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The Iowa e-SRT laboratory Robert Mutel, Laura Spitler*, Kevin Ivarsen† University of Iowa URSI Boulder Jan 2006 * Now at MPI, Bonn † Now at UNC Summary • Astronomical lab course – – – – Mostly junior/senior undergrads 1/3 each: data analysis, optical labs, radio labs Optical half uses Iowa Robotic Observatory Radio half used modified Haystack SRT (‘eSRT’) – Also teach ‘science-based’ radio astronomy course • e-SRT – Hardware modifications • Optical encoders added • Digital receiver replaced with ‘traditional’ super-heterodyne receiver • Spectrometer replaced with 1024 channel autocorrelation receiver (USB interface) – Software modifications • JAVA-based Haystack system replaced with Python modules • Spectrometer control uses C – Curriculum examples URSI Boulder Jan 2006 Iowa Robotic Observatory (located 50 mi SE Tucson AZ) URSI Boulder Jan 2006 Radio astronomy labs: LC filter Filter ‘Lite’ Program URSI Boulder Jan 2006 e-SRT Telescope modifications • Elevation axis • inclinometer (±0.1° resolution) • Serial interface • ~ $100 • Azimuth axis •10-bit absolute encoder (US Digital) • ~ $200 URSI Boulder Jan 2006 e-SRT receiver system I: Frontend Box URSI Boulder Jan 2006 e-SRT Receiver II: IF Rack URSI Boulder Jan 2006 e-SRT IF Rack URSI Boulder Jan 2006 e-SRT III: 1024 channel auto-correlator • Uses ‘quaint’ CMOS correlator (UNM 1993, also used at GBT) • 1024 lags, 2 or 3-level, 100 Ms/s max. – e-srt mode: • 4Ms/s (2 MHz = 422 km/s range) • N x 0.523 sec integrations • Output I/O either PCI or USB • Correlator software written in C • Still in development – Overheats unless reset pulse applied on power-up – Occasional random failures – USB interface not complete URSI Boulder Jan 2006 e-SRT Telescope control software • Written in Python 2.3 (with WX-Python for GUI) • Runs on Linux/Windows/Mac • More flexible control of telescope • (Probably) easier to modify on-site • Correlator control software currently in C (port to Python in progress). May not be portable. URSI Boulder Jan 2006 e-SRT software: Scripting and web-scheduled operations URSI Boulder Jan 2006 Lab project write-ups (available on web) URSI Boulder Jan 2006 e-SRT observational projects I: Spillover temperature and telescope beamwidth using Sun FWHM = 5.1°± 0.1° URSI Boulder Jan 2006 e-SRT observational projects II: Mapping HI 21cm emission along galactic plane URSI Boulder Jan 2006 HI 21 cm longitude-velocity plot along galactic plane URSI Boulder Jan 2006 Mapping the local spiral arms URSI Boulder Jan 2006 HI Column density sky plot URSI Boulder Jan 2006 Finale: Field trip to North Liberty Iowa VLBA site! e-SRT to scale URSI Boulder Jan 2006 Summary • Goal: redesign SRT to more closely emulate ‘standard’ radio telescope • SRT modifications: – Telescope: optical encoders for better positioning (no homing needed) – Receiver: replace with super-heterodyne, • Add many test points, 50 ohm load, test signal injection – Correlator: replaced with 1024-channel autocorrelator • Faster than SRT receiver (all 1024 channels available) – Software: Replaced JAVA code with Wx-python • more modular, • also transportable, • added user features URSI Boulder Jan 2006