Before iPhones and laptops there were human computers, some of whom worked at the Harvard College Observatory. Women like Henrietta Swan Leavitt, Williamina Fleming, and Annie Jump Cannon made some of the most important discoveries in astronomy in the early 20th century. Their work was even featured in the TV series Cosmos, hosted by Neil deGrasse Tyson. Now, Harvard is seeking your help to transcribe the logbooks that record the century-long observations behind (and beyond) their discoveries. Learn how to transcribe this project and get started now.
The Harvard College Observatory spent more than a century (1885-1992) repeatedly photographed the night sky with telescopes in both the northern and southern hemispheres. More than 500,000 glass plate photographs remain, nearly 3 times as large as the next largest collection. This century long investment in repeated images of every portion of the sky played a major role in changing our understanding of humanís place in the cosmos. While most plates contain 50,000 to 100,000 stars, very few on each plate have ever been examined or studied.
DASCH, Digital Access to a Sky Century at Harvard, aims to preserve the plates by digitizing them. Once digitized, custom software measures both the position and brightness of every resolved object on each plate. The software accurately measures exactly where on the sky the image was taken. However, for the position and brightness to be useful for studies of the variability of any given object, we must have the date and time of the exposure. This can only come from the logbooks in which the original telescope operator recorded the details of each exposure. We need your help to transcribe the original logbooks by typing in selected parts of the logbook entry for each plate. Once we have the metadata and we scan the plates, we can study the variability of stars (and black holes at the center of galaxies known as quasars) which is now a "hot" field in astronomy commonly referred to as ìTime Domain Astrophysicsî. Digitizing the Harvard photographic glass plate collection allows the temporal variations of stars (and quasars) to be studied, for the first time on timescales from days to a century.
As some of the metadata have been transcribed and currently about 15% of the plates digitized, Harvard scientists have already found unexpected phenomena. Some of the most exciting finds are black hole-dwarf star pairs that erupt for a month every 50-100 years. Before DASCH, only two historical outbursts for these black holes were known. In the past two years, with less than 10% of the plates having been digitized, DASCH has found three more. By measuring their historical outbursts and recurrence times, we can deduce how many we are missing and so how many must be in our Galaxy. Your entries of logbook metadata will enable many other exciting studies made possible by DASCH, such as the habitability of planets discovered by the Kepler Space Telescope around other stars, some of which may have violent flares only revealed by the 100 year perspective.
We invite you, the public, and scientists from around the world to check out our website (http://dasch.rc.fas.harvard.edu/). If you navigate to the search image tab you can type in the precise coordinates on the sky or the astronomical name for any object you want. If we have digitized plates for which that object is included, the website will generate a plot of its brightness vs. time ñ a lightcurve. We hope you can help us transcribe the metadata from the telescope logbooks. With your help over the next year, we can complete the digitization and full analysis of all the plates by 2017. As the scanning progresses, both the images and access to the lightcurves are all released in full through Data Releases (3 of the 12 planned are already available) on the DASCH website.
The MF #21 logbook contains information about photographic plates MF26492 - MF28464, which were taken between 1939 and 1940 by the Harvard 10-inch Metcalf triplet telescope located in Bloemfontein, South Africa.
For more information about the DASCH project, please visit our website at http://dasch.rc.fas.harvard.edu/.