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lbaops:lbascheduling [2019/02/28 15:30]
cormac
lbaops:lbascheduling [2020/02/11 14:32] (current)
cormac
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 Since April 2017 Hobart and Ceduna should normally be scheduled as HOB_DBBC and CDDBBC to use the DBBC, unless otherwise instructed. Since April 2017 Hobart and Ceduna should normally be scheduled as HOB_DBBC and CDDBBC to use the DBBC, unless otherwise instructed.
  
-Tid antennas should usually be scheduled to use the LBA DAS unless otherwise instructed. ​+Tid antennas should usually be scheduled to use the DVP unless otherwise instructed. ​
  
 ===== DAS Setups ===== ===== DAS Setups =====
 Some LBA observatories use the ATNF DAS, which is a digital filter bank. The ATNF observatories (Parkes, ATCA, Mopra) each have  Some LBA observatories use the ATNF DAS, which is a digital filter bank. The ATNF observatories (Parkes, ATCA, Mopra) each have 
-2 DAS installed, while 1 is available at Hobart and Ceduna. The DAS have two independent "​IFPs"​ which sample the +2 DAS installed, while 1 is available at Hobart and Ceduna ​(though they normally use the DBBC). The DAS have two independent "​IFPs"​ which sample the 
 analogue signal and produce up to two digitised channels each, which are then recorded. The two IFPs are generally ​ analogue signal and produce up to two digitised channels each, which are then recorded. The two IFPs are generally ​
 connected to the two polarisations of the receiver but can be set up to record two different frequencies of the same  connected to the two polarisations of the receiver but can be set up to record two different frequencies of the same 
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 Older versions of SCHED will not necessarily produce a correct .vex file for a current observation. Older versions of SCHED will not necessarily produce a correct .vex file for a current observation.
  
-SCHED is installed on linux machines at ATNF (hydra and draco) or+SCHED is installed on linux machines at ATNF (e.g. draco) or
 can be obtained from ftp://​ftp.aoc.nrao.edu/​pub/​sched/​ . can be obtained from ftp://​ftp.aoc.nrao.edu/​pub/​sched/​ .
 Example LBA .key files are distributed with the latest version of SCHED Example LBA .key files are distributed with the latest version of SCHED
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 ==== Frequency setup ==== ==== Frequency setup ====
 +Please prepare your schedule using one of the standard LBA setup files
 +distributed with SCHED ($SCHED/​setups/​lba*). The lba* setup files distributed
 +with SCHED should cover all standard continuum modes. If your schedule requires
 +a non-standard mode or frequency (e.g., for spectral line observations) then
 +please consult with ATNF staff before submitting your schedule.
 +
 The ATCA and Mopra  LO chain generally restricts the frequency selection to 1 MHz steps. For continuum experiments this The ATCA and Mopra  LO chain generally restricts the frequency selection to 1 MHz steps. For continuum experiments this
 should not cause any difficulty (particularly if you use the standard setups!). For spectral line experiments,​ letting ​ should not cause any difficulty (particularly if you use the standard setups!). For spectral line experiments,​ letting ​
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 However, the mixed backends on the LBA, with their often mismatched filters, means that SCHED'​s automated Doppler setting often does not work for LBA experiments. Its use is deprecated, but if used its results should be carefully checked. However, the mixed backends on the LBA, with their often mismatched filters, means that SCHED'​s automated Doppler setting often does not work for LBA experiments. Its use is deprecated, but if used its results should be carefully checked.
 +
 +
 ==== Fringe Finders ​ ====  ==== Fringe Finders ​ ==== 
  
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   *  The array usually needs to be "​re-phased"​. At lower frequencies this may only be every hour or more, but at 20 GHz potentially every 10-20 minutes depending on the array baseline lengths and weather. It is highly recommended you discuss calibration strategies with ATNF LBA support staff. Generally recommendations would be to make sure you regularly observe an appropriate ATCA calibrator source within a few degrees of your target. These sources need to be compact enough that they have close to zero structure phase, have enough flux so the phase spread between the antennas can be quickly determined AND the scan must be long enough to allow the observer to see the phase and run calibration if required. One minute on a compact source with flux density >~ 200 mJy is needed at most frequencies.   *  The array usually needs to be "​re-phased"​. At lower frequencies this may only be every hour or more, but at 20 GHz potentially every 10-20 minutes depending on the array baseline lengths and weather. It is highly recommended you discuss calibration strategies with ATNF LBA support staff. Generally recommendations would be to make sure you regularly observe an appropriate ATCA calibrator source within a few degrees of your target. These sources need to be compact enough that they have close to zero structure phase, have enough flux so the phase spread between the antennas can be quickly determined AND the scan must be long enough to allow the observer to see the phase and run calibration if required. One minute on a compact source with flux density >~ 200 mJy is needed at most frequencies.
 +
 +  * Due to the frequent resets that are likely to happen during the fringe finder observations at the start of an observation it is strongly recommended that you do not re-phase ATCA during this part of the schedule.
  
 It is strongly recommended to schedule so that phase recalibration happens automatically. You need to be confident the chosen source is an appropriate ATCA calibrator (if it has structure or is weak you will make things worse). You can check the suitability of your source on the ATCA calibrator database: ​ It is strongly recommended to schedule so that phase recalibration happens automatically. You need to be confident the chosen source is an appropriate ATCA calibrator (if it has structure or is weak you will make things worse). You can check the suitability of your source on the ATCA calibrator database: ​
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 Note that you must reset the intent to some other value (e.g. OBSERVE_TARGET) on the following scan or the previous intent will be inherited by all ensuing scans! Note that you must reset the intent to some other value (e.g. OBSERVE_TARGET) on the following scan or the previous intent will be inherited by all ensuing scans!
  
 +
 +==== Amplitude Calibration ====
 +
 +Tsys measurements from LBA telescopes are frequently missing or subject to significant errors, especially at frequencies where RFI is an issue. This is a significant complication for data analysis especially where accurate flux deck densities are required. It is strongly recommended to regularly observe a compact calibrator that is part of the ATCA calibrator monitoring program to provide amplitude calibration bootstrapping. Such a source should preferably be within approx 10 degrees of your target sources. Your phase calibrator will often be suitable.
 +
 +It is also possible to use the ATCA local interferometry data to provide this calibration for a source that is not in the monitoring program. Please consult with observatory staff before committing to this strategy.
  
 ===== Wiki ===== ===== Wiki =====
lbaops/lbascheduling.1551328214.txt.gz · Last modified: 2019/02/28 15:30 by cormac