CCOR-1 (Compact CORonograph-1)

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

By covering the Sun's surface (photosphere), it allows to observe its atmosphere called corona.^[2][3] It is millions of times fainter than the Sun itself, roughly as bright as full Moon.^{[4][5][6][7][8][9]} It is important to monitor the corona, as coronal mass ejections (CME) can damage power grids, interrupt GPS systems and cause damage to technology resulting in a cost of repair counted in millions or even billions of dollars.^[2][10]

The instrument's goal is obtaining white light images of the solar corona as well as tracking CMEs and downlinking the data within 30 minute latency.^{[11][12][13][14][15][2]} The data is then used to make a space weather forecast.^[1][11][14] CCOR's purpose is also replacing aging research coronographs like SOHO/LASCO or STEREO/COR.^[12][2]

It was launched on 25 June 2024 5:26 PM EDT using Falcon Heavy rocket from John F. Kennedy Space Center.^{[11][16][17][2]} On 19 September 2024 it obtained its first light image, however it was made public on 22 October.^{[18][19][20][21]} The instrument (and the entire satellite) was handed over to NOAA on 29 January 2025.^[22]

On 7 April 2025 it was declared an official operational satellite on GOES-East, located at 75.2°W longitude.^[22][11][23]

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 35,786 kilometers (22,236 miles) above the equator.

• Prepared for shock testing
• After magnetic characterization
• Electromagnetic testing
• Other image from shock testing

CCOR-1 was developed and tested by US Naval Research Laboratory (NRL).^[11][2][13] It is placed on a Sun Pointing Platform (SPS) specifically designed for solar instruments.^[11][13][2] It is mounted aside EXIS and SUVI.^[11][2]

Since the instrument is flying on geocentric orbit, it experiences eclipses once a day.^[16][15][2] Around 20 days before and after any equinox, the Earth eclipses half of the images.^[15] CCOR-1 performs a 180-degree roll maneuver called yawflip to decrease solar array stray light in the camera.^[15]

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

Note:

${\displaystyle B_{\odot }}$ stands for solar surface brightness ${\displaystyle \approx }$ –10.7 mag/arcsec${\displaystyle ^{2}}$

${\displaystyle R_{\odot }}$ is Sun's radius = 695,700 kilometres (432,300 miles) = 0.266°. The FOV is measured at 1 AU (149.6 million km; 93.0 million mi), counted from the outermost edge of the star.

• FOV of 3.7 – 17${\displaystyle \leq }$ ${\displaystyle R_{\odot }}$
• S/N ratio of 10 and resolution of ${\displaystyle \leq }$ 50 arcseconds for 5.1 ${\displaystyle R_{\odot }}$ – 21.0 ${\displaystyle R_{\odot }}$(1.36° – 5.6°)
• Visible light bandpass
• Accuracy of measurements of solar corona brightness down to 10% error or better
• Minimum solar corona intensity of ${\displaystyle 1.0\times 10^{-11}}$${\displaystyle B_{\odot }}$
• Maximum solar corona intensity of ${\displaystyle 1.0\times 10^{-8}}$${\displaystyle B_{\odot }}$
• Cadence of 15 minutes for full resolution images and 5 minutes for 2×2 binned
• Latency of ${\displaystyle \leq }$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 ${\displaystyle R_{\odot }}$
• CME velocity estimate with ${\displaystyle \leq }$5% error for 200–3,400 km/s (120–2,110 mi/s; 450,000–7,610,000 mph)
• CME mass estimate with ${\displaystyle \leq }$ 50% error for ${\displaystyle 1.0\times 10^{7}}$ kg to ${\displaystyle 5.0\times 10^{14}}$ kg range
• Coronal brightness measurement of ${\displaystyle \leq }$10% error
• Reclosable door for possible 5 year on orbit storage
• Mission of 5 years length with 5 years of resources

Parameter	Value
Mass	19.1 kilograms (42.1 lb), 25 kg (55.1 lb) entire instrument
Power System Box	2.3 kilograms (5.1 pounds)
Pixel size	10 µm × 10 µm
Power	25 W
Focal length	109.53 mm
Plate scale	19.33"/px in inner FOV | 19.10"/px in outer FOV
Detector pixels	2048 × 1920 px
FOV in degrees (width, height)	10.8°, 10.2°
Inner FOV geometric cutoff	3.7 ${\displaystyle R_{\odot }}$(0.984°)
Inner FOV photometric cutoff (S/N ratio ${\displaystyle \geq }$ 1)	4.0 ${\displaystyle R_{\odot }}$
Outer side FOV (radially from the Sun surface)	18.8 ${\displaystyle R_{\odot }}$
Outer diagonal FOV	22.5 ${\displaystyle R_{\odot }}$
Resolution	2 pixels = 39 arcseconds
Field with this resolution	5 ${\displaystyle R_{\odot }}$ – 20 ${\displaystyle R_{\odot }}$
Bandpass FWHM	470 – 740 nm
Bandpass	450 – 750 nm / 480 – 730 nm (different sources)
Vignetting FOV	to 17.4 ${\displaystyle R_{\odot }}$
F-number	6.84
Number of occulting disks	19
Cadence in full resolution	15 minutes
Latency	${\displaystyle \leq }$15 minutes
Operational temperature	−35 degrees Celsius (−31 degrees Fahrenheit)
Boot mode length	65 – 130 seconds
Telemetry modes	3 – Housekeeping, Science, Engineering
Data transfer speed	32 bps

CMEs are detected by PyCat – open-source software created by NOAA/SWPC and UK Met Office.^[24] 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.

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.^[15] 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).^[15] 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.^[15]

L0B then undergoes several processings. These are as follows:^[15]

• 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.^[15]

CCOR_0A_20251002T000025_V00_N2.fits

CCOR_1A_20251002T000025_V00_NC.fits

CCOR_1B_20251002T000025_V00_NC.fits

CCOR_2_20251002T000025_V00_NC.fits

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 the slowly changing straylight 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.^[15]

CCOR-1 allows observations of near Sun comets, especially sungrazers.^[25] 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.^[26]

To 28 May 2025, 47 comets were officially confirmed via NASA's Sungrazer Project program.^[27]

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