SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA COS Pipeline Calibration Goals of CALCOS Association Table Input and Output Files High Level Outline of CALCOS Outline of Calibration Steps Coding Issues Test Plan Development Schedule

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 2 of 12 Goals of CALCOS If data are in TIME-TAG mode:If data are in TIME-TAG mode: Produce corrected event list table Produce corrected event list table Produce calibrated ACCUM image from corrected event list Produce calibrated ACCUM image from corrected event list If data are in ACCUM mode:If data are in ACCUM mode: Produce calibrated ACCUM image from raw ACCUM image Produce calibrated ACCUM image from raw ACCUM image Produce flux-calibrated 1-D spectrumProduce flux-calibrated 1-D spectrum Combine FP-split or repeatobs spectraCombine FP-split or repeatobs spectra

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 3 of 12 Association Table Column names MEMNAME, MEMTYPE, MEMPRSNTColumn names MEMNAME, MEMTYPE, MEMPRSNT MEMNAME is the rootname for a file or set of filesMEMNAME is the rootname for a file or set of files MEMTYPE distinguishes science from wavecal, and exposure from productMEMTYPE distinguishes science from wavecal, and exposure from product MEMPRSNT = true implies that input files with the specified rootname should existMEMPRSNT = true implies that input files with the specified rootname should exist

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 4 of 12 Input and Output Files There can be several input files, distinguished by suffix:There can be several input files, distinguished by suffix: Science spectrum (A and B segments, if FUV) Science spectrum (A and B segments, if FUV) Pulse-height histogram if FUV ACCUM (A and B) Pulse-height histogram if FUV ACCUM (A and B) Target-acquisition image Target-acquisition image Support file (not used by CALCOS) Support file (not used by CALCOS) There can be several output files from CALCOS:There can be several output files from CALCOS: Corrected event list (if input is TIME-TAG) Corrected event list (if input is TIME-TAG) Corrected ACCUM image Corrected ACCUM image Sum of individual ACCUM images, if repeatobs Sum of individual ACCUM images, if repeatobs 1-D spectrum for each FP-split location or repeatobs exposure 1-D spectrum for each FP-split location or repeatobs exposure Sum of 1-D spectra (this is identified as PRODUCT) Sum of 1-D spectra (this is identified as PRODUCT)

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 5 of 12 High Level Outline of CALCOS User supplies the name of an association tableUser supplies the name of an association table Read and interpret association table:Read and interpret association table: get a list of the input files get a list of the input files open one input file to get header keywords: open one input file to get header keywords: determine which calibration steps are to be done determine which calibration steps are to be done get a list of reference file names get a list of reference file names check that all required files are readable check that all required files are readable Calibrate:Calibrate: partially calibrate each wavecal partially calibrate each wavecal determine offset from calibrated wavecal determine offset from calibrated wavecal calibrate each input science file calibrate each input science file partially calibrate each TA1 file partially calibrate each TA1 file Average the individual FP-split or repeatobsAverage the individual FP-split or repeatobs

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 6 of 12 Outline of Calibration Steps TIME-TAG dataTIME-TAG data Copy input data into output array Copy input data into output array Add pseudo-random number to each X and Y position (FUV only) Add pseudo-random number to each X and Y position (FUV only) Thermal correction (FUV only) Thermal correction (FUV only) Geometric correction (FUV only) Geometric correction (FUV only) Flat field correction Flat field correction Livetime correction Livetime correction Data quality assignment Data quality assignment Filter by pulse height (FUV only) Filter by pulse height (FUV only) Filter by time Filter by time Orbital and heliocentric Doppler corrections Orbital and heliocentric Doppler corrections Create 2-D ACCUM images Create 2-D ACCUM images

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 7 of 12 Outline of Calibration Steps (cont.) ACCUM dataACCUM data Verify good pulse-height distribution (FUV only) Verify good pulse-height distribution (FUV only) Find stim pulses and compute thermal distortion coefficients (FUV only) Find stim pulses and compute thermal distortion coefficients (FUV only) Convert ACCUM to temporary coordinate list (FUV only) Convert ACCUM to temporary coordinate list (FUV only) Add pseudo-random number to each X and Y position (FUV only) Add pseudo-random number to each X and Y position (FUV only) Thermal correction (FUV only) Thermal correction (FUV only) Geometric correction (FUV only) Geometric correction (FUV only) Data quality assignment Data quality assignment Compute orbital and heliocentric Doppler shifts Compute orbital and heliocentric Doppler shifts Create 2-D temporary count rate ACCUM image Create 2-D temporary count rate ACCUM image Convolve flat field with Doppler shift and divide into count rate image Convolve flat field with Doppler shift and divide into count rate image Livetime correction Livetime correction Create 2-D effective count rate image Create 2-D effective count rate image

