1. Simulations of the tracking station
Following these success of VSOP, science targets of VSOP-2 approach the central region of AGN.
studies of accretion disks and jets in AGN
studies of non-thermal emission from YSOs
And we revenge the maser observations.
the highest resolution studies of Galactic masers and extragalactic megamasers.
And the capability of other observations have been discussing.

2. Astro-G link coverage simulation by FAKESAT (1/2)
1 tracking station coverage is % which is highly depends on small-omega value.
Most possible 3 tracking station network (Usuda, Greenbank and Yebes), gives, % coverage.
Missing the tracking station in southern hemisphere (SH), drops the coverage to 50 % time. If we have 3 tracking stations including one SH tracking station, coverage will be %, and we can have ideal location of 3 tracking station (2 northern, 1 southern), we can have 80 % coverage for all time.

3. Astro-G link coverage simulation by FAKESAT (2/2)
If we can use the Usuda tracking pass with the elevation angle of more than 10, or 15 degree, (because of its low margin of link budget). Coverage is less than 40 % in some period. (If we can use Tid, the results may be changed.)
GTO (higher apogee height) gives better coverage. But the link budget become worse.
El limit is critical to decide the coverage, when apogee is in southern hemisphere, if we have only northern tracking station.
Tracking station in southern hemisphere is required if we need to keep more then % observing time.

4. Simulation conditions
Nominal orbit
Apogee 1000km, Perigee 25000km, I = 31 deg
Elevation limit Use > 5, 10, 15 for Usuda and
> 5 deg (for other tracking station)
GTO
Apogee 1000km , Perigee 36000km, I = 31 deg
Elevation limit Use > 10, 15 for Usuda and
> 10 deg (for other tracking station)
Calculate (small-omega) – (link coverage in 14 days) dependence
Assume Usuda, Green Bank, Madrid (Yebes) are basic 3 station
Add one southern hemisphere station from Hartebeesthoek, Tidbinbilla, and Santiago
Value of Small-omega is defined by initial of 14 days

5. Coverage of the single tracking station
Nominal orbit (Apogee: 25,000 km, Perigee: 1,000 km I=31)
Usuda with EL limit of (5, 10, 15 degree)
各局の傾向
Coverage by Usuda, Gbank, Madrid,
Hart, Santiago, Tidbinbira
El limit = 5 deg

6. Coverage by 3 stations Nominal orbit Usuda + Greenband +Madrid
(with changing Usuda El limit)
南半球局の有効性
All EL > 5
All EL > 5
Usuda + Greenbank +
(Southern TS or Madrid)
Usuda + Madrid +
(Southern TS or Greenbank)

7. Four stations Nominal orbit Usuda+Greenbank+Madrid (+ Southern TS)
El > 5 for TS, except for Usuda
Usuda EL < 5
臼田の悪条件はオーストラリア局でカバーできる
Usuda EL < 10
Usuda EL < 15

8. GTO (Geo-stationally orbit Transfer Orbit)
(Apogee: 36,000 km,
Perigee: 1,000 km I=31)
Red: Normal, U+G+M (EL > 5)
GTOだと可視時間は増加、問題はリンクバジェット
Red: Normal, U+G+M (EL > 5)
Red: Normal, U+G+M (EL > 5)
GTO:
Usuda EL < 5
GTO:
Usuda EL < 15

9. GTO Usuda EL>10,15deg Others EL>10deg
Red: Normal, U+G+M (EL > 5)
4局あればEL>10degでもなんとか補える・・・？
GTO:
Usuda EL < 10
GTO:
Usuda EL < 15