This page (revision-13) was last changed on 07-Dec-2016 14:14 by Peter Young

This page was created on 12-Nov-2009 15:08 by PeterYoung

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Page References

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EISPointing
EISPointing

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At line 1 added 2 lines
[{ALLOW edit EISMainUsers}]
[{ALLOW view Anonymous}]
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__%%(color:red;)Update%%__ It has been found that the coordinates returned by the EIS software can be incorrect by up to 30" in the Y direction during the eclipse season (May-August), due to a drift in the relative EIS-spacecraft pointing. The actual Y-coordinate will be up to +30" larger than the software coordinates given by the methods outlined below. A software fix for this effect is being worked on. The effect also currently affects planned pointings, such that an observation planned to be centered on an active region will actually be positioned up to 30" north of the active region center.
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!!Improved EIS pointing information __%%(color:red;)Update%%__
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From 2014 a new EIS routine yields the spatial offset between EIS and AIA. It is called as
{{{
IDL> xy=eis_aia_offsets(date)
}}}
At present the correction needs to be applied manually to the pointing values described in the sections below. So, for example,
{{{
IDL> xcen=xcen+xy[0]
IDL> ycen=ycen+xy[1]
}}}
The EIS-AIA offsets are determined regularly by co-aligning EIS slot images with AIA images. They should lead to much-improved pointing accuracy, to the level of 5" or better. In particular, the large variations seen during the eclipse season are corrected for.
Note that the EIS-AIA offsets do not correct the short-term (orbit period) jitter of EIS, only the longer-term (~ days) pointing variation.
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where WVL is the wavelength you are interested in. If WVL is not specified then 256.32 (the wavelength of the He II line) is assumed. Note that the raster center in solar-Y varies with wavelength by up to 18" due to the tilt of the EIS grating relative to the detector and a spatial offset between the two CCDs.
where WVL is the wavelength you are interested in. If WVL is not specified then 195.12 (the wavelength of the strong Fe XII line) is assumed. Note that the raster center in solar-Y varies with wavelength by up to 18" due to the tilt of the EIS grating relative to the detector and a spatial offset between the two CCDs.
This page (revision-13) was last changed on 07-Dec-2016 14:14 by Peter YoungTop