SIST EN 17350:2020
(Main)SCM - Scheduling and Commanding Message - Standard
SCM - Scheduling and Commanding Message - Standard
1.1 Purpose:
The "Scheduling and Commanding Messages" (SCM) specifies a standard format for observing system commanding and scheduling. This document aims to ease the planning and operation processes and to reduce the effors from researchers that use several different observing systems and/or simulation software products.
The SCM establishes a common language for exchanging information on planning, scheduling, and executing observations of celestial objects. In the end this will:
a) Facilitate interoperability and enable consistent warning between data originators who supply celestial observations and the entities or researchers who use it; and
b) Facilitate the automation of observation processes.
1.2 Applicability:
The SCM is applicable to ground-based activities related to the planning, scheduling, and execution of the observations of celestial objects. It is used by planning software, scheduling software, telescope commanding software. It is applicable for optical telescopes.
Raumfahrt - Überwachung der Weltraumlageerfassung - Planungs- und Kommando-Nachricht
1.1 Zweck:
SCM - Scheduling and Commanding Messages - legt ein Standardformat für die Zeitplanung und Befehlserteilung von Beobachtungssystemen fest. Dieses Dokument soll Planungs- und Betriebsprozesse vereinfachen und den Aufwand für Forscher reduzieren, die mehrere verschiedene Beobachtungssysteme und/oder Simulationssoftwareprodukte verwenden.
Die SCM legt eine allgemeine Sprache für den Austausch von Informationen zu Planung, Zeitplanung und Durchführung von Beobachtungen von Himmelskörpern fest. Dadurch wird letztlich Folgendes erreicht:
a) die Interoperabilität wird vereinfacht und das Ausgeben einheitlicher Warnungen zwischen Daten-urhebern, die Himmelsbeobachtungen durchführen, und den Stellen oder Forschern, die diese Daten nutzen, ermöglicht und
b) die Automatisierung von Beobachtungsprozessen wird vereinfacht.
1.2 Anwendbarkeit:
Der SCM-Standard ist auf bodengestützte Aktivitäten hinsichtlich der Planung, Zeitplanung und Durch-führung von Beobachtungen von Himmelskörpern anwendbar. Er wird von Planungssoftware, Scheduling-Software und Teleskop-Befehlssoftware eingesetzt. Er ist auch bei optischen Teleskopen anwendbar.
SCM - Message de planification et de commande - Norme
1.1 Objet :
Le « SCM » (Scheduling and Commanding Message) spécifie un format normalisé pour les commandes et la planification du système d'observation. Le présent document vise à faciliter les processus de planification et d'exploitation et à alléger le travail des chercheurs qui utilisent plusieurs systèmes d'observation et/ou logiciels de simulation différents.
Le SCM définit un langage commun permettant d'échanger des informations sur la planification, l'ordonnancement et la réalisation d'observations d'objets célestes. Au final, cela permettra :
a) de faciliter l'interopérabilité et de transmettre des notifications cohérentes entre les émetteurs de données qui fournissent les observations célestes et les entités ou les chercheurs qui les utilisent ; et
b) de faciliter l'automatisation des processus d'observation.
1.2 Applicabilité :
Le SCM s'applique aux activités au sol liées à la planification, à l'ordonnancement et à la réalisation d'observations d'objets célestes. Il est utilisé par des logiciels de planification, d'ordonnancement et de commande de télescope. Il s'applique aux télescopes optiques.
SCM - Obrazec za časovno razporejanje in vodenje - Standardizirani format
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 17350:2020
01-oktober-2020
SCM - Obrazec za časovno razporejanje in vodenje - Standardizirani format
SCM - Scheduling and Commanding Message - Standard
Raumfahrt - Überwachung der Weltraumlageerfassung - Planungs- und Kommando-
Nachricht
SCM - Message de planification et de commande - Norme
Ta slovenski standard je istoveten z: EN 17350:2020
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
SIST EN 17350:2020 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 17350:2020
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SIST EN 17350:2020
EUROPEAN STANDARD
EN 17350
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2020
ICS 49.140
English version
SCM - Scheduling and Commanding Message - Standard
SCM - Message de planification et de commande - SCM - Planungs- und Befehlsnachricht - Standard
Norme
This European Standard was approved by CEN on 17 May 2020.
CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical
references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to
any CEN and CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2020 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. EