Analysis of the September ε-Perseid outburst in 2013

We analyze the outburst experienced by the September ε-Perseid meteor shower on 9 September 2013. As a result of our monitoring the atmospheric trajectory of 60 multistation events observed over Spain was obtained and accurate orbital data were derived from them. On the basis of these orbits, we have tried to determine the likely parent body of this meteoroid stream by employing orbital dissimilarity criteria. In addition, the emission spectra produced by two events belonging to this meteor shower were also recorded. The analysis of these spectra has provided information about the chemical nature of their progenitor meteoroids. We also present an estimation of the tensile strength for these particles

Light pollution in Spain. An european perspective

Using DMPS satellite night images taken in 2000 we have estimated the saturated surface in many European countries. The objective of this study is to compare the illumination conditions and its effects in light pollution. We have measured the surface of the saturated zone. We compare this parameter with the ratio of population density of the country. To avoid bias, normalize by dividing the area built in each country prior to the comparison. In this way only takes into account the surface that really makes sense to illuminate. We have gathered the official data on energy consumption in public lighting in Spain. After plotting the evolution along the years we found changes in the way this value is obtained in different provinces of Spain and we made a more pessimistic prediction for the present energy consumption

Calibration of SQM-L photometers for the NixNox project

Twelve SQM-L night sky photometers have been tested and analyzed to determine their internal precision and differences in response. These photometers will be used by amateur astronomers around Spain, under the supervision of the Sociedad Española de Astronomía (SEA), to locate and characterize sites with dark skies well suited to perform astronomical observations (NixNox Project). A simple experimental setup has been built to obtain zero offsets for each photometer in order to correct all the observations

Orbits and emission spectra from the 2014 Camelopardalids

We have analysed the meteor activity associated with meteoroids of fresh dust trails of Comet 209P/LINEAR, which produced an outburst of the Camelopardalid meteor shower (IAU code #451, CAM) in 2014 May. With this aim, we have employed an array of high-sensitivity CCD video devices and spectrographs deployed at 10 meteor observing stations in Spain in the framework of the Spanish Meteor Network. Additional meteoroid flux data were obtained by means of two forward-scatter radio systems. The observed peak zenithal hourly rate was much lower than expected, of around 20 meteors h(-1). Despite of the small meteor flux in the optical range, we have obtained precise atmospheric trajectory, radiant and orbital information for 11 meteor and fireball events associated with this stream. The ablation behaviour and low tensile strength calculated for these particles reveal that Camelopardalid meteoroids are very fragile, mostly pristine aggregates with strength similar to that of the Orionids and the Leonids. The mineral grains seem to be glued together by a volatile phase. We also present and discuss two unique emission spectra produced by two Camelopardalid bright meteors. These suggest a non-chondritic nature for these particles, which exhibit Fe depletion in their composition

Magnitude to luminance conversions and visual brightness of the night sky

The visual brightness of the night sky is not a single-valued function of its brightness in other photometric bands, because the transformations between photometric systems depend on the spectral power distribution of the skyglow. We analyze the transformation between the night sky brightness in the Johnson-Cousins V band (mV, measured in magnitudes per square arcsecond, mpsas) and its visual luminance (L, in SI units cd m^(-2) ) for observers with photopic and scotopic adaptation, in terms of the spectral power distribution of the incident light. We calculate the zero-point luminances for a set of skyglow spectra recorded at different places in the world, including strongly light-polluted locations and sites with nearly pristine natural dark skies. The photopic skyglow luminance corresponding to m_(v)=0.00 mpsas is found to vary between 1.11-1.34 x 10^(5) cd m^(-2) if m_(v) is reported in the absolute (AB) magnitude scale, and between 1.18-1.43 x 10^(5) cd m^(-2) if a Vega scale for m_(v) is used instead. The photopic luminance for m_(v)=22.0 mpsas is correspondingly comprised between 176 and 213 µcd m^(-2) (AB), or 187 and 227 µcd m^(-2) (Vega). These constants tend to decrease for increasing correlated color temperatures (CCT). The photopic zero-point luminances are generally higher than the ones expected for blackbody radiation of comparable CCT. The scotopic-to-photopic luminance ratio (S/P) for our spectral dataset varies from 0.8 to 2.5. Under scotopic adaptation the dependence of the zero-point luminances with the CCT, and their values relative to blackbody radiation, are reversed with respect to photopic ones

3C a multi-wavelength database for the future GTC cosmological surveys

The 3C Database aims to provide complete multi-wavelength information over different cosmological fields, such as GOODS, Groth or Sa68 allowing detailed studies on wide samples of galaxies

Study of a complete sample of Hα emission-line galaxies from the UCM survey

The Universidad Complutense de Madrid survey is a long-term project with the aim of finding and analyzing star forming galaxies using the Hα line as the tracer for star formation processes. In order to obtain a representative and complete sample of the population detected, spectroscopic observations were carried out for the full sample of Hα emission-line galaxy (ELG) candidates of the UCM lists 1 and 2. The ELGs types most commonly found (47%) are intermediate to low-luminosity objects with a very intense star-formation region which dominates the optical energy output of the galaxy. This kind of ELGs is similar to the galaxy population detected in the blue objective-prism surveys. And what is more important, a second population (43%) of star-forming galaxies with low ionization or high extinction properties has been found. This ELGs group is detected neither in the blue (University of Michigan survey, Case survey) nor in other surveys (Kiso, IRAS, Markarian) using other selection techniques

Automatic selection of new Hα emission-line galaxies using MAMA

A full set of algorithms for the automatic analysis of low-resolution objective-prism spectra has been developed with the aim of finding new emission-line galaxies (ELGs) candidates from the Universidad Complutense de Madrid (UCM) survey prism plates. An objective-prism plate and a direct plate, used for pairing objects and to perform star-galaxy separation, have been scanned with the MAMA machine. The plates were taken in the red region of the spectrum, using the Hα+[NII] blend in emission as selection criterion. The procedure, applied to digitized spectra, is able to automatically select ELGs candidates. Density to intensity transformation has not been used in our method; the detection of the emission is performed applying three independent criteria over the one-dimensional spectra in raw data. The automatically selected sample is compared with that obtained after a careful visual scan. Spectroscopic observations at moderate spectral resolution are presented for the whole sample of candidates in order to study the drawbacks and the biases of both methods

Discovery of an emitting ring in the seyfert 1 galaxy UCM 2329+2500

We analyze a rather interesting galaxy discovered during the UCM survey for new Hα emission-line galaxies. The new galaxy UCM 2329+2500 presents a compact core that hosts a Seyfert 1 nucleus. The spectrum of the Seyfert nucleus presents broad components (FWHM=8000 km s^-1) and asymmetric profiles at the Balmer lines showing a secondary peak more apparent on the Hβ line and also observed in the Hα deblended line. Only traces of profile variability have been detected during spectroscopic observations at four different dates spanning 29 months. Eight kpc away from the nucleus, a ring-like structure that surrounds the core is observed. A long slit spectrum at PA 45° has revealed emission lines coming from both sides of the ring. The emission detected is prominent at a condensation observed on the red image. Star formation is the most plausible explanation. A high obscuration is also observed. All this information is coherent with a galactic encounter scenario

Monitoring long-term trends in the anthropogenic night sky brightness

Monitoring long-term trends in the evolution of the anthropogenic night sky brightness is a demanding task due to the high dynamic range of the artificial and natural light emissions and the high variability of the atmospheric conditions that determine the amount of light scattered in the direction of the observer. In this paper, we analyze the use of a statistical indicator, the mFWHM, to assess the night sky brightness changes over periods of time larger than one year. The mFWHM is formally defined as the average value of the recorded magnitudes contained within the full width at half-maximum region of the histogram peak corresponding to the scattering of artificial light under clear skies in the conditions of a moonless astronomical night (sun below −18◦, and moon below −5 ◦ ). We apply this indicator to the measurements acquired by the 14 SQM detectors of the Galician Night Sky Brightness Monitoring Network during the period 2015–2018. Overall, the available data suggest that the zenithal readings in the Sky Quality Meter (SQM) device-specific photometric band tended to increase during this period of time at an average rate of +0.09 magSQM/arcsec2 per year