First results from the ALHAMBRA-Survey

TL;DR

The ALHAMBRA survey, using 20 medium-band filters and deep near-infrared imaging, has successfully observed a galaxy sample with precise photometric redshifts, demonstrating the survey's data quality and calibration procedures.

Contribution

This paper reports the first results from ALHAMBRA, showcasing the survey's design, data quality, calibration, and initial galaxy sample analysis with accurate photometric redshifts.

Findings

Approximately 10,000 galaxies with precise photometric redshifts in a 15x15 arcmin area.

Initial estimate of about 500 galaxies with redshift z>2.

Successful validation of survey pipelines and calibration procedures.

Abstract

We present the first results from the ALHAMBRA survey. ALHAMBRA will cover a relatively wide area (4 square degrees) using a purposely-designed set of 20 medium-band filters, down to an homogeneous magnitude limit AB~25 in most of them, adding also deep near-infrared imaging in JHK. To this aim we are using the Calar Alto 3.5m telescope. A small area of the ALHAMBRA survey has already been observed through our complete filter set, and this allows for the first time to check all the steps of the survey, including the pipelines that have been designed for the project, the fulfilment of the data quality expectations, the calibration procedures, and the photometric redshift machinery for which ALHAMBRA has been optimised. We present here the basic results regarding the properties of the galaxy sample selected in a 15x15 square arcmin area of the ALHAMBRA-8 field, which includes approximately 10000 galaxies with precise photometric redshift measurements. In a first estimate, approximately 500 of them must be galaxies with z>2.