2026-02-03 12:30

Ref0141 / Deadline: April 3rd, 2026 (23:59 CET)

Abierto / Open

Offer description

The Centro de Estudios de Física del Cosmos de Aragón (CEFCA) invites applications for a Data Quality Assurance (DQA) position focused on the automation of quality assessment of OAJ survey images, to start as soon as possible. The position is offered for a duration of 21 months within the framework of the “Knowledge Generation Projects 2024” project PID2024-162229NB-I00, with Dr. Mohammad Akhlaghi as the PI, and titled “STREAMDECODE: Decoding the stellar streams in the halos of nearby galaxies”, funded by the Spanish Ministry of Science, Innovation and Universities (MICIU/AEI/10.13039/501100011033) and the European Regional Development Fund (ERDF/EU).

The Observatorio Astrofísico de Javalambre (OAJ) conducts large-scale multifilter surveys (J-PAS, J-PLUS and J-VAR), involving the processing of a very large number of images obtained through more than 70 filters, each with specific optical and electronic characteristics. In particular, single-exposure data must be quality-checked before being injected into the data reduction pipeline. During the initial stages of J-PAS, image quality assessment relied heavily on visual inspection, an approach also applied across other OAJ projects. However, given the volume of data produced, this method is not sustainable in the medium term. Therefore, automatic procedures to detect and flag problematic exposures must be defined, implemented, and validated. In addition to automating established validation processes, new methodologies suitable for automation should be identified and developed. The experience gained will also contribute to the simulation of more realistic artifacts for the ARRAKIHS mission, in which CEFCA is actively involved.

In the framework of the DQA, the performance of the image processing is key. All images acquired at the OAJ are reduced using a custom-built pipeline, named jype, developed mostly in Python at CEFCA. It is planned to progressively incorporate routines from GNU Astronomy Utilities (Gnuastro, an official GNU package), given that its creator (and PI of STREAMCODE) is the Pipelines Researcher at CEFCA. Newly available routines implemented in Gnuastro or in other software packages involved in the image reduction process (e.g., astrometry, cosmic-ray detection, image combination, ghost detection, extended PSF subtraction, etc.) should be systematically tested and compared with those currently used in the OAJ pipeline. This evaluation will enable the incorporation of improved algorithms and enhanced functionalities into the main OAJ data processing system.

The successful applicant will contribute to the definition of the required quality evaluation algorithms and will be responsible for their implementation and validation. This may involve the use of machine learning techniques. The appointed candidate will join CEFCA’s Data Processing and Archiving Department (DPAD). The main tasks associated with the position include:

• Design, implementation, and validation of automated quality-control procedures at the exposure level, including the detection and flagging of problematic observations based on observational and reduction diagnostics.
• Development and optimization of image-analysis algorithms for the automatic identification and characterization of instrumental artifacts in reduced data products (e.g., strong gradients, reflections, optical ghosts, and residual reduction artifacts).
• Implementation of automation tasks identified during the project to progressively replace manual or visual quality assessment procedures.
• Performance comparison of alternative algorithms identified within DPAD, with the aim of improving and updating the current OAJ pipeline.
• Quality assessment of incoming OAJ images.
• Production and validation of master calibration frames and definition of their validity periods within the pipeline.
• Analysis of data quality metrics and generation of diagnostic reports to support operational decisions.

CEFCA in a nutshell

CEFCA is a research institution located in Teruel (Spain). It is responsible for the operation, data management, and scientific exploitation of the Observatorio Astrofísico de Javalambre (OAJ). The OAJ is an astronomical facility specifically designed to conduct large-area surveys using wide field-of-view telescopes: the 2.5m Javalambre Survey Telescope (JST250) and the 83cm Javalambre Auxiliary Survey Telescope (JAST80).

JST250 is equipped with JPCam, a ~1.2Mpix panoramic camera consisting of a mosaic of 14 CCDs of ~9.2k x 9.2kpix. The JPCam/JST250 system provides a 3.4 deg² FoV and hosts a complete new set of 54 filters of ~140A width, covering the whole optical spectral range plus two broader filters at the blue and red ends. In the coming years, JPCam/JST250 will be primarily devoted to carry out the Javalambre Physics of the accelerating Universe Astrophysical Survey (J-PAS), which is producing photo-spectra of hundreds of millions of astronomical objects with wide-ranging applications in astrophysics and cosmology. The first Early Data Release (J-PAS EDR) was released in November 2024 with 12deg² in all the filters.

