About The Mauna Loa Solar Observatory
The Mauna Loa Solar Observatory (MLSO) occupies part of the NOAA Mauna Loa research site located on the flank of Mauna Loa at an elevation of 3440 meters on the island of Hawaii. It is operated by the High Altitude Observatory, a division of the National Center for Atmospheric Research, which is located in Boulder, Colorado.
The MLSO telescopes are operated via several workstations in the on-site control center. Seated at the desk is chief observer Darryl Koon.
Click on the image to start a short slideshow about HAO, MLSO and the Sun.
ACOS: Advanced Coronal Observing System
A suite of instruments designed to observe the solar atmosphere, including the Chromospheric Helium Imaging Photometer (CHIP, 1083.0nm), H-alpha prominence and solar disk monitor (PICS, 656.3nm), and the Mk4 K-coronameter, which observes the white light K-corona from 1.12-2.79 solar radii (700-950 nm).
White Light Corona: Mark-III K-Coronameter & Mk4 K-Coronameter
The Mark-III instrument was the third generation white light K-coronameter instrument at MLSO, and it operated from 4 February, 1980 through 30 September, 1999.
The field of view of the Mark-III K-Coronameter (Mk3) was 1.122 to 2.44 solar radii (as measured from sun center). The sun's corona was scanned by a linear array detection system which is rotated in solar position angle about the center of the solar disk. It took about three minutes to acquire one coronal image.
The Mark-III K-Coronameter data are scaled such that 104.4 pixels corresponds to one solar radius. Spatial sampling is 10 arcseconds radially by 0.5 degrees in azimuth. All data are rotated so that solar north is oriented straight up; solar north is known to within three degrees. Daily averaged images and mass ejection images from the K-Coronameter have instrumental `vignetting' left in the data to offset the coronal radial density gradient, allowing for better viewing of the corona. Calibrated images in units of polarization brightness (pB) are available and may be requested via the E-mail address listed above.
The Mark-IV K-coronameter, was constructed by HAO in collaboration with Rhodes College (Memphis, Tennessee). It has been in operation since October, 1998 at MLSO.
The Mark-IV K-coronameter replaces its predecessor, the Mark-III and features a high speed liquid crystal polarization modulator, a low noise CCD line array detector, and an achromatic polarizing beam splitter to measure Stokes I, Q, and U. Mark-IV produces polarization brightness maps of the lower corona in white light (700 to 900nm) from about 1.14 to 2.86 solar radii at a 3-minute cadence. Its plate scale is 5.95"/pixel, with data accuracy of approximately %15 and a noise level of approximately 4x10-9 B/Bsun.
The Mark-IV instrument is a significant improvement over its predecessor in the following ways: lower system noise due to an improved detector and associated electronics, better sky noise rejection due to improved polarization optics and faster polarization modulation rate, higher spatial resolution, and a wider field of view.
These improvements result in higher quality polarization-brightness images which may be taken over a greater range of sky conditions than was heretofore possible.
For additional information about the Mark-III K-Coronameter instrument, see Fisher et al. (1981).
For information about the Mark-III K-Coronameter calibration technique, see Elmore et al. (1996).
For information about the Mk4 K-Coronameter calibration technique, see Elmore et al. (199?).
H-alpha Disk & Limb: Prominence Monitor, Digital Prominence Monitor,
Polarimeter for Inner Coronal
Studies, and Coronado SolarMax60
The first H-alpha [656.3 nm] telescope at MLSO was the Prominence Monitor (PMON), which went into operation on 4 February 1980. It acquired both disk and limb images on B/W 35mm film.
On 20 February 1994, the Acme 35mm film camera was upgraded to a Kodak Megaplus [Model 1.6] CCD detector (1534x1030 pixels) with a sample size of 3 arcseconds, and the telescope was renamed the Digital Prominence Monitor (DPM).
On 25 September 1997, the PICS instrument replaced the Digital Prominence Monitor at MLSO. It provides several improvements over the DPM instrument, including optics for polarization measurement (since removed), improved temperature control, a narrower bandpass filter for disk observations, and improved optics for limb observations. PICS takes images at 656.3 nm, with a FOV of 2.3 solar radii, a spatial resolution of 2.9"/pixel, and a nominal cadence of 3 minutes.
PICS was decommissioned on 23 Feb, 2010 to make room on the tracking spar for the Coronal Multi-channel Polarimeter (CoMP). In its place, a small Coronado SolarMax60 Halpha imager was installed. The Coronado has a full FOV out to 2.25 Rsun at low latitudes and 1.6 Rsun over the poles before cropping (for large EPLs, the full FOV can be provided). Its spacial resolution is 1.77 arcseconds per pixel, with a nominal cadence of 3 minutes (capable of obtaining an image per second).
Helium-I Disk: Chromospheric Helium-I Imaging Photometer (CHIP)
The Chromospheric Helium-I Imaging Photometer (CHIP) was installed at the Observatory in April 1996. CHIP is a differential device using properties of the Helium-I line at 1083 nm as an indicator of both chromospheric and coronal structures. CHIP records images of the sun at 1083 nm, as well as at a number of other nearby wavelengths (for calibration purposes). It is basically composed of a liquid crystal variable retarder (tuneable) Lyot filter connected to an IR CCD.
CHIP is unique compared with other Helium-I imagers, in that it obtains images every 3 minutes, the high cadence crucial to study the rapid evolution of CMEs. In addition, observations from CHIP should provide better understanding of coronal holes, coronal arcades, and the interaction between open and closed magnetic field structures.
Seven line and continuum exposures are recorded within 2 seconds. The difference of line and one continuum exposures is computed every 3 minutes to produce one 1083 nm image.
The CHIP FOV is approximately 1.8 solar radii. The CCD pixel size is 2.29 arcseconds and the measured spatial resolution is ~8 arcseconds. For additional information on the tuneable filter see Kopp et al. (1996).
The Precision Solar Photometric Telescope (PSPT) is the centerpiece of the National Science Foundation Radiative Inputs from Sun to Earth (RISE) program whose aim is to measure and understand variability in the solar radiative output. The PSPT produces seeing-limited full-disk (2048x2048 with 1.05"/pixel) images in the blue continuum (409.4nm, FWHM 0.3nm), red continuum (607.1nm, FWHM 0.5nm), CaII K (393.4nm, FWHM 0.3nm), CaII K Narrow Band Wing (NBW) (393.6nm, FWHM 0.1nm), and CaII K Narrow Band Core (NBC) (393.4nm, FWHM 0.1nm), with an unprecedented 0.1% pixel-to-pixel relative photometric precision.
The National Solar Observatory (NSO) designed and built three PSPT units, a prototype which is currently in operation at the Osservatorio Astronomico di Roma (OAR), and two primaries for installation at NSO Sac Peak and Mauna Loa Solar Observatory (MLSO). Currently, the units at MLSO and OAR are operated daily, with the NSO Sac Peak unit set aside for debugging and spare parts.
The observatory begins daily operations (weather permitting) at approximately 17:00 U.T. and continues recording images for 3-10 hours depending on the weather. Fifty to one hundred white light coronal images are recorded on a typical observing day as well as approximately 100-200 full limb and disk H-alpha images and 100-200 full disk Helium-I images.
Calibrated Mark-IV data are available approximately ten days after the raw data are recorded. Qualitative Mark-IV images are posted the day they are taken.
Daily H-alpha disk, H-alpha limb and He-I images, daily activity reports, and synoptic maps, are also available. Mass ejection images are provided as time allows.
Access to this data is available via the Data & Movies tab at the top of this web page.