Quality of stellar radial velocities improved in DR6
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The wavelength calibration of the SDSS spectra is problematic in
the blue, because of a dearth of strong lines in the calibration lamps
and in the nighttime sky. This led to systematic errors at the level
of 10-15 km/s (i.e., 0.15-0.25 pixels) in the wavelength calibration
at the extreme blue end, which was affecting both stellar model fits
and the determination of radial velocities. More robust fitting
algorithms brought these problems under control in DR6 and beyond.
The identity of the actual template stars are tabulated below. The
'Template Number' corresponding to the highest cross correlation peak
match for any spectrum may be found under the keyword 'BESTTEMP' in
the PDU header of a SDSS spSpec-$mjd-$plate-$fiberid.fit file.
Template number | Sp Type | Plate | MJD | FiberID |
1 | sdO | 593 | 52026 | 265 |
2 | sdB | 301 | 51942 | 431 |
3 | sdB | 390 | 51900 | 115 |
4 | BHB | 480 | 51989 | 112 |
5 | A | 300 | 51666 | 128 |
6 | early F | 289 | 51990 | 5 |
7 | early G | 306 | 51637 | 295 |
8 | late F | 273 | 51957 | 304 |
9 | G | 310 | 51990 | 356 |
10 | G/K | 396 | 51816 | 605 |
11 | early M | 402 | 51793 | 204 |
12 | M | 367 | 51997 | 593 |
Last modified: Sun Jul 15 14:47:10 CEST 2007
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