In-Orbit Focal Adjustment of the AKARI Telescope with Infrared Camera (IRC) Images

[摘要] AKARI,currentlyinspace,carriesonboardacryogenicallycooledlight-weighttelescopewithsiliconcarbidemirrors.ThewavefronterroroftheAKARItelescope,obtainedinlaboratorymeasurementsat9K,showedthattheexpectedin-orbitimagingperformancewasdiffraction-limitedatawavelengthof6.2$$mu$$m.TheAKARItelescopehasafunctionoffocusadjustmentbyshiftingthesecondarymirrorinparalleltotheopticalaxis.Onthe4thdayafterjettisonofthecryostataperturelidinorbit,weobservedastarwiththeInfraredCamera(IRC)onboardAKARI.Sincetheinitialstarimagesobservedinthenear-infrared(NIR)bandsweresignificantlyblurred,wetwicemovedthesecondarymirrorforafocaladjustmentbasedontheresultsofmodelanalysesaswellasdataanalysesofNIRbandimages.Asaconsequence,wesuccessfullyadjustedthefocusofthetelescope.Thethus-obtainedin-orbitimagingperformancefortheAKARItelescopeisdiffraction-limitedatawavelengthof7.3$$mu$$m,slightlydegradedfromthatexpectedfromlaboratorymeasurements.

[学科分类] 天文学(综合)

[关键词] "infrared: general";"techniques: image processing";telescopes