MagE reduction cook book

I'm planing to post  a MagE reduction cookbook for python's based pipeline... I think it will be a nice idea in case someone wants to use it and not spend ages trying to figure it out.

Cansancio

Ah! que terrible, me quede dormida para asistir al seminario de hoy! uff! parece que estoy mas cansada de lo usual... A tomar cafe se ha dicho

Astronomical Spectroscopy

MEGA SHORT REVIEW OF

Astronomical Spectroscopy
P. Massey & M. M. Hanson

A basic astronomical spectrograph contains: a slit on to which focused the light from

the source; a collimator, which would take the diverging light beam and turn it into para-

llel light; a disperser; and a camera that would then focus the spectrum onto the detector.

Spectroscopy is a fundamental tool in astronomy, since allows to determine the chemical

compositions, physical properties and radial velocities of astronomical sources.

There are different kinds of blocking filters in order to achieve the wanted wavelength

observation and avoid order overlapping.

Conventional Long-Slit spectrographs are the most versatile, allowing to take spectra of

bright or faint sources and obtain spatially resolved spectra of extended sources. Some steps

involved in the reduction of Long-slit spectrographs data are as followed: Over scan (20-40

columns on the right side of the chip) must be fitted and subtracted. Trim the blank areas. If

the CCD camera had bias structure, it must be removed. Then, depending either one want to

flux calibrate or normalise the spectrum, one should choose the best flat normalisation. After

this, one must remove the non-uniformity in the spatial direction (slit illumination function)

and identify the sky and the object. After this, one needs to identify and fit the lines to the

pixel number in order to perform the wavelength calibration. Finally, one must normalise

the spectrum (in order to perform abundance analysis or measuring radial velocities) or flux

calibrate (in order to model the spectral energy distribution or determine reddening among

others) the spectrum.

Echelle spectrographs avoids to waste detector area by cross dispersing the various or-

ders, spreading them across the detector. This brings some difficulties of flat-fielding.

Multi-objects spectrometers uses an slit mask containing dozen or even hundreds of slits

(Multi-slit spectrograph) or multi-object fibre positioner (Fiber-fed Bench-Mounted spectro-

graphs) to allow multiple objects observation. Multi-object reduction is basically the same as

mentioned in long-slit spectrographs, but there are some differences. For fibers, sky subtrac-

tion must be done by having some fibers assigned to blank sky. For multi-slits, there will be

a very challenging reduction, since the wavelength coverage of each slitlet will depend upon

its placement in the field.

Fabry-Perots and Integral Field spectroscopy obtain spatially resolved spectroscopy of an

extended source.

When observing with a NIR spectrometer, there must be some changes in the reduction,

since the detectors are different, but mainly it presents significant background radiation and

strong absorption from the Earths atmosphere. In order to remove this features, telluric stan-

dards observations must be made with similar declination to the target object, but to transit

30-60 minutes before or after in order to get similar air masses.

Multiwavelength Observations of Accretion in Low-Mass X-ray Binary Systems

Really short review of this paper (1/2 page!) for my PhD reading list

Multiwavelength Observations of Accretion in Low-Mass X-ray Binary Systems

Robert I.Hynes

Low-Mass X-ray binaries (LMXBs) stars are formed by a X-ray emmiter primary star that can

be a neutron star or a stellar mass black hole and a late type G-M donor star with masses

below 1,5M . In this systems, the compact star accretes material from the donor mostly by

Roche lobe overflow.

LMXBs transients are often ultra-soft spectra and in quiescence are often dominated by

the companion star. All transient systems are recurrent, but not at the same timescale. It is

believed that the outburst are as the disk instability modell, originally developed to explain

dwarf novae outbursts.

Spectral energy distributions of LMXBs have prouf to be persuasive evidence on Black

Holes Jets. About LMXBs light curves, we can say that the simplest optical curve comes from

ellipsoidal variations in quiescence, who take a near sinusoidal form with 2 cycles per binary

orbit and is mostly determined by the system inclination. Superhumps are observed as well,

due disk eccentricity and precession, most likely occurring in black holes systems as these

have more extreme mass ratios than most neutron star LMXBs. Quasi-periodic oscillations,

repeating signals not strictly periodic, are common in LMXB. A transient signal it will manifest as a quasi-periodic oscillation. In eclipsing systems, structure from disk axisymmetry can

be observed. Also, eclipses provides precise constraints on the system inclination with sub-

sequent more accurate parameters derived from it, but there are not known eclipsing black

hole in our Galaxy. It is believed that this might be a selection effect.

LMXBs observation is multiwavenength. The most usual lines present in a LMXB spectra

are the Balmer lines, HeI, HeII(optical and ultraviolet). Besides hydrogen and helium, other

lines seen are NIII, CIII around 4640Å, known as the Bowen blend. This donor star lines are

very useful in luminous systems, have prove being a good tool for mass determination. In

quiescent systems, the period and radial velocity of the secondary are enough to estimate

the mass since Kepler’s third law.

Finally, it is possible to say that for the fully understanding of LMXB not only X-ray obser-

vations are necessary, but also optical and spectroscopic.

Here is the link with the real paper
http://adsabs.harvard.edu/abs/2010arXiv1010.5770H

Un sitio muy bueno para ver anime subtitulado latino

Tiene cosas super buenas, todas para ver online en idioma original, subtituladas al espagnol, HD casi todas... recomendado 100%

Cliquear en el titulo para llegar XD

Attention MagE Users!

If you are using MagE spectrograph in order to do some time resolved observation and you want to use MagE's Python based pipeline (by Dan Kelson), you will have to do an extra step.

MagE's python based pipeline took all of your spectra that have the same header and add them in order to get better S/N.  So if you want to have them one by one, you must change the headers in order that every single spectra is named different and, subsequently will be reduced alone.