Red Barn Observatory MPC/IAU H68

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Getting Started--SOHO Comet Hunting Techniques/Instructions

This is only a small addition to the current and some advanced SOHO comet hunting techniques.


There are a few necessities that one needs to acquire before searching for SOHO comets. A computer with at least a 17" monitor is recommended (but not necessary) and an Internet connection. A high-speed Internet connection is recommended but is not required because a standard dial-up connection will work just fine (it's only slower). Other items you will need is the proper software used for accurately measuring and "pin-pointing" the potential comets (x,y pixel positions) and also for stacking/blinking images, a pencil or pen, paper to jot down any suspects, lots of time, and the most important tool needed is PLENTY OF PATIENCE. The main point to keep in mind is that you should not report every little "speck" of well-aligned noise noticed over 2-3 images. Once you begin to constantly report noise and begin to "clutter up" the reports page over a long period of time, the SOHO comet hunters that are allowed to confirm comets will begin to overlook your claims. And finally, once you have discovered a new SOHO comet, you WILL know it!

Spend a lot of time in this website:

Also visit the "Other Links" section of the sungrazer website. There is a huge amount of information in these very experienced SOHO comet hunter websites that should be read and at the least "partially" understood before moving on. An understanding of SOHO comet groups, paths and trajectories is recommended before you try and find one of your own. If you know the vicinity of the predicted paths of the known SOHO comet groups, then your chance of discovering one will definitely increase.

Step 1: The Images

The images can be obtained several different ways. The most convenient site to download C2 and C3 images is from Here you can choose from the different sizes available (512x512 or 1024x1024). The 1024x1024 are the most productive but they can take several minutes per image to download on a dial-up Internet connection. Other web sites to download images are and for a lesser quality but a faster downloadable image try

Visit the SOHO Comets website at and determine the last confirmed comet discovered that was bright enough to be observed in many images.

The report will look something like this:

Feb 28 2006 16:18:03 >> Date and Time of the report (is automatically posted)

Potential comet:
Images: C3 (0,0) Upper Left.       >>Images & (0,0) position
1024x1024 images.                     >> Image Size (in pixels)
20060228                                   >> Year, Month and Date entered by the observer
Kreutz group comet.                    >> Comet Group Type
1635 161 772                             >>time/ x position/ y position
1835 180 758
2035 200 744                             *Notice the times in this report are in two hour intervals

--Observers Name                      >> Name of Observer Entering Data

(This particular Kreutz group comet was traveling at an average rate of 10 x pixels and 7 y pixels per hour--the normal speed for a Kreutz group comet for this time of year. As they approach the sun they will gain velocity.)

Feb 28 2006 17:10:28

Confirming comet of:
Images: C3 16:18:03 022806
Kreutz group comet.
--Confirming Observers Name

This is an example of a comet that you may use to measure and practice with. Do not try and report a new comet without first practicing on one that has already been discovered! For example: if the comet was in 10 1024x1024 C3 images from 10:18 through 20:18, and in 4 1024x1024 C2 images from 21:54 through 22:52, download all of these C3 and C2 images. Create a folder on your computer desktop and name it SOHO images month of ?? (i.e. 2006 SOHO Images Feb). Inside this folder create two other folders named C2 and C3. These will be the folders you will store all of your C2 and C3 images so they can be easily found. Other folders can also be added such as SWAN, FITS, etc….. When the SOHO month has completed, the folder can simply be copied and stored on a CD or DVD for future reference. After the images have been downloaded and organized, go to Step 2.

Step 2: The Software

The images that were downloaded in step 1 can now be loaded into an "image viewing/processing" software program. The (0,0) position on the software being used needs to be determined first. (0,0) Stands for (x pixel, y pixel).  (A pixel is simply defined as a "dot" on a computer screen. So, in a 1024x1024 image, there are 1024 x pixels and 1024 y pixels.)  The (0,0) position for most programs is located in the upper-left corner of the image but it will vary according to the program you are using.. When the (0,0) position is determined, go back to the last comet discovery in Step 1 and observe the measurements reported. If the (0,0) in the report matches your (0,0), then you can go ahead and use the report just as it reads to measure the comet as it travels across the images.

The software you use to view and measure C2 and C3 SOHO images will be determined by your own preferences. Every SOHO Comet hunter has his/her preferred software to use. I found two of my SOHO comets by simply using multiple "MS Paint" programs running simultaneously and clicking between the windows.

Searching SOHO images for moving objects is a little "tougher" but can be more productive than searching standard images taken with a ground-based telescope. The SOHO images are constantly being bombarded by cosmic rays that can sometimes appear to be a comet moving across the FOV (field of view) and the satellite itself is also moving in an orbit around the sun that also cause the background stars to move across the FOV. Imagine a ground based telescope imaging a section of the sky without any guide motors to track the stars. The stars would move a little between each image as they do in the SOHO images.

Many of the image processing programs can be downloaded via the Internet and there is also a java tool on the LASCO page that will allow you to measure positions on the images.

Step 3: Reporting/Retracting a Potential Comet

Once you are sure you have potentially discovered a new SOHO comet and you have checked all recent reports, you will report it here. If you have never filled a SOHO comet report before, you will have to select "New User" from the list of names and fill out the new user form along with the potential comet form. Mr. Sungrazer will then enter your name into the list of SOHO comet hunters. Go back to Step 1 and review the correctly filled form. If the form is filled out incorrectly and you enter the wrong x,y positions, someone else can report your comet and it will be your loss.....

Any report that is made and the potential comet turns out to be well-aligned noise, then it must be retracted ASAP. To do this, go back to the reports form and select the "Retracting my Claim of..." from the drop box your originally reported your potential comet. The time and date listed in BOLD above your initial report is the correct time to use when you "retracting my claim of...." or "further to my post of...".   Here's a program to check your positions that was designed by Marcelo Saavedra. SOHOCalc

Once you have complete the form whether it is a "potential comet" claim, a "retracting my claim of..., or a "further to my post of...", etc., you will then click the "preview" button. This will insert all information into the box below for further review. Once you are satisfied your claim is correct, you finally click on "submit". Finally go back and refresh the SOHO Comet Recent Reports page to verify your information has successfully loaded.

Steve E. Farmer Jr.



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Copyright © 2006 The Cometary Space Web of Steve E. Farmer Jr.

Last modified 08/31/2010 02:35 PM -0700

This web site has been active since March 1, 2006

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