.. _fluxcal_verification_200: ############################################################ Verification of the flux calibration in the UV nominal grism ############################################################ Overview ======== The new uv-grism flux calibration is valid over the whole detector, and makes also a correction for coincidence-loss. The first integrated software version is ``UVOTPY-0.9.7.0``, but we will do the verification to the 0.9.7.1 version which has patches for the sensitivity-loss and flux model interpolation. 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/calobs_locations_200.png :width: 640px :align: left :height: 480px Figure 2: 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. **GSPC-P041C spectra (F0 V)** ========= =========== ======= ===== ================= anchor ``obsid`` ``ext`` % err plot ========= =========== ======= ===== ================= 800, 980 00057953006 1 12 :ref:`P041C_Fig8` 800, 980 00057953003 1 14 :ref:`P041C_Fig8` 920,1273 00057951006 1 12 :ref:`P041C_Fig9` 1213,1175 00057954004 1 6 :ref:`P041C_Fig10` ========= =========== ======= ===== ================= **GSPC P177D spectra (F0 V)** ========= =========== ======= ===== ================= anchor ``obsid`` ``ext`` % err plot ========= =========== ======= ===== ================= 850,1320 00056760022 5 11 :ref:`P177D_Fig5` ========= =========== ======= ===== ================= **WD1057+719 spectra** ========= =========== ======= ===== ====================== anchor ``obsid`` ``ext`` % err plot ========= =========== ======= ===== ====================== 645, 762 00055201005 1 7.4 :ref:`WD1057+719_Fig5` 1490,1066 00055201009 1,2 30 :ref:`WD1057+719_Fig6` 1360, 462 00055203003 2 9 :ref:`WD1057+719_Fig7` ========= =========== ======= ===== ====================== **WD0320-539 spectra** ========= =========== ======= ===== ====================== anchor ``obsid`` ``ext`` % err plot ========= =========== ======= ===== ====================== 562, 665 00054254008 2 16 :ref:`WD0320-539_Fig1` 1310,1449 00054251047 1 5 :ref:`WD0320-539_Fig2` 850,1480 00054252003 1,2 7 :ref:`WD0320-539_Fig3` ========= =========== ======= ===== ====================== **GD153 spectra** ========= =========== ======= ===== ====================== anchor ``obsid`` ``ext`` % err plot ========= =========== ======= ===== ====================== 685, 590 00055501008 1 15 :ref:`GD153_Fig1` 685, 590 00055501010 1 15 :ref:`GD153_Fig1` 610,1240 00055503026 1,2 15 :ref:`GD153_Fig2` 1145, 685 00055503010 1 7 :ref:`GD153_Fig3` 1145, 685 00055503012 1 7 :ref:`GD153_Fig3` ========= =========== ======= ===== ====================== Result of the verification ========================== The errors are typically 10% or less. The response below 1750A shows some inconsistencies which is partly due to the low sensitivity, partly to the coincidence-loss correction as can be seen in GD153, which has a correction of about 50% due to coincidence-loss in the bright part of the spectrum.