Determine Photometric Zeropoint WBS: 02C.03.01 Determine initial Photometric Model of the Raw Exposure, by using the detected Sources to determine the Photometric Zero Point. This model may further be refined by later processing steps, for example by taking into account the Exposures from adjacent CCDs. Scenario Steps Summary Rejoins at Detect bright point-like Source(s) Measure instrumental PSF Flux Match the detected Source(s) to AstroObject(s) in the Level 2 AstroObject Catalog. Until Level 2 coverage of the entire sky is in Basic Path place, External Catalog(s) will be used as a reference. Fit the constant Photometric Zero Point minimizing the difference between recalibrated instrumental and cataloged fluxes Determine PSF WBS: 02C.03.01 Determine the shape and variation of the Point Spread Function ( PSF) on the Exposure based on a sampling of high signal-to-noise stars. Scenario Steps Summary Rejoins at Subtract Sky Background Model from Raw Exposure Detect point-like Source(s) using an approximate Basic Path PSF model Model the PSF given detected high-S/N Source(s) Determine Sky Background Model WBS: 02C.03.01 Determine the Sky Background Model for the Calibrated Exposure. Scenario Steps Summary Rejoins at Subdivide the Raw Exposure into 128 by 128 pixel bins (or similar) For each bin: .....Estimate the sky level by computing a robust statistic Basic Path (e.g., median) of observed Pixel values: done: Fit a function to the resulting grid, resulting in a Sky Background Model. Determine WCS
Determine Photometric Zeropoint WBS: 02C.03.01 Determine initial Photometric Model of the Raw Exposure, by using the detected Sources to determine the Photometric Zero Point. This model may further be refined by later processing steps, for example by taking into account the Exposures from adjacent CCDs. Scenario Steps Summary Rejoins at Basic Path Detect bright point-like Source(s) Measure instrumental PSF Flux Match the detected Source(s) to AstroObject(s) in the Level 2 AstroObject Catalog. Until Level 2 coverage of the entire sky is in place, External Catalog(s) will be used as a reference. Fit the constant Photometric Zero Point minimizing the difference between recalibrated instrumental and cataloged fluxes Determine PSF WBS: 02C.03.01 Determine the shape and variation of the Point Spread Function ( PSF) on the Exposure based on a sampling of high signal-to-noise stars. Scenario Steps Summary Rejoins at Basic Path Subtract Sky Background Model from Raw Exposure Detect point-like Source(s) using an approximate PSF model Model the PSF given detected high-S/N Source(s) Determine Sky Background Model WBS: 02C.03.01 Determine the Sky Background Model for the Calibrated Exposure. Scenario Steps Summary Rejoins at Basic Path Subdivide the Raw Exposure into 128 by 128 pixel bins (or similar) For each bin: .....Estimate the sky level by computing a robust statistic (e.g., median) of observed Pixel values: done: Fit a function to the resulting grid, resulting in a Sky Background Model. Determine WCS