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  On-Orbit Performance of the Helioseismic and Magnetic Imager Instrument onboard the Solar Dynamics Observatory

Hoeksema, J. T., Baldner, C. S., Bush, R. I., Schou, J., & Scherrer, P. H. (2018). On-Orbit Performance of the Helioseismic and Magnetic Imager Instrument onboard the Solar Dynamics Observatory. Solar Physics, 293: 45. doi:10.1007/s11207-018-1259-8.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0001-2B92-A Version Permalink: http://hdl.handle.net/21.11116/0000-0001-2BFB-5
Genre: Journal Article

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 Creators:
Hoeksema, J. T., Author
Baldner, C. S., Author
Bush, R. I., Author
Schou, Jesper1, Author              
Scherrer, P. H., Author
Affiliations:
1Department Solar and Stellar Interiors, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832287              

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Free keywords: Instrumentation and data management Instrumental effects Velocity fields, photosphere Magnetic fields, photosphere
 MPIS_PROJECTS: SDO
 MPIS_PROJECTS: SDO: German Data Center
 MPIS_PROJECTS: SOHO
 Abstract: The Helioseismic and Magnetic Imager (HMI) instrument is a major component of NASA's Solar Dynamics Observatory (SDO) spacecraft. Since commencement of full regular science operations on 1 May 2010, HMI has operated with remarkable continuity, e.g. during the more than five years of the SDO prime mission that ended 30 September 2015, HMI collected 98.4% of all possible 45-second velocity maps; minimizing gaps in these full-disk Dopplergrams is crucial for helioseismology. HMI velocity, intensity, and magnetic-field measurements are used in numerous investigations, so understanding the quality of the data is important. This article describes the calibration measurements used to track the performance of the HMI instrument, and it details trends in important instrument parameters during the prime mission. Regular calibration sequences provide information used to improve and update the calibration of HMI data. The set-point temperature of the instrument front window and optical bench is adjusted regularly to maintain instrument focus, and changes in the temperature-control scheme have been made to improve stability in the observable quantities. The exposure time has been changed to compensate for a 20% decrease in instrument throughput. Measurements of the performance of the shutter and tuning mechanisms show that they are aging as expected and continue to perform according to specification. Parameters of the tunable optical-filter elements are regularly adjusted to account for drifts in the central wavelength. Frequent measurements of changing CCD-camera characteristics, such as gain and flat field, are used to calibrate the observations. Infrequent expected events such as eclipses, transits, and spacecraft off-points interrupt regular instrument operations and provide the opportunity to perform additional calibration. Onboard instrument anomalies are rare and seem to occur quite uniformly in time. The instrument continues to perform very well.

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Language(s): eng - English
 Dates: 2018-04-182018
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1007/s11207-018-1259-8
 Degree: -

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Title: Solar Physics
  Other : Sol. Phys.
Source Genre: Journal
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Affiliations:
Publ. Info: Dordrecht, Holland : Kluwer, etc.
Pages: - Volume / Issue: 293 Sequence Number: 45 Start / End Page: - Identifier: ISSN: 0038-0938
CoNE: https://pure.mpg.de/cone/journals/resource/954925445694