JAST80 is equipped with the panoramic camera T80Cam, hosting one CCD identical to those in JPCam. The T80Cam/JAST80 system provides an effective FoV of 2 deg². Since 2016, it is primarily dedicated to conducting the Javalambre Photometric Local Universe Survey (J-PLUS), whose fourth data release (~ 5000deg²) was made public in November 2025.

The OAJ is a Spanish ICTS (Unique Scientific and Technical Infrastructure). As such, CEFCA offers 20% of OAJ Open Time to competitive PI-led projects, including Legacy Surveys with JAST80.

ARRAKIHS (Analysis of Resolved Remnants of Accreted Galaxies as a Key Instrument for Halo Surveys) is an ESA F-class mission (F for “fast”) and the first ESA mission led by Spain, with a planned launch around 2030. ARRAKIHS will observe approximately 100 Milky Way-like galaxies in the optical and infrared, aiming to constrain the nature of dark matter and improve our understanding of galaxy formation through ultra-deep observations.

CEFCA is a core institution of the ARRAKIHS consortium. A ground-based replica of ARRAKIHS is installed at OAJ to support calibration planning, pipeline development, and science preparation. CEFCA leads several key components of the mission, including the assembly and operation of the replica and the Data Reduction work package (RED) within the Instrument Operations and Science Data Center (IOSDC).

All OAJ data are reduced, calibrated, and released by the Data Processing and Archiving Department (DPAD) at CEFCA. In parallel, data from the main CEFCA surveys (e.g., J-PAS and J-PLUS) are scientifically validated and exploited by researchers within CEFCA’s Research Area.

Evaluation criteria

Evaluation will be based on a cover letter and the CV.

The list below outlines the evaluation criteria, which should be clearly addressed in the cover letter and CV. As with personal data, all submitted documents will be used solely for evaluation purposes and will be deleted afterwards.

1. Coding experience (60%)
   1. Practical experience in Python programming.
   2. Practical experience in Shell/Bash scripting.
   3. Previous experience implementing machine-learning or statistical methods for data.
   4. Experience using SQL/ADQL.
   5. Experience in other data analysis programming languages, e.g. in C.
   6. Experience in control version software like e.g. Git.
2. Data analysis experience in optical imaging (40%)
   1. Experience in astronomical image reduction and calibration procedures (bias, dark, flat-field correction, artifact identification).
   2. Experience in astromical-related packages; e.g.: Gnuastro, AstroPhot, SExtractor, etc.
   3. Experience in visual inspection and quality assessment of optical imaging data.
   4. Experience in quantitative analysis of large imaging datasets.

Evaluation process

The selection committee will be composed of several members of CEFCA staff, who will assess the suitability of the candidates in an initial phase based on their submitted cover letter and CV, in accordance with the criteria established above. The highest-ranked candidates will be shortlisted for a final interview. Candidates will be informed by email of whether or not they have progressed through each phase of the process.

Recognizing the impact that family-related leave and career breaks (including maternity, paternity, adoption, and the care of dependent family members or relatives with serious health conditions) may have on scientific and technical careers, such circumstances, when properly documented, will be duly taken into account during the evaluation process.

To strengthen objectivity in the selection process, applicants are offered the possibility of submitting a blind curriculum vitae. A blind CV is a format that deliberately omits information regarding sex, age, origin, disability, or other personal circumstances, including exclusively details related to the applicant’s education, experience, and professional merits and competencies.

For questions on this position and application process, please contact Dr. Héctor Vázquez Ramió (hvr [at] cefca.es).

Requirements and conditions

Work–life balance measures:

In accordance with the current CEFCA Collective Agreement, the standard working time is a 37.5-hour working week, with flexible working hours outside the established core time, up to 20% teleworking, and leave and absence entitlements in line with applicable regulations.

CEFCA is an equal opportunity employer committed to increase the diversity in its workplace. Applications of candidates from underrepresented social groups in our staff are welcome.

CEFCA is committed to promoting gender parity among its staff. Hence, applications from women are strongly welcome.