Above is an image of a Chandra Low Energy Transmission Grating (LETG)
spectrum of a very bright X-ray source, the nova XTE J1118+480,
showing only the shortest wavelengths. The major features are:
- Bright spot in center = the source (i.e., 0th order of the spectrum)
- Bright diagonal line extending corner to corner =
the main dispersed spectrum (1st and higher orders)
- Bright line perpendicular to the main spectrum =
cross-dispersion spectrum of 0th order, caused by the LETG
- Faint six-pointed star pattern in the center = diffraction of 0th
order by the triangle-pattern coarse-support structure
- Faint fan of whiskers on either side = cross-dispersion orders
caused by the fine-support structure. The main dispersed
spectrum is 0th order of the cross-dispersion spectrum.
My primary job is to:
I also conduct my own research, often using Chandra data, mostly on
solar wind charge exchange
My graduate school research was on
X-ray atomic physics
Electron Beam Ion Trap (EBIT).
After that I was hired by SAO to help build the system
used to collect Chandra pre-flight ground calibration data
analyze those data.
After launch I switched over to the
CXC Calibration group
to work on the
- Calibrate the intensities of the various LETG diffraction components
- Calibrate the responses and efficiencies of the detectors (ACIS and HRC)
used to record grating spectra
- Monitor detector changes over time and adjust operating parameters
- Develop methods to reduce detector background
- Assist LETG observers in setting up their observations.