Doc Greiner Research Observatory SOHO Sungrazer Comet Hunting Method

By Matt Mills

 

The Solar and Heliospheric Observatory (SOHO) was launched on December 2nd, 1995 to study the Sun.  It is currently the main source of near-real time solar data for space weather prediction.  The Large Angle and Spectrometric Coronagraph (LASCO) aboard SOHO consist of three coronagraphs: C1, C2, and C3.  Coronagraphs C2 and C3 are both useful for observing the outer solar atmosphere (corona) from near the solar limb to a distance of 21 million kilometers.  LASCO blocks direct light from the surface of the Sun with an occulting disk, creating an artificial eclipse, 24 hours a day, 7 days a week.  LASCO has also become SOHO’s principal comet finder.

 

The Kreutz, Meyer, Marsden and Kracht Sungrazers are families of comets characterized by orbits taking them extremely close to the Sun at perihelion. Many hundreds of smaller members of the families, some only a few meters across, have been discovered since the launch of the SOHO satellite in 1995.  None have survived their perihelion passage.  More than 75% of the SOHO Sungrazers have been detected by amateur astronomers analyzing SOHO's observations via the Internet.

 

Our streamlined method has been developed to search for Sungrazers using LASCO C2 and C3 images for the internet using IrfanView and MaxIM DL software programs.

  1. Use the Search for SOHO Real-time Data webpage to quickly download C3 1024 x 1024 images for best resolution.
  2. Unzip the images to a file.  Choose the latest five images to search for Sungrazers. 
  3. Batch convert the .gif images with IrfanView to .bmp files

 

 

Note: Use the Set advanced options in IrfanView to convert to grayscale for better comet definition.

 

  1. Use MaxIM DL to Animate the .bmp images.  Use the Overlay function to Align the images.

 

 

  1. Use the fastest speed to Animate the images.  Check the Loop box.
  2. If everything is correctly set up the (0,0) position on the image will be in the Upper Left hand corner.  You are now ready to search the images for comet movement and measure its position.
  3. Use the SOHO LASCO Comet Finders' Page to report your find.  The Sungrazer has to be visible in at least four consecutive images.
  4. Use the Recent Reports Page to see your report posted.
  5. Use the printable GRO SOHO Spreadsheet.xls to quickly jot down data for your reports or to compare with previous reports.
  6.  Watch for your Confirmation here or at Recent MPECs.  All Sungrazers found in this manner are named for the SOHO satellite, i.e. Comet 2006 Y9 (SOHO).  You are credited for the comet detection.