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Comet McNaught in 2007
15-years of SOHO Comets
STEREO/SECCHI L4/L5 campaignDuring 2009, the STEREO spacecraft will periodically be making 180-degree rolls so that the heliospheric imager ("HI") instrument can observe the L4 and L5 Lagrange points. The hope is that we may be able to discover objects in the HI images that are clustering at these gravitationally stable points in space. You can read more about this campaign in press releases here and here.
Getting the DataAs with all of our data, the images we take during this campaign will be freely distributed online as soon as we have processed them. The only difference will be that we will not be producing "pretty" versions of them. You will need to download the "FITS" images and play with them yourselves. You can get the files at the STEREO Science Center where you will follow the link to "Instrument Data Archived at SSC" and locate the "img" data for "secchi" (spacecraft "a" or "b"). Alternatively, for convenience, the appropriate data sets are available below as ZIP files:
There are several techniques for playing with the FITS files to make them "prettier", but often a simple median filter and rescaling will enhance the images significantly. You could also try subtracting a simple 'background model' made by taking the minimum value of a stack of all the images. A previous news article on this site discussed processing of SOHO/LASCO files. The procedure is similar for SECCHI. Note that it does require limited skills with some kind of image manipulation software (e.g. GIMP, ImageJ, ImageMagick, etc.) For just viewing the 'raw' FITS image, the "DS9" image viewer.
Identifying ObjectsIf you think you have found an unknown object in one of the L4/L5 campaign images, the process for reporting it is no different to that of any new STEREO/SECCHI object, and is described on the "STEREO Comets" reporting page. We do ask that you first try to verify that the object you are seeing is not a planet (which tend to be very bright), or a star (which all move at the same speed). A typical asteroid will be very small, and will move at a slightly slower or faster rate than background stars, and possibly in a different direction.
So how do you tell if the object you are seeing is a "known" asteroid? Well to help out, the following lists give the name and x,y pixel location of many of the known asteroids that are in the images at that time. Please note the following regarding these lists:
Here are the lists:
Further Informations and ResourcesFor more information about the SECCHI instrument fields of view, try the SECCHI Instrument Overview page. You can also click here for an image that shows the fields of view of the SECCHI instruments. (Note that the HI instruments will be pointing in a different direction during the L4/L5 Campaign rolls.) Other resource you might find useful are the Heliospheric Imager home page, the STEREO Science Center or the STEREO Home page. The latter has many links to further resources.
You are welcome to contact the webmaster if you have questions.