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I. Introduction

The HyperLeda FITS archive (HFA) has been open in January 1999. In June it contained about 35000 files.

The archived data are broad band images (BBI) and long-slit spectra (LSS) plus their associated template and calibration files.

The data in HFA can enter into the HyperLeda processing pipeline and the results can be freely downloaded.

The team involved in the project gather:

...... The rest of this page is out of date .....
The pre-PhaseA study has been conducted by Ph. Prugniel and V. Golev and resulted in the present document.

The idea is to initially restrict the project to an archive of 2 dimensional spectra of galaxies: The pre-PhaseA resulted in:

Definition of the file system (structure of the archive)
Preliminary definition of the FITS keywords
Implementation of low-level routines for accessing the archive
Implementation of the index of the HFA
The aim of Phase A was to design a "pipe 0" efficient enough to convince everybody that using this system of archive is not a waste of time.
Phase A was terminated on Dec. 22th 1998. It resulted in the archiving of several dataset, including the "Library of Medium Resolution Spectra". This allowed to check and improve the consistency of the set of keywords. At this stage, a preliminary definition and implementation of the pipeline processing was achieved.
[The obtained with "Library of Medium Resolution Spectra" contains data the CARELEC spectrograph over the period 1992-1998. They are described in the series of papers by Simien and Prugniel (1997a,b,c 1998) and by Golev et al. (1998).]
The HFA is presently stored in Lyon, but the architecture allows for a segmentation on several file systems possibly located in different sites. (A segment of HFA will be soon located in Milano).
The HFA is mirrored on two HyperLeda mirrors (Lyon and Brera), the other HyperLeda mirrors redirect the requests to Lyon.
Phase B will extend over the first semester of 1999.
We will work as soon as possible on a serious implementation of Pipe0, correctly documented...
We will add different processing procedures on the pipeline: sky subtraction, cosmic removal, filtering...
We will implement analysis procedures on the pipeline, in particular the line strength analysis and stellar kinematics standard procedures.

II. Data contained in the archive

The archive presently contains both images and spectra.
The images are broad ban images in U B V R and I but does not constitute any complete sample. We will add further dataset in the future. The spectra make a complete collection of the observations done with the CARELEC spectrograph (OHP) in the frame of the large programs concerning the fundamental plane of early-type galaxies and the scaling relations of spirals (Prugniel, Simien and collaborators).
The Library of Medium Resolution Spectra (ie. resolution = 1000 to 3000)

III. Structure of the archive

IV. FITS keywords

V. FITS extensions

VI. Software


Issues to address

Classification of the keywords

Keywords independent of the processing Unaffected by "linear" processing, like flat-fielding, w-calibration, cosmetic processing, analysis... But possibly affected by "non-linear" processing like combining frames (average flat-field), compositing frames (eg. to remove the cosmics)...
General Setup
Telescope, Instrumental frozen setup, Detector
Observation Setup
Characteristics of the actual observation
H_DTSET dataset identifier
H_CONTXT context: LSS, BBI, ...
H_DRON Detector Read out noise, in electrons
H_DPIX Detector Pixel size (in microns)
Scale (arcsec/pixel)
Slit width (arcsec)
Dispersion (Angstrom/mm)
DATE-OBS Date of observation
MJD-OBS Date of observation
EXPTIME Exposure time
OBJECT Object identifier
H_TYPE Type of exposure

PA of the slit
Keywords affected by the processing
General Setup Observation Setup
Gain [e/ADU]
Saturation level [ADU]
Bias [ADU]

Image size
Sky value [ADU]
Magnitude calibration constant (mag/arcsec2)

Keywords affected by the processing
Related frames
Processing History

HyperLeda Questions: leda@univ-lyon1.fr