Frankfurt Quasar Monitoring


TXS 0506+056 = MG 0509+0541
Object data

  Cross-Identifications   MG J0509+0541, TXS 0506+056, ZS 0506+056
  QSO B0506+056, RX J0509.3+0541, 0506+056
  2MASS J05092597+0541353, GB6 J0509+0541
  87GB 050645.2+053747, 1FGL J0509.3+0540
  EGR J0509+0550, 1RXS J050927.0+054145
  CGRaBS J0509+0541, MG1 J050927+0541
  WISE J050925.96+054135.3
  Equat. coordinates   RA  05 09 25.9     DE  +05 41 35     (J2000)     
  Constellation   Orion
  Type   BL Lac
  Redshift (2)   z=0.3365
  Distance (3) (4)
  ~1750 Mpc
  Total mag range (mv) (5)   14.23 - 16.1
  Catalog Magnitude (1)   16.00
  Absolute Magnitude (1)   --- MB
  Light Travel-Time (6)   3.78 × 109 yrs
(1) Véron-Cetty & Véron 2006, A&A 455, 776
(2) Paiano et al. (2018)
(3) Luminosity Distance
(4)
Keivani et al. (2018)
(5) FQM / CRTS
(6) NASA/IPAC Extragalactic Database

Finding chart
0506+056_chart_fqm.jpg

Comparison stars

star B V
1 15.143 (0.041) 14.495 (0.037)
2 15.273 (0.083)
14.649 (0.049)
3 15.337 (0.036)
14.926 (0.051)
4 15.583 (0.023) 15.032 (0.055)
5 15.692 (0.023) 15.241 (0.050)
6
16.050 (0.114) 15.364 (0.035)
7
16.227 (0.095) 15.824 (0.056)
comparison stars from APASS (DR6)

Colour chart
0506+056_color_fqm.jpg
Credit: DSS2  /  Size 14´x 14´ /  Chart by S. Karge
Light curve
0506+056_lc2107_fqm.jpg

Notes
TXS 0506+056 = MG 0509+0541 is a variable BL Lac object in Orion, roughly 4° W of Bellatrix (Gam Ori). The designation TXS 0506+056 refers to the Texas Survey of Radiosources (TXS), where this object was discovered as a radio source in the period 1975-1981.
The other designation, MG 0509+0541, stands for the MIT-Green Bank 5 GHz Survey (MG). During this radio survey the object was not only detected as well in 1981-82, but the stellar optical counterpart was identified on POSS plates with a magnitude of B=16.0 and R=15.5, respectively.
Today,
TXS 0506+056 is classified as a BL Lac object due to its (nearly) featureless spectrum. It took until 2018, when the first redshift could be determined based on very weak emission lines, detected with the 10.4-metre Gran Telescopio Canarias.

TXS 0506+056 attracted attention in September 2017, when a high-energy neutrino was detected
by IceCube, designated IceCube-170922A. The arrival direction of this 290 TeV neutrino (!) was
consistent with the location of gamma-ray blazar
TXS 0506+056 = MG 0509+0541, observed to be
in a flaring state (see light curve above) with enhanced gamma-ray activity in the GeV range.


As for most BL Lac objects, this source was found to be rapidly variable in the optical by nearly 2 magnitudes, ranging between 14.2 - 16.1 mag. During bright state, visual observers may observe this blazar with telescopes of 8- to 10-inch of aperture. The object appears stellar even with large apertures.
CCD observers, as well as visual observers, shall use the comparison stars given above.

____________

TXS 0506+056 is located in eastern Orion, only about 4° W of Bellatrix (Gamma Ori). The constellation Orion is well known for its spectacular nebula landscapes, like the Great Orion Nebula M42/43 (12° SE), the Horse Head Nebula B33/IC 434 (11° SE) and the Flame Nebula NGC 2024 (11° SE), just to mention the most popular ones.

A more challenging deep sky object is another quasar, PKS 0405-12, a bright 14-mag stellar object at a distance of more than 5×109 light-years, located some 23° SW in Eridanus.



Literature
Amirkhanyan, V.R., Gorshkov, A.G., et al. 1992, SvA, 36, 115; Complete Sample of Radio Sources at 3.9, 4.8,
     7.5, and 11.2 GHz from the Zelenchuk Survey.
Beasley, A.J., Gordon, D., et al. 2002, ApJS, 141, 13; The VLBA Calibrator Survey - VCS1.
Chavushyan, V., Mujica, R., et al. 2001, Arep, 45, 79; Radio and Optical Spectra of Objects from Two Complete
     Samples of Radio Sources.
Douglas, J.N., Bash, F.N. et al. 1996, AJ 111, 1945; The Texas Survey of Radio Sources Covering -35.5 degrees
     < declination < 71.5 degrees at 365 MHz.
Halpern, J.P., Eracleous, M., Mattox, J.R. 2003, AJ, 125, 572; Redshifts of Candidate Gamma-Ray Blazars.
Karge, S.; Helle Quasare für 8- bis 10-Zoll Teleskope. Ein Beobachtungsführer zur visuellen Beobachtung von
     Quasaren und BL Lacertae Objekten; Frankfurt 2005.
Keivani, A., et al. 2018, ApJ 864, 84; A Multimessenger Picture of the Flaring Blazar TXS 0506+056: Implications
     for High-energy Neutrino Emission and Cosmic-Ray Acceleration.
Lawrence, C.R., Bennett, C.L., et al. 1986, ApJS, 61, 105; 5 GHz Radio Structure and Optical Identifications of
     Sources from the MG Survey. II - Maps and Finding Charts.
Paiano, S., et al. 2018, ApJ 854L, 32P; The Redshift of the BL Lac Object TXS 0506+056.
The IceCube Collaboration et al. 2018, Science 361, eeat1378; Multimessenger Observations of a Flaring Blazar
     Coincident with High-Energy Neutrino IceCube-170922A.
Véron-Cetty, M.-P., Véron, P. 2001, A&A 374, 92; A Catalogue of Quasars and Active Nuclei: 10th edition.
Véron-Cetty, M.-P., Véron, P. 2003, A&A 412, 399; A Catalogue of Quasars and Active Nuclei: 11th edition.
Véron-Cetty, M.-P., Véron, P. 2006, A&A 455, 776; A Catalogue of Quasars and Active Nuclei: 12th edition.
Véron-Cetty, M.-P., Véron, P. 2010, A&A 518, 10; A Catalogue of Quasars and Active Nuclei: 13th edition.



© Stefan Karge  /  last obs. 2021-07-21






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