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Scientific Operations | |
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Notes for Planners
Important tips/rules for CDS planners Latest revision: Tuesday, 22-Jan-2019 15:07:18 GMT. This page will be maintained as an up to date record of recent and/or important information for CDS planners. There is already a wealth of documented help for planners (eg see CDS software note #42, A guide for the visiting scientist.) However, with the weekly rota system useful bits of information often get overlooked and so all planners must familiarize themselves with the contents of this page prior to starting the week's plan. Any planners who come across information they think could be usefully recorded in here should contact John Rainnie or Andrzej Fludra.
S/C Roll: The planner should not take account of any roll of the s/c when using Mk_plan or Image_tool. The cpt program will automatically apply any necessary offsets. Contacts WHO DO I SPEAK TO IF THERE ARE PROBLEMS? In the CDS operations room in the EOF, the telephone numbers of key operations staff are clearly posted, including home numbers. Minor problems can be dealt with locally - e.g. questions about running the planning tools, questions about operations procedures.
Feature Tracking We have recently had more incidents with a request for 'feature tracking' not producing the expected effect. Please read software note #45 and remember the feature tracking option cannot be relied on to give stable pointing at the 2" level. Remember also the difference between feature tracking and rotation compensation.
Emergency Study A few things to remember about the use of the Emergency Study (ES) option in XCPT in MK_PLAN.
The 5% rule Don't forget the 5% rule when planning. Until further notice do not append studies to run for more than 4-5 hours in a single block, and then leave a 5% margin in time before starting the next time-tagged group. This does not apply to studies following the daily synoptic study whose duration is pretty well known by now. Science Plan entries The CDS science_plan can never be blank - there is always something happening even if it's nothing. Please ensure that something is always recorded in the science plan Use of mirror/slit steps instead of OPS in XCPT Because the effect of OPS movement is uncertain at the few arcseconds level, there is an option in XCPT (within MK_PLAN) which allows the planner to request that the pointing changes between rasters be catered for by changes in the mirror and/or slit positioning rather than by OPS movement. Since the mirror and slit have limited ranges, it is not always possible to accede to this request. For instance in an NIS raster that covers 240" in Solar X, there is no further mirror range to allow off-pointing of the raster centre. In such cases the request will be ignored and the OPS used as normal. On the other hand, for smaller NIS rasters it will be possible to offset the raster centre without using the OPS. However, please note that NO movement of the slit location is permitted for NIS rasters. Therefore, if a request is made to relocate in Solar Y with this option switched on (eg if a series of rasters is moved to compensate for solar rotation, and a small delta Y is calculated) then the Solar X motion may well be achieved by offsetting the mirror but the Solar Y motion will be achieved by moving the OPS (the only permitted mechanism). Experience has shown that that will more than likely mess up the X pointing as well. Therefore, if the requirement is for accurate off-pointing in Solar-X, it is encumbent upon the planner to ensure that NO change in Solar Y location is requested (possibly by resetting to zero the delta-Y pointing calculated in the 'rotate' option). The option to repoint by moving the scan mirror rather than the OPS is obviously limited by the scan range of the mirror, but if the requested pointing is within range, taking due account of the raster size, this option will work for the following types of planned study.
As MK_PLAN is not aware of the choice to use the mirror/slit for pointings (XCPT is called after MK_PLAN !) it cannot accurately allow for the time it takes to move the mechanisms between rasters, especially for GIS studies. For GIS studies The Planner MUST leave a larger time gap AFTER each group of tagged studies where this option is used. (Obeying the 5% rule is not sufficient) As a rule of thumb allow at least an extra 60 secs per raster. Failure to do this will cause STUDY ABORTS and data loss it may also crash the CDS processors ! Telemetry Submode Changes As telemetry submode changes become more frequent it is the planners and ops staffs duty to be aware of when these changes are to occur. It is especially important if CDS is to be switched out of Medium, Low or Hi rate. Please consult the CDS SCIENCE OPERATIONS PLAN and the SOHO Calender for details of all submode changes. Whenever telemtry rate submode changes are scheduled then the CDS instrument MUST NOT be running any science studies. Medium rate is the normal mode of operation of CDS. In low rates CDS can only perform limited science and only studies approved for that rate should be run. In Hi rate CDS has studies available that are optimised to this rate, but most medium rate studies can still be run, though they may not benefit fully from the HI telemetry rate. Real Time Operations There are three ways of using CDS to make scientific observations -
