Differences between v3 and v3.1
Multiexposed spectra:
| v3 |
v3.1 |
- 2 methods of coadding
- High SNR: The single 1D spectra are coadded
- Low SNR: The single images are coadded without extraction of the single spectra
- No proper cosmic correction
|
- All spectra are extracted
- The final spectrum is extracted from the coadded image
- Cosmic correction performed during the coadding
|
Example for the improvement of the cosmic correction
Merging:
The blaze normalised spectra of the single orders are not flat with a trend. They are
show also a curvature. Through the weighted averge of the counts in the overlap region,
one get a trough. To avoid this, only the small region of the order, where the order are
crossed, are used for the order merging, except the Ca II IRT region. For consistent reasons,
the merging is performd in the old fashion.
Comparison of the merging in v3 and v3.1
RV estimation:
The absolute RV values have an offset from ∼250 m/s in the reduction 3.
In the v3.1 version, this offset removed. The RV precision is ∼120 m/s and
the RV accuracy is inside the precision.
