Abstract
The Heliospheric Imager (HI) instruments on the Solar TErrestrial RElations Observatory (STEREO) observe solar plasma as it streams out from the Sun and into the heliosphere. The telescopes point off-limb (from about 4° to 90° elongation) and so the Sun is not in the field of view. Hence, the Sun cannot be used to confirm the instrument pointing. Until now, the pointing of the instruments have been calculated using the nominal preflight instrument offsets from the STEREO spacecraft together with the spacecraft attitude data. This paper develops a new method for deriving the instrument pointing solutions, along with other optical parameters, by comparing the locations of stars identified in each HI image with the known star positions predicted from a star catalogue. The pointing and optical parameters are varied in an autonomous manner to minimise the discrepancy between the predicted and observed positions of the stars. This method is applied to all HI observations from the beginning of the mission to the end of April 2008. For the vast majority of images a good attitude solution has been obtained with a mean-squared deviation between the observed and predicted star positions of one image pixel or less. Updated values have been obtained for the instrument offsets relative to the spacecraft, and for the optical parameters of the HI cameras. With this method the HI images can be considered as “self-calibrating,” with the actual instrument offsets calculated as a byproduct. The updated pointing results and their by-products have been implemented in SolarSoft.
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References
Calabretta, M.R., Greisen, E.W.: 2002, Representations of celestial coordinates in FITS. Astron. Astrophys. 395, 1077 – 1122.
Davis, C.J., Harrison, R.A.: 2005, STEREO/HI from near-Earth objects to 3D comets. Adv. Space Res. 36, 1524 – 1529.
Davies, J.A., Harrison, R.A., Rouillard, A.P., Sheeley, N.R., Perry, C.H., Bewsher, D., Davis, C.J., Eyles, C.J., Crothers, S.R., Brown, D.S.: 2008, A synoptic view of solar transient evolution in the inner heliosphere using the heliospheric imagers on STEREO. Geophys. Res. Lett., submitted.
Freeland, S.L., Handy, B.N.: 1998, Data analysis with the SolarSoft system. Solar Phys. 182, 497 – 500.
Fulle, M., Leblanc, F., Harrison, R.A., Davis, C.J., Eyles, C.J., Halain, J.-P., Howard, R.A., Bockeleé-Morvan, D., Cremonese, G., Scarmato, T.: 2007, Discovery of the atomic iron tail of comet MCNaught using the heliospheric imager on STEREO. Astrophys. J. 661, L93 – L96.
Harrison, R.A., Davis, C.J., Eyles, C.J.: 2005, The STEREO heliospheric imager: how to detect CMEs in the heliosphere. Adv. Space Res. 36, 1512 – 1523.
Harrison, R.A., Davis, C.J., Eyles, C.J., Bewsher, D., Crothers, S.R., Davies, J.A., Howard, R.A., Moses, D.J., Socker, D.G., Newmark, J.S., Halain, J.-P., Defise, J.-M., Mazy, E., Rochus, P., Webb, D.F., Simnett, G.M.: 2008, First imaging of coronal mass ejections in the heliosphere viewed from outside the Sun Earth line. Solar Phys. 247, 171 – 193.
Howard, R.A., Moses, J.D., Vourlidas, A., Newmark, J.S., Socker, D.G., Plunkett, S.P., Korendyke, C.M., Cook, J.W., Hurley, A., Davila, J.M., Thompson, W.T., St Cyr, O.C., Mentzell, E., Mehalick, K., Lemen, J.R., Wuelser, J.P., Duncan, D.W., Tarbell, T.D., Wolfson, C.J., Moore, A., Harrison, R.A., Waltham, N.R., Lang, J., Davis, C.J., Eyles, C.J., Mapson-Menard, H., Simnett, G.M., Halain, J.P., Defise, J.M., Mazy, E., Rochus, P., Mercier, R., Ravet, M.F., Delmotte, F., Auchere, F., Delaboudiniere, J.P., Bothmer, V., Deutsch, W., Wang, D., Rich, N., Cooper, S., Stephens, V., Maahs, G., Baugh, R., McMullin, D., Carter, T.: 2008, Sun Earth connection coronal and heliospheric investigation (SECCHI). Space Sci. Rev. 136, 67 – 115.
