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.
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 | GSPC-P041C Figure 8 |
800, 980 | 00057953003 | 1 | 14 | GSPC-P041C Figure 8 |
920,1273 | 00057951006 | 1 | 12 | GSPC-P041C Figure 9 |
1213,1175 | 00057954004 | 1 | 6 | GSPC-P041C Figure 10 |
GSPC P177D spectra (F0 V)
anchor | obsid |
ext |
% err | plot |
---|---|---|---|---|
850,1320 | 00056760022 | 5 | 11 | GSPC-P177D Figure 5 |
WD1057+719 spectra
anchor | obsid |
ext |
% err | plot |
---|---|---|---|---|
645, 762 | 00055201005 | 1 | 7.4 | WD1057+719 Figure 5 |
1490,1066 | 00055201009 | 1,2 | 30 | WD1057+719 Figure 6 |
1360, 462 | 00055203003 | 2 | 9 | WD1057+719 Figure 7 |
WD0320-539 spectra
anchor | obsid |
ext |
% err | plot |
---|---|---|---|---|
562, 665 | 00054254008 | 2 | 16 | WD0320-539 Figure 1 |
1310,1449 | 00054251047 | 1 | 5 | WD0320-539 Figure 2 |
850,1480 | 00054252003 | 1,2 | 7 | WD0320-539 Figure 3 |
GD153 spectra
anchor | obsid |
ext |
% err | plot |
---|---|---|---|---|
685, 590 | 00055501008 | 1 | 15 | GD153 Figure 1 |
685, 590 | 00055501010 | 1 | 15 | GD153 Figure 1 |
610,1240 | 00055503026 | 1,2 | 15 | GD153 Figure 2 |
1145, 685 | 00055503010 | 1 | 7 | GD153 Figure 3 |
1145, 685 | 00055503012 | 1 | 7 | GD153 Figure 3 |
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.