The COronal Solar Magnetism Observatory (COSMO) is a proposed facility dedicated to studying coronal and chromospheric magnetic fields and their role in driving solar activity such as coronal mass ejections (CMEs). COSMO is comprised of 3 instruments: 1) a 1.5 m coronagraph dedicated to the study of coronal magnetic fields; 2) a chromospheric and prominence magnetometer ; and 3) a K-coronagraph. The National Center for Atmospheric Research (NCAR), via the National Science Foundation (NSF), provided full funding for the COSMO K-coronagraph, which was recently deployed to the Mauna Loa Solar Observatory (MLSO) in Hawaii. It will measure the polarization brightness (pB) of the K-corona formed by Thomson scattering of photospheric light by coronal free electrons. With a field-of-view of 1.05 to 3.0 solar radii and an image cadence of 15 seconds, it is ideally suited for studying the formation and propagation of CMEs which are the primary driver of space weather at Earth. It replaces the aging MLSO K-coronameter ( currently known as Mk4) which had been in operation since The objective lens is made of fused silica, which is extraordinarily pure and has very low levels of birefringence. K-cor observes at a wavelength of 735 nm with a 30 nm pass band filter. The corona is recorded using two modified Photon Focus MV-D1024E x 1024 cameras with frame rates of 140Hz, full well depth of 185,000 photoelectrons and full CameraLink interface. The instrument uses a 4-state Stokes definition scheme to record the Stokes vectors I, Q, and U, where I is the total intensity and Q and U are the linear polarization states. A pair of 2-state Ferroelectric Liquid Crystals change the state of the modulator. A calibration diffuser provides flat-field and absolute intensity of coronal gain. An instrument designed to study CME formation, evolution and acceleration … coming this fall! (2013) Joan Burkepile(1), Alfred deWijn(1), Steve Tomczyk(1), Scott Sewell(1), Dennis Gallagher(1), Greg Card(1), Alice Lecinski(1), Brandon Larson(1), Lee Sutherland(1), Pete Nelson(2), Pei Huang(3), Rich Summers(1), Don Kolinski(1), Leonard Sitongia(1), Allen Stueben(1), Ben Berkey(1) 1=National Center for Atmospheric Res.; (2) = Sierra Scientific Solutions (3) = Huang Assoc. CONTACT INFO: Joan Burkepile, Principal Investigator: Alfred deWijn, Instrument Scientist: 2734 mm total optical track High Quality Fuse Silica Objective Lens AFT OPTICS Color Corrector Lens Cemented doublet 1 st imaging lens group- Two element lens common to both optical paths. One plano concave. one plano-convex lens Common Glasses S-LAL-7 S-NPH1 S-LAL14 SF1 50X50mm Beam splitter SF1 Lyot Stop 0.92X(85%) Lyot Spot F/ mm EFL IMAGING ASSEMBLY (ZOOMED) AFT OPTICS (ZOOMED) Plano BK7 field lens from OptoSigma Band pass filter and vignetting disk. FLC Modulator Color Corrector optics Beam splitter camera lens assembly Occulter Station IMAGING ASSEMBLY 2 nd imaging lens group 2X – 2 lenses One plano-convex, one plano-concave Calibration optics Objective Lens Occulter and Field Lens Aft Optics: Modulator Beam Splitter Imaging Assembly Mechanical Layout of K-coronagraph DESIGN HIGHLIGHTS: Field-of-view: 1.05 to 3 solar radii Temporal cadence: 15 seconds with goal of 8 seconds ( vs. 3 minutes for the MLSO Mk4 K-coronameter) 20 cm aperture Internally occulted Pass band: ~720 to 750 nm Out-of-band rejection <= 1 part in a million (factor of 10 better signal – to – noise than the MLSO Mk4 K-coronameter Minimization of scattered light through use of unocated, ultra-high quality singlet objective lens, Hepa clean air system, baffles, coatings, and out- of-band rejection filters. DESIGN HIGHLIGHTS: Field-of-view: 1.05 to 3 solar radii Temporal cadence: 15 seconds with goal of 8 seconds ( vs. 3 minutes for the MLSO Mk4 K-coronameter) 20 cm aperture Internally occulted Pass band: ~720 to 750 nm Out-of-band rejection <= 1 part in a million (factor of 10 better signal – to – noise than the MLSO Mk4 K-coronameter Minimization of scattered light through use of unocated, ultra-high quality singlet objective lens, Hepa clean air system, baffles, coatings, and out- of-band rejection filters. A K-cor image composited with a SDO AIA 171 image both from October 31, K-cor is the first white light coronagraph able routinely view into the first scale height of the corona (1.05 Rsun) outside of an eclipse.