Experiments and Design of a wavelength calibration procedure for MOSFIRE Principal Investigator: David Guerrero, Cal Poly SLO Research Advisor: Ian McLean, UCLA Research Supervisors: Emily Rice, UCLA Jason Weiss, UCLA August 11, 2006 CfAO Mainland Internship Program

MOSFIRE Large (4,000 lb) cryogenic Multi-Object Spectrometer for the near Infra-Red (~ 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 46 slits Advantages: Multi-Object Observation Reduced Integration time Increased efficiency Real-time configurable mask Disadvantages: No tilted slits No more than 1 slit/row Increased complexity to calibrate

The Big Picture MOSFIRE Proposal Preliminary Design Design Modeling Testing Fabrication/ Assembly Shipping OpticalElectronicMechanicalSoftware 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. Using arc lamps inside the instrument would mean a financial and opto-mechanical challenge. ACHIEVED!

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 Central λ= 2*sin(B)*cos(Q/2) m*T VARIABLES Order (m) = 3,4,5, or 6 Grating Angle (GA) = ˚ or ˚ Field angle (FA) = -180 to180 arcsec Reciprocal Linear Dispersion (RLD)= Ả/mm CONSTANTS Blaze angle(B)=22.61˚ Groove density(T)=110.5 l/mm Focal length of Collimator (F coll )=1813 mm Focal length of Camera (F cam )=250 mm Spectrograph angle (Q) =40.0˚ RLD = 10 7 *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, “Building IDL Applications” Research Systems, Inc. April, “IDL Reference Guide” Vol. 1 & 2. Research Systems, Inc. March, ual.html / /

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 THANKS!