J/A+A/708/A382 7918 blazar-selected AGN CAZ catalog and LC (Kouch+, 2026)
CAZ catalog and optical light curves of 7918 blazar-selected active galactic
nuclei.
Kouch P.M., Lindfors E., Hovatta T., Liodakis I., Koljonen K.I.I., Paggi A.,
Nilsson K., Jormanainen J., Fallah Ramazani V., Kankkunen S., Wierda F.,
Wagner S.W., Graham M.J.
<Astron. Astrophys. 708, A382 (2026)>
=2026A&A...708A.382K 2026A&A...708A.382K (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; QSOs ; Radio sources ; X-ray sources ;
Optical
Keywords: catalogs - galaxies: active - BL Lacertae objects: general -
galaxies: jets - quasars: general - galaxies: statistics
Abstract:
Active Galactic Nuclei (AGN) are some of the brightest and most
variable objects in the universe. Those with relativistic jets
observed at small viewing angles are blazars. Due to Doppler-boosting,
blazars exhibit extreme stochastic variability. While the origin of
this variability is thought to be changes in the accretion flow and
jet dynamics, much about blazar variability remains unknown. In this
paper we use several blazar-dominated AGN samples to form a catalog of
7918 blazars and candidates -- the largest to date. We also collect
source types, redshifts, peak frequencies of the spectral energy
distribution (SED), radio variability Doppler factors, and X-ray flux
densities for as many sources as possible. We use all-sky surveys
(CRTS, ATLAS, and ZTF, abbreviated as "CAZ") to extract their
optical multiband flux density on a nightly basis between 2007 and
2023, and construct as long and as high cadence light curves as
possible for as many sources as attainable. We quantify the
variability of the light curves and apply the Bayesian blocks
algorithm to determine their flaring periods. The CAZ catalog and
light curves as well as the corresponding Bayesian blocks and flaring
periods are all provided in the accompanying electronic tables,
enabling many analyses involving jetted-AGN variability with
unprecedented sample-sizes. Overall, we find: (1) optical flares
generally have a faster rise than decay; (2) optical brightness and
variability are strongly dependent on the synchrotron peak frequency;
(3) flat spectrum radio quasars and BL Lac objects have comparable
optical variability and flare characteristics at the same synchrotron
peak frequency; and (4) optical flare times tend to decrease and
amplitudes increase with increasing radio variability Doppler factor.
Description:
Here we provide the CAZ catalog containing 7918 sources along with
their compiled physical parameters as well as the corresponding CAZ
light curves, Bayesian block (BB) information, and BBHOP flare
information.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
catalog.dat 363 7918 Catalog containing all available info about
the CAZ sources
files/* . 7830 Individual CAZ light curves, Bayesian block (BB)
information, and BBHOP flare information files
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See also:
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
J/ApJS/263/24 : The 4LAC-DR3 catalog (Ajello+, 2022)
J/A+A/632/A77 : 3HSP blazars catalog (Chang+, 2019)
J/ApJS/175/97 : CGRaBS: survey of γ-ray blazar candidates (Healey+, 2008)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- CAZ Source name in the format CAZJHHMM+DDMM
16- 36 A21 --- fLC File name for source's CAZ light curve,
in subdirectory files (1)
38- 58 A21 --- fBB File name for source's BB info,
in subdirectory files (1)
60- 83 A24 --- fBBHOP File name for source's BBHOP flares,
in subdirectory files (1)
85- 91 F7.3 deg RAdeg CAZ Right Ascension (J2000)
93- 99 F7.3 deg DEdeg CAZ Declination (J2000)
101-110 A10 --- RFC Source name in RFC catalog (2)
112 A1 --- RFCc [Yes No] Source is in RFC complete
subsample (3)
114-130 A17 --- 4LAC Source name in 4LAC catalog (4)
132-151 A20 --- 3HSP Source name in 3HSP catalog (5)
153-162 A10 --- CGRaBS Source name in CGRaBS catalog (6)
164-178 A15 --- 5BZC Source name in 5BZC catalog (7)
180-207 A28 --- Other Other common source name
209 A1 --- Type Source type (8)
211-216 A6 --- r_Type Reference for source type
218-225 E8.5 --- z ?=- Redshift estimate
227-232 A6 --- r_z Reference for redshift estimate (9)
234-239 F6.3 [Hz] Snu ?=- Synchrotron peak frequency
241-244 A4 --- SnuClass Synchrotron peak frequency class (10)
246-249 A4 --- r_Snu Reference for synchrotron peak frequency
251-256 F6.3 [Hz] Henu ?=- High-energy peak frequency (11)
258-263 F6.3 --- Dvar ?=- Radio variability Doppler factor
265-270 F6.3 --- E_Dvar ?=- Radio variability Doppler factor
positive error bar
272-277 F6.3 --- e_Dvar ?=- Radio variability Doppler factor
negative error bar
279-281 A3 --- r_Dvar Reference for radio variability Doppler
factor (12)
283-293 E11.6 mW/m2 SXray ?=- Median X-ray flux density (13)
295-305 E11.6 mW/m2 E_SXray ?=- Median X-ray flux density
positive error bar
307-317 E11.6 mW/m2 e_SXray ?=- Median X-ray flux density
negative error bar
319-327 E9.4 mW/m2 SXrayUL ?=- X-ray flux density 3-sigma upper limit
329-333 F5.3 --- FvarC ?=- Fvar of the CRTS portion of the CAZ
light curve (14)
335-339 F5.3 --- FvarZ ?=- Fvar of the ZTF portion of the CAZ
light curve (14)
341-343 A3 --- VarS [Yes No -] CAZ light curve is classified as
variable (15)
345-352 F8.6 --- BB95f BB95 fraction (16)
354-361 F8.6 --- BBHOPdc Duty cycle of prominent BBHOP flares (17)
363 A1 --- Cmrg [Yes No] CRTS portion is merged with the rest
of the light curve
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Note (1): Only if available (applies to the rest of the catalog).
