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The Astronomy Legacy Project


Acknowledging Those Who Made the Astronomy Legacy Project Possible


A thousand terabytes of astronomical data stored in emulsions of photographic plates currently are essentially inaccessible. The Astronomy Legacy Project (ALP) will bring the diverse and rich dataset of 20th century analog astronomy into the 21st century digital world.  Analog data recorded by generations of astronomers and left as their legacy will be digitized. It will convert to digital form the spectral, surface brightness, astrometric, and photometric information recorded on any type of photographic emulsion without sacrificing the inherent high spatial resolution of photographic emulsions. Converting the presently inaccessible analog data to digital form will give astronomers science historians, and the public worldwide the ability to sort, search, explore, implement, and integrate the archival data for new research programs.

Collections will be made available on this webpage to the public as the collections are digitized.  Any image, or set of images, may be downloaded after digitization of a collection is complete. The digitized images will be stored in several formats including TIFF, JPEG, and FITS on the 400 TB storage system located in the PARI Data Center.  This storage system has a backup system off-campus, so the data is well protected.  The metadata to search through the images will include original date of observation and the coordinates of the centers of the images, plus the digitization setup conditions that includes camera specifications, steps sizes, and image overlap conditions.


The UpDates that follow began on the Indiegogo crowdfunding campaign for this project. The campaign webpage can be found at and has additional information about the Astronomy Legacy Project.

1 August 2014

August 1, 2014

We have nearly completed the hardware acquisition for digitizing astronomical photographic plates.  We have three systems that meet different needs.  Shown below is the Epson scanner we purchased in May 2014.  This scanner is used for lower resolution scanning of plates. Our first batch scanned were the Harvard College Observatory (HCO) plates we described in the previous update.  Those plates have now been scanned by a summer intern, along with plates taken of the nearby galaxies called the Large and Small Magellanic Clouds. 

To give you an idea of what we may expect to find, we searched one HCO plate (#25).  We found a star that was about 3 magnitudes brighter when the plate was taken in 1900 than it is now.  We don’t know anything about this star – what made it fade over a period of 100 years.  So, we have more work to do.  The image below shows the field of view and the known stars are circled.  The one that is not circled is the one that was much brighter 100 years ago.

We have also completed the stationary digitizing station that uses a Nikon D800E and lens to capture an entire plate.  The station is shown below. This was used by another summer college intern to digitize a set of Harvard-Smithsonian meteor films.  We have 40,000 of these film, but our student digitized about 200.

One of our interns inspected a series of 200 films he digitized by comparing similar fields of view.  He found several anomalous features, but the best one is shown below.  The circle shows a star in one film, which has disappeared in another film taken about 3 years later.  Very interesting.  We now have even more work to do!


The third station is the adaptation of another Nikon D800E on a research-grade digitizing instrument.  The instrument had used a single pixel photomultiplier tube sensor in a raster scan mode to digitize images.  In this mode, even a small section of plate the size of pencil eraser would take 20 minutes!  With the camera in place, an entire plate will take less than a few minutes.  The station is shown below.  The camera zoom lens will image a small section of plate, about 60 mm x 60 mm, then is moved very precisely (to within 1 micron) to another section, and this process is repeated until images of an entire plate is taken.  This station will be used to digitize plates which require the highest precision.  We have all the pieces in place.  The code is being written and we expect this machine to up and running by the end of September.


Also, we are working very hard on the data pipeline.  The pipeline must merge the digitized plate image with all of the known properties of the plates – like plate number, what part of the sky the plate imaged, the camera exposure time, and other important properties.  The computer server for this pipeline has been set-up and the code is being written.

We are now almost ready to go full steam ahead!

11 June 2014

June 11, 2014

We have started to digitize the Harvard College Observatory All-Sky Survey Plates using the Epson Expression 11000XL-PH scanner.  One of our PARI summer interns, a student from Western Carolina University, is the person doing the scanning.  The size of a digitized image from one of these plates is 840 MB.  We cut out a small portion of an image of HCO Plate number 12 and it is shown below.  The original plate was taken January 4, 1902 of a region of the sky near the constellation Aurigae. Note the open cluster of several hundred stars in the lower right of the image.  Our intern will be making comparisons of modern day images with these 102 year old images.


