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SINFONI Quality Control:
telluric STD frames

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QC PLOTS
STD: CURRENT HISTORY
net flux levels
strehl ratios
persistence (over-flux test)
image quality J-band
image quality H-band
image quality K-band
image quality H+K-band
QC1 database (advanced users): browse | plot
   Click on CURRENT to see the current trending (Health Check).
   Click on HISTORY to see the historical evolution of the trending.


top General Information

Telluric standard star observations are required for all near-infrared spectroscopic observations in order to be able to remove the telluric (atmospheric) absorption features in the data. Telluric standards are not standard stars in the classical sense; they are simply bright stars of known spectral type for which the intrinsic stellar features are either negligible or easily separated from features introduced by the earth's atmosphere. The telluric standard star is usually taken directly after the science spectrum with the same spectroscopic setup and the same average airmass of the target, in order to avoid significant changes in the shape and intensity of the telluric absorption lines. When the science target is reduced with the same spectroscopic flat as the telluric standard star, the lamp features cancel out. The standard star data is processed with the same pipeline routine as is used for science frames. Telluric standard star products are stand-alone deliverables; the pipeline does not correct the science spectra for telluric absorption features.

Telluric standard star pipeline products include:

PRO.CATG description
COADD_STD full cube coadded from jittered cubes
MASK_COADD_STD cube with weight factors
OBS_STD N object cubes before being coadded
STD_NODDING_STACKED N stacked object frames before being "cubed"
MED_COADD_STD median of collapsed COADD_STD frame
STD_STAR_SPECTRA table with extracted spectrum and response function
STD_STAR_SPECTRUM extracted spectrum in fits format

 

 

STD_NODDING_STACKED

A SINFONI telluric STD frame. This is a stack of N target frames before being combined into a cube (STD_NODDING_STACKED).

MED_COADD_STD

The median collapse of a telluric STD cube (MED_COADD_STD).

 

top SCIENCE parameters trended

QC1 plots

The QC1 plots for the SINFONI STD star trending are divided into two sections (STD and image_quality). The QC1 STD trending pages monitor the following:

STD trending plots:

  • a test for an over-flux condition (>= 10,000 ADU) and, if detected, the number of affected pixels.
  • net flux (ADU/pixel) of standard star over a 3 sigma aperture.
  • strehl ratio (median value over all wavelengths).
  • a test for an over-flux condition (>= 10,000 ADU) and, if detected, the number of affected pixels.

image_quality trending plots:

  • standard star image quality (FWHM) as compared to the DIMM seeing which has been corrected to the same wavelength and airmass (J-band).
  • standard star image quality (H-band).
  • standard star image quality (K-band).
  • standard star image quality (H+K band).

 

QC1 parameters

Parameter Table: Name (QC1 database) Description of Procedure
net flux level

sinfoni_std: qc.net.flux

SExtractor (Bertin and Arnouts 1996 A&A 117,393) is run on the MED_COADD_STD frame and the brightest detected source is assumed to be the STD. The total flux integrated over a 3 sigma detection aperture is divided by the number of pixels in this aperture. This "net" flux per pixel is monitored for all filters and pixel scales. Values above 5 ADU/pixel are considered acceptable.

median strehl ratio

sinfoni_std: qc.strehl.med For each plane (wavelength step) in the COADD_STD cube the pipeline computes the strehl ratio of the STD star. The median value over all cube planes is monitored for all filters and pixel scales.
test for over-flux

sinfoni_std: qc.persist.danger, qc.Npersist

A histogram is created from the STD_NODDING_STACKED image. If there are more than 10 instances of 6 or more contiguous pixels having count levels above 10,000 ADU, then this frame is in danger of persistence. In this case qc.persist.danger = 1, otherwise it is set to 0. If a danger of persistence is detected, the number of affected pixels is also given (qc.Npersist).

image quality (J-band)

sinfoni_std: qc.delta.fwhm, qc.fwhm.sinfo

Delta_IQ = sinfoni telluric standard star FWHM - DIMM seeing (whereby the DIMM seeing has been adjusted to the wavelength and airmass of the standard star observation). The image quality (IQ) plot shows the FWHM of the STD star and the corrected DIMM plotted against one another. CLOSED loop (AO) observations are plotted as solid circles, while OPEN loop (non-AO) observations are shown as open circles (J-band with all pixel scales).

NOTE: The conversion from pixels to arcsec for the image FWHM takes into account the fact that the reconstructed SINFONI cube has rectangular pixels. The reconstructed pixels are such that on-sky Delta_X = 0.5*Delta_Y. The correct conversion, in terms of the source position angle (PA), is:

pixel_scale is given by the keyword INS.OPTI1.NAME.

image quality (H-band)

sinfoni_std: qc.delta.fwhm, qc.fwhm.sinfo

As above. (H-band with all pixel scales).

image quality (K-band)

sinfoni_std: qc.delta.fwhm, qc.fwhm.sinfo

As above. (K-band with all pixel scales).

image quality (H+K-band)

sinfoni_std: qc.delta.fwhm, qc.fwhm.sinfo

As above. (H+K -band with all pixel scales).

 

QC Reports for telluric STD Frames

QC Report 1                                                                                            QC Report 2

QC Report 1QC Report 2

QC Report 1:
UL: the STD_NODDING_STACKED full detector intermediate product image with the number of saturated pixels listed.
UR: the MED_COADD_STD median cube collapsed image. A number of paramters are listed: the Obs ID, the target name, and for the brightest source detected:
source center (pixels), the integrated flux (within 3 sigma), the isophotal area (3 sigma), the net flux per pixel, the image FWHM (arcsec), the DIMM seeing corrected for the same airmass and filter used by this standard star, the status of the AO loop (OPEN or CLOSED), the position angle of the brightest source (degrees CCW from the x-axis), and its elongation and ellipticity. The source center, its position angle, and its FWHM are marked on the image.
LL: the (scaled) difference between two cube planes. Plane 100 - Plane 2072. The wavelengths of these planes are listed to the right of this image.
LR: a horizontal (blue line) and vertical (red line) cut through the center of the brightest detected source of the MED_COADD_STD median cube collapsed image. The respective averages through this center are
shown as dotted lines.

QC Report 2:
UL: three single column traces of the current product (STD_NODDING_STACKED) through: x = 500 (dark grey), x = 1000 (middle grey), x = 1500 (light grey) and an averaged sum of all columns (blue).
UR: three single row traces of the current product (STD_NODDING_STACKED) through: x = 500 (dark grey), x = 1000 (middle grey), x = 1500 (light grey) and an averaged sum of all rows (blue).
LL: the background-subtracted standard star spectrum (STD_STAR_SPECTRA) extracted by the pipeline.
LC: the strehl ratio as a function of wavelength (microns). The median strehl ratio (dotted green line) and the area denoting the 1 sigma strehl ratio (shaded green area) are shown.
LR: a logarithmic histogram of the STD_NODDING_STACKED full detector image is shown as a dark blue line, while the reflection of the non-positive flux histogram is shown in light blue.

 

QC Report 3 (only created if an over-flux is detected!)

QC Report 3

QC Report 3
TOP: a logarithmic histogram of the STD_NODDING_STACKED full detector science image with the persistence critical region shown as a red dotted line.
LL: the STD_NODDING_STACKED full detector intermediate product image.
LR: an estimate of the location of possible persistence critical pixels.

 

A more technical description of the QC procedures used for the telluric standard stars can be found here.

 

Trending and Issues

 


History

Trending and scoring of SINFONI telluric standards began 2009-05-01

 

 

 


 
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