.. _VISCalibratedFrame: ========================== Calibrated Frame Product ========================== Data product name ================= .. DataProductNameStart CalibratedFrame .. DataProductNameEnd Data product custodian ====================== .. DataProductCustodianStart VIS .. DataProductCustodianEnd Data model tag ============== .. DataModelTagStart R-1.6.7 .. DataModelTagEnd Name of the Schema file ======================= .. NameSchemaStart euc-test-vis-CalibratedFrame.xsd .. NameSchemaEnd Schema documentation tag ======================== .. SchemaDocTagStart No documentation element was found in schema file! Data Model custodian: even minimal information can be helpful .. SchemaDocTagEnd Data product elements ===================== .. DataProductElementsStart Header of type: sys:genericHeader Data of type: vis:calibratedFrameVIS Parameters of type: ppr:genericKeyValueParameters .. DataProductElementsEnd Processing Element(s) creating/using the data product ===================================================== .. PECreatorStart .. PECreatorEnd Processing function using the data product ========================================== .. PFUsingStart SHE and MER processing functions. .. PFUsingEnd Detailed description of the data product ======================================== .. DetailedDescStart .. Comment by Editor (MS): I have made changes in the use of latex to include the command \propto. Otherwise it was not possible to have a proper latex output. I have also significantly changed the use of the figure directive, and introduced markup for references instead of explicit references. This way figure numbering is consistent throughout the document. I also think you need to check the usage of the reference directive: it does not show either in the html or in the latex output (this Bertin & Arnouts ref). The VIS processing function provides a Calibratedframe product consisting of 3 FITS files by exposure; a **calibrated VIS individual exposure**, and the corresponding **PSF model** and **background**. The **calibrated VIS individual exposure** is a multi-extension FITS file containing 3 extensions per CCD, one for pixel data, one for the associated RMS map and one for the associated Flagmap, to make 108 extensions for a full 36 CCDs which constitutes an exposure. Pixel data is 32-bit floating point format. Each extension contains the keyword **EXTNAME**, which will be **.SCI**, **.RMS** or **.FLG** for Science, RMS map or Flagmap. The “detector id” describes the extension following the scheme given on VIS FPA ICD (EUCL-SAP-ICD-6-001 and :numref:`VISCCDNum`). .. _VISCCDNum: .. figure:: images/CCD_numbering.png :scale: 100 % :align: center :figclass: align-center : CCD numbering and location at detector plane level (Front view) from VIS FPA ICD (EUCL-SAP-ICD-6-001) issue 2.5 2014/20/10 The different extensions may appear in any order. In all extensions, pixels are delivered at the native pixel scale. All extensions have the same pixel scale and size. When combining multiple dithered exposures from separate detectors with gaps it becomes important to assign a “confidence” to each detector pixel so that overlapping exposures can be combined and the noise level at each pixel can be correctly estimated. Many different conventions exist for producing these confidence maps. Internally, the VIS processing function uses relative "weight maps", which are defined as :math:`w_j \propto \frac{1}{{\sigma_{j}}^{2}}`, where :math:`\sigma_j` is the standard deviation (or “RMS” of the :math:`j_th` pixel). Currently to meet the requirements set by other PFs, “RMS” maps are simply generated directly from the output image using **SExtractor** ([Bertin & Arnouts 1996]_). These maps are generated by computing the standard deviation of pixels in a sliding window on the input images, after removing objects. Note that these RMS maps only contain a noise contribution from the background, and do not contain a contribution from the Poisson noise of each individual source. This is because combining images weighted in this way will produce a magnitude-dependent bias in the photometry of each individual source. We will now describe the content of each extension of the **calibrated VIS individual exposure**: **SCI extension** The SCI extension contains calibrated pixel data for each of the VIS instrument CCDs. The individual images contain both an astrometric and photometric solution written in the FITS header. No flux scaling is applied, but the results of the photometric solution computed by VIS is written in the FITS header keywords. The astrometric solution is described as a PV projection. Images are not resampled and are delivered at the native VIS pixel scale (this means of course that instrument optical distortion is still present). The images are not background subtracted but a background map is provided as a FITS file with the same pixel size as the individual images. **RMS extension** The RMS map (described above) contains the noise at each pixel in the corresponding Science image, expressed as the absolute standard deviation. **FLG extension** The Flagmap data format is defined in the `data model here `_ and is described in `human-readable format here `_. .. [Bertin & Arnouts 1996] Bertin, E. & Arnouts, S. 1996, ApJS, 117, 393 .. DetailedDescEnd