Report on AXIS run at TNG, November 27-29, 2000

- Observers: Ismael Perez-Fournon (IAC) with help of Dario Fadda (IAC)

- Support astronomers: Antonio Magazzu (27 and 28), Marco Pedani (29)

- Instrument: Dolores Low-Resolution Spectrograph

- Grisms used: 
Low-Resolution Blue (LR-B), all nights and 
Low-Resolution Red (LR-R), only the first night

- Scales: 
Aprox. 3 AA/pixel and 0.275 arcsec/pixel

- Spectral range
Aprox. 6300 AA

- Nominal readout noise: 
Aprox. 9 electrons, but check noise structure 

- Slit widths:
Most spectra were taken with long-slits of 1.5" width, some 
with 1" width, some standards were observed without slit because 
of the lack of wide slits for flux calibrations (the widest 
one has a width of 1.5")

- Wavelength calibration: 
Thorium and Argon lamps

- Flat fields
Sky flats for imaging
Tungsten (internal lamp or dome) flats for spectroscopy 

- CCD windows
Imaging: variable window sizes
Spectroscopy: full size in the spectral direction, several hundred 
pixels in the spatial direction

- Position angle of the slit
In general the PA was chosen close to the paralactic angle, 
in some cases the PA was selected to include two objects in the 
slit.

- Acquisition 
Several images were needed to acquire the objects. In general, the 
last one or two images were taken with the autoguider switched on. 
If the last offsets were small, then the spectroscopic exposure 
was started without taking a new image. Therefore, small offsets 
may be present between the position of the object in the last 
saved image and in the 2D spectrum. 

Typical acquisition sequence:

a) Measure the position of the centre of the slit (X,Y))
b) Rotate the Dolores rotator to the desired Position Angle
c) Move to object position and take first image
d) Measure the offset to the slit position (X,Y)
e) Offset the telescope, start the autoguider and take the second image
f) Measure the offset
g) If the last offset is small (several arcsec), offset the telescope 
and start the spectrum; if the last offset is large, offset the telescope, 
start another acquision image and repeat "f" and "g"


- Seeing
Typically 1.5 arcsec, check acquisition images for an estimate of the 
seeing for each object.

- Depth of acquisition images
The acquisition images (of about 30 sec), taken without filters, and 
in dark sky observing conditions, go quite deep, with depths 
comparable to the 10 min INT WFC images. 

-Weather conditions

Night of Nov. 27: strong wind at the beginning of the night
Night of Nov. 28: thin cirrus part of the night
Night of Nov. 29: