50 μas resolution VLBI images of AGN's at λ3 mm Rantakyrö, F. T.; L.B. Båå th; Backer, D. C. ...
Astronomy & astrophysics. Supplement series,
09/1998, Letnik:
131, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We present 15 images from the global mm-VLBI sessions in 1990 April at 100 GHz and 1993 April at 86 GHz. These observations probe the central engines of the 16 observed AGN's with up to 50 μas ...resolution. Among other sources previously observed with λ3 mm VLBI we present the first λ3 mm maps of 0735+178, 0748+126, 1055+018, 2145+067, and CTA 102, in total we have been able to image 13 out of the 16 observed sources. 6 out of the 13 imaged sources observed exhibit curvature and rapid structural changes, although the low dynamic range in two thirds of the maps limits the detection of weak features. Most of the sources have unresolved cores even at this high resolution. There is substantial evidence that the observed sources can be grouped into two general groups: A misaligned population with parsec scale jets in the form of low pitch helices and an aligned population with straight jets with small changes in PA due to intrinsic bends.
We present 15 images from the global mm-VLBI sessions in 1990 April at 100 GHz and 1993 April at 86 GHz. These observations probe the central engines of the 16 observed AGN's with up to 50 mu as ...resolution. Among other sources previously observed with lambda 3 mm VLBI we present the first lambda 3 mm maps of 0735+178, 0748+126, 1055+018, 2145+067, and CTA102, in total we have been able to image 13 out of the 16 observed sources. 6 out of the 13 imaged sources observed exhibit curvature and rapid structural changes, although the low dynamic range in two thirds of the maps limits the detection of weak features. Most of the sources have unresolved cores even at this high resolution. There is substantial evidence that the observed sources can be grouped into two general groups: A misaligned population with parsec scale jets in the form of low pitch helices and an aligned population with straight jets with small changes in PA due to intrinsic bends.
A 3mm heterodyne imaging array Erickson, N. R.; Goldsmith, P. F.; Predmore, C. R. ...
1987 Twelth International Conference on Infrared and Millimeter Waves,
1987-Dec.
Conference Proceeding
A heterodyne imaging array is under construction to tune the 95-115 GHz range with a 3×5 array. The mixers will use Schottky diodes operated at 20 K with integrated HEMT IF amplifiers. Image sideband ...rejection is done with a quasi-optical filter which terminates the image at 20 K. Polarization interleaving is used to minimize the array size on the sky.
3mm Continuous Comparision Radiometer Predmore, C. R.; Erickson, N. R.; Huguenin, G. R. ...
1982 12th European Microwave Conference,
1982-Sept.
Conference Proceeding
A 3mm wavelength dual-beam radiometer utilizing quasi-optics and Schottky diode mixers has been developed at the Five College Radio Astronomy Observatory. This cryogenic system eliminates the need ...for mechanical beam or load switching, continuously subracting out atmospheric effecrs, and gives a root mean-square (rms) sensitivity of .025 K in 1 sec.
A Cooled Schottky-Diode Mixer for 75-120 GHz Raisanen, Antti V.; Predmore, C. Read; Parrish, Peter T. ...
1980 10th European Microwave Conference,
1980-Sept.
Conference Proceeding
A cryogenic, ultra low noise mixer has been designed and built at the Five College Radio Astronomy Observatory. New details of this mixer include improved waveguide, backshort, RF-filter and ...IF-matching and bias circuit designs. The mixer works evenly at frequencies 75-120 GHz. This mixer is used in a cooled receiver (15 K) where LO is coupled by an adjustable ring-filter and the mixer is followed by a 4.5-5.0 GHz IF system of TIF = 24 K. For the receiver we measured Trec, DSB = 140 K at fLO = 110 GHz when the LO power was only 30 μW. This result implies a mixer noise temperature of TM, DSB < 60 K.
PDF
