Instrument configuration
TNG/NICS with grism disperser AMICI which provides a spectral range from 0.8 to 2.5 microns. Dispersion is 30-100 Å/pixel and spatial scale 0.25 arcsec/pixel.Slit - match to seeing, but maximum 1 arcsec, to avoid compromising the resolution.
NICS allows slit widths of: 0.5, 0.75, 1, 1.5, 2 arcsec
Grism - AMICI
Calibrations Arc-lamps are not useful for wavelength calibration. TNG staff recommends using a look-up table for that. Lamp-flats and bias are needed, but ask the support astronomer. Ask the support astronomer for cleaning the detector before taking a long exposure and/or after taking a broad-band image. I suggest to do some dithering, i.e. take more than one spectrum moving the target along the slit by several arcsecs. A couple of standards is needed to correct from instrumental spectral response. I guess that a short broad-band imaging is needed to acquire the target into the slit.
More examples in Maiolino et al 2004 (A&A, 420, 889)
Observations required
Standards.
The best list of infrared spectrophotometric standards I've found so far is:
http://www.ls.eso.org/lasilla/sciops/ntt/sofi/IRstandards/
where you can explore the Skymap to select the appropriate star.
[Added 4/08 - Ignacio recommends A0V or G5 stars with no absorption
features.]
During the night:
Difficult to say. The exposure time calculator from TNG web page gives the following figures, assuming 1" slit, 1" seeing, and
S/N=10 per pixel (to get S/N=20 per resolution element, i.e. 4 pix)
K=16 190 s
K=17 1200 s
K=18 7400 s
QSO colours are r-K ~ 1.5 or more (depending on redshift). If we restrict to bright QSOs, say r<18, then K<16.5.
Target list
The targets are all point
sources (click here for Fran's list, with links to finding charts).
Click here for Igancio's listing of the observable sub-sample
3 - 19 hours (146 entries).
Example QSO spectra
Observations made
Below are summary night reports from the observers.
All-night astro support by Gloria, operator = Albar.
20080125 (Chris/Sarah)
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Cloudy for most of night, seeing ~ 1.6 arcsec. Used 1" slit.
Initial telescope focus in J band.
Telescope pointing rms is ~ 1 arcmin over sky, but over a small
area of sky, the required offset is similar, within ~ 10 arcsec rms.
Observed most objects at parallactic angle.
Autoguiding on all objects.
Using ABBA dither along slit, in ABBA_itp01.txt.
Obtained spectra of:
q11/14, 36
q12/22, 30, 39, 41
q14/67
with total integration 120 * 3 sec (co-adds) * 4 (dither) =
1440 sec per object.
Total counts per pixel (i.e. integrating spatially) ~ 200 - 400
apart from q12/30 (70 counts).
The detector gain is not documented, but is believed to be
8 e-/count, so the S:N per pixel is ~ 30.
Data: DVD received (2 copies), and the data are in the TNG archive.
Notes on TNG/NICS/AMICI:
- Fixed format, spectrum runs 400 < x < 700, with blue at high x.
- Use sky flats, not continuum lamp
- Arc lamps not useful, use wavelength lookup table
- Detector linear to ~ 12k, saturates ~ 20k.
Automatic log for 20080125.
20080126 (Chris)
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Cloud all night, dome not opened.
20080127 (Sarah)
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Cloud all night, dome not opened.
20080314 (Ignacio, Chris)
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Clear most of night
20080315 (Ignacio)
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Some cirrus
20080412 ()
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20080413 ()
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J. Ignacio González Serrano
Version: 2008 Apr 11