In-Flight Calibration
The in-flight calibration for the SOLSTICE instruments includes long-term multi-wavelength observations of bright, blue stars, and redundant channels. The wavelength calibration for the in-flight data uses the many well-known solar emission features to determine the wavelength scale. Retrieval of solar irradiance requires detailed knowledge of long term sensitivity changes in the SOLSTICE instruments. These changes, which result primarily from exposure to solar radiation, are measured by observing an ensemble of bright O-B stars. Table 2 lists the stars used to track changes in the UARS SOLSTICE instrument. The same stars will be used during the SORCE mission.
Table 2: UARS SOLSTICE Calibration Stars
| Star Name | RA (2000) | Dec (2000) | V Mag | Spec Type | Priority | Calibration* |
|---|---|---|---|---|---|---|
| ε Per | 3 57.8 | 40 0 | 2.90 | B0.5 III | 2 | a,b,g |
| α Cma | 6 45.1 | -16 43 | -1.46 | A1 V | 10 | a,b,g |
| κ Vel | 9 22.1 | -55 1 | 2.50 | B2 IV-V | 2 | b |
| α Leo | 10 8.4 | 11 58 | 1.35 | B7 V | 7 | a,b,e |
| δ Cen | 12 8.4 | -50 43 | 2.60 | B2 IVne | 4 | a,b |
| α Cru | 12 26.6 | -63 7 | 1.35 | B0.5 IV + B1 V | 9 | b |
| α Vir | 13 25.1 | -11 10 | 0.97 | B1 IV + B2 V | 9 | b,d,e,f |
| η uma | 13 47.5 | 49 15 | 1.86 | B3 V | 7 | a – e,h |
| ζ Cen | 13 55.5 | -47 17 | 2.55 | B2.5 IV | 7 | a,b |
| β Cen | 14 3.8 | -60 22 | 0.61 | B1 III | 7 | a,b |
| γ Lup | 15 35.1 | -41 10 | 2.78 | B2 IV | 3 | a,b |
| δ Sco | 16 0.3 | -22 37 | 2.32 | B0.5 IV | 2 | a,b |
| τ Sco | 16 35.9 | -28 13 | 2.82 | B0 V | 4 | a,b |
| α Lyr | 18 36.9 | 38 47 | 0.03 | A0 Va | 2 | a,b, |
| σ Sgr | 18 55.3 | -26 18 | 2.02 | B2.5 V | 3 | a,b |
| α Pav | 20 25.6 | -56 44 | 1.94 | B2.5 V | 4 | a,b |
| α Gru | 22 8.2 | -46 58 | 1.74 | B7 IV | 2 | a,b,d |
| α PsA | 22 57.7 | -29 37 | 1.16 | A3 V | 2 | a,b |
Table 3: UARS SOLSTICE Calibration Dark Regions
| Region | RA (2000) | DEC (2000) | Priority | Calibration |
|---|---|---|---|---|
| 1 | 0h 0.0m | 71° 0′ | 8 | – |
| 2 | 0 48.0 | -80 0 | 6 | – |
| 3 | 3 44.0 | 28 0 | 10 | – |
| 4 | 4 28.1 | -18 48 | 6 | i |
| 5 | 7 20.0 | -84 0 | 10 | – |
| 6 | 8 16.0 | 32 0 | 10 | – |
| 7 | 9 56.1 | -43 0 | 10 | – |
| 8 | 10 56.0 | 74 48 | 7 | i |
| 9 | 14 44.0 | 85 0 | 10 | – |
| 10 | 15 40.0 | -57 0 | 10 | – |
| 11 | 15 48.0 | -11 0 | 10 | – |
| 12 | 17 44.0 | 35 0 | 10 | – |
| 13 | 20 5.9 | -20 0 | 10 | b |
| 14 | 21 44.0 | 33 0 | 10 | – |
* (a) td-1 [Jamar et al., 1976; Macau-Hercot et al., 1978]; (b) Voyager [Holberg et al., 1982]; (c) rocket [Bohlin et al., 1974]; (d) Apollo 17 [Henry et al., 1975]; (e) rocket [Bless et al., 1976]; (f) rocket [Brune et al., 1979]; (g) rocket [Woods et al., 1985]; (h) IuE [Bohlin et al., 1980]; (i) shuttle uVX [Tennyson et al., 1987].
