Astronomical Photographic Data Archive (APDA)

APDA — the Astronomical Photographic Data Archive at PARI

The Astronomical Photographic Data Archive (APDA) was established by a consortium of 31 international scientists who had gathered at PARI to develop a plan to preserve astronomical photographic data collected throughout North America.

The situation: Before the advent of digital cameras in the 1990s astronomers used photographic glass plates and film to record and store their observations of the night sky. The estimated one to two million plates they accumulated represent the entire recorded history of astronomy prior to the digital age.

The problem: This treasure trove of astronomical observations is scattered across the continent, often stored in basements, musty closets or other unsafe locations. Astronomers who need this data cannot get it, and many of these collections are in danger of being destroyed.

The solution: APDA. APDA is tasked with collecting, preserving and restoring these rich archives—then digitizing them to make them available to scientists and the public worldwide, now and forever.

Time Domain Astronomy

Understanding the physics of astronomical objects relies heavily on observations of change. Short-term changes can be studied through new observations, but what of changes that happen slowly over decades, sometimes almost imperceptibly, occasionally violently, often serendipitously? We can know nothing of those phenomena unless we can access observations taken over a long period of time. This process is known as Time Domain Astronomy.

APDA is one of the primary resources, worldwide, for Time Domain Astronomy.

APDA Today

Housed in a highly secure building on the PARI campus, APDA has a director and a collection of more than 340,000 photographic plates and films. APDA also possesses several high precision digitizing instruments. APDA’s GAMMA II scanner was originally constructed for NASA and the Space Telescope Science Institute (STScI) to develop the Guide Star Catalog and Digitized Sky Survey projects that guide and direct the Hubble Space Telescope. At PARI it has been rebuilt with a digital camera for more efficient digitization of photographic plates. APDA also has a high precision transmission scanner and another stationary digital camera for lower spatial resolution digitization projects. EMC Corporation donated a networked storage system and software that can store and analyze more than 200 terabytes of research data.

The donations to date by PARI, STScI and EMC have allowed the APDA to begin its work. Funding is now needed to ensure that it can continue.