Open Universe for Blazars

Open Universe for blazars is a programme developed as part of the Open Universe Initiative (Giommi et al. 2018) to support multi-frequency/multi-temporal blazar science by creating source catalogues and high-transparency data products that are ready for use or enable anyone interested in astronomy, with or without data analysis expertise, to do the same using innovative analysis methods.


A master list of blazars


This project relies on a blazar reference list that was assembled by combining the 5BZCAT, the 3HSP, and the 3LAC catalogs. The list currently includes 5340 objects, 3561 of which are from BZCAT, 1353 are sources from the 3HSP catalogue that are not included in BZCAT, and the remaining objects are 3LAC blazars that are not listed in the BZCAT or the 3HSP catalogue

This table will be updated as new blazars lists become available.





Scientific publications

The first paper

Accepted for publication in Astronomy & Astrophysics

This paper is dedicated to the analysis of all the Swift-XRT X-ray images including a blazar taken by Swift between November 2004 and November 2018. The analysis was carried out using Swift_deepsky, a data analysis pipeline built on top the official HEASoft-XRTDAS-XIMAGE software packages and encapsulated into a Docker container. The resulting catalog, called 1OUSXB, includes intensity and spectral information of 33,396 sources, 8,896 of which are single or multiple detections of 2,308 distinct blazars. The Swift_deepsky container is the most innovative part of the project as it automatically downloads the low level data and calibration files, it does not require any expertise in X-ray astronomy, and runs on Mac, Linux, and Windows operating systems. The Swift_deepsky container is available here .

Plot of the XRT count rate in the 0.3-10.0 keV band versus exposure time for all the sources included in the 1OUSXB catalog. Different type of blazars appear in color, serendipitous sources in light grey.


Paper II


Giommi, Perri, Capalbi et al., in preparation

This paper presents a detailed X-ray spectral analysis of all the Swift observations (in PC and WT mode) of the 28 blazars that have been observed with XRT more than 100 times during the mission. X-ray light curves have been constructed using both the fluxes from the spectral best fits, when the sources are bright enough for a detailed spectral analysis and for the fainter sources, using the image analysis presented in Paper I. See Giommi (2015) for a description and some preliminary results.

Hammer-Aitoff plot of the sky in Galactic coordinates showing the position of the 28 sources in the sample. The names of HBL sources appear in blue color, while those of IBLs and LBLs are green and red respectively. The darker area highlights the part of the sky south of the equator, illustrating how most of the blazars best observed by Swift are in the northern hemisphere.

Paper III

Fermi-LAT adaptive-bin light-curves of bright blazars




Sahakyan et al., in preparation

Fermi Adaptive bin and fixed bin (2 day) light-curve of the blazar CTA 102.

Paper IV

NuSTAR spectra of Blazars from the public archive


Middei et al. in preparation

Data access

The source catalogs and the spectral/timing high-transparency data products resulting from this program can be accessed in a variety of ways.

Paper I

The following data products and services are available for paper I
  1. Catalogs in FITS format
  2. Catalogs in CSV format
  3. On-line query interface at the Brazilian Science Data Center, BSDC
  4. Data integrated in the VOU-Blazars, VOU-SED and SSDC-SED tools accesible from the openuniverse.asi.it portal or as standalone tools (VOU-BLazars, Docker container version, VOU-Blazars, source code, SSDC-SED Builder).
  5. Access via Virtual Observatory Simple Conesearch Service (SCS) (e.g. from TOPCAT, Aladin etc...).

Paper II

Products and services for paper II

Spectral and timing data integrated in the VOU-Blazars, VOU-SED and SSDC-SED tools accesible from the openuniverse.asi.it portal or as standalone tools

Upcoming activities

  • Regular updates (every ~6months) of all catalogs and high-transparency data products
  • Release of a new version of VOU_Blazar tool and publication of the associated technical paper
  • Publication of SED movies of bright and densely observed blazar . For an example see the movie below presented in Padovani et al. 2018, MNRAS, 480, 192