Preliminary Report of the Global 3mm-VLBI Session May 4 - 8, 2006 
===================================================================

General: the following stations have observed:
         EB, PV, On, Mh, VLBA(8)

         Shortly before the start of the session the H-maser
         on Plateau de Bure (PdB) died, and PdB could not participate
         in the this session. A new, more modern and reliable maser
         has been ordered already half a year ago and hopefully
         will be available in autumn 2006.

Note:   Except Onsala and PdB, all stations observed in dual polarization.
        On, PdB observed in LCP.


Detailed Station reports:
-------------------------

Effelsberg: excellent weather conditions during the whole session,
            clear sky, low humidity (22- 50%). Atmospheric opacity 0.06 - 0.15,
            with lower values during night time.
            During day time sun causing strong temperature gradients on
            the telescope structure, which affects pointing and focus.
            

Pico Veleta: May 4: bad weather (fog and thick clouds) at the beginning
                    hard to see any source, no data during 19:00-21:00
                    and 23:00 - 00:15, 11 scans lost on 3C273B/3C279
                    
             May 5: acceptable weather during night hours.
                    Scans #032 lost, #074 and #078 only LCP because of B100 receiver problem
                    Bad weather from 10:15 to 13:13 and stopped from 13:30 to 20:15. 
                    Bad weather again till 24:00. CTA102, MANOLIS and OJ287 affected.

             May 6: Scans 173 to 177 lost because of rain, scans 194 and 195 as well, 
                    RSOPH and 1741-038 affected.
                     ~2 UT, improved weather, resume observing, Tsys = 100 K
                    From 16:33 to 19:18 bad conditions or stopped. 3C273b and 3C274 affected.
             
             May 7: Good weather most of the time. From  05:15 to 07:15 and from 11:15 to 
                    12:00 stopped due to technical problems. NRAO150 and BLLAC affected.

             May 8: very good weather and no problems till end of schedule, Tsys = 90 K at 6 UT.


Polarization Calibration: After the VLBI part finished, PV continued observing the
                         polarization of the VLBI sources at 3mm. This should facilitate
                         a proper determination of the electric vector position angle (EVPA).


Onsala:      May 4  cloud coverage 10%, no rain, Tsys=700 K
             May 5  cloud coverage 0-20%, no rain, Tsys=500 K
             May 6   0-12 UT, cloud coverage 0-20%, no rain, wind 5-7 m/s, Tsys=330 K
                    12-24 UT, cloud coverage 40-100%, no rain, wind 3-8 m/s, Tsys=1200 K
             May 7   0-10 UT, cloud coverage 10-40%, no rain, wind 6-8 m/s, Tsys=520 K
                    10-23 UT, cloud coverage 0-5%, no rain, wind 3-5 m/s, Tsys=580 K

             May 8  Tsys=715 K

             Rather high Tsys in general. May is not an optimum month for
             mm-observations at OSO.

             Problem with module mpi-0157 (around 22:00, day number 127). 
             Changed to OSOD-045.

Metsahovi:   May 4, start observations under clear sky conditions.
             The session was uneventful :-):-) at Metsahovi: 
             weather was from good to excellent all the time, i.e. no 
             clouds, certainly some high humidity during the nights but 
             days quite low, even below 40%. Both LCP and RCP should have worked, 
             though RCP was significantly less sensitive. 
             In this session new hot-cold TPI measurements were done. This should
             improve the station calibration.



VLBA         waiting for TSMPLOTS, will be made available on /astronomy/may06/c061a
             Downtime Summary, Total downtime : 4038 min
             Percentage downtime of observing: 11.3%

             inspection of weather report via web, showed the following
            
             May 5, noon:      LA thin clouds
                               all other sites clear
             May 5, evening:   LA, NL overcast, other stations ok
             May 6, morning:   no wind, no rain, no gust
                    evening:   MK fog and rain, other stations ok (clear sky for most)
             May 7, noon:      MK rain, other stations ok
                    evening:   MK rain, other stations ok


Summary in terms of experiments:

            GD022A  DODSON      3C273/3C279       no PdB, only very few data from Pico expected
            GD022B  DODSON      CTA102            no PdB, only very few data from Pico expected
            GR026B  RASTORGUEVA OJ287             no PdB, Pico weathered out, Eff ok
            MAHB01  BREMER      RS Oph            no PdB, only data for Eff-PV, some scans lost at PV
            GK035A  KRICHBAUM   3C454.3           no PdB, will depend how good data to Pico are
            GK033C  KRICHBAUM   M87               no PdB, should be ok at the time when Pico observed 
            GA022C  AGUDO       NRAO150           Effelsberg could not observe most of the BLLAC
                                                  scans, slew too long, no pointing, no calibration
                                                  PV should be ok
            MAHE02A ECKART      Sgr A*            no PdB, only one baseline PV-Eff