Nordic Optical Telescope

Piskunov Loral

On 31/1/2002 we have done wide-slit observations with camera 2 of flux-standard star HD93521. These on-blaze results are for AirMass=1, and do not include slit losses. Exposure times for a U=B=V=R=I=10 star in typical observing conditions reaching S/N=100 per pixel at the blaze in the extracted unbinned spectrum are given as well (for the case of no slit losses).

AB magnitude: the magnitude of a star giving 1 e-/Å/s.
Efficiency: ratio of detected and emitted stellar flux (with flux in energy/s/Hz/area).

wavelength AB magnitude NOT+SOFIN+Loral efficiency expo time for
S/N=100 and m=10 Dispersion
Å/pixel

3500 13.9 0.5% 19000s (670000 e-/Å) 0.015

3600 14.1 0.6% 15000s (690000 e-/Å) 0.015

4000 15.3 1.9% 4400s (590000 e-/Å) 0.017

4500 15.9 3.8% 2300s (550000 e-/Å) 0.018

5000 16.1 4.9% 1800s (480000 e-/Å) 0.021

5500 16.1 5.6% 1600s (450000 e-/Å) 0.023

5800 16.1 5.6% 1500s (410000 e-/Å) 0.025

6500 16.0 5.9% 1400s (350000 e-/Å) 0.028

7500 15.8 5.6% 1600s (320000 e-/Å) 0.032

8000 15.4 4.1% 2100s (290000 e-/Å) 0.035

8500 15.1 3.3% 2500s (270000 e-/Å) 0.037

9000 14.8 2.6% 3200s (260000 e-/Å) 0.039

Fringing starts to become noticable from 6600Å redwards in the extracted spectra. At 7000Å the fringes are 10% peak-to-peak in the extracted spectra. At 9000Å the fringes are 50% peak-to-peak in the extracted spectra.

Note that we expect the blue response of the system to improve after the telescope mirrors have been realuminized (May 2002). It is also worthy to note that the athmosphere was rather dusty when the above observations were made, again affecting the blue response the most.

In November 2002 Dr. I. Ilyin carefully cleaned dust particles from the CCD surface and window, in order to improve the cosmetics of the flat field.

Last modified: April 19 2023