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lbaops:lbascheduling [2018/05/14 17:55]
cormac [Scan times]
lbaops:lbascheduling [2018/07/20 16:59] (current)
cormac
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 Example LBA .key files are distributed with the latest version of SCHED Example LBA .key files are distributed with the latest version of SCHED
 ($SCHED/​examples/​lba*.key). Please prepare your schedule using one of these. ($SCHED/​examples/​lba*.key). Please prepare your schedule using one of these.
-The lbasetup files distributed with SCHED should cover all standard +The lba setup files distributed with SCHED ($SCHED/​setups/​lba*) ​should cover 
-continuum modes. If your schedule requires a non-standard mode or +all standard continuum modes. If your schedule requires a non-standard mode or 
-frequency (e.g., for spectral line observations) then you will need +frequency (e.g., for spectral line observations) then you will need to consult 
-to consult with correlator ​personnel before submitting your schedule.+with ATNF personnel before submitting your schedule.
  
 Standard configs are described at Standard configs are described at
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 frequency to the nearest MHz. E.g.: frequency to the nearest MHz. E.g.:
  
- DOPINCR = 1000+<​code>​ 
 +DOPINCR=1000 
 +</​code>​
  
-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.+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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 A [[http://​www.atnf.csiro.au/​vlbi/​observing/​fringefinders.html | list of standard fringe finders]] is available. {{lbaUP.pdf | This plot}} shows the optimal fringe finder to use at any given Parkes LST for a typical array. (It is not usually possible to fringe test Parkes and Hart at the same time, so here is {{hartup.pdf | a similar plot}} for fringe finding Hart with only a subset of the LBA). A [[http://​www.atnf.csiro.au/​vlbi/​observing/​fringefinders.html | list of standard fringe finders]] is available. {{lbaUP.pdf | This plot}} shows the optimal fringe finder to use at any given Parkes LST for a typical array. (It is not usually possible to fringe test Parkes and Hart at the same time, so here is {{hartup.pdf | a similar plot}} for fringe finding Hart with only a subset of the LBA).
  
-In addition, you should always observe a few strong compact sources during your experiment, probably every three hours (e.g. 3 times for a 6 hour experiment). The fringe finders help in the correlation process for adjusting the clock offsets and checking the correlation process is working properly. They also are good candidates for use with the real-time fringe testing software so any observational problems can be fixed immediately (see next point). ​ Choose one which is strong at your observing frequency and has minimal slew time to your target sources. Note that if you know your target source is quite strong, you may not need to observe a separate fringe finder, but you should note this+In addition, you should always observe a few strong compact sources during your experiment, probably every three hours. The fringe finders help in the correlation process for adjusting the clock offsets and checking the correlation process is working properly. They also are good candidates for use with the real-time fringe testing software so any observational problems can be fixed immediately (see next point). ​ Choose one which is strong at your observing frequency and has minimal slew time to your target sources. Note that if you know your target source is quite strong, you may not need to observe a separate fringe finder, but you should note this
 in your schedule file (using the '​note'​ keyword at the top of the schedule and in your schedule file (using the '​note'​ keyword at the top of the schedule and
 the '​intent'​ keyword at the relevant scan - see below). Please always add a note in the "​NOTE"​ section which sources are the '​intent'​ keyword at the relevant scan - see below). Please always add a note in the "​NOTE"​ section which sources are
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 Please use SCHED'​s [[http://​www.aoc.nrao.edu/​software/​sched/​INTENTs.html | '​INTENT'​]] keyword to identify your fringe finder scans. E.g.: Please use SCHED'​s [[http://​www.aoc.nrao.edu/​software/​sched/​INTENTs.html | '​INTENT'​]] keyword to identify your fringe finder scans. E.g.:
  
-dur = 2:00 source = '​1921-293'​ intent = '​FIND_FRINGE'​ / \\ +<​code>​ 
-dur = 2:00 source = '​target'​ intent = '​OBSERVE_TARGET'​ /+grabto='​file'​ grabtime=2,10 
 +dur=3:00 source='​1921-293'​ intent='​FIND_FRINGE'​ / 
 +grabto='​none'​ 
 +dur=2:00 source='​target' ​gap=1:​00 ​intent='​OBSERVE_TARGET'​ / 
 +</​code>​
  
 Note that you must reset the intent to some other value (e.g. OBSERVE_TARGET) on the following scan or the first 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 first intent will be inherited by all ensuing scans!
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 DIFX software correlator. The fringe plot is made available on the web. This DIFX software correlator. The fringe plot is made available on the web. This
 allow observatories to be confident they have their observing setup correct, or allow observatories to be confident they have their observing setup correct, or
-correct any problems. Scheduling a few strong sources throughout your+identify (and hopefully ​correctany problems. Scheduling a few strong sources throughout your
 experiment (and adding an  experiment (and adding an 
 INTENT='​FIND_FRINGE'​ in the schedule) will increase the chance of success for your experiment. INTENT='​FIND_FRINGE'​ in the schedule) will increase the chance of success for your experiment.
  
-If you are using any stations with Mark5 recorders (AuScope, Hartebeesthoek,​ +If you are using any stations with Mark5 recorders (Hobart, Ceduna, ​AuScope, Hartebeesthoek,​ 
-NewZealand), fringe test scans must allow a 1 minute gap //after// the fringe finder to allow some data to be copied off the Mark5 following [[lbaops:​lbaobservingnotes:​mark5fringe | these instructions]] (please request assistance if required).+Warkworth), fringe test scans must allow a 1 minute gap //after// the fringe finder to allow some data to be copied off the Mark5 following [[lbaops:​lbaobservingnotes:​mark5fringe | these instructions]] (please request assistance if required).
  
