.. _fluxcal_verification_1000: ********************************************************************** Verification of the flux calibration in the visual grism: nominal mode ********************************************************************** Overview ======== The new v-grism flux calibration is valid over the whole detector, and makes also a correction for coincidence-loss. The first integrated software version is ``UVOTPY-0.9.7.3``. With the choice of data, we have an independent set from the spectra used to construct the effective area. Of course, spectra from the same targets are used. Method ====== Calibration spectra that were not used in the flux calibration are reprocessed using the new flux calibration and then compared to the known stellar flux. The spectra for verification are located on the detector between the areas with the spectra used to determine the effective areas for the flux calibration. .. figure:: _figures/anchor_positions_1000_cal_spectra.png :width: 640px :align: left :height: 480px The anchor positions of the calibration spectra marked by target. The boxes are enclosing sources used to derive an effective area for the location of the box. Data used for verification ========================== The approximate location of the anchor of the spectra, their ``obsid``, and number of the ``fits extension`` is listed. First the cool stars are listed, followed by the hot white dwarfs. **WD1121+145 spectra** ========= =========== ======= ===== ======================= ========== anchor ``obsid`` ``ext`` % err plot aspect correction ========= =========== ======= ===== ======================= ========== 845,1304 00055250072 2 20 :ref:`WD1121+145_Fig41` None 912,1256 00055250072 3 20 :ref:`WD1121+145_Fig42` None 1015,1280 00055250072 4 15 :ref:`WD1121+145_Fig43` None 1080,1230 00055250072 1 15 :ref:`WD1121+145_Fig44` None ========= =========== ======= ===== ======================= ========== **GD108 spectra** ========= =========== ======= ===== ================== ========== anchor ``obsid`` ``ext`` % err plot aspect correction ========= =========== ======= ===== ================== ========== 631, 989 00055050016 1 20 :ref:`GD108_Fig41` yes 924, 924 00055051003 1 20 :ref:`GD108_Fig42` yes 949, 920 00055050012 1 20 :ref:`GD108_Fig43` yes ========= =========== ======= ===== ================== ========== **GD153 spectra** ========= =========== ======= ===== ================== ========== anchor ``obsid`` ``ext`` % err plot aspect correction ========= =========== ======= ===== ================== ========== 615,1050 00055501004 1 15 :ref:`GD153_Fig41` yes 952,1550 00055502008 1 10 :ref:`GD153_Fig42` yes 1019,1563 00055502004 1 20 :ref:`GD153_Fig43` yes 1456, 889 00055503020 1 10 :ref:`GD153_Fig44` yes ========= =========== ======= ===== ================== ========== Result of the verification ========================== Errors were read off the figures as being typical. The errors are typically 20% or less. For a large part these are due to inaccuracy in the coincidence loss correction and the Poisson error in the counts.