The following calibration coefficients and procedure does not correct for
The pixel values are in units of apparent radiance, with units of mW/(sr-cm2).
Given a Clementine UVVIS camera image, the equations here provide how to convert from counts (or DN values) to an estimate of apparent in-band radiance for any given pixel in the FPA of the UVVIS camera. The hat notation is used to remind the user that this calibration coefficients are based on estimates. The errors associated with these estimates will be provided later.
The derived calibration coefficients estimated from in-flight VEGA observations are provided below.
Note: the postfix 'hat' is also used to denote an estimated value.
The following provides the estimated gain values as a function of gain_ids= 1,2,3, and 4,
gain_id | ghat |
1 | 1 |
2 | 3.01 |
3 | n/a |
4 | 6.906 |
The estimated value of c1hat(j,i) is expressed in terms of the estimates of c1 while looking at VEGA, and the estimated value of the non-uniformity matrix. The following provides c1hat(j,i) for each filter
For 415nm: c1hat(j,i) = 1.39*Uhat(j,i)/1.00734
Where Uhat(j,i) is the estimated nonuniformity matrix file. Noticed that in the above procedure the same nonuniformity matrix estimate is used for all filters. The next version of the calibration equation will have individual calibration matrices for each of the filters.
| coefficient | expression | ||||||||
| c1 |
wavelength dependent
| ||||||||
| c2 | c2hat = 0.0005*(FOCAL_PLANE_TEMPERATURE-273.15)+0.0032 | ||||||||
| c3 | c3hat = 7.70 | ||||||||
| c4 | c4hat = -8.18*(OFFSET_ID) | ||||||||
| c5 | c5hat = 13.3 |
ACT's 9/20/95 UVVIS calibration data files can be found under the following ftp server:
