S

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Space VLBI
Sándor Frey FÖMI Satellite Geodetic
Observatory P.O. Box 546, H-1373 Budapest,
Hungary frey_at_sgo.fomi.hu http//www.sgo.fomi.hu/v
lbi/
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Space
Very Long Baseline Interfero- metry
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SVLBI in principle ground-space baseline
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VSOP (VLBI Space Observatory Programme)
ISAS (Japan)
HALCA start February 12, 1997 (new M-V rocket)
8-m parabolic antenna on board HALCA observing
frequencies 1.6 and 5 GHz recording data rate
128 Mbps bandwidth 32 MHz orbital period 6.3
h 21 400km (apogee) 560 km (perigee) baselines
up to 30 000 km
http//www.vsop.isas.ac.jp/
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Highly Advanced Laboratory for Communications
and Astronomy
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Usuda 64 m
a truly global VLBI gt40 ground radio
telescopes from all over the world
5 ground tracking stations (USA, Japan,
Australia, Spain)
Usuda 10 m
3 correlators (USA, Canada, Japan)
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• VSOP scientific program
• General Observing Time (50 of operational time)
• open for the scientific community via
  peer-reviewed proposals
• (deadlines now coincide with ground VLBI
  deadlines,
• 3 times per year)
• a few declared key science programs
• blazars
• high brightness temperature / intra-day
  variability
• jet motions (3C 273, 3C 279 and 3C 345)
• key sources (NGC 4258, Centaurus A and Virgo A)
• nearby AGN
• absorption in AGN
• stars

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• VSOP scientific program (cont.)
• VSOP Survey Program (25)
• led by the mission at ISAS
• coordinated by the international Survey Working
  Group
• 200 brightest, pre-selected AGN to be imaged at
  5 GHz
• limited ground resources (typically 3-5 GRTs)
• mainly S2 recording extractions from GOT
  experiments
• homogeneous information on sub-mas structures,
• for statistical studies
• data base will be publicly available

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Fomalont et al. (2000), ApJS 131, 95
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Selected VSOP scientific results Selection
criteria for inclusion in this talk
interesting
important
spectacular
certain people in this room are involved...
including myself
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Large collections of various VSOP-related
papers "VSOP Results and the Future of Space
VLBI", Proc. COSPAR Symposium, Nagoya, Japan,
July 1998, eds. Hirabayashi H., Preston R.A.
Gurvits L.I., Advances in Space Research 26, No.
4 (2000) "Astrophysical Phenomena Revealed by
Space VLBI", Proc. VSOP Symposium, Sagamihara,
Japan, January 2000, eds. Hirabayashi H., Edwards
P.G. Murphy D.W., ISAS (2000) VSOP Special
Issue, Publications of the Astronomical Society
of Japan 52, No. 6 (2000)
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Orion-KL water maser outburst the only VSOP
image _at_ 22 GHz peak 1.3 ? 105
Jy/beam elongated structure VLBA
monitoring overlapping maser spots?
Kobayashi et al. 2000, VSOP Symp., 109
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1519273 at 1.6 GHz the first-ever SVLBI image,
June 1997
VLBA VLA
HALCA added
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M87 (Virgo A)
VLA
No proper motion is detected in 1.5 years VSOP
monitoring _at_ 5 GHz (in contrast with superluminal
motion at VLA HST scales)
Junor et al. 2000, VSOP Symp., 13
VSOP 1.6 GHz
Reid 1998, Science 281, 1815
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the impact of improved angular resolution
transverse jet structure resolved edge-brighteni
ng regular, oscillating patterns instabilities
propagating along the jet
Lobanov et al. 2000, AdSpR 26, 669 Lobanov et al.
2000, VSOP Symp., 239
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1928734 (z0.3) monitoring
core
Murphy et al. 2000, VSOP Symp., 47
1997 Aug 22 1997 Dec 16
1998 Apr 29
1998 Jul 9
circumpolar superluminal quasar, ideal for VSOP
monitoring substantial changes near the core on
months time scale a variety of different
phenomena, inconsistent with a simple straight
jet model
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first Chandra target, thought to be unresolved
? luminous kpc-scale X-ray jet 1999
Aug coordinated VSOP and Chandra
observations radio (ATCA) vs. X-ray jet
structure striking coincidence and radio jet
bending polarization E-vectors perpendicular
to the jet until X-rays detected to W, then
begin to be parallel with the jet simple
synchrotron model is not sufficient to explain
all data (incl. HST optical) VSOP/VLBI
mas-scale jet direction, 11c superluminal
motion
0637752 quasar (z0.65)
VSOP 5 GHz
Australia Telescope Compact Array (8.4 GHz,
contours)
Chandra X-ray (color)
Lovell et al. 2000, VSOP Symp., 215
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The most distant radio-loud quasars (zgt3)
2215020 (z3.57) VLBAEVN ground-only _at_ 1.6 GHz
J4
baselines to HALCA included resolved jet
cross-section ? 4109 Mo estimated cental black
hole mass
Lobanov et al. 2001, ApJ 547, 714
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1351-018 (z3.71) earlier VLBA _at_ 5 GHz Frey et
al. 1997, AA 325, 511
SVLBI _at_ 5 GHz dramatic change in jet direction
between sub-mas and 10 mas scale
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VSOP phase-referencing HALCA cannot switch
rapidly between sources ...
but 1308326 / 1308328 quasar pair (14.3
arcmin separation) HALCA primary beam 26 arcmin
_at_ 5 GHz VLBA Effelsberg switched between the
sources phase reference mapping, relative
astrometry with VSOP 1342662 / 1342663
quasar pair (4.8 arcsec separation) sources lie
within the primary beam of HALCA VLBA
antennas it works! satellite orbit
reconstruction error 3 m
Porcas et al. 2000, VSOP Symp., 245
Guirado et al. 2001, AA 371, 766
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VSOP polarization HALCA receives only
left-circularly polarized radiation ...
but despite the other complications (lower
sensitivity, difficult polarization calibration),
it is technically feasible to obtain
high-resolution polarization images test
observations with the VLBA and VLA _at_ 1.6 and 5
GHz of sources with sufficiently high correlated
polarized flux density good perspectives for
next-generation SVLBI
Kemball et al. 2000, PASJ 52, 1055
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0235164 a highly variable BL
Lac VSOP _at_ 5 GHz the highest brightness temperat
ure measured with VSOP TB gt 5.8 ? 1013 K
Frey et al. 2000, PASJ 52, 975
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The Pearson-Readhead Survey from Space
HALCA VLBA EVN imaging of 27 sources
from the P-R survey (Pearson Readhead
1988, ApJ 328, 114) original sample 65
sources (?gt35?, S5gt1.3 Jy, ?b?gt10?)
sub-sample for SVLBI Scorrgt0.4 Jy on ground
baseliness
2200420 (BL Lac) _at_ 5 GHz ground-only
SVLBI
Lister et al. 2001, ApJ 554, 948
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The Pearson-Readhead Survey from Space results
imaging true dynamic range typically 301 1001
Lister et al. 2001, ApJ 554, 948
source properties correlation analysis
(morphology, IDV, core dominance, optical
polarization, emission line equivalent width,
etc.) ? support to the beaming model
Lister et al. 2001, ApJ 554, 964
brightness temperature distribution a
significant proportion has TBgt1012 K relation
between high TB and IDV activity
Tingay et al. 2001, ApJ 549, L55
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The VSOP Survey Program preliminary results
sample among 402 sources (S5gt0.95 Jy, ?gt0.45,
?b?gt10?), 289 sources sufficiently compact for
VSOP _at_ 5 GHz half of the data sets reduced,
even more observed
rest-frame brightness temperature (TB)
distribution shows apparent violation of inverse
Compton limit (1012 K) ? relativistic beaming
is common
Hirabayashi et al. 2000, PASJ 52, 997
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VSOP proposals, observations and data reduction

• open proposals deadlines 1 February, 1 June
  1 October
• all info at www.vsop.isas.ac.jp/obs/AO.html
• Proposers Guide, cumulative observation list,
  etc.
• severe observing constraints (on-board
  equipment, tracking,
• ground network availability, etc.)
• assistance user software, sample (u,v)-coverages

• schedule is done by the VSOP mission

• data reduction AIPS and Difmap are available
• calibration information on the VSOP web

• general info e-mail newsletter (also on the
  web, with some
• delay)

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Next generation Space VLBI
SVLBI technically feasible, scientifically
interesting ? next generation satellites with
improved performance (sensitivity, frequency
coverage, etc.)

• 10? increase over VSOP sensitivity
• 20-40 000 km apogee
• 10-m antenna
• frequencies (1.6?), 5(8), 22, 43, (86?) GHz
• data rate 1 (2?) Gbit/s
• launch vehicle modified M-V
• launch 2008 ?

VSOP-2 is being proposed at ISAS in Japan
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ARISE (Advanced Radio Interferometry between
Space and Earth)

• 5? ground-based resolution
• (max. 10-20 ?as)
• 50? VSOP sensitivity
• 40-50 000 km apogee
• 25-m inflatable antenna
• frequencies 5(8), 22, 43, 86 GHz
• single-dish 60 GHz
• data rate 8 Gbit/s
• lifetime ? 3 years
• launch 2008 ?

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http//arise.jpl.nasa.gov/