Tracking Chandra Science Productivity Publication Metrics special thanks to Mihoko Yukita (CDO) Sherry Winkelman (Archive Group) Paul J. Green (CDO)

Why Use Publications? An accepted measure of scientific productivity. An accepted measure of scientific productivity. Existing databases (e.g., ADS) allow trackable, reproducible statistics. Existing databases (e.g., ADS) allow trackable, reproducible statistics. Comparisons can be made to other observatories. Comparisons can be made to other observatories. What else is there? (News articles, Press releases, funding…) What else is there? (News articles, Press releases, funding…)

Which Metrics? PhD dissertations papers citations pages including all publications refereed papers highly cited papers certain journals

Chandra Bibliography Database Queries the ADS daily. Queries the ADS daily. Requires human scanning, culling, and categorization. Requires human scanning, culling, and categorization. Allows searching and statistics. Allows searching and statistics. Database now current and backfilled to launch. Database now current and backfilled to launch. Plans for public search page soon, with links to related data. Plans for public search page soon, with links to related data. See Archive Group presentation – A. Rots

TOTALS BY YEAR Refereed only All proposal types GO, GTO, TOO, DDT (no CAL) Statistics through 18 Dec 2003 Colored by paper category

Illustrates ramp-up in operations, archive size, & user familiarity Σ(Chandra Papers published that year)

Same ramp-ups convolved with publication-to-citation delay. Σ(Citations in that year to all previous Chandra Papers)

MEANS BY YEAR Refereed, Category 1 only All proposal types GO, GTO, TOO, DDT (no CAL) Statistics through 18 Dec 2003 Colored by paper category N.B. multiple countings

Σ(Papers published in each year)/ Σ(Targets used in those Papers)

Comparisons Comparing to other scopes is tricky, e.g., Who’s the audience? Who’s the audience? What’s the purpose? What’s the purpose? How do you normalize paper or citation counts ? How do you normalize paper or citation counts ? aperture area? (meaningless across wavelengths) aperture area? (meaningless across wavelengths) program dollars? (space vs. ground!) program dollars? (space vs. ground!) photons? photons? pointings! pointings! HST has 15x the citation impact of a 4-m ground-based telescope, but costs 100x as much. Benn & Sanchez 2001, PASP, 113

Doctoral Theses Doctoral Theses Searching the dissertation abstracts as of 22 Dec 2003 Year Chandra AND HST OR Year Chandra AND HST OR X-ray Hubble Space Telescope X-ray Hubble Space Telescope TOTAL 3132 TOTAL 3132

Other Trends for Study The CXC Archive group database also allows study of publication metrics by journal (e.g., Nature citation rate 8x ApJ) journal (e.g., Nature citation rate 8x ApJ) most-cited papers most-cited papers observation type (DDT, TOO, LP, VLP) observation type (DDT, TOO, LP, VLP) subject area subject area PI institution PI institution proposal grade… proposal grade… These all take effort!

Upcoming Public Metrics Page Simple statistics, updated monthly Simple statistics, updated monthly Omit inter-telescope comparisons Omit inter-telescope comparisons Links to Chandra Bibliography Database Links to Chandra Bibliography Database