EUROPEAN SOUTHERN OBSERVATORY
What does the pipeline do? -- Quick-look on-line data reduction.
This means that the pipeline automatically classifies every file
produced by SofI, and reduces it according to pre-defined rules, with
one of the specific SofI recipes. The recipes are specialized data
reduction tools, similar to the IRAF task but more comprehensive. They
are written in C. The SofI pipeline recipes are available upon request
starting the beginning of P78.
The data product is transferred to the off-line workstation wg5off where the user can review the file. Note: to view the newly arrived files on wg5off with Gasgano, one has to "refresh" the content of the Gasgano file list.
All file transfers are transparent to the user.
Purpose of the pipeline:
-- To provide reasonably well reduced data that can be reviewd by the observer in nearly real time to facilitate making decisions about the quality of the acquired data.
-- To provide data quality control parameters measured from the data itself, such as: zero points, central wavelength for the given spectroscopic setup, readout noise, gain, illumination level for the flats, dark/bias level, etc. These parameters are used for both data quality control and for instrument health check.
What type of data does the pipeline reduce? --
As a rule of thumb, the pipeline
fares well on good, high signal-to-noise data and tends to fail on
poor quality data. The parameters of the recipes are tuned to
encompass as larger variety of scientific observations as
possible. Of course, it is not possible to address all observing
strategies, so do not expect the pipeline to reduce your complicated
imaging program that alternates between four objects and a sky field.
The pipeline is likely to fail if you do spectroscopy of faint
objects, or objects with weak continuum, or a galaxy without sharp
central peak. Polarimetry is not supported.
Most likely the pipeline will reduce AutoJitter-taken imaging and spectroscopy of reasonably bright stars obtained with nodding along the slit.
Consult your support astronomer to determine whether you need the pipeline products, what are the chances of getting good reduction or any other pipeline related issues and all imaging and spectroscopic daytime calibrations.
What recipes are available? -- Here is a short description of the recipes, with some data quality parameters that they calculate:
Where can I get a detailed description of the recipes? -- Use the ISAAC pipeline page, which can be found here and here. There are some differences such as the treatment of the crosstalk and the current release of the SofI pipeline still is lacking certain recipes. Ask the SofI instrument scientist for details.
How to review the pipeline products? -- The easiest way is to use Gasgano on the astro@wg5off. The raw data are in sub-dir /data/raw/2006-04-19 or similar, and the reduced data are in sub-dir /data/reduced/2006-06-24 or similar. The quality control parameters, incl. the zero points are written in *.tfits or *.paf files. The names of the reduced files starts with "r.*". Remmeber to "refresh" the Gasgano content to see the latest data products.
How to get the pipeline products? -- The pipeline products are not part of the visitor's back up. The users can ftp the reduced data from wg5off or use the CD/DVD burner on that machine to back them up by themselves. Talk to your support astronomer about this.
Disclaimer: The data products are not science grade. The first and foremost reason for that is the fact that the pipeline calibration database is updated once every 1-3 months. Supplying more frequent calibration is not foreseen and is not going to be implemented.
Alternative to the pipeline: the SofI recipes are available via Gasgano and the user can run them interactively. Please, do not confuse it - Gasgano is an interface to an installation of the recipes on a different machine, and it is not automatic! The users should treat is as off-line data reduction tool, similar to IRAF or MIDAS, only tailored to the features of SofI. A detailed description of the manual data reduction via Gasgano can be found here. Description of Gasgano is available here.
Rules: The pipeline is maintaned and operated by the data handling administrator. In case of problems the user should allert the support astronomer or the telescope and instrument operator. The users should refrain from starting, stopping and any other tampering with the pipeline.
|Send comments to: SofI team
Created: Sept 12, 2006 (Valentin D. Ivanov). Last Update: Sept 13, 2006 (Valentin D. Ivanov)