Archive for category HMI
We are currently experiencing some technical difficulties with our main Helioviewer server. While we work on fixing it, we have moved all helioviewer.org services over to our backup server. All normal helioviewer.org services should be operating nominally. Please contact us if you notice anything amiss with helioviewer.org. JHelioviewer services are currently not operational, but we hope to have these up and running as soon as possible. Near real-time AIA and HMI images should be available as usual; streams of images from SOHO, STEREO and PROBA2 should be back to near real-time within 24 hours.
We apologize for the interruption to Helioviewer services, and we thank you for your patience.
From today’s SDO blog entry:
Today, starting at 1315 UTC (8:15 am ET), SDO will execute the EVE Field of View maneuver followed by the HMI/AIA Flatfield at 1630 UTC (11:30 am ET). During these maneuvers the science data will be interrupted. These maneuvers and last weeks’ Delta-H thruster firing were flipped in the schedule published earlier.
Instruments can degrade in the harsh environment of space, and so it is important to calibrate at regular intervals to make sure that we have the best data available at all times. SDO therefore occasionally makes special maneuvers that enable the measurements to be made that can be used to help calibrate the instruments onboard. Whilst these maneuvers are going on, some of the AIA and SDO images may look unusual.
SDO has three instruments onboard: AIA, HMI and the Extreme Ultraviolet Experiment, EVE. The EVE instrument is designed to measure the solar extreme ultraviolet (EUV) irradiance. The EUV radiation includes the 0.1-105 nm range, which provides the majority of the energy for heating Earth’s thermosphere and creating Earth’s ionosphere (charged plasma). The majority of EVE data are time-series of measurements of the spectral content of solar extreme ultraviolet irradiance, although some low spatial resolution x-ray images are also taken by the EVE Solar Aspect Monitor (SAM) instrument (see the example below). EVE gives us lots of information on the spectral content of the Sun’s radiation changes with time, which is very important for understanding the Earth-Sun connection.
SDO AIA and HMI images are currently lagging behing real time by about 18 – 22 hours. This is due to some necessary hardware upgrades in the processing pipeline that have interrupted the flow of images. The availability of LASCO, EIT, COR1, COR2, EUVI and SWAP images is unaffected by these hardware upgrades. We expect that the lag in SDO AIA and HMI images compared to real time will be caught up in the next few hours. We apologize for the interruption in availability of near real time AIA and HMI images.
A new version of JHelioviewer is available for download. What’s new? This update release contains improved movie export functionality, an updated LASCO C2 coronagraph mask, the new SDO Cutout Service plug-in plus various bug fixes.
The new movie export menu makes it easier to set the exact scaling of the area you are interested in, and the processing itself is now performed on the graphics card using OpenGL:
The SDO Cutout Service plug-in allows you to request science-quality image data from the SDO/AIA and HMI instruments for the region of interest and time range selected in JHelioviewer:
As you may have noticed, we are currently experiencing a lag in the availability of SDO images. The lag is happening upstream of Helioviewer. The Helioviewer Project provides images of scientific data. The science data is beamed down from the spacecraft , to a dedicated ground station (as outlined here) in New Mexico. The packets of data are first re-assembled to form the raw science data, and then have some corrections applied to yield data suitable for science applications. Data is constantly streaming off the spacecraft and being processed through this pipeline, which involves many different locations and institutions.
One of those science applications is visualization of the data. The Helioviewer Project takes that science data and converts those data to JPEG2000 images, which we then make available via www.helioviewer.org and www.jhelioviewer.org. We have to have the science data available to make the JPEG2000 images.
As soon as new SDO-AIA and HMI images become available, we will make them available to you. We regret the interruption to the stream of SDO data. Other data-sets are unaffected, and are available as usual.
The most recent LASCO, EIT, COR1/2 and EUVI images are currently unavailable to Helioviewer Project browse clients. This is because the computer that converts the science data to JPEG 2000 images experienced a mechanical failure on Friday January 13th. We will replace the failed machine, and make an announcement via the blog concerning the resumption of the availability of images from LASCO, EIT, COR1/2 and EUVI. We are apologize for any inconvenience this may cause. Finally, images from AIA and HMI should be unaffected.
Some of you may have noticed that helioviewer.org was not displaying recent AIA or HMI images in the last 24 hours. This was due to a glitch in the processing pipeline, and we apologize for this. The issue has been resolved and newer images are now coming online. We expect to be caught up within the next few hours. If you spot any problems, please let us know.
The latest JHelioviewer update adds support for SDO/HMI data and features a new contrast filter, as well as an improved plugin to access the Heliophysics Event Knowledgebase (HEK).
Today we are making available images from the Helioseismic Magnetic Imager (HMI), an instrument on board the Solar Dynamics Observatory. HMI is designed to study oscillations and the magnetic field at the solar surface, or photosphere. We are providing line-of-sight magnetograms and continuum images* based on HMI science data. A line-of-sight magnetogram measures the flux of magnetic field as seen along the line of sight from HMI to the Sun. A continuum image is formed by filtering portions of the visible light part of the spectrum.
The line-of-sight magnetograms shows blobs of dark emission, and blobs of brighter emission. These correspond to opposite polarity magnetic fields breaking through the Sun’s photosphere. The magnetic field is important as it is related to the activity seen in layers of the Sun’s atmosphere such as the corona (which is observed by AIA). The continuum images allow us to track the evolution of sunspots. These images are important as they allow us to better understand the dynamic nature of the solar atmosphere.
The primary goal of the Helioseismic and Magnetic Imager (HMI) investigation is to study the origin of solar variability and to characterize and understand the Sun’s interior and the various components of magnetic activity. HMI makes measurements of the motion of the solar photosphere to study solar oscillations and measurements of the polarization in a specific spectral line to study all three spatial components of the photospheric magnetic field. HMI produces data to determine the interior sources and mechanisms of solar variability and how the physical processes inside the Sun are related to surface magnetic field and activity. It also produces data to enable estimates of the coronal magnetic field for studies of variability in the extended solar atmosphere, which is where the Earth is. Solar variability that affects the Earth is called “space weather”. HMI observations will help establish the relationships between internal dynamics and magnetic activity. In turn this will lead to better understanding of solar variability and its effects.
For much more information on HMI, please visit http://hmi.stanford.edu/. For more information on SDO, please visit http://sdo.gsfc.nasa.gov.
* HMI is a successor to the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The Helioviewer Project has MDI line-of-sight magnetogram and continuum images going back to early 1996.