Sensitivity Mark Wieringa Australia Telescope CSIRO Astronomy and Space Science.
CABB Observations Preparations and Observing Mark Wieringa.
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Transcript of CABB Observations Preparations and Observing Mark Wieringa.
Preparing for the observations
• Plan Frequencies• 20/13 – not yet
• aiming for summed L+S or single 2 GHz band covering both
• 6cm – 5500 MHz
• 3cm – 9000 MHz
• mm – more freedom – two frequencies no more than 6 GHz apart• At 7mm, both frequencies need to be on same side of 41 GHz
• Decide on single/dual freq
• No zoom bands yet, no choice in channel width yet• In progress: 4 zooms per band; 64 MHz channels (for NASA & VLBI)
• RFI• Now unavoidable in lower freq bands (e.g. 5100 MHz)
• Trapped modes show up too
• Set tvchan range in CACOR if calibration affected
• Surveys in progress
CABBScheduler
• New web based scheduler• http://www.narrabri.atnf.csiro.au/observing/sched/cabb
• New schedule format, Caobs no longer accepts old schedules
• New scheduler reads old format schedules (and writes new)
• Features• Recognizes calibrators (from cal database)
• Find calibrator near source (search cal)
• Show calibrator database info
• Integrated velocity calculator (for zoom bands)
• Pick sources from your own catalogue
• Global changes
• Recalculate velocities (for different day/time)
• Missing• Command line, @files, move multiple scans
Observing - CAOBS
• CAOBS• Looks the same (mostly)
• Some commands missing (e.g., set atten/coarse, disable auto)• Only mm attenuators remain
• Some commands added (e.g., corr dcal a)• Alternative to typing in cacor window
• Reads only new format schedules
• CACAL • Is no more..
• Calibration is done via CABB commands
• CAMON• Obsolete – use MoniCA gui client instead
• atmon – terminal based MoniCA client• Available for testing, still under development
Observing – VNC based
Caobs and cacor run in separate vncservers (on xbones and caccc0)
A baseline solution at left
Note: delay on cals <0.02ns
Can see atmosphere on CA06
Observing – Vis
• Assistance• Available – needs more ‘tuning’ for CABB
• Obsolete checks removed, no new ones added (yet)
• May be replaced by an ATCA TOAD in few months time
• Vis• Available, working as normal
• May change behind the scenes
• SPD• Available, some new commands (that may change..)
• [no]acs – turn auto correlation display on/off
• [no]ccs – turn cross correlation display on/off
• Off/On F1 – don’t show/show Freq 1 correlations
Observing – Setup/Calibration
• New CABB attenuators may need attention at new frequencies• atts on / off in cacor
• look at ‘Samplers’ tab in CACOR to check for rms values near 20
• Calibration now happens in CABB• CACOR Commands:
• Delay calibration: dcal [a]• “dcal” show calculated delays, “dcal a” applies the delay correction
• Phase calibration: pcal [a]• Amplitude calibration: acal flux1 [flux2] [a]
• Supply source fluxdensity for Freq1 [and Freq2]
Observing – Setup/Calibration
• Calibration through CAOBS• CAOBS passes commands on to CACOR
• Prefix with corr, e.g. CAOBS> corr dcal a• May need to do dcal twice if delays are off a long way (>30ns)
• Detailed numbers only visible in CACOR window• Error messages do come back to caobs• When on 1934-638:
• CAOBS> corr acal a
• This will fill in the flux for 1934 before sending cmd to correlator
• Current fit runs from 1GHz to 28 GHz, with CABB 1934 is strong enough at 7mm too (fit will be extended)
• A cacal command may appear in caobs
• Tip• Detach unused antennas to avoid using them in the calibration