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Transcript 
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
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