Status of VLBI data analysis
with AIPS
Hiroshi Imai (Kagoshima University)• Status of AIPS

• Calibration in AIPS
• Automatic pipeline for AIPS
• Future prospective

The greatest astrometricaccuracy obtained with AIPS
~10 μaswith VLBA
+ phase referencing+ astrometric calibration
For IC10 H2O masers(Brunthaler et al. 2003)
For W3 (OH) H2O masers(Hachisuka et al. 2004)
Annual parallax of an H2O
maser spot at 2.1 kpc(Hachisuka et al. 2004)

The movie of an SiO maser source
Not only entertainment!

 TX Cam(Diamond &Kemball 2003)
 75 image cubes A graduate student
has created 2 imagecubes per week.
 (I, Q, U, V)
image cubes
 Other sources
 R Cas, S Per
 Orion KL, Cep A
 NGC4258
 W43A, .....

What is necessary in VLBI data
analysis more?
Accurate and reliable data calibration
Complex gain factor (amplitude & phase, delay, rate) Antenna gain (Tsys, Ae, τ0) Systematic delays (instrument, atmosphere, geometry)μas-level astrometry may be achievable with AIPS.
 100μ Fast (automatic) data analysis
 Full calibration >> full imaging >> full image analysis
 Automatic data flagging
 A-few-day mapping is achievable with AIPS.

 Archiving the analyzed data
 AIPS plots, history, calibration tables, ....

(Not available now, in construction)

Calibration with AIPS Necessary items for calibration
Observation log
Status and valid time range of each station
Azimuth-elevation data of telescopes

Tsys data from VERA stations (every 30-60s)(automatically shipped to mtksp1)
Antenna gain information (Ae/2k~constant)
Delay information ofthe VERA dual-beam system(every 10s)
(automatically shipped to mtksp1)

Calibration with AIPS
AIPS extension tables (SN, TY, GC)

are attached in FITS files (by Suda).
No shipping calibration files
Applying only “APCAL”.
Caution the tables from multiple FITS files.

Data reduction recipe will be published.
Station coordinate will be maintained byVERA correlation operation team.
Caution the coordinates in data

ΔD~30 cm).
recently released (ΔCurrent VERA astrometricresults with AIPS QSO-QSO pair: 3C345-NRAO512(Inomata’s presentation, sub-mas astrometry)

Current VERA astrometricresults with AIPSQSO-maser pairs
Dual-beam focussing success: ρOph East -- J1625-2527 (Nakashima’s poster)
Mon R2 -- J0607-0834 (Hirota’s poster)W3(OH) -- J0244+6228 (Kameya’s presentation)
W49N-- OH43.8 (Honma’s presentation, not with AIPS)

Dual-beam focussing failure:W51M -- 2 reference sources (Kan-ya’s poster)Many other sources
Due to poor (u, v, w) accuracy
Due to weak emission of reference sources
Due to missing atmospheric delay information

Current VERA astronomicalresults with AIPS Maps of H2O masers
 Full mapping (scanning for ~8 hours):

W3(OH), Orion KL, VY CMa, ρOph East,W51 North/Main/South/West, IRAS19312+1950,W75N,
S140, ... (see posters and presentations) Snap-shot mapping successful
 scanning for ~1 hours, observing for ~4 hours
 with 3 or 6 baselines

 SiO masers (v=1 &2, J=1--0)(Shimizu’s poster) Phase calibration of v=1 data with v=2 data Cotinuum sources: Mainly fringe finding and phase-calibrating
 Calibrator mapping (Nakagawa’s poster) Scientific result: Cyg X-3 (Kim’s presentation)

Automatic pipeline for AIPS Fundamental(continuum)＋advanced(maser) Wide-field imagecube synthesis
and analysis
 Pipeline available(contact to Imai)Fundamental functions in the pipelines
 Automatic processing
 Fringe fitting Self-calibratiion

 Creating temporary

analyzed results Plots (PostScript files)
 Messages (text files)
 History (text files)

 Creating archival data Calibration (extension)tables (CL, SN, FG, TY, GC, ....)
 Trial & final images

Advanced functions in the pipelinesWide-field image-cube synthesis+analysisImage statistics(rms noise,peak intensity)
Rough to fineimage cubes
“SAD”≒“CLUMP FIND”(Gaussian fitting)Wide-field image synthesis with the pipelines
W51North/West H2O masers(Kan-ya’s poster) 1-day calibration
 1 week

mapping&analysis
 ~500 spectral channels
 4096x4096 grids

x 5 fields inrough mapping Dummy spots may be

still contaminating.
 4-station data arenecessary.
 Previous working
efforts for 1 monthFuture prospective
 Estimating unknown

zenith atmospheric excess path delays
 LISTR >>> fitting >>> CLCOR (OPCODE’ATMO’) Using GPS data

 Automatic bad-data flagging
 Flag information from the scheduling program An automatic log creator for each station
 Automatic bad-visibility flagging in AIPS Semi-full automatic data analysis
Analyzing cross-power spectra and images
Analyzing gaussian fitting results Pipeline know-how will be transported tothe new VERA analysis program.