1,621 reputation
515
bio website linkedin.com/in/neilsen
location Illinois
age 44
visits member for 3 years, 6 months
seen Feb 16 at 2:41

Astronomer and software developer with interest and expertise in sky surveys, observing strategy and efficiency, data science, open science, and image processing.


Jun
7
accepted How does atmospheric seeing evolve over time?
Jun
7
comment How does atmospheric seeing evolve over time?
I am currently looking at data for the PSF widths for long SDSS runs as baseline historical data.
Jun
7
asked How does atmospheric seeing evolve over time?
Jun
6
answered What is meant when it is said that the universe is homogeneous and isotropic?
Jun
5
answered What is the typical career path to become a professional Astronomer?
Jun
4
comment When taking a sequence of exposures for stacking/coaddition, what dither patterns are most commonly desired? Why?
The context is that I am working on a project supplying a camera for the Blanco telescope on which the community will be able to apply for time, and I was party to a conversation about what dither patterns would be most useful for the observing software to support by default. (I am not responsible for deciding or implementing this, but am in a position to make suggestions.) Choice of dither patterns is a common issue faced, so seemed like a good "seed question" for the astronomy SE.
Jun
4
answered How can a spiral galaxy exist?
Jun
3
asked What criteria were used to set the “useme” flag in the NOMAD astrometric catalog?
Jun
2
comment How are Cepheids used to evaluate their distance?
Modern calibrations (eg Feast & Catchpole) use parallax, but I believe Leavitt measured a bunch in the LMC, which are all effectively at the same distance, and noted the correlation between the apparent magnitude and period.
Jun
2
asked When taking a sequence of exposures for stacking/coaddition, what dither patterns are most commonly desired? Why?
Jun
2
comment What is Dark Energy, and how was it discovered?
When astronomers say they are studying dark energy, they typically mean that they are exploring this anomaly. This acceleration of the expansion seems to imply an unknown energy density (hence the name dark energy), but not many astronomers are committed to specific explanations at this point.
Jun
2
comment What is a spectrometer, and why are they so useful in science?
In addition, the spectrum is also useful in measuring the velocity of the observed object relative to the instrument: relative velocity shifts the pattern of emission and absorption lines. Because the Hubble expansion is the dominant factor in the relative velocity of distant objects, the spectra can be used to measure distances on cosmological scales. This is how the large 3d maps from surveys such as 2df and SDSS are made.
Jan
13
awarded  Autobiographer