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 8 of 12 Outline of Calibration Steps (cont.) Steps common to TIME-TAG and ACCUMSteps common to TIME-TAG and ACCUM Extract 1-D spectrum: Extract 1-D spectrum: Compute net count rate Compute net count rate Compute error estimate Compute error estimate Compute maximum and average data quality Compute maximum and average data quality Compute wavelengths Compute wavelengths Compute flux from count rate Compute flux from count rate Combine FP-split or repeatobs Combine FP-split or repeatobs

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 9 of 12 Coding Issues Use a combination of Python and CUse a combination of Python and C Assume all data fit in memoryAssume all data fit in memory Expect to use Python:Expect to use Python: High level control High level control Lists of information, e.g. file names Lists of information, e.g. file names I/O using PyFITS I/O using PyFITS Much of the processing can be done using numarray Much of the processing can be done using numarray Expect to use C when individual event or pixel access is requiredExpect to use C when individual event or pixel access is required Workstation requirementsWorkstation requirements Will simultaneously need to access event list and two output ACCUM images Will simultaneously need to access event list and two output ACCUM images One Gb is likely to be sufficient One Gb is likely to be sufficient

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 10 of 12 Coding Issues (cont.) Functions that will need to be written in C:Functions that will need to be written in C: Bin X,Y coordinates from an event list into a 2-D ACCUM image Bin X,Y coordinates from an event list into a 2-D ACCUM image Sum the events (unweighted) to make count rate image Sum the events (unweighted) to make count rate image Sum the weight of each event to make effective count rate image Sum the weight of each event to make effective count rate image Exclude events flagged by data quality column Exclude events flagged by data quality column Make a pseudo-event list (X & Y coords) from a 2-D ACCUM image Make a pseudo-event list (X & Y coords) from a 2-D ACCUM image Make a 2-D data quality image array from data quality initialization table Make a 2-D data quality image array from data quality initialization table Bitwise OR the DQ column in events table with 2-D DQ image array Bitwise OR the DQ column in events table with 2-D DQ image array Assign weight column in events table from 2-D flat field image Assign weight column in events table from 2-D flat field image Find an interval of time in a time column (returns indices) Find an interval of time in a time column (returns indices)

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 11 of 12 Test Plan Test thermal, geometric, and flat field corrections by calibrating a flat field observation, then compare with baseline reference frame and data quality flags.Test thermal, geometric, and flat field corrections by calibrating a flat field observation, then compare with baseline reference frame and data quality flags. Test 1-D extraction and wavecal processing by calibrating a line lamp observation, then compare with template lamp spectrum.Test 1-D extraction and wavecal processing by calibrating a line lamp observation, then compare with template lamp spectrum. Compare TIME-TAG and ACCUM observations of the same target, e.g. a line lamp, to check for such problems as one-pixel offsets.Compare TIME-TAG and ACCUM observations of the same target, e.g. a line lamp, to check for such problems as one-pixel offsets. Test Doppler correction by calibrating an external target with known radial velocity and well defined lines; use multiple exposures with beginnings of exposures at different locations in the orbit.Test Doppler correction by calibrating an external target with known radial velocity and well defined lines; use multiple exposures with beginnings of exposures at different locations in the orbit. Test flux correction by calibrating an observation of a flux standard.Test flux correction by calibrating an observation of a flux standard. Except for Doppler and flux correction, all these tests can all be done using thermal vac data.Except for Doppler and flux correction, all these tests can all be done using thermal vac data.

COS PIPELINE CDR P. Hodge July 24, 2001CALCOS Space Telescope Science Institute 12 of 12 Development Schedule Finish by Description Oct 2001 Overall design, prototype code Dec 2001 High level control, prototype calibration Mar 2002 Basic calibration, prototype 1-D extraction Jun D extraction, wavecal processing Sep 2002 Combine FP-split or repeatobs