CCOR-1 (for Compact CORonograph-1) is a space-based coronograph aboard a geostationary satellite GOES-19 owned by NOAA. Its goal is providing realtime solar data used for space weather forecasting.

It is the first out of planned three coronographs from Compact Coronograph series. CCOR-2 started operating in June 2026.

By covering the Sun's extremely bright surface (photosphere) allows observations of its atmosphere called corona. It is millions of times fainter than the Sun itself, its surface brightness roughly comparable to full Moon's.. It is important to monitor the corona because coronal mass ejections (CME) can damage electric devices like transformers or power grids.

Mission The instrument's goal is obtaining white light images of the solar corona and downlinking the data within 30 minute latency.. The data is then used to make a space weather forecast. CCOR's purpose is also replacing aging research coronographs like SOHO/LASCO or STEREO/COR.

It was launched on 25 June 2024 5:26 PM EDT using Falcon Heavy rocket from John F. Kennedy Space Center.. On 19 September 2024 it obtained its first light image, however it was made public on 22 October.. The instrument (and the entire satellite) was handed over to NOAA on 29 January 2025.

On 7 April 2025 it was declared an official operational satellite on GOES-East, located at 75.2°W longitude.

It is on a geostationary orbit which means that the angular motion of the satellite is equal to Earth's, therefore the object seems to „hang" above a specific spot on the planet. This orbit is placed above the equator.

Technicals CCOR-1 was developed and tested by US Naval Research Laboratory (NRL). It is placed on a Sun Pointing Platform (SPS) specifically designed for solar instruments. It is mounted aside EXIS and SUVI.

Since the instrument is flying on geocentric orbit, it experiences eclipses once a day. Around 20 days before and after any equinox, the Earth eclipses half of the images. CCOR-1 performs a 180-degree roll maneuver called yawflip to decrease solar array stray light in the camera.

Requirements The list of requirements that the instrument has to follow is written below:

Note:

stands for solar surface brightness –10.8 mag/arcsec

is Sun's radius = = 0.266°. The FOV is measured at , counted from the outermost edge of the star.

FOV of 3.7 – 17 S/N ratio of 10 for 5.1 – 21.0 (1.36° – 5.6°) and spatial resolution of 50 arcseconds Visible light bandpass Accuracy of measurements of solar corona brightness down to 10% error or better Minimum solar corona intensity of Maximum solar corona intensity of Cadence of 15 minutes for full resolution images and 5 minutes for 2×2 binned Latency of 30 minutes Capability for meeting all mission requirements during solar storm of intensity S4 and flare intensity of X50 Inner geometric cutoff of 3.7 CME velocity estimate with 5% error for CME mass estimate with 50% error for kg to kg range Coronal brightness measurement of 10% error Reclosable door for possible 5 year on orbit storage Mission of 5 years length with 5 years of resources

Specifications

The actual specifications are:

+ParameterValueMass25 kg (55.1 lb) entire instrumentPower System Box massPixel size10 µm × 10 µmPower22.5 WFocal length109.53 mmPlate scale19.33"/px in inner FOV | 19.10"/px in outer FOVDetector pixels2048 × 1920 pxFOV in degrees (width, height)10.8°, 10.2°Inner FOV geometric cutoff3.7 (0.984°)Inner FOV photometric cutoff (S/N ratio 1)4.0 Outer side FOV (radially from the Sun surface)18.8 Outer diagonal FOV22.5 Spatial resolution≤50 arcseconds at ≥10% MTFField with this resolution5 – 20 Bandpass FWHM470 – 740 nmBandpass450 – 750 nm / 480 – 730 nm (different sources)Vignetting FOVto 17.4 F-number6.84Number of occulting disks19Cadence in full resolution15 minutesLatency15 minutesOperational temperatureBoot mode length65 – 130 secondsTelemetry modes3 – Housekeeping, Science, EngineeringData transfer speed25 kilobits per second (average)

Coronal mass ejection detection CMEs are detected by PyCat – open-source software created by NOAA/SWPC and UK Met Office. It is a modernized version of older CAT. PyCat studies the morphology of the event from L1 files (check Ground Processing Algorithm below) and compares its appearance from different satellites. Using this data, it can calculate speed, mass and direction of CME.

Ground Processing Algorithm In order for the raw images from the coronograph to be usable, they have to be processed upon being received. The data sent to the ground by SWPC is already compressed into FITS format files. CCOR-1 images have six processing levels.

First processing level is called L0. It is the raw readout of packets from the detector and metadata (header). From L0 two L0A files are assembled. These are inner FOV and outer FOV parts of image. After L0A images are combined and rotated so solar north is pointing upwards, a L0B file is created.

L0B then undergoes several processings. These are as follows:

Reconstructing the onboard bias subtraction Correcting associated with detector linearity Division by exposure time Time normalization Storing factor of calibration (Data Unit/s/px –> MSB) Converting the brightness to MSB (Mean Solar Brightness) Vignetting correction

These calibrations create L1A file. L1A serves as the source for creating models, i.e. earthshine and median background. Earthshine is computed from L1A and then used for subtraction from the image and that creates L1B. It is the only level available in real time.

Example filenames CCOR_0A_20251002T000025_V00_N2.fits CCOR_1A_20251002T000025_V00_NC.fits CCOR_1B_20251002T000025_V00_NC.fits CCOR_2_20251002T000025_V00_NC.fits

Median background L1A is used for median background determination. A median background of the entire day is called Daily Median (DM). After that, a minimum background is calculated to mirror a slowly changing stray light and F-corona (F-corona is Sun's light reflected of dust particles). 14 days of median background create Monthly Minimal Background (MM), while 7 days is called Minimal background. L1 products then get processed by subtracting either to get L2 level. L2 binned to 2×2 is L3.

Comet discoveries

CCOR-1 allows observations of near Sun comets, especially sungrazers. The first discovery was a Kreutz comet found by an US citizen scientist Robert Pickard on 11 February 2025. It was accompanied by two fragments.

By 30 August 2025, 101 comets were discovered via NASA's Sungrazer Project program.

References

External links CCOR-1 official website Realtime processed images (SWPC) including running difference images