Spring 2024 Calibration Maneuvers Begin Today

Today SDO will execute the EVE Field of View (at 1315 UTC, 9:15 am ET) and the HMI/AIA Flatfield (at 1630 UTC, 12:30 pm ET) calibration maneuvers. During these maneuvers SDO science data may be missing or blurred.

Calibration Activities Today 1700-2030 UTC

The SDO Team will power cycle Inertial Reference Unit #2 (IRU-2) today. These cold starts are used to maintain the IRUs and ensure their longevity. The spacecraft will execute a series of off-point maneuvers after the power cycle. These will be done in all three axes, so images will appear to move left to right, nod up and down, and roll to and fro. Once the testing and calibrations are over SDO will return to routine science data collection.

During the calibration activity science data may be missing, blurred, or shifted.

Perihelion Interrupts Instrument Calibrations

SDO executed the EVE FOV and HMI/AIA Flatfield instrument calibration maneuvers yesterday, 04 Jan 2023, at 1415 UTC (9:15 am ET) and 1730 UTC (12:30 pm ET), respectively. During these maneuvers, at 1617 UTC (11:17 am ET) the Earth reached perihelion, the point in its orbit when it is closest to the Sun. Here is a picture comparing AIA 1600 images at 1649 UTC (10:49 am ET, right) and 04 Jul 2022, 0711 UTC (03:11 am ET, during DST, on left) when the Earth is farthest from the Sun.

The blues lines are drawn to touch the poles of the Sun in the image from last July. You can see that the Sun appears to be a bit larger near perihelion than at apohelion. The SDO telescopes cannot change the size of their images and HMI in particular had to allow for this change in apparent size when designing the optics.

Happy Perihelion 2023!

Fall 2022 Calibration Maneuvers Begin

Today SDO will execute the EVE Field of View (at 1315 UTC, 9:15 am ET) and the HMI/AIA Flatfield (at 1630 UTC, 12:30 pm ET) calibration maneuvers. During these maneuvers SDO science data may be missing or blurred.

October 2021 Instrument Calibration Maneuvers have Finished

The October 2021 Instrument Calibration maneuvers have finished. During an instrument calibration maneuver SDO science data may be missing, blurry, or misaligned. The first two cannot be corrected but roll angle is no longer seen as a rotation of the solar image.

• 13 Oct 2021: EVE Cruciform, 1400–1852 UTC (10:00 am - 2:52 pm ET)
• 20 Oct 2021: HMI Roll Maneuver, 1400-2040 UTC (10:00 am - 4:40 pm ET)
• 27 Oct 2021: EVE FOV and HMI/AIA Flatfield Calibrations (EVE FOV @ 1315 UTC; HMI/AIA Flatfield @ 1630 UTC)

The next set of calibration maneuvers will be in January 2022 (EVE Cruciform, EVE FOV, and HMI/AIA Flatfield) and April 2022 (HMI Roll).

Guidance System Calibrations Yesterday

Yesterday, June 16, 2021, from 1700-2000 UTC (1-4pm ET), SDO ran calibration maneuvers for the pointing system. These tests were to restart one of the inertial reference units and then a roll of the satellite to help refine some of the parameters in the Kalman filter. During this time science data may be missing or blurry. The tests were successful and will help maintain SDO's pointing accuracy for years to come.

My congratulations to the Flight Operations Team for completing an excellent set of calibration maneuvers!

Winter Calibration Maneuvers, January 6, 2021

SDO will execute two calibration maneuvers on January 6, 2021. The EVE Field of View (FOV) maneuver will begin at 1315 UTC (8:15 am ET). The HMI/AIA Flatfield maneuver will begin at 1630 UTC (11:30 am ET). During a calibration manuever the SDO science data may be missing or blurred.

Calibration Maneuvers Today

SDO will execute the EVE Field of View (FOV) calibration maneuver starting at 1315 UTC (9:15 am ET). That will be followed by the HMI/AIA Flatfield calibration maneuver starting at 1630 UTC (2:30 pm ET). During these maneuvers the SDO science data may be missing or blurry.

Calibration Maneuvers Today

Today from 1315-1915 UTC (8:15 am - 2:15 pm ET) SDO will perform the EVE Field of View and HMI/AIA Flatfield calibration maneuvers. Science data recorded during these maneuvers may be missing, incomplete, or blurry.

