4 ms·
A lot of the atmospheric affects are on longer timescales than the sampling times, which means they can be calibrated out. Most observations of this nature (in
by ajford 7y ago
A lot of the atmospheric affects are on longer timescales than the sampling times, which means they can be calibrated out.
Most observations of this nature (interferometric observations) will point at a nearby calibrator source (usually a well characterized quasar or other "point source" star/object), and an atmospheric noise model will then be constructed based on this calibrator to apply to each dish to minimize/account for the atmospheric influence.
This is often repeated periodically to account for changing weather over time. And on top of that, a benefit of the location chosen for ASKAP was relatively dry air (being in the western desert climate of Australia).
- cmendel 7y agoThat's really interesting! Would you be able to point me towards some resources to learn more about this?
- ajford 7y agoA lot of it I learned when I studied Radio Astronomy in college (my major). I'm a little rusty now after about 7 years. However, here's a few resources I remember and was able to dig up. 1) A presentation from Max Plank University, which has one of the strongest radio astro programs around: https://www.mpifr-bonn.mpg.de/3244052/IMPRS_BB_HRK5.pdf https://www.mpifr-bonn.mpg.de/3244052/IMPRS_BB_HRK5.pdf 2) Presentation from ASTRON, an interferometric array in the Netherlands, part of the Netherlands Institute for Radio Astronomy: https://www.eso.org/sci/meetings/2015/eris2015/L6_Heald_calibration.pdf https://www.eso.org/sci/meetings/2015/eris2015/L6_Heald_cali... 3) George Moellenbrock's slides from the 14th Synthesis Imaging Workshop (hosted by the National Radio Astronomy Observatory) is pretty detailed on calibration specifically: https://science.nrao.edu/science/meetings/2014/14th-synthesis-imaging-workshop/lectures-files/MoellenbrockCalibration2014_FINAL.pdf https://science.nrao.edu/science/meetings/2014/14th-synthesi... There was at one time a video of the last link, but it appears the hosting site is no longer live. There are other lecture slides on radio interferometry available from the Synthesis Workshop site: https://science.nrao.edu/science/meetings/2014/14th-synthesis-imaging-workshop/lectures https://science.nrao.edu/science/meetings/2014/14th-synthesi...