Figure 1. Self-calibrated images of 4C 39.25 (left) and 0945+408 (right) at 22 (upper) and 43 GHz (lower). The beams are shown in the lower left corner. The contour levels start from 3 times the r.m.s level and increase by a factor of 2.
Figure 2. visibility phases of 4C 39.25 along MIZ baselines at 43 GHz before (dots) and after (crosses) applying FPT from 22 GHz; Each point on the plot corresponds to a temporal average of 10 seconds.
Figure 3. Fractional flux recovery as functions of solution intervals for phase self-calibration, for the visibility phases before (dot-dashed line) and after (dashed line) applying FPT. The coherence time corresponds to a fractional flux recovery of 0.6.
Figure 4. SFPRed visibility phases of 0945+408 on all baselines at 43 GHz with a temporal average of 60s. The numbers in the parentheses in each panel correspond to the station codes of each antenna used by the correlator.
Figure 5. KaVA SFPRed map of 0945+408 at 43 GHz. The beam is 1.28 × 0.70 mas with a position angle of −71°. The grid serves as a visual guide for the offset of the peak of brightness from the center of the map.
Figure 6. Comparison of astrometric results from the SFPR analysis on the KaVA (squares) and KVN (circles) data with point source models (open symbols), structural models in Section 3.1 (half-filled symbols), and structual models from Niinuma et al. 2014 for 4C 39.25 (filled symbols).
References
- Algaba, J.-C., Zhao, G.-Y., Lee, S.-S., et al. 2015, Interferometric Monitoring of Gamma-Ray Bright Active Galactic Nuclei II: Frequency Phase Transfer, JKAS, 48, 237
- Beasley, A. J., & Conway, J. E. 1995, VLBI Phase-Referencing, Very Long Baseline Interferometry and the VLBA, 82, 327
- Blandford, R. D., & Konigl, A. 1979, Relativistic Jets as Compact Radio Sources, ApJ, 232, 34 https://doi.org/10.1086/157262
-
Dodson, R., Rioja, M. J., Jung, T., et al. 2014, Astrometrically Registered Simultaneous Observations of the 22 GHz
$H_2O$ and 43 GHz SiO Masers toward R Leonis Minoris Using KVN and Source/Frequency Phase Referencing, AJ, 148, 97 https://doi.org/10.1088/0004-6256/148/5/97 - Dodson, R., Rioja, M. J., Jung, T., et al. 2017, The Science Case for Simultaneous mm-Wavelength Receivers in Radio Astronomy, NewAR, 79, 85 https://doi.org/10.1016/j.newar.2017.09.003
-
Dodson, R., Rioja, M., Bujarrabal, V., et al. 2018, Registration of
$H_2O$ and SiO Masers in the Calabash Nebula to Confirm the Planetary Nebula Paradigm, MNRAS, 476, 520 https://doi.org/10.1093/mnras/sty239 - Han, S.-T., Lee, J.-W., Kang, J., et al. 2008, Millimeter-Wave Receiver Optics for Korean VLBI Network, IJIMW, 29, 69
- Han, S.-T., Lee, J.-W., Kang, J., et al. 2013, Korean VLBI Network Receiver Optics for Simultaneous Multifrequency Observation: Evaluation, PASP, 125, 539 https://doi.org/10.1086/671125
-
Jiang, W., Shen, Z., Jiang, D., et al. 2018, VLBI Imaging of M81* at
$\lambda$ = 3.4 mm with Source-Frequency Phase-Referencing, ApJL, 853, 14 https://doi.org/10.3847/1538-4357/aa93df - Jung, T., Sohn, B. W., Kobayashi, H., et al. 2011, First Simultaneous Dual-Frequency Phase Referencing VLBI Observation with VERA, PASJ, 63, 375 https://doi.org/10.1093/pasj/63.2.375
- Jung, T., Dodson, R., Han, S.-T., et al. 2015, Measuring the Core Shift Effect in AGN Jets with the Extended Korean VLBI Network, JKAS, 48, 277
- Jung, T., et al. 2019, JKAS, in preperation.
- Kino, M., Niinuma, K., Zhao, G.-Y., et al. 2015, Key Science Observations of AGNs with KaVA Array, PKAS, 30, 633
- Lee, S.-S., Oh, C. S., Roh, D. G., et al. 2015a, A New Hardware Correlator in Korea: Performance Evaluation Using KVN Observations, JKAS, 48, 125
- Lee, S.-S., Byun, D.-Y., Oh, C. S., et al. 2015b, Amplitude Correction Factors of Korean VLBI Network Observations, JKAS, 48, 229
- Lister, M. L., Aller, M. F., Aller, H. D., et al. 2013, MOJAVE. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in Active Galactic Nuclei, AJ, 146, 120 https://doi.org/10.1088/0004-6256/146/5/120
- Middelberg, E., Roy, A. L., Walker, R. C., & Falcke, H. 2005, VLBI Observations ofWeak Sources Using Fast Frequency Switching, A&A, 433, 897 https://doi.org/10.1051/0004-6361:20042078
- Niinuma, K., Lee, S.-S., Kino, M., et al. 2014, VLBI Observations of Bright AGN Jets with the KVN and VERA Array (KaVA): Evaluation of Imaging Capability, PASJ 66, 103 https://doi.org/10.1093/pasj/psu104
- Rioja, M., & Dodson, R. 2011, High-Precision Astrometric Millimeter Very Long Baseline Interferometry Using a New Method for Atmospheric Calibration, AJ, 141, 114 https://doi.org/10.1088/0004-6256/141/4/114
- Rioja, M., Dodson, R., Asaki, Y., et al. 2012, The Impact of Frequency Standards on Coherence in VLBI at the Highest Frequencies, AJ, 144, 121 https://doi.org/10.1088/0004-6256/144/4/121
- Rioja, M., Dodson, R., Jung, T. H., et al., 2014, Verification of the Astrometric Performance of the Korean VLBI Network, Using Comparative SFPR Studies with the VLBA at 14/7 mm, AJ, 148, 84 https://doi.org/10.1088/0004-6256/148/5/84
- Rioja, M. J., Dodson, R., Jung, T., & Sohn, B. W. 2015, The Power of Simultaneous Multifrequency Observations for mm-VLBI: Astrometry up to 130 GHz with the KVN, AJ, 150, 202 https://doi.org/10.1088/0004-6256/150/6/202
-
Yoon, D.-H., Cho, S.-H., Yun, Y., et al. 2018, Astrometrically Registered Maps of
$H_2O$ and SiO Masers toward VX Sagittarii, Nature Communications, 9, 2534 https://doi.org/10.1038/s41467-018-04767-8 - Zhao, G.-Y., Algaba, J. C., Lee, S. S., et al. 2018, The Power of Simultaneous Multi-Frequency Observations for mm-VLBI: Beyond Frequency Phase Transfer, AJ, 155, 26
- Zhao, G.-Y., Jung, T., Dodson, R., Rioja, M., & Sohn, B. W. 2015, KVN Source-Frequency Phase-Referencing Observation of 3c 66A and 3c 66B, PKAS, 30, 629