4C +21.35 multiwavelength SED

4C +21.35 is a flat-spectrum radio quasar (FSRQ) at redshift z = 0.434. Its MMDC SED has 9,294 points from 45 catalogues, with dated data from 2007–⁠2024. Download the SED as CSV.

Updated 29 October 2026.

Names and position

Also known as 1FGL J1224.7+2121, 1FLAT J122454.5+212246, 1OUNYU J122454+2122.7, 3FGL J1224.9+2122, 4C21.35, 5BZQ J1224+2122, BZQ J1224+2122, CRATES J122455+212245, PCCS1217G255.07+81.65, PKS 1222+21, QSO B1222+216, TeV J1224+213.

Class: FSRQ
Redshift: z = 0.434
Position (ICRS): RA 186.22691°, Dec 21.37955°
Galactic: l 255.073°, b 81.660°

Other names and measurements: NED and SIMBAD within 5″ of this position.

The SED

Data: 9,294 points (194 upper limits) from 45 catalogues
Dated data: 2007–2024 (MJD 54191–60613)
Undated catalogue values: 256
Frequency range of detections: log ν = 7.9–26.2 [Hz] (radio, microwave, infrared, optical, ultraviolet, X-ray, γ-ray)
Swift measurements analysed by MMDC: 870 UVOT and 655 XRT
Largest catalogues (points): ASAS-SN (1,999), ZTF (1,572), MMDCXRT (1,245), XRTSPEC (1,223), MMDCGR (1,008)

Data by band

All 7 bands have data. The X-ray band has the most points, 3,319 of 9,294; its largest catalogue is MMDCXRT with 1,245.

Band	Points	Catalogues	Dated data
radio	48	7	undated
microwave	46	9	2013–2017
infrared	2,342	10	2009–2024
optical	2,492	5	2007–2024
ultraviolet	2	1	undated
X-ray	3,319	6	2007–2018
γ-ray	1,045	7	2008–2023

Get the data

The SED as CSV from the MMDC SED API (docs.mmdc.am).

In Python, with astro-mmdc:

from astro_mmdc import MMDC
sed = MMDC().sed.get(ra=186.22691, dec=21.37955, name="4C +21.35")

The interactive SED plot, with time filtering and modeling (needs JavaScript).

Nearby sources

TXS 1221+229, 1.3° away
MS 1221.8+2452, 3.2° away
ON 246, 4.1° away
TXS 1212+171, 5.0° away

Other FSRQs

How to cite

Sahakyan, N., Vardanyan, V., Giommi, P., et al. 2024, AJ, 168, 289, doi:10.3847/1538-3881/ad8231 (arXiv:2410.01207).