive charge (higher charge density near top)• additional E-field applied• subsequently generated electrons get trapped in potential well near top9Charge Trapping10Advanced CCD Technology• orthogonal transfer– 30–100 Hz readout– tip/tilt wavefont correction– ~30% improvement in “seeing”– large-format CCDs• low-light CCDs– gain register clocked out withhigher voltage (40–60V vs.~10V)– 1–2% probability of generating2nd electron at each gatetransfer– total gain enhancement:~1.01N = 145 for N=500transfers11Analog-to-Digital Converters• X electrons = 1 digital unit (counts)– X is “gain”: usually 1–10• CCD saturation depends on– well capacity• ~300,000 photolectrons for “deep depletion” CCDs• “flat tops” when saturated– number of bits in ADC• n=16 bits: maximum is 216–1 = 65535 counts• column “bleeding” when saturated12Read Noise• electrons / pix / read• sources– A/D conversion not perfectly repeatable– spurious electrons from electronics (e.g.,from amplifier heating)• nowadays: <3–10 electrons13Dark Current• electrons / pixel / second• source: thermal noise at non-zero temperature14Non-Linearity• differential (digitization noise)• integral– examples of non-linearity in SDSS CCDs:15Outline• Overview of previous lecture– CCDs• Basic imaging data reduction16Detector Calibration• bias frames– non-zero bias voltage– 0s integrations• dark frames– equal to science integrations• flat field frames– QE of detector pixels is non-uniform in 2-D– QE is dependent on observing wavelength• bad pixels17Sky and Telescope Calibration• sky background images• photometric calibration:– airmass curve, filter transmission• sky transmission– spectrum of a star of a known spectral energy distribution• astrometric calibration– binary with a known orbit– star-rich field with precisely known positions: HSTobservations of globular clusters• point-spread function calibration– nearby bright star (for on-axis calibration)– star-rich field (2-d information on


View Full Document
Loading Unlocking...
Login

Join to view Exercise Lab 1 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Exercise Lab 1 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?