22 May 2014

May 22, 2014

We have been busy on the Astronomy Legacy Project.  Funding from the Indiegogo crowdsourcing campaign is in and we have started to order and recieve digitizing equipment.  Here is where we are so far:

We have received the Nikon D800E camera, the Nikkor 105mm f/2.8 lens, and the camera control software.  A computer has been assembled by the IT staff at PARI for this digitizing instrument.  Here is a photo of Alex Armstrong, our Technical Photographer with the stand he built and the camera attached.  We are still waiting on the electroluminescent panels for the background light source that shines through a plate for digitizing.  Those panels should arrive in the next two weeks.

The Epson Expression 11000XL-Ph has also arrived. Thurburn Barker, APDA Director, and Lee Rottler, Instrument Scientist, wasted no time in setting it up.  He is shown below taking one of the first scans of a plate taken with the 4-m telescope at Cerro Tololo InterAmerican Observatory. 

The image on the plate is the globular cluster Kron 3.  The image is shown below. Kron 3 is a globular cluster in Tucana, in the Small Magellenic Cloud.  Kron 3 is about 5 billion years old and contains about 100,000 stars located about 200,000 light years away.  Really Cool!

To give the digitizing process a quick start, we will have two undergraduate interns this summer who will be working with us digitizing the collections we have designated for the Astronomy Legacy Project.  Once digitized, they will be studying variables stars called RR Lyrae stars.  These stars pulsate over several days, and are used as a tool to measure distances to stars.

20 March 2014

We will be hosting a Reddit Ask Me Anything session on March 21, 2014 from 1:00 pm - 4:00 pm EDT. Please feel to
join in. We will be answering questions about the imapct of advances in technology on astronomical discovery. And, we
will be particularly interested in how modern data analysis techniques applied to digitized plates can
impact even further astronomical discoveries. To see the Reddit session, go to and look for "I am Michael Castelaz, and astronomer for 30+ years - AMA" at 1 pm on Friday
March 21.

12 March 2014
We have two weeks to go and are looking forward to digitizing!  Thanks so much to the 120 who have donated so far putting us past 25% towards the goal!  Your tweets, facebook posts, and emails continue to help others who would like to donate become aware of the vision to make the astronomical photographic plates and films accessible to everyone. 

Another example of what we can expect - Here's a photo of M83 (NGC 5236) taken using the 74" Reflector at Pretoria, S.A. This is a film print from plate #A 3024 taken on 02 Aug 1956 on 103aO emulsion for 60-minutes.  It's about 1/3 the size of the full moon, at a magnitude of 7.6 in the constellation Hydra. M83 is classified as intermediate between normal and barred spiral galaxies by G. de Vaucouleur; i.e., SAB(s)c. M83 is about 15 million light years away and about 50,000 light years in diameter.  This photo is part of the diverse collection of astronomical photographic plates from University of Texas and McDonald Observatory that are now located in APDA.

4 March 2014
We’ve been getting a bit technical in these UpDates.  So, we thought we would just stop and take a look at the type of gorgeous images we will digitizing. This image is the Eta Carina Nebula taken March 22/23, 1975 (your birthday?) with the 4-m telescope at Cerro Tololo InterAmerican Observatory.  This is a 10 minute exposure and is absolutely beautiful!


3 March 2014

The Astronomy Legacy Project will digitize astronomical plates and films. Your continued support will make this a reality and because of you, current and future generations will have the opportunity to explore 100 years of celestial objects ranging from planets to quasars.   

While we get the Astronomy Legacy Project off the ground, we thought you might be interested in one of our other projects.  The Astronomical Photographic Data Archive (APDA) and the High Altitude Observatory (HAO) in Boulder, CO are working together to determine the level of effort and cost to digitize and catalog 150 films of our nearest star, the Sun.  The films were taken from 1980 to 1994 using the Prominence Monitor (PMON) located at the Mauna Loa Solar Observatory (MLSO: facility operated by HAO.  

