MIDI design, performance, operations, and science Markus Schöller (INS)
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Transcript of MIDI design, performance, operations, and science Markus Schöller (INS)
MIDI design, performance, operations, and science
Markus Schöller (INS)
Why do we use interferometers?
Objects Single Telescope Interferometric Fringes
Angular Resolution: ~ /D ~ /B
Small starSmall star
Big starBig star
MIDI in the VLTI lab
IRIS
FINITO
MIDI in the VLTI lab
The MIDI cold optics
Coaxial beam combination
MIDI lab fringes
The VLTI Telescopes
VLTI Optical Layout
Configurations
The uv-plane
Where do we sample the spatial frequencies?
If you have never tried to FFT-1…
Phase is essential for interferometric imaging
Coming next: MATISSE
MATISSE will provide:
•Four telescope beam combination (six baselines, four closure phases)•L/M/N band•Roughly identical sensitivity•R~30-1000 (L/M), R~30-200 (N)
MIDI design, performance, operations, and science
Christian Hummel (USD)
MIDI Publications
• Nature:– Jaffe et al. 2004 The central dusty torus in
the active nucleus of NGC 1068– Van Boekel et al. 2004 The building blocks of
planets within the terrestrial region of proto-planetary disks
• A&A (72), MNRAS (2), ApJ (9), Icarus (2)
Source: ESO Telescope Bibliography at http://telbib.eso.org
VLTI publications
From: Basic ESO Publication Statistics, 2012, prep. by Grothkopf & Meakins
OLBIN
Science with MIDI
Jaffe et al.
van Boekel et al.
Zhao-Geisler
Science Operations
• VLTI UT scheduled in blocks• Night astronomer selects telescopes from quadruplets• OBs selected from MIDI and AMBER queues• LST intervals allow user to achieve specific projected• Science targets interleaved with interferometric
calibrators
Operational efficiency
MIDI
XSHOOTER
SQ
L/ID
L co
de c
ourt
esy
of V
ince
nzo
Mai
nier
i
Acquisition with Coudé guide stars
Instrument modes
• HIGH_SENS: no photometric channels, separate observation for photometry– GRISM: R=320– PRISM: R=30
• SCI_PHOT: simultaneous photometry, chopping– PRISM GRISM
Spectrum extraction and sky windows
Dispersed interference fringes
λ
OPD
Courtesy: Th. Ratzka
0
Fringe scanning
SCI_PHOT mode (simultaneous chopping)
Visibility amplitude calibration
Calibrator:HD 50778D = 3.8 mas
Calibrator selection
Jean-Marie Mariotti Center (JMMC) tools
Visibility amplitudes of a binary source
Observing with MIDI
• OK with seeing up to 1.5” (limited by MACAO/STRAP)• SCI-CAL or CAL-SCI-CAL sequences in concatenations
(p2pp3)• 25 minutes execution time per OB independent of target• Simple model fitting only, spatial resolution 15 – 130 mas• Resources
– http://www.eso.org/sci/facilities/paranal/instruments/midi/ (MIDI page)– http://www.eso.org/~chummel/midi/midi.html (data reduction)– http://home.strw.leidenuniv.nl/~nevec/MIDI/index.html (software)– http://olbin.jpl.nasa.gov/news/index.html (Long Baseline Interferometry)