 ==== Phase Calibrator Sources ==== ==== Phase Calibrator Sources ====
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 ==== Scan Gaps ==== ==== Scan Gaps ====
-Sched allows you to insert a "​gap"​ before a scan to allow for telescope slew time, etc.  For schedules using only the LBA DAS it is recommended not to insert manual gaps. If you need to allow extra time +Sched allows you to insert a "​gap"​ before a scan to allow for telescope slew time, etc.  For schedules using only the LBA DAS (ATCA, Mopra and usually Parkes) ​it is recommended not to insert manual gaps. If you need to allow extra time 
-for a long slew, increase the length of the scan instead. ​At the beginning of the scan section of your schedule it is  +for a long slew, increase the length of the scan instead.
-recommended you use:+
  
- ​gap=0 +If there are Mark5 stations participating in your schedule, then you must include regular gaps of at least 15 seconds in your schedule to allow the Mark5 to insert breaks in the recording. SCHED will warn you if you have insufficient gaps, but you should make them as frequent as you can without compromising your ability to get good quality phase referencing.
- +
-If there are Mark5 stations participating in your schedule ​(e.g. Hartebeesthoek,​ Warkworth, Katherine, Yarragadee - on special occasions Hobart and Parkes may also use Mark5 recorders), then you must include regular gaps of at least 20 seconds in your schedule to allow the Mark5 to insert breaks in the recording. SCHED will warn you if you have insufficient gaps, but you should make them as frequent as you can without compromising your ability to get good quality phase referencing.+
 The required frequency of the gaps depends on the data rate, but every 15 minutes is a good guide. The required frequency of the gaps depends on the data rate, but every 15 minutes is a good guide.
  
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 Please ensure all scans lengths are rounded to the nearest 5 seconds. The ATCA observing systems run on a 5 second cycle. This is another reason not to use "​dwell"​ observing. Please ensure all scans lengths are rounded to the nearest 5 seconds. The ATCA observing systems run on a 5 second cycle. This is another reason not to use "​dwell"​ observing.
  
-=== Prescan ​=== +=== PRESTART ​=== 
-SCHED has a parameter called 'prescan' which purports to start recording media early (but only works as prescribed ​for VLBA controllersand should be explicitly set to 0 for LBA schedules (in some versions of SCHED it does not default to 0). Before any scans in your .key file, add the line:\\ +SCHED has a parameter called 'PRESTART' which purports to start recording media earlybut only works as described ​for VLBA controllersand so should be explicitly set to 0 for LBA schedules (in some versions of SCHED it does not default to 0). Before any scans in your .key file, add the line: 
-''​prescan ​= 0''​ +<​code>​ 
 +prestart=0 
 +</​code>​
 ==== Scan Overhead ==== ==== Scan Overhead ====
 There is a 3 "​cycle"​ overhead at  ATCA. This means that at the ATCA there is a always a minimum 15 sec of invalid data between scans (this includes frequency changes, two scans observing the same source at the same frequency etc). This is not additional to slew time (ie the invalid time between scans is either 15sec or the slew time, whichever is largest).  ​ There is a 3 "​cycle"​ overhead at  ATCA. This means that at the ATCA there is a always a minimum 15 sec of invalid data between scans (this includes frequency changes, two scans observing the same source at the same frequency etc). This is not additional to slew time (ie the invalid time between scans is either 15sec or the slew time, whichever is largest).  ​
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 Please use the following as a minimum selection of summary items (more are available): Please use the following as a minimum selection of summary items (more are available):
  
- sumitem=el1,​ el2, slew, dwell +<​code>​ 
 +sumitem=el1,​ el2, slew, dwell 
 +</​code>​
  
 ==== ATCA Issues ==== ==== ATCA Issues ====
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   * If you plan to use the ATCA local interferometry data for flux monitoring please make sure to include a scan on an ATCA flux calibrator (preferably 1934-638).   * If you plan to use the ATCA local interferometry data for flux monitoring please make sure to include a scan on an ATCA flux calibrator (preferably 1934-638).
  
-  *  The array usually needs to be "​re-phased"​. At lower frequencies this may only be every few hours, 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.
  
-  *  ​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: ​
  
 [[http://​www.narrabri.atnf.csiro.au/​calibrators/​]] [[http://​www.narrabri.atnf.csiro.au/​calibrators/​]]
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 [[http://​www.aoc.nrao.edu/​~cwalker/​sched/​INTENTs.html | '​INTENT'​]] keyword to mark the relevant scans as '​AUTOPHASE_DETERMINE'​. E.g.: [[http://​www.aoc.nrao.edu/​~cwalker/​sched/​INTENTs.html | '​INTENT'​]] keyword to mark the relevant scans as '​AUTOPHASE_DETERMINE'​. E.g.:
  
-dur = 2:00 source = 'strong-cal' intent = '​AUTOPHASE_DETERMINE'​ / \\ +<​code>​ 
-dur = 2:00 source = 'weak-target'​ intent = '​OBSERVE_TARGET'​ /+dur = 2:00 source = 'atca-cal' intent = '​AUTOPHASE_DETERMINE'​ / 
 +dur = 2:00 source = 'vlbi-target'​ intent = '​OBSERVE_TARGET'​ / 
 +</​code>​
  
 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!
lbaops/lbascheduling.1526284545.txt.gz · Last modified: 2018/05/14 17:55 by cormac