Meredith L. Rawls, PhD

Developing software for a firehose of telescope data and characterizing changing things — they aren't all satellites

I work with the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) group at the University of Washington. I am a Research Scientist in the Department of Astronomy and a DiRAC Fellow. The LSST will collect frames for a ten-year high-res full-color movie of the night sky beginning in 2023. My background is in stellar astrophysics, and I also work to understand and disseminate how the proliferation of Low-Earth-orbit satellites affects astronomy.

My CV in PDF form is available here.

Software for Rubin Observatory and beyond

Astronomy encompasses observations ranging from the unaided eye all the way to giant telescopes, and modern-day astronomers use and develop a wide array of software to study digital images of the sky.

screenshot of blue circles of varying sizes indicating variable objects in the sky

Difference imaging for alert production

Rubin will subtract a deep reference template image from new images to identify sources that change or move. I work to measure and reduce false positives in difference images for precursor datasets so we are ready for the LSST. Try our Science Pipelines.

two satellite streaks crossing a field of view, one slightly dimmer than the other


I am leading a team at DiRAC with Dino Bektesevic to build an open data repository for astronomical data products affected by satellites. This service will give observers a place to share images and allow groups to characterize the extent of the problem as it evolves. Follow Trailblazer on GitHub.

Satellites pose a serious problem to astronomy

Several companies and countries plan to launch tens of thousands of low-Earth-orbit satellites in the coming years. This has the potential to harm ground-based astronomy, clutter the orbital environment, and disrupt stargazers worldwide.

mosaic image of b&w starry sky with more than a dozen bright satellite streaks

Crucial mitigations for operators

I am chairing the SATCON2 Observations Working Group and have co-authored reports from several workshops on satellite constellation brightness mitigation. Key recommendations include designing satellites to be 7th V magnitude or dimmer, sharing timely, accurate and precise trajectories, and keeping all satellites at low altitudes (below 600 km). While important, these will not fully mitigate the problem.
Learn more from the Dark & Quiet Skies I and SATCON1 workshops.

multi-color image of the DECam field of view with a difference imaging cartoon overlaid

Assessing brightness mitigations

We must measure satellite streaks in real telescope images to quantify the impact of numerous bright low-Earth-orbit satellites on observational astronomy. This figure (by me, from Tyson et al. 2020) shows a darkening mitigation from SpaceX Starlink's "DarkSat" (1130) observed in early 2020. This is a fast-developing research area that lacks a clear funding source.

Stars are not always predictable

But when stars come in pairs (or more!), or pulse or flicker in unusual ways, we can reveal stellar secrets by observing how they vary in brightness.

illustration of comet and dust debris blocking thie light from a star

Searching for mysterious dippers

I collaborated with researchers in UW's DIRAC Institute to search new data from the Zwicky Transient Facility for strange variable stars similar to Boyajian's Star. I co-wrote an Astrobite about this mysterious sytem when it was first discovered.

multi-color image of the DECam field of view with a difference imaging cartoon overlaid

Comparing difference imaging pipelines

I worked with undergrad Thomas Waters to compare variable sources classified in the High Cadence Transient Survey (HiTS) data release with the same data processed with LSST software. Thomas is interested in Active Galactic Nuclei and black holes, and subsequently joined Jessica Werk's research group. Courtney Hooks also worked on this project with us in Fall 2019 with the Pre-MAP 15 Cohort.

illustration of the portion of the sky APOGEE observed that includes the Kepler field

Pairing data from APOGEE and Kepler

I led a research collaboration to identify and model eclipsing binary systems observed by both the Kepler space telescope and the APOGEE spectrograph. The main result was a paper by Joni Marie Clark Cunningham for whom this project comprised the majority of her Master's Thesis. The collaboration had team members from Fisk-Vanderbilt, New Mexico State University, and UW.

cartoon of a red giant binary with oscillations being eclipsed by a main sequence star

Eclipsing binaries and asteroseismology

Because there are many more oscillating stars than eclipsing binaries, my PhD thesis modeled binaries as a benchmark for measuring stellar properties with asteroseismology. My team and I revealed that some evolved red giants in binary systems don't oscillate at all. Read about one particularly interesting binary.

Beyond research and programming

I am involved in a variety of projects in addition to Rubin Observatory, satellites, and stellar astronomy.