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Accuracy and Consistency in the Production of the American Sunspot Number (Ra)



Contributed by Carl E. Feehrer (FEEC)

Guidelines for new solar observers

Guidelines for New Solar Observers

  • Do not look directly at the sun without the protection offered by a filter. For naked eye viewing, a piece of #14 welder's glass provides adequate protection. Do not use overexposed film, dark glasses, or other media that are not designed specifically for solar viewing.

Useful links for new solar observers

A vast amount of useful and informative material relating to the appearance of the sun at different wavelengths, visual and instrumental observation, and analyses and records of sunspot data are available via the Internet. The list below is intended to provide the new observer with some initial points of contact with this resource. Some entries in the list present the full address required to get to a specific display or table.

Solar News

February 20, 2013

  • The NASA SDO mission released a fascinating video showing "rain" from a magnetic loop falling back onto the surface of the Sun.  It's not rain, but hot plasma magnetically levitated off the Sun!

February 15, 2013

Solar Photo Gallery

Here are a number of solar photographs obtained by AAVSO solar observers over many years.  Thanks to all of the photographers for sharing their images with us!



Atmospheric seeing conditions for solar observing

Atmospheric Seeing Conditions

Contributed by Tom Fleming (FLET)

Reports and observations submitted to the AAVSO use the following ratings for atmospheric turbulence (Seeing): Poor, Fair, Good and Excellent.

In Memoriam: Casper Hossfield

Cap Hossfield

Casper H. Hossfield (1918-2002)

Sunspot Report Form

The sunspot reporting form below has been created with a variation of the SUNKEY.exe program
and embodies the information and column/character alignments required by the AAVSO Solar
Division data processing software. It can be used by any observer who has previously sent an
email report to the Division using SUNKEY.exe or the regular-mail paper report. OBSERVERS WHO

Solar Software Downloads

The software listed here may be downloaded for free. These programs will help you to prepare and analyze solar observations. If you have any questions please feel free to contact us:

Guidelines for Solar Observers

Solar observing is unique among the objects that AAVSO observers pursue because it is so bright. The most important guideline for solar observing is observe safely. This cannot be stressed enough, and if you are uncertain about any of the following equipment and safety recommendations, please request assistance before making any observations of the Sun with your equipment.


AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484