CAZJHHMM+DDMM_LC.csv : CAZ light curve of a CAZ source
------------------------------------------------------------
Column 1: MJD (day) Time of the flux density measurement
Column 2: S (mJy) Shifted flux density
Column 3: Se (mJy) Error on the shifted flux density
Column 4: Filt (---) Filter code (1)
Column 5: sFac (---) Shift factor (2)
Column 6: sInfo (---) Shift info (3)
------------------------------------------------------------
Note (1): The filter codes are given in the format "[s]f" where "s" denotes the
survey or monitoring program and "f" denotes the filter (see Sect. 3.3).
Note (2): The shift factor can be used to recover the original flux density of
each filter. It is done via dividing "S" by "sFac" (likewise, "Se" by "sFac"
to get the the original flux density error).
More details are given in Sect. 3.3.
Note (3): This shows which filters are merged onto each other.
For example, [s1]f1+[s2]f2 means that the filter 1 of survey 1 was merged
onto filter 2 of survey 2. More details are given in Sect. 3.3.
CAZJHHMM+DDMM_BB.csv : BB information of a CAZ source
------------------------------------------------------------
Column 1: LMJD (day) Start (left side) of the Bayesian block (BB)
Column 2: RMJD (day) End (right side) of the BB
Column 3: BBS (mJy) Average flux density within the BB
Column 4: BBSe (mJy) Error on the average flux density within the BB
Column 5: Num (---) Number of individual flux density data points
within the BB
Column 6: Segm (---) Segment of the light curve the BB belongs to (1)
Column 7: BB95 (---) BB is considered a BB95 (Yes or No) (2)
------------------------------------------------------------
Note (1): "All" means the CRTS and other portions of the CAZ light curve for
this source were merged and the BB is from this merged light curve.
"CRTS" and "nonCRTS" mean that the CRTS could not be merged with the rest of
the CAZ light curve. In this scenario, "CRTS" means the BB is from the CRTS
portion of the light curve and "nonCRTS" means the BB is from its other
portion.
Note (2): Details are given in Sect. 4.2.
CAZJHHMM+DDMM_BBHOP.csv : BBHOP flares of a CAZ source
------------------------------------------------------------
Column 1: sMJD (day) Starting time of the BBHOP flare
Column 2: sS (mJy) Starting flux density of the BBHOP flare
Column 3: sSe (mJy) Starting flux density error of the BBHOP flare
Column 4: pMJD (day) Peak time of the BBHOP flare
Column 5: pS (mJy) Peak flux density of the BBHOP flare
Column 6: pSe (mJy) Peak flux density error of the BBHOP flare
Column 7: tMJD (day) Terminal time of the BBHOP flare
Column 8: tS (mJy) Terminal flux density of the BBHOP flare
Column 9: tSe (mJy) Terminal flux density error of the BBHOP flare
Column 10: stP (---) BBHOP flare is considered prominent (Yes or No)
------------------------------------------------------------
Notes: See Sect. 4.3 for more details.
Note (2): The version of the Radio Fundamental Catalog (RFC) used is
https://astrogeo.org/sol/rfc/rfc_2023d/.
Note (3): If a source has an X-band radio flux density greater than 150mJy,
then it is in the RFC complete subsample (see Sect. 2).
Note (4): 4LAC info is from Ajello et al., 2022ApJS..263...24A 2022ApJS..263...24A,
Cat. J/ApJS/263/24.
Note (5): 3HSP info is from Chang et al., 2019A&A...632A..77C 2019A&A...632A..77C,
Cat. J/A+A/632/A77.
Note (6): CGRaBS info is from Healey et al., 2008ApJS..175...97H 2008ApJS..175...97H,
Cat. J/ApJS/175/97.
Note (7): 5BZC info is from Massaro et al., 2015Ap&SS.357...75M 2015Ap&SS.357...75M, Cat. VII/274.
Note (8): Source type as follows:
Q = Flat Spectrum Radio Quasars or candidates
B = BL Lac objects or candidates
G = host-galaxy dominated BL Lac objects
U = blazars of unknown type or blazar candidates
A = non-blazar AGN or AGN candidates (see Sect. 2).
Note (9): Possible references are the above catalogs, the OCARS catalog
(Malkin et al., 2018ApJS..239...20M 2018ApJS..239...20M), or SIMBAD; see Sect. 2 for more info.
Note (10): Synchrotron peak frequency class as follows:
LSP = low-synchrotron-peaked source
ISP = intermediate-synchrotron-peaked source
HSP = high-synchrotron-peaked source
EHSP = extremely high-synchrotron-peaked source
These are determined based on CAZsNu limits given in Sect. 1.
Note (11): All values are taken from the 4LAC catalog.
Note (12): References as follows:
L18 = Liodakis et al., 2018ApJ...866..137L 2018ApJ...866..137L, Cat. J/ApJ/866/137
New = values calculated in this study (see Sect. 2).
Note (13): Details given in Sect. 2.
Note (14): Details given in Sect. 4.1.
Note (15): Some CAZ light curves were too short or had too few data points for
their variability to be evaluated. These have "-" as their VarS.
More details are given in Sect. 4.1.
Note (16): Details given in Sects. 4.2 and 5.2.
Note (17): Details given in Sect. 4.3.
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Acknowledgements:
Pouya Kouch, pouya.kouch(at)utu.fi
(End) Patricia Vannier [CDS] 12-Feb-2026