Re: [Bicep2-list] BICEP2 Team meeting and B2/Keck CMB analysis telecon today (6 Aug 2013) noon Eastern

Hi John, We did look into this. If I remember correctly: 1) I think the Wandelt algorithms rely on precalculating maps folded with each "beam mode" - with frightening storage and memory implications. Presumably they need to be full sky rather than the cutdowns we normally use. 2) As you know the way the pipeline works is to perform an interpolation off the input map per trajectory timestep and per detector. The computational expense of including in this operation on-the-fly convolution of an arbitrary beam shape with arbitrary rotation angle on the sky presumably scales with the number of modes necessary to describe the beam to the desired precision - even if we are just adding up precalculated numbers it will be a high cost. Many approximations are possible to speed up but they will all involve fundamental changes to the basic mode of operation (like precalculations for a limited set of angles on the sky etc). For the specific purpose of approximating the response to far sidelobes such approximations may of course be acceptable. Clem -- ********************************************************************** Clem Pryke - Associate Professor - Physics University of Minnesota, Room 313 Tate, 116 Church Street S.E. Minneapolis, MN, 55455 Tel: 612-624-7578 Fax: 612-624-4578 email: pryke(a)physics.umn.edu **********************************************************************