Kaiser, M.L.: 2005, The STEREO mission: an overview. Adv. Space Res. 36, 1483 – 1488.
Rouillard, A.P., Davies, J.A., Forsyth, R.J., Davis, C.J., Harrison, R.A., Lockwood, M., Bewsher, D., Crothers, S.R., Eyles, C.J., Hapgood, M., Perry, C.H.: 2008a, First imaging of corotating interaction regions using the STEREO spacecraft. Geophys. Res. Lett. 35, L10110.
Rouillard, A.P., Davies, J.A., Forsyth, R.J., Savani, N., Sheeley, N.R., Thernisien, A., Burlaga, L.F., Zhang, T., Vourlidas, A., Howard, R.A., Wang, Y.-M., Rees, A., Anderson, B., Krimigis, T., Slavin, J., Carr, C.M., Tsang, S., Lockwood, M., Davis, C.J., Harrison, R.A., Bewsher, D., Brown, D.S., Crothers, S.R., Eyles, C.J., Hapgood, M., Perry, C.H., Whittaker, I., Jones, G.H., Coates, A.J., Grande, M., Frahm, R.A., Winningham, J.D.: 2008b, A solar storm observed from the Sun to Venus by using the STEREO, Venus Express and MESSENGER spacecraft, J. Geophys. Res., submitted.
Sheeley, N.R. Jr., Herbst, A.D., Palatchi, C.A., Wang, Y.-M., Howard, R.A., Moses, J.D., Vourlidas, A., Newmark, J.S., Socker, D.G., Plunkett, S.P., Korendyke, C.M., Burlaga, L.F., Davila, J.M., Thompson, W.T., St Cyr, O.C., Harrison, R.A., Davis, C.J., Eyles, C.J., Halain, J.P., Wang, D., Rich, N.B., Battams, K., Esfandiari, E., Stenborg, G.: 2008a, SECCHI observations of the Sun’s garden-hose density spiral. Astrophys. J. 674, L109 – L112.
Sheeley, N.R. Jr., Herbst, A.D., Palatchi, C.A., Wang, Y.-M., Howard, R.A., Moses, J.D., Vourlidas, A., Newmark, J.S., Socker, D.G., Plunkett, S.P., Korendyke, C.M., Burlaga, L.F., Davila, J.M., Thompson, W.T., St Cyr, O.C., Harrison, R.A., Davis, C.J., Eyles, C.J., Halain, J.P., Wang, D., Rich, N.B., Battams, K., Esfandiari, E., Stenborg, G.: 2008b, Heliospheric images of the solar Wind at Earth. Astrophys. J. 675, 853 – 862.
Thompson, W.T.: 2006, Coordinate systems for solar image data. Astron. Astrophys. 449, 791 – 803.
Vourlidas, A., Davis, C.J., Eyles, C.J., Crothers, S.R., Harrison, R.A., Howard, R.A., Moses, D.J., Socker, D.G.: 2007, First direct observation of the interaction between a comet and a coronal mass ejection leading to a complete plasma tail disconnection. Astrophys. J. 668, L79 – L82.
Watt, A.: 2000, 3D Computer Graphics, 3rd edn., Addison-Wesley, Reading.
Zacharias, N., Monet, D.G., Levine, S.E., Urban, S.E., Gaume, R., Wycoff, G.L.: 2004, The Naval Observatory merged astrometric dataset (NOMAD). Bull. Am. Astron. Soc. 36, 1418.
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Brown, D.S., Bewsher, D. & Eyles, C.J. Calibrating the Pointing and Optical Parameters of the STEREO Heliospheric Imagers. Sol Phys 254, 185–225 (2009). https://doi.org/10.1007/s11207-008-9277-6
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DOI: https://doi.org/10.1007/s11207-008-9277-6