CHARIS astrogrid calibration
For detailed information about CHARIS, please refer to the CHARIS website.
Astrogrid applied - raw data.
After subtraction.
Settings
| Astrogrid settings | |
|---|---|
| Parameter | Value(s) |
| Angular separation from PSF core | 5.3 λ/D, 7.5 λ/D, 11.2 λ/D, 15.9 λ/D or 22.5 λ/D |
| Brightness relative to central PSF | 1e-4 to 1e-2 |
| Number of spots | 2 or 4 |
| Phase modulation | 2 kHz |
| Spatial modulation (optional) | Synchronized with CHARIS exposures |
| Coronagraph | Lyot, Vortex |
Calibration Performance
On-sky calibration photometric and astrometric precision has been estimated by measuring the flux ratio and relative position between calibration spots. Numbers are shown in the table below, and indicate the astrometric and photometric calibration precision for bright targets. Photon noise and readout noise may dominate on faint targets. Precision scales as the inverse square as exposure time.| Astrogrid calibration precision (measured on star Beta Leo with 8.8nm DM modulation, 30mn observation) | ||
|---|---|---|
| Wavelength band | Photometry | Astrometry |
| J | 0.26 % | 1.7 mas |
| H | 0.33 % | 1.67 mas |
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