Introduction: ------------- Goal: - NCS delegates the telescope calibration to reduction packages - need a telescope calibration library, perhaps inside GILDAS "Desirable" Features - Re-use what is available - avoid duplication of efforts - Standardization - Easy maintenance Contraints - many actors - short timescales - Portability - backward compatibility (must be able to process old data) - new ATM version Alternative(s) - per package solution ? leads to maintenance issues, and serious loss of time... - make a common library - requires to define needs and interfaces - requires clients to adapt to the library constraints Beware: - RED lifetime was 20 years... - Wide distribution of the library through GILDAS - IRAM has a record of success, which leads to high expectations - Failure is not an option (success is easily forgotten) For a library, we need to define: - Functionalities - Interfaces with outside world (ATM / Reduction packages / NCS / other libraries) - Internal data format - Internal design (backend handling, fitting, ...) *************************************************************************** Conclusions: ------------ - A somewhat cryptic table of the current situation is attached. - List of desirable library functionalities: * Focus * Pointing * Chopper * Skydips * Sideband rejection * Array geometry * Array gains * Baseline * Regridding (* Fitting maybe for specialized algorithms) - J.Penalver is now in charge of Pointing Models for the 30m. Pointing models thus are outside the scope of the library at least in its first iteration. - Language to be used: F90 with derived types, modules for at least derived types and definition of function interfaces. - Goals: * 1st version of library should be available by end of year (November 2004 if possible). * 1st version meaning same functionalities as providing now by red: focus, pointing, chopper (for spectra), skydips (for spectra), sideband rejection * Priorities in library building: 1 Focus 2 Pointing 3 Chopper 4 Skydips 5 Sideband rejection - Work distribution: o Related work without timescale: * A.Sievers to distribute an example of 30M-FITS file with corresponding documentation for each back-end as soon as they become available starting with bolometer and then 4MHz. * H.Wiesemeyer to provide translation from 30M-FITS to CLASS data format. * A.Bacmann and S.Guilloteau to make a memo on bandpass calibration at the 30m and PdBI to take into account bandwith increase and new ATM possibilities. o Library work: * Small description of sideband rejection measurement at the 30m. => A.Sievers (ASAP) * Iteration on interfaces and practical derived types: => J.Pety and S.Guilloteau 31.05.2004 * Test on minimization routines (eg can we realiably use a 2-D minimization routine to fit a 1-D problem?): => S.Guilloteau 30.06.2004 * One fully working example (focus): => J.Pety and H.Wiesemeyer 30.06.2004 * A point will then be made enabling new work distribution round. *************************************************************************** Pointing Methods - least square fit * Input - lambda offsets - beta offsets - lambda derivatives - beta derivatives - intensities - weights - fitting shape (e.g. Gaussian,n-Gaussians) Parameters, Guesses, Fixed/Fitted, Boundaries??? * Output - parameters - errors - quality flags - evalute fitted function * Input - fitting shape, parameters - input coord (lambda,beta) * Output - intensities - plotting: Fit overplotted over data for two crosses * Input: - System, Units * Output: - Screen plot - results for NCS * Input: - Output of fit - Logging info * Output: - XML file - sic procedure (OBS) Comments: - dealing with spillover on multi-beam receivers ? - start with "single-pixel" version - can deal with multi-pixel in two different ways - changing the lambda(i), beta(i) for each pixel - or putting the relative positions of the beams into the fitting function - is there a gain to be obtained by fitting a broadened beam for planets ? need to evaluate that issue separately. --------------------------------------------------------------------------- Focus Methods: Very similar to pointing... --------------------------------------------------------------------------- Sideband Rejection: - currently being done using the Martin-Pupplet settings, by coupling one of the sidebands with the cold load, the others with the hot load. - is the method accurate enough ? - can we rely on the engineer tables ? - measurement seems to be the most accurate method, but the precision is unknown ? - should it be frequency dependent ? First step: transfert what is currently done in RED into the library .. --------------------------------------------------------------------------- Chopper: * Input: - El - sideband rejection(i) - RF Frequency nu(i) and Bandwidth dnu(i) - Signed IF Frequency - Hot,Cold,Sky,Offset(dark count) temperature T(i) - Hot and Cold Temperatures T(i) and coupling coefficients f(i) - Telescope specific: Pamb, Water scale height, altitude, latitude - Date Pin = fhot B(Thot) + (1-fhot) B(Tamb) = B(Teff) * Output: - Trec(i) - Water - Water and Others Zenith Opacities(i) Tcal: * Input: - El - RF Frequency nu(i) - Signed IF Frequency - Sideband rejection - Set of Tamb (cabine, ground) and coupling coefficients f(i) - Water - (Interpolated) Trec(i) for dual load * Output - Tcal(i) - Water and Others Zenith Opacities(i) for DSB analysis --------------------------------------------------------------------------- Skydip * Input: - El(j) - sideband rejection(i) - RF Frequency nu(i) and Bandwidth dnu(i) - Signed IF Frequency - Hot,Cold,Offset(dark count) temperature T(i) TSky(i,j) - Hot and Cold Temperatures T(i) and coupling coefficients f(i) - Telescope specific: Pamb, Water scale height, altitude, latitude - Date - Bolometer bandpass(i) * Output: - Value and errors of Water vapour(i) - Value and errors of Feff(i) - Quality flag --------------------------------------------------------------------------- Baseline 1-D - Fitting: * Input - Abscissa(i) - Ordinate(i) - Weights(i) (may be 0 to exclude a window) - Fitting shape (eg polynomial,spline) * Output - Fitted parameters - RMS - Baseline computation: * Input - Abscissa(i) - Fitting shape - Fitted parameters * Output - Baseline(i) - Baseline application * Input - Baseline(i) - Ordinate(i) * Output - Baseline(i)-Ordinate(i) --------------------------------------------------------------------------- Baseline 1-D: On-Off => To be discussed later. --------------------------------------------------------------------------- Baseline 2-D: spectral x time - Fitting: * Input - Frequency nu(i) - Space x(j) - Ordinate y(i,j) - Weights(i,j) (may be 0 to exclude a window) - Fitting shape: * Factorized polynomials * Box averaging of independant polynomials * Cubic spline interpolation of independent polynomials * Cubic spline interpolation of independent cubic spline * sinusoidal(nu) with coefficients being polynomials(t) * Output - Fitted parameters - RMS - Baseline computation: * Input - Abscissa(i) - Fitting shape - Fitted parameters * Output - Baseline(i) - Baseline application * Input - Baseline(i) - Ordinate(i) * Output - Baseline(i)-Ordinate(i) On-off: simultaneous fitting of background and baseline --------------------------------------------------------------------------- Baseline 2-D: Spatial data => to be discussed later --------------------------------------------------------------------------- Regridding 1-D * Input - Abscissa(i) - Ordinate(i) - Weights(i) - New reference pixel, value, increment, dimension - Algorithm * Output - New abscissa(i) - New ordinate(i) - New weights(i) - Transformation matrix for signal and weight Comment: Special case for already regularly sampled data --------------------------------------------------------------------------- Regridding 2-D - If it can be factorized (eg space x spectral), then use 1-D regridding - Else * Input - Abscissa(i) - Ordinate(i) - Weights(i) - New reference pixel, value, increment, dimension - Algorithm * Output - New abscissa(i) - New ordinate(i) - New weights(i) - Transformation matrices for signal and weight --------------------------------------------------------------------------- Array geometry: No consensus yet. In the first iteration of the library, this functionality will be delivered by MOPSIC.

Gildas manager 2014-07-01