Frankfurt Quasar Monitoring


PKS 1424+240
Object data

  Cross-Identifications   PG 1424+240, TXS 1424+240, B2 1424+24, OQ+240
  KUV 14247+2401, 7C 1424+2401, QSO B1424+240
  PKS 1424+240, RGB J1427+238, 2E 1424.7+2401
  SDSS J142700.39+234800.0, GB6 B1424+2401
  FBQS J142700.4+234800, RX J1427.0+2348
  0FGL J1427.1+2347, RBS 1395, 1424+240
  Equat. coordinates   RA  14 27 00.5     DE  +23 48 00     (J2000)
  Constellation   Bootes
  Type   BL Lac
  Redshift   z=0.160 (2)  /  z>0.603 (5)
  Distance (2) (3)
  638 Mpc
  Total mag range (mv) (4)   14.0 - 18.39
  Catalog Magnitude (1)   14.28
  Absolute Magnitude (1)   ---
  Light Travel-Time   1.930 × 109 yrs (2)  /  >5.5 × 109 yrs (approx.) (6)
(1) Véron-Cetty & Véron 2006, A&A 455, 776
(2) NASA/IPAC Extragalactic Database
(3) Co-Moving Radial Distance
(4) Literature
(5) Furniss et al. (2013)
(6) Frankfurt Quasar Monitoring


Finding chart
1424+240_chart_fqm.jpg

Comparison stars

star V Rc Ic
C1 13.59 (0.04)
13.20 (0.04)
12.80 (0.04)
C2 13.70 (0.05)
13.32 (0.05)
12.91 (0.04)
C3 15.91 (0.09)
15.57 (0.08)
15.21 (0.08)
comparison stars from Fiorucci et al. 1996, A&AS, 116, 403

Colour chart
1424+240_sdss_fqm.jpg
Credit: SDSS  /  Size 13´× 13´ /  Chart by S. Karge

Light curve
1424+240_lc2301_fqm.jpg

Notes
PKS 1424+240 is a variable stellar object in Bootes, about 1° NE of Arcturus. The designation PKS:1424+240 refers to the Parkes Radio Survey (PKS), where this object was cataloged as a radio source in 1973. PKS 1424+240 was discovered as a radio loud point source by the Ohio Radio Survey (OQ). Independently, it was identified with a blue stellar object by the Palomar-Green Bright Quasar Survey (PG), where this object was initially classified as a white dwarf due to its featureless spectrum. In the 1980s, it was finally identified as an extragalactic object. PKS 1424+240 was classified as a BL Lac object in the 1990s, after X-ray observations were carried out by ROSAT.

Due to the featureless spectrum no accurate redshift has been determined to date. CDS Strasbourg Database, as well as NASA/IPAC Extragalactic Database, published a
(tentativ) redshift of z=0.16 (Aleksić et al. 2011), which is not fully accepted by Véron-Cetty et al. 2001-2010. A recent spectroscopic study found a new redshift lower limit of z>0.6035 (Furniss et al. 2013). This would make PKS 1424+240 the most distant TeV-emitting Blazar ever detected. However, the true distance as well as the absolute luminosity still remain uncertain.

PKS 1424+240 displays large and rapid changes in optical brightness with a total range of about 4 magnitudes. Usually, it is a bright object of about 14 mag. Visual observers need at least an 8- to 10-inch telescope to glimpse this stellar object during bright state. CCD observers, as well as visual observers, shall use the comparison stars given above.
____________

Looking at some interesting objects around PKS 1424+240, we first take a look at RX Boo, a type RR Crb variable some 2° NE, ranging between 8.6-11.3 mag (340d, M6.5-M8).
Another extragalactic variable object is NGC 5548, a well known AGN, some 2.4° to the NW. This type 1 Seyfert galaxy shows a total optical variability ranging between 11.9 mag and 14.3 mag.
Some 12° NNE of PKS 1424+240, bright 14-mag quasar MRK 478 might also attract your interest.
And finally, two other bright 15-mag quasars are located nearby:
MRK 813 can be found about 4° to the south, and PG 1402+261 lies about 5.4° to the west.


Literature
Aleksić, J., et al. 2011, ApJ, 729, 115A; Gamma-ray Excess from a Stacked Sample of High- and Intermediate-
     frequency Peaked Blazars Observed with the MAGIC Telescope.
Condon, J.J., Hicks, P.D., Jauncey, D.L. 1977, AJ, 82, 692; Optical identifications of Parkes sources with flat spectra.
Dixon, R., Kraus, J. 1968, AJ, 73, 381; A High-Sensivity 1415 MHz Survey at North Declinations between 19° and 37°.
Fiorucci, M., Tosti, G. 1996, A&AS, 116, 403; VRI photometry of stars in the fields of 12 BL Lacertae Objects.
Fiorucci, M., Tosti, G. 1996, A&AS, 117, 475; Automatic optical monitoring of 10 Blazars.
Fleming, T.A., Green, R.F., et al. 1993, AJ, 106, 1729; Three new BL Lacertae objects in the Palomar-Green survey.
Furniss, A., Williams, D.A., et al. 2013, arXiv:1304.4859; The firm redshift lower limit of the most distant TeV-
     detected Blazar PKS 1424+240.
Green, R., Schmidt, M., Liebert, J. 1986, ApJS, 61, 305; The Palomar Green Catalogue of Ultraviolet-Excess Stellar
     Objects.
Impey, C.D., Tapia, S. 1988, ApJ, 333, 666; New blazars discovered by polarimetry.
Karge, S.; Helle Quasare für 8- bis 10-Zoll Teleskope. Ein Beobachtungsführer zur visuellen Beobachtung von Quasaren
     und BL Lacertae Objekten; Frankfurt 2005.
Katajainen, S., Takalo, L.O., et al. 2000, A&AS, 143, 357; Tuorla quasar monitoring. I. Observations of 1995-1997.
Mead, A.R.G., Ballard, K.R., et al. 1990, A&AS, 83, 183; Optical and infrared polarimetry and photometry of blazars.
Scarpa, R., Falomo, R. 1995, A&A, 303, 656; Spectral energy distribution of Palomar-Green BL Lacertae objects.
Scarpa, R., Falomo, R. 1997, A&A, 325, 109; Are high polarization quasars and BL Lacertae objects really different?
     A study of the optical spectral properties.
Shimmins, A.J., Bolton, J.G., Wall, J.V. 1975, AuJPA, 34, 63; The Parkes 2700 MHz Survey (Tenth Part): Supplementary
     Catalogue for the Declination zone +4° to +25°.
Steinicke, W.; Beobachtungsliste für helle Quasare; Umkirch 1999.
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.

  


Links:

Landessternwarte Heidelberg

Sloan Digital Sky Survey


© Stefan Karge  /  last obs. 2023-01-18






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