Completing the DASCH Project

DASCH is the project to scan Harvard’s glass plates.

Annie Jump Cannon. Bettmann / Getty Images

Learn more: dasch.cfa.harvard.edu

• The plates are photographs of the night sky
• Harvard’s collection is the largest in the world (>500,000)
• A unique scientific, historical, and cultural resource
• DASCH is digitizing them with a custom-built scanner
• Instigated and championed by Prof. Josh Grindlay

Photometry from the Harvard plates: ~15B V-band magnitudes, all-sky, ~110-year time baseline, depths of V ~ 14–16, rms ~ 0.15 mag.

We hope to complete scanning in four months.

The DASCH scanner circa 2006

The primary DASCH scanning effort (~450k plates) is about 97% complete.

After a hiatus, scanning resumed in November, and we estimate completion in April …

… if the DASCH scanner cooperates and there are no major mishaps.

Currently scanning about 180 “A” plates per day.

DASCH data access is opening up.

RY Cnc (same data plotted twice)

We have refreshed the “Cannon” data portal (accessed via dasch.cfa.harvard.edu)

Current data restrictions: FITS mosaics and sources at b < 0 are upon-request

These restrictions will be relaxed soon (months or even weeks)

Also soon: a new “Starglass” plate information portal and API! Foregrounding historical as well as astrophysical connections, especially the “women computers”.

Atop that, plan to build an astroquery package, sample notebooks, tutorials, etc.

Here’s a summary.

1. We hope that DASCH primary scanning will complete in four months
2. DASCH data access is opening up: dasch.cfa.harvard.edu
3. The data can be intimidating but I am here to help!
4. The new Starglass “graph database” is coming soon
5. Get updates from my newsletter: www.newton.cx/~peter/

Thanks for your attention!

Peter K. G. Williams • pwilliams@cfa.harvard.edu • @pkgw@mastodon.world • newton.cx/~peter/