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Experiments and Design of a wavelength calibration procedure for MOSFIRE CfAO Mainland Internship Program Principal Investigator: David Guerrero, Cal Poly SLO Research Advisor: Ian McLean, UCLA Research Supervisors: Emily Rice, UCLA Jason Weiss, UCLA August 11, 2006 MOSFIRE • Large (4,000 lb) cryogenic Multi-Object Spectrometer for the near Infra-Red (~ 0.972.45 µm) • $ 12 M project over 4 years. • Being developed for the W.M. Keck Observatory by UCLA, CIT, and UCSC. Slit Mechanism (CSU) •Based on a prototype developed by the Suisse Center for Electronics and Materials (CSEM) for James Webb Space Telescope. •46 bars Advantages: •Multi-Object Observation 46 slits Disadvantages: •No tilted slits •Reduced Integration time •No more than 1 slit/row •Increased efficiency •Increased complexity to calibrate •Real-time configurable mask The Big Picture MOSFIRE Proposal Design Preliminary Design Optical Testing Modeling Electronic Shipping Fabrication/ Assembly Mechanical Software Calibration Procedure Analysis of Problem Based on NIRSPEC calibration procedure, assist in modeling MOSFIRE wavelength calibration. • Spatial Calibration • Spectral Calibration OH Lines Problem Solving Approach • Find a relationship between the different slit configurations and the corresponding position of their spectra on the detector. ACHIEVED! • Using arc lamps inside the instrument would mean a financial and opto-mechanical challenge. Project as a whole Create an IDL application that calculates the exact position and linear dispersion of spectrum on the detector Investigate Physics involved in the optics system Develop an IDL code that does the math Design a friendly user interface for the input and output of results Physics Behind Optics System Basic IDL Code CONSTANTS Blaze angle(B)=22.61˚ Groove density(T)=110.5 l/mm Focal length of Collimator (Fcoll)=1813 mm Focal length of Camera (Fcam)=250 mm Spectrograph angle (Q) =40.0˚ VARIABLES Order (m) = 3,4,5, or 6 Grating Angle (GA) = 42.614˚ or 41.524˚ Field angle (FA) = -180 to180 arcsec Reciprocal Linear Dispersion (RLD)= Ả/mm Central λ= 2*sin(B)*cos(Q/2) m*T RLD = 107*cos(Q-GA) m* Fcam*T Graphical User Interface (GUI) Input Fields Output Fields References • Mclean, Ian. “Electronic Imaging in Astronomy Detectors and Instrumentation.” Wiley & Praxis. West Sussex, England, 1997. • “Building IDL Applications” Research Systems, Inc. April, 1998. • “IDL Reference Guide” Vol. 1 & 2. Research Systems, Inc. March, 1997. • www.astro.ucla.edu/~irlab/mosfire/ • http://www2.keck.hawaii.edu/inst/nirspec/manual/nirspec_man ual.html • www.gemini.edu • www.stsci.edu • www.answers.com/topic/infrared-astronomy • http://cfao.ucolick.org/ Acknowledgements • Special thanks to Prof. Ian McLean, Emily Rice, Jason Weiss, and all the personnel at the Infra-Red Lab at UCLA for their valuable help during my research experience. • Funding provided through the CfAO a NSFSTC, AST-987683 THANKS!