Aris Zhu - atmospheric transmission determination

Intro, notes by Stubbs June 9, 2022

Goal is to learn how to extract reliable atmospheric transmission parameters from Rubin Observatory Auxiliary Telescope data. The instrument is a 'slitless spectrograph', that produces a spectrum of a star.
That spectrum is attenuated by the Earth's atmosphere, which imprints information about attenuation at each wavelength.
If we knew both the star's spectrum and the response function of the instrument, we'd divide the observed spectrum by the product of those two and the result would be the atmospheric transmission spectrum

details on this instrument are here: Dissertations and History in Nick Mondrik's PhD dissertation.

Looking through more atmosphere introduces more attenuation. If atmosphere is uniform then this depends only on 'zenith angle', or 'airmass': https://en.wikipedia.org/wiki/Air_mass_(astronomy)

airmass ~ secant(zenith angle).

Rubin data:

Start here to look at historical data:
https://roundtable.lsst.codes/rubintv/auxtel/historical

Cutouts from https://roundtable.lsst.codes/rubintv/auxtel/specevents/2022-02-16/774:

spectrum on detector:

Extracted one-dimensional spectrum, pixels on x-axis, flux on y-axis:

This is run through some analysis software that extracts features like the atmospheric O2 absorption line at pixel 1600, stellar lines at around pixel 1400, water vapor trough at around pixel 2100, etc.

Line strengths are quoted as 'equivalent widths', units are nm

https://en.wikipedia.org/wiki/Equivalent_width#:~:text=The%20equivalent%20width%20of%20a,relation%20to%20underlying%20continuum%20level.

Our initial task is to make some diagnostic plots, for each night of observing, of these extracted parameters.

Summarize the quantities that are generated by the spectral analysis code, and make a notebook that puts them into a single format (should we make a database?)
make some diagnostic plots:

plot O2, water, ozone atmospheric line strengths vs. airmass, for each star
same plot, for all stars
plot stellar line strengths for each distinct target star as.a function of time, for single night
same plot for all nights

an example:

to-do:

learn how to edit this Wiki page and use it as an electronic lab book for the duration. Check!
ensure account access on Research Computer system works
do background reading

Data are here:

/n/holystore01/LABS/stubbs_lab/Lab/Auxtel_data/spectrum_data

Goal-for-the-week:

set up Research Computing access

make a plot of data using a Jupyter notebook!