BB325BK / GCN565443 / SGR J1745-29 - The GC Magnetar


Ran with T+30 schedule. Bug in gogrb meant it had to be run manually. Nonetheless it ran and data is coming.


The source wasn't a GRB as it turned out - it looks like SGR J1745-29 (i.e. the Galactic center magnetar that's been causing all the hoopla) according to the Circular. The ATEL 5032 gives the Chandra position as:
 RA 17:45:40.19, Dec: -29:00:30.37 (with a 0.3" 1sigma statistical error; not boresight corrected). 

With our observing setup at 1.4 GHz, the scattering disk will be huge, so in all likelihood, the VLBA will resolve out any emission from the magnetar, and we'll see nothing. Apparently, Michael Kramer et al. have measurements of the scattering disk, but haven't published yet. From Nord et al citing Bower 2004 somewhere, the scattering disk of SgrA* is roughly

theta = 1.39 mas * (20cm/1cm)**2 = 556 mas

Our resolution is 5 mas (or maybe 10mas if we flag the longer baselines), so we'll probably be hard pressed to detect anything. Oh well.


Observers Log


Project:        BB325BK
Observer:       Bannister, K.
Project type:   VLBA
Obs filename:   bb325bkcrd.*
Date/Day:       2013AUG05/217
Ants Scheduled: SC HN NL FD LA PT KP OV BR

           Operator is Paul Padilla                                             
           UT1-UTC: 0.05, VClock: 0.020, GPS delta: 2.0                         
     0239  Begin                                                                
0239-0317 *FD MASER is bad, out of observation C133446           TIME   100   38
0239-0317 *OV,BR out of disk space, not in observation           REC    200   76
     0314  HN ends                                                              
     0317  End.                                                                 

Downtime Summary:
   Total downtime : 114 min
   Percentage downtime of observing: 33.3%
   Average downtime per hour : 20.0 min

    Total scheduled observing time (# Antennas): 342 min (9)

    * = Entries where data was affected.
    % = Entries where data may have been affected.
    & = Entries where the site tech was called out.
  WEA = Weather entries.
  MF# = Maintenance form or major downtime category associated with a problem.
  %AD = The percentage of an antenna affected by a problem.
  AMD = Total antenna-minutes downtime for a problem.
 Tsys = System Temperature (TP/SP x Tcal/2)
  ACU = Antenna Control Unit
  FRM = Focus/Rotation Mount
  RFI = Radio Frequency Interference
  VME = Site control computer
   CB = Circuit Breaker
 vclock = Program that compares site clock time to a standard.

Reduction Results

I had a quick look at the calibration source (fringe finder) - there were not finges on it at all. THis isn't surprising, as the fringe finder was Sag Astar and it would have been substantially scattered, which would have washed out the fringes. -- KeithBannister - 2013-08-05
Topic revision: r3 - 2013-09-10, KeithBannister
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