The U.S. National Science Foundation (NSF) Announces Decision to Close Sunspot Solar Observatory

In the article here, NSF has announced the closure of the Sunspot Solar Observatory. It will remain closed to the public indefinitely.

Following the January 5, 2026 discovery of liquid mercury on the platform inside the Dunn Solar Telescope, and the subsequent indentification of a leak originating from the main bearing, the U.S. National Science Foundation has determined that the most prudent course of action is to completely drain and remove the mercury from the site as soon as possible. This action, while necessary for safety and environmental reasons, will render the DST inoperable. At this time, and through the remediation of the DST, the visitor's center will remain closed to the public for safety purposes.

In order to ensure the safety of all workers, personnel and the public, Sunspot Observatory (including the Dunn Solar Telescope, the Visitor Center, the surrounding areas, and local hiking trails) is CLOSED TO THE PUBLIC for the foreseeable future. We apologize for any inconvenience.

On the morning of January 5th, two NMSU staff members inside the Dunn Solar Telescope (DST) observed liquid mercury on the platform. Proper safety protocols were implemented immediately to ensure the safety of both on-site personnel. The DST, the surrounding observatory building, and visitor center will remain closed until further notice while appropriate remediation measures are implemented. There is no immediate concern for public or environmental safety, and the proper authorities have been notified.

Instruments

Research & Instruments

Dunn Solar Telescope's open optical bench system makes it easy for solar astronomers to collaborate with DST on scientific research.

The Dunn Solar Telescope, or DST as it is also known, was inaugurated as the world's premier high spatial resolution optical solar telescope in 1969. Today, one high-order adaptive optics (AO76) bench produces sub-arc-second imaging (0".14 @ 430 nm) for an array of advanced instruments. Data taken at the Dunn are available to the public at our data site.

Optical Path

Aerial view of the interior of an observation tower, showcasing various scientific equipment and instruments set up for research purposes.

Instruments at DST

Here are some instruments that organizations have constructed to be used in collaboration with DST for solar research.

ROSA (ARC, QUEEN'S UNIVERSITY BELFAST)

The Rapid Oscillations in the Solar Atmosphere instrument is a high-cadence, high-efficiency solar imaging instrument. Designed by the Astrophysics Research Center at Queen's University Belfast in Northern Ireland, ROSA consists of six cameras, each sensitive to a different wavelength band. ROSA is capable of a cadence greater than 30 fps, and is capable of extremely high resolution, corresponding to a spatial scale ranging from 52-98 miles (84-158 km) in the solar atmosphere.

More ROSA information and publications

FIRS (IFA, UNIVERSITY OF HAWAI'I)

The Facility InfraRed Spectropolarimeter is an advanced slit-based spectropolarimeter designed to provide simultaneous coverage of visible and infrared wavelengths. It was designed by the Institute for Astronomy at the University of Hawai'i, with support from the National Solar Observatory (NSO). It is designed to maximize efficiency when observing the spectral lines of Helium and Iron. By positioning the spectrograph slit in multiple locations along a region of interest, FIRS can be used to build a map of the region at a high spatial and spectral resolution.

More FIRS information and publications

SPINOR (HAO & NSO)

The Spectro-Polarimeter for INfrared and Optical Regions is a slit-based spectropolarimeter built by the High Altitude Observatory (HAO) in Boulder, CO, and the NSO. Up to four synchronized cameras sample different spectral lines, with up to two infrared channels, providing spectropolarimetry for much of the visible and near-infrared regime.

Research at DST

Here are some published research articles that reference their collaborative efforts with DST.

SELECTED PUBLICATIONS, ROSA:

1. Jess, D.B., Mathioudakis, M., Christian, D.J., Keenan, F.P., Ryans, R.S.I., Crockett, P.J., 2009,
Solar Physics, 10, 1007,
ROSA: A high cadence, synchronized, multi-camera solar imaging system

2. Jess, D.B., Mathioudakis, M., Christian, Crockett, P.J., Keenan, F.P., 2010,
The Astrophysical Journal Letters, 719, L134-L139,
A Study of Magnetic Bright Points in the NaI D1 Line

3. Crockett, P.J., Mathioudakis, M., Jess, D.B., Shelyag, S., Keenan, F.P., Christian, D.J., 2010
The Astrophysical Journal Letters, 722, L188-L193,
The Area Distribution of Solar Magnetic Bright Points

SELECTED PUBLICATIONS, FIRS:

1. Jaeggli, S.A., Lin, H., 2009
The First Vector Magnetogram Comparison Group Meeting, October 2009, NSO/Tucson
FIRS: A New Instrument for Multi-Wavelength Spectropolarimetry

2. Jaeggli, S.A., Lin, H., Mickey, D. L., Kuhn, J. R., Hegwer, S. L., Rimmele, T. R., Penn, M. J., 2009
NSO Workshop #25, September 2009, Sacramento Peak
FIRS: A New Instrument for Photospheric and Chromospheric Studies the Dunn Solar Telescope

3. Jaeggli, S.A., Lin, H., Uitenbroek, H., 2010
The 6th Solar Polarization Workshop, Ka'anapali, June 2010
Molecule Formation and Magnetic Field Evolution in Sunspots

SELECTED PUBLICATIONS, SPINOR:

1. Socas-Navarro, H., Elmore, D., Pietarila, A., Darnell, A., Lites, B.W., Tomczyk, S., Hegwer, S., 2006
Solar Physics, 235, 55-73
SPINOR: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory