LAMOST is a 4m reflecting Schmidt telescope special designed for conducting multifiber spectroscopic survey with 4000 fibers. Fiber position errors greatly impact spectral data SNR. There are three groups of sources that contribute to fiber position errors: errors orthogonal to the optical axis of telescope, errors parallel to the optical axis, and the fiber tilt from the telescope optical axis. It is difficult to measure these errors, especially during the observation. In this poster, we propose an indirect method to calculate the total and systematic position errors for each individual fiber from spectra data by constructing a model of magnitude loss due to the fiber position error for the point source.
Before LAMOST spectra release, raw data need to go through a series of processes, i.e. a pipeline after observed,
including 2D reduction, spectral analysis, eyeball identification. It is a proper strategy that utilizing a database to
integrate them. By using database the coupling between relative modules would be reduced to make the adding or
removing of them more convenient, and the dataflow seems to be more clearly. The information of a specific object,
from target selection to intermediate results and spectrum production, can be efficiently accessed and traced back
through the database search, rather than via FITS reading. Furthermore, since the pipeline has not been perfected yet, the
eyeball check is needed before the spectra are released, and an appropriate database can make the feedback period of
eyeball check result more conveniently, thus the improvement of the pipeline will be more purposely. Finally, database
can be a data mining tools for the statistics and analysis of massive astronomical data. This article focuses on the
database design and the data processing flow built on it for LAMOST. The database design requirement of the existing
routines, such as input/output, the relationship or dependence between them is introduced. Accordingly, the database
structure suited for multiple version data process and eyeball verification is presented. The dataflow, how the pipeline is
integrated relied on such a dedicated database system and how it worked are also explained. In addition, some user
interfaces, eyeball check interfaces, statistical functions are also presented.
Large sky area multi-object spectroscopic telescope(LAMOST) is a reflecting schmidt telescope, the unique
telescope structure make it compatible with both large sky area and large aperture. While the vignetting effect
of the telescope is not the same everywhere, the flat field is quite different from the common flat field which use a
lamp projecting to a fixed white screen. We describe the Schmidt reflector(MA) cover solution of the LAMOST
flat field, simulation shows the variation across the field of view is less than 2 percent. The material of flat field
screen is carefully chosen to have both high reflectivity and diffusion. We also describe the material test for the
LAMOST flat field screen. Flat field lamp should have high color temperature to raise the sinal in the shorter
wavelength. The possible solution for the flat field lamp is described.