Mount Wilson Solar

Photographic Archive

Digitization Project

Mount Wilson Solar

Photographic Archive

Digitization Project

The 60-foot Solar Tower in 1914.The 60-foot Solar Tower in 1914.

Project PersonnelProject Personnel

• Roger Ulrich, P.I.• Ferenc Varadi, Geophysicist• John Boyden, Programmer• J. Javaraiah, Post Doc, Data Analyst• Sandrine Lefebvre, Post Doc, Data Analyst• Liz Werden, Archivist

• Roger Ulrich, P.I.• Ferenc Varadi, Geophysicist• John Boyden, Programmer• J. Javaraiah, Post Doc, Data Analyst• Sandrine Lefebvre, Post Doc, Data Analyst• Liz Werden, Archivist

Why Study Old Solar Images?

• The level of solar activity is measured by The level of solar activity is measured by the brightness of the Ca II K line.the brightness of the Ca II K line.

• Rotation of solar features can be measured Rotation of solar features can be measured at high latitudes using the Ca K images.at high latitudes using the Ca K images.

• The level of solar activity is measured by The level of solar activity is measured by the brightness of the Ca II K line.the brightness of the Ca II K line.

• Rotation of solar features can be measured Rotation of solar features can be measured at high latitudes using the Ca K images.at high latitudes using the Ca K images.

Variability of the Solar

Cycle

• The Sunspot Number has systematically increased during the 20th Century.

• The period of no sunspots is called the Maunder Minimum

Variability of the Solar

Rotation Rate

• The rotation rate can be determined by tracking the traversal of features across the solar disk

• At the end of the Maunder Minimum the sunspot rotation rate was reduced.

The Mount Wilson Solar Photographic Archive

The Mount Wilson Solar Photographic Archive

• George Ellery Hale Established the Mount Wilson Solar Observatory in 1906.

• Starting in 1915 spectroheliograms in the light of the Ca II K line were taken twice per day.

• Also about the same time “White Light” Direct images were taken once per day.

• There are approximately 45,000 images in the K line and approximately 30,000 images in white light.

• These images will be digitized and posted for distribution on the web.

• George Ellery Hale Established the Mount Wilson Solar Observatory in 1906.

• Starting in 1915 spectroheliograms in the light of the Ca II K line were taken twice per day.

• Also about the same time “White Light” Direct images were taken once per day.

• There are approximately 45,000 images in the K line and approximately 30,000 images in white light.

• These images will be digitized and posted for distribution on the web.

A Full Deck Scan

A Full Deck Scan

• The large-bed scanner can scan 5 plates simultaneously.

• Presently only 3 plates can be accommodated.

• The full-deck scan is 300 Mbytes in size.

• Details of this image are shown in the next few slides.

• The large-bed scanner can scan 5 plates simultaneously.

• Presently only 3 plates can be accommodated.

• The full-deck scan is 300 Mbytes in size.

• Details of this image are shown in the next few slides.

July 1, 1925

June 20, 1921

June 30, 1921

One Solar Image

One Solar Image

• This shows more detail.

• This shows more detail.

The Image

with the Clear Plate

Enhanced

The Image

with the Clear Plate

Enhanced

Aug. 17, 1915 to Aug. 21,

1915

Aug. 17, 1915 to Aug. 21,

1915

A Sequence of Images Showing

Solar Rotation

A Sequence of Images Showing

Solar Rotation