The first telescope at MLSO, in 1980, was called the Prominence Monitor (PMON). PMON was designed with an opaque disc to block out the Sun’s disk, except for the sun’s edge where solar flare events can be seen.  PMON acquired both disk and limb images on rolls of B/W 35mm movie film. A batch of 4-6 disk and limb images were produced with cadence of 4-minutes from 2-4 hours daily.

Each PMON film roll contains approximately 11 days of solar observations yielding 2,300+ images per roll. The Debenham Media Group of Coraopolis, PA, converted one roll of PMON high definition images at 1560x1080 pixels resolution.  This is equivalent to the modern digital camera now used with a resolution of 1534 x 1030 pixels.  The video is a 5 second part of that digitized roll.  The numbers at the top of the images are frame number, Coordinated Universal Time, number of day in the year, and year.  The 5 second clip shows a solar flare on the right limb. The date of the clip is August 4, 1991.  You can see the video on YouTube We hope you enjoy this! 

The video was added to the ALP Indiegogo crowdfunding Gallery as well.
28 February 2014
For all those who have joined, or will join, us in the Astronomy Legacy Project – we are time travelers.  We travel 10, 20, or a hundred years into the past and bring back views of the night sky not seen since those days.  It is really remarkable when you think about it.  What a future our past astronomers have left us. In the previous UpDate, we described experiments with cameras and lenses that will produce the best digital representation of a plate. 

When we are in production, the camera/lens combination will actually zoom in on a much smaller section of plate to digitize at the highest, sharpest resolution to replicate the original plate as closely as possible.  This means, we need to image many small sections of a single plate and stitch them together. The image below shows a plate divided up into a grid, and 4 examples of areas that would be digitized.  When completed, we would have 16 digital images that would be stitched together.

As important as the camera and lens are, the critical component is the ability to precisely move the camera from one section of a plate to another.  The more precisely we can move the camera from one area to another, the more precisely we can stitch the images.  The OPTEK 463 VSM allows us to move a camera repeatedly to within 3 microns!  We need this machine.

27 February 2014
We are fortunate that our newest team member here at APDA, Alex Armstrong, is a professional technical photographer.  He has been experimenting with his top quality professional camera/lens combinations to search for those that are the best for digitizing astronomical photographic plates.  We are looking for distortion free images that cover the largest plate area – ideally an entire 8 inch x 10 inch (20 cm x 25 cm) plate.  

To do this, Alex tried several lenses.  The most successful so far has been a Nikor 28-70 f/2.8 AFS ED Optics lens. Very careful adjustment was needed.  He digitized a plate image of the globular cluster NGC 1866.  The jpeg of his TIFF image is shown below, along with 10X and 100X zoomed in images. As Alex was saying during the experiment “This is incredible!”  The images of individual stars are easily seen.  If you would like the original TIF image, let us know and we’ll make it available to you. 

The plate was taken 3/4 February 1976 using the 4-m telescope at Cerro Tololo InterAmerican Observatory (plate#1677).  For those who are interested, the emulsion was IIaO with a GG385 filter – this means the plate was sensitive to very blue light.  All images were saved in TIF format, and each was 108 MB in size.  The camera is a Nikon D800 with 36 megapixels.Our next step is to image stellar field where we know the positions of stars, and doing very precise stellar position measurements.  This will tell us about the very smallest distortions.  We will compare those results with measurements we have from our precise stellar position measurement machine.  If comparable, and borrowing Alex’s best lens/camera combination, perhaps we can begin digitizing some plate collections right away!   

25 February 2014

We thank 101 funders who have donated so far – welcome to the Astronomy Legacy Project team! We have
30 days left to the campaign. The continued effort by all of us to let people know about the
Astronomy Legacy Project will bring the project closer to its goal!

Here’s an interesting fact about APDA. We compiled a list of institutions in the U.S. with astronomical
photographic plate collections. From the list, we constructed a map that shows where the collections
are located, and the sizes of the collections. The largest collection is at Harvard – where digitization
of their 600,000 plates is already taking place. In fact they were our inspiration for digitizing our
plates! The second largest collection is at the Carnegie Observatories in Pasadena CA. The third
largest collection shown on the map is ours - here at the Astronomical Photographic Data Archive (APDA).
Perhaps in the future, once the Astronomy Legacy Project is well underway, we can share our digitizing
experience with the other institutions. A world-wide map would be very interesting, but we haven’t
compiled that one yet. The U.S. collections map is shown here. We thought you’d like to see it.

19 February 2014

We are getting close to 100 funders and approaching one quarter of the funding goal!  Keep sharing the vision! We are excited to welcome Alex Armstrong of Fine Technical and Artistic Photography to PARI as a volunteer on the Astronomy Legacy Project!  Alex brings a wealth of expertise in digital cameras and lenses - equipment needed for accurately reproducing the types of plates and films we have in APDA.  You can meet Alex in a short 5 minute video presented in the Gallery of the Indiegogo project or go to the YouTube He is more excited than we are! 

17 February 2014
We thought you might like to see one of the first plates we will digitize from the Henize collection which was taken over a 3 year period.Dr. Henize wrote his Ph.D. Dissertation from the images he recorded.  Thurburn Barker, Director of APDA is holding up an astronomical photographic plate which is 38 cm x 38 cm.  The image on the plate is the Carina Nebula.

The plate was taken in June 1951 by astronomer Karl Henize. He used the 0.27-m (10-inch) refractor at the Lamont-Hussey Observatory. The exposure is in the red part of the spectrum and the exposure time was 240 minutes.  The detail we will get after digitizing this plate will be exceptional!

Here are two archival photos Dr. Henize developing one of the plates in his collection and inspecting the developed plate.  This is so cool!

13 February 2014
Thanks to everyone who has contributed so far. We are at 15% of the goal for the Astronomy Legacy Project. Please continue
sharing the project with your social media friends!

We put another poster presentation in PDF format in the Gallery. This poster was presented recently at the
223rd American Astronomical Society Meeting, January 7, 2014. The poster is titled
"Surveys, Fields, and Collections in the Astronomical Photographic Data Archive at PARI" and authored by
PARI staff J.D. Cline, M.W. Castelaz, T.H. Barker. If you print this, make sure to select
the "fit to page" option for your printer, and as one funder pointed out make sure you use the Horizontal print setting as well.
The actual physical size of this PDF is 48 in x 36 in
(120 cm x 90 cm).

12 February 2014:
We are 2 days into this campaign and have reached more than 10% of our goal!
Thanks to everyone who has contributed so far. Let's hope this is a good sign of things to come.

We have put a poster presentation in PDF format in the Indiegogo campaign Gallery. This poster was presented at the
221st American Astronomical Society Meeting, January 9, 2013. The poster is titled
"Meeting Archival Standards in the Astronomical Photographic Data Archive at PARI" and authored by
PARI staff J.D. Cline, M.W. Castelaz, T.H. Barker, L. Rottler. If you print this, make sure to select
the "fit to page" option for your printer. The actual physical size of this PDF is 48 in x 36 in
(120 cm x 90 cm).

10 February 2014:
We are excited to announce that the Astronomy Legacy Project was launched today! You can find it at

We are fully committed to digitizing 120 years of photographic films and plates, placing this treasure in
your hands. Help bring the past 120 years of the night sky into the future! Contribute what you can:
donations are welcome, posts are welcome, tweets are welcome, and your expertise and encouragement are
welcome! You become a part of the Astronomy Legacy Project Team with your contribution – part of a legacy
itself for generations to come.

Follow us on Twitter @remarkablestars.

4 February 2014:
Your pledge from last Fall encouraged us to once again set in motion the Astronomy Legacy Project fundraising campaign
to bring the diverse and rich dataset of 20th century analog astronomy into the 21st century digital world.

We wanted you to know that we will re-launch the Astronomy Legacy Project campaign on February 10, 2014 on
Indiegogo: or

If you like, you can preview the draft campaign homepage at
The team is planning on purchasing a very high precision scanner to digitize collections in the Astronomical
Photographic Data Archive. The legacy of generations of astronomers will finally be shared with the entire world.
Once funded, and plate digitizing begins, the images will be forever in the digital world and you will have
been a part of that process! We hope you share our vision and will consider donating.

13 January 2014:
If you like to follow, you can find the Astronomy Legacy Project at @remakablestars .
Or go to
The tweets are also sent to the Pisgah Astronomical Research Institute (home of the Astronomical Photographic Data
Archive) Facebook page at
We'll keep you up to date on our plans and happenings in the Astronomical Photographic Data Archive and the
Astronomy Legacy Project!

12 December 2013:
We received our microscope on Tuesday December 10. We set it up temporarily to check out the features and operation
of the microscope on December 11. Here is a photo of the microscope with a 14 megapixel camera attached.


The photo shows a digitized spectrum of the astronomical photographic plate of the spectrum of the star system Algol.
Algol is actually a double star system and is famous for being the prototype of eclipsing binaries. The spectrum is
one of the 20,000 from the Ann Arbor collection, and the one shown here was taken on August 23, 1913. The spectrum
is now digitized and preserved in the digital world. Only 19,999 to go!

We will spend the next few weeks installing and calibrating the instrument in a lab in the Astronomical Photographic
Data Archive. The installation process will include alignment to the focal plane and putting in place a robust
plate holder so plates are consistently put in the same place in the focal plane. The calibration process will
include establishing the characteristics of the CCD camera such as pixel width and light table intensity.

This is good first and small step for the Astronomy Legacy Project!


04 December 2013: We were very fortunate in receiving some funding, about $2,000, that we were able to use to purchase
a microscope with a wide field of view. The microscope will be used to begin digitizing a collection of very
small astronomical photographic plates. Take a look at this one and a half minute video that shows the collection.
The Ann Arbor Spectrograph collection consists of spectra of stars, rather than images of stars. There are spectra
of 400 stars in the collection, where the spectrum of each star has been photographed many times over many years.
The result is 20,000 astronomical photographic plates! The earliest photographic plate spectrum we have was
taken in 1910.

The microscope is from and is a 2X-270X Zoom stereo microscope with a 9 megapixel and a 14
megapixel camera. The zoom factor allows a large field of view which will easily capture the entire spectrum on
the Ann Arbor Spectral plates. The cameras have very small, 1.75 micron pixels, so we anticipate digitizing
to the level of the photographic plate grain size.

We also have several other collections of small plates - some are images of nebulae! As a result we can now
begin a small project digitizing plates - totaling about 15% of all the plates in APDA.

26 November 2013: It's been a week since our crowdfunding campaign ended. We are just as committed to the project
as we were during the campaign and expect to once again start a funding campaign in early in 2014. The form of
that campaign is still being developed. In the meantime, we'd like to make you aware of one project we have underway
which is a citizen science project. It's called "Stellar Classification Online - Public Exploration" or SCOPE.
You can find it at SCOPE gives you the opportunity to classify stars by looking at scanned
images of astronomical photographic plates of star spectra. The SCOPE webpage explains this fairly well.
The scanned images were done with a commercial desktop transmission scanner which provides the information needed for
the citizen science project, but not all the details, down to the grain size, of a photo which we will ultimately
require for the main tool for the Astronomy Legacy Project. As Thurburn Barker, Director of the Astronomical
Photographic Data Archive says "Extraordinary photographs require extraordinary scanners." Happy Thanksgiving!

19 November 2013: Our crowdfunding campaign ended, but you can still view the campaign content on Kickstarter at
We will be adding updates as we proceed with new efforts to raise funds to support this project.


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