Testing of AIA Today, 1800-1900 UTC

Today from 1800-1900 UTC (2-3 pm ET), AIA will record some test images. This will exercise the ability to command AIA to produce partial (cropped) and uncompressed images. Other instruments will be unaffected. The actual testing is scheduled to last approximately 10 minutes. Test images will be in focus but may be missing a part of the Sun.

Calibration Maneuvers on October 9, 2019

SDO executed the EVE Field of View and HMI Flatfield calibration maneuvers on October 9, 2019. During these maneuvers the science data may be blurry or mission.

HMI Focus Adjustments Today, Data may be Unavailable

Anything looking at the Sun tends to heat up. The SDO instruments have been looking at the Sun for 8.5 years. Although they are designed to look at the Sun for a long time, some changes still happen.

For example, the coatings on the HMI instrument housings and optical surfaces have been degrading slowly but steadily, causing the instrument to absorb more solar radiation and heat up. The front surface of HMI’s telescope is now hot enough that the HMI team is having difficulty maintaining proper focus. Without some adjustments, this problem will only get worse as the instrument continues to age.

For this reason, the HMI team is going to increase the operating temperatures of the front of the telescope and adjust the internal focus mechanism. This should give the instrument many more years of precise control and excellent data. The process of increasing the operating temperatures is a slow one — the team will begin heating the front telescope tube up at 1000 UTC on Tuesday, October 16, and will then wait six hours for the temperature to stabilize. The next step is to fine-tune the temperatures. These smaller changes will need about an hour for the temperature to become constant. Science data will not be available during the time it takes to bring the instrument back into focus. That also means there will be no magnetic field, continuum, or Doppler NRT data products.

HMI resumed taking science data before 2130 UTC, October 16. Fine tuning of the focus will occur Wednesday, October 17, but science data will not be interrupted.

Today's Maneuver and Schedule for the rest of 2018

Today at 1500 UTC (11:00 am ET) SDO will perform the HMI roll. The spacecraft rolls once around the axis pointed towards the Sun to provide calibration information for the instruments. These measurements are also used to learn how round the Sun is.

Here are other planned maneuvers through the rest of 2018.

• 07/18 @ 1945 UTC (3:45 pm ET) - Momentum Management #32
• 07/21 @ 0433 UTC (12:33 am ET) - Handover Season Starts with First Handover
• 07/25 @ 1230 UTC (8:30 am ET) - EVE Cruciform
• 08/08 @ to be determined - Simulated comet observation
• 08/12 @ 0710 UTC (3:10 am ET) - Fall 2018 Eclipse Season Starts
• 08/15 @ 2225 UTC (6:28 pm ET) - Station Keeping #17
• 09/04 @ 0654 UTC (2:54 am ET) - Fall 2018 Eclipse Season Ends
• 09/09 @ 2030-2130 UTC (4:30-5:30 pm ET) - Lunar Transit, 92% obscuration
• 09/10 @ 0152-0241 UTC (9:52-10:41 pm ET) - Lunar Transit, 34% obscuration
• 09/18 @ 0405 UTC (12:05 am ET) - Last Handover Completes & Handover Season Ends
• 11/07 @ 2024-2116 UTC (3:24-4:16 pm ET) - Lunar Transit, 44% obscuration
• 12/12 @ to be determined - Momentum Management #33

The pair of Lunar Transits on September 9th and 10th are separated by approximately 4 hours 22 minutes, so they are considered separate events. However, the relative motion of SDO and the Moon cause what could be a single transit to split into two. We will discuss this more as we approach the transits.

The sun and moon will be separated by 0.604° on August 21, 2018. (The Sun is 0.5° across, so the Moon is not in the field of view of the SDO images.) This is not close enough to be flagged as a transit, but the proximity may be of interest.

Today's Maneuvers

Today SDO is performing the EVE Field of View and HMI Flatfield calibration maneuvers. Between 1315 and 1910 UTC (9:15 am - 3:10 pm ET) SDO will move in patterns about the Sun. Science data may be unavailable at these times or blurry. Here is an AIA 193 Å image from 1354 UTC with the bottom right corner of the Sun cutoff by SDO pointing away from the center of the Sun.