We have not used the inter-instrument flags (yet). CDS has raised the question of their use at two recent PI meetings, but the other instruments were reluctant to use them. The standard pre-planned operations activity is the way we have proceeded so far, and for most scientific observations this is fine. Indeed, there are few scientific questions which require the rapid sequence/pointing alterations which can be made using items (ii) and (iii), above. With CDS we are not running a random scientific operation; we take in requests for observations and plan and execute operations accordingly. The way we operate is governed by the incoming requests, i.e. by the user community. Thus, there are TWO golden rules concerning real time operation and these have been stated before: THE TWO GOLDEN RULES FOR REAL TIME OPERATION
Please note that REAL TIME OPERATIONS OF THIS KIND WILL BE RARE, it is not something which we will take lightly. Flares The observation of flares raises another set of questions. Given the upturn of the solar cycle and observations of active regions we are going to see flares at times whether we like it or not. Given the nature of our detector systems we rejected any thoughts of observing flares for the first year and a half of scientific operation. Discussions in October 1997 concerning the NIS detector system in particular paved the way to a series of e-mail discussions between the RAL team and the NIS and GIS detector people. One output of this discussion was the guideline for observing active regions when considering the predicted flare probabilities. THIS GUIDELINE IS ALWAYS WRITTEN INTO THE WEEKLY PLANNING NOTE AND SHOULD BE TAKEN SERIOUSLY. The discussions culminated in a relaxing of the blanket 'no' to flare observations. Observing flares is an activity which involves careful planning and some special actions in order to 'prepare' the operation. It is also something which can be detrimental to aspects of the detector system. So, it is something we do not do lightly. Given the relaxed position with regard to flares, we responded to a request which was subsequently run at the end of April with the first 'official' flare observation with CDS. NOTE THAT THE REQUEST WENT THROUGH THE NORMAL PLANNING CHANNELS AND WAS ACCOMPANIED BY A WELL THOUGHT OUT OBSERVATION SCENARIO AND OBSERVING SEQUENCE. CDS will not become a flare hunting device (in any case it is the PI's opinion that flares are really rather boring!). All CDS requests will be dealt with in a non-biased manner - as has always been the case. If you want to observe flares (or anything else for that matter), you must follow the usual course of action - i.e. plan out the observing sequence and make a request to the PI. An active region may be observed using CDS regardless of the flare probabilities given by NOAA. If the planned Study is with the NIS, the GIS should be at a parked voltage. If a flare is seen, the NIMCP Study (see above) should be run as soon afterwards as is possible. In any case WIDE SLIT (90"x240") STUDIES ON ACTIVE REGIONS ARE NOT PERMITTED!!! When performing flare studies where there is a good potential for seeing a flare, it is best if the rastering is not done over a small area. This is to avoid just sitting on a flare, without moving off it. If an active region Study is to be run, and it is not aimed at the study of flares, it is best to avoid active regions with very high chances of large (M or X) class flares. Check the NOAA forecast on Alternately use the CDS current conditions page that contains all the necessary references.
OPS Pointing via DCS It is possible to update OPS pointing values that have already been loaded into the DCS without the necessity of replanning and reloading the plan via (IDL) MK_PLAN and (Perl script) LOADPLAN. This means that under favourable circumstances some studies can have their pointing updated only a matter of minutes before they are due to run. The operations staff will run the necessary software after receiving a request from the planner, and judging whether it is prudent to attempt the update (bearing in mind commanding constraints etc.). Pointing commands are only put into the DCS if the study is time-tagged and the pointing is different from the previous study. If either of these does not apply then you will still have to go the MK_PLAN route to change anything. Note: that only the initial pointing of a series of pointings of the same study (eg for rotation compensation) is put into the DCS and hence this technique should not be used on those plan entries. To use this new option the operators run the IDL procedure NEW_DCS_OPS (only master has the correct setup to allow this). This displays in a widget list the details of the last DCS dump that was sent. That dump usually originates from the last running of the Perl script LOADPLAN. The display is the same as in the DCS editing program DCS_EDIT, but the user interaction is slightly different. To change an OPS pointing, highlight with the cursor either (not both) of the OPS left/right pointing command lines. A widget will appear that prompts the user for the new solar (X,Y) values to be uplinked in place of the highlighted pair. Enter these as decimal values separated by a space or comma. Multiple pointing commands may be edited anywhere in the DCS list. If you edit the same pair of commands more than once only the last entered edit will be saved. Hit the 'Done' button when finished. A summary of the commands to be uplinked is given in the IDL session. These instructions are saved in files which the Perl script NEW_DCS_OPS will use as input. When ready the operations staff will run the script cpt/NEW_DCS_OPS At the end of the script a new dump of the DCS is made. You can therefore check if the edits have been successful by inspecting this dump either from the STM options menu or in the planning IDL session using either the NEW_DCS_OPS or DCS_EDIT widget based routines or (more quickly) using SHOW_DCS for a quick screen listing. Three points to bear in mind.
Spatial offset between NIS and GIS From the CDS Operations Management Team in the Space Science & Technology Department at CCLRC Rutherford Appleton Laboratory Site maintained by John Rainnie. Last revised on Tuesday (22/Jan/2019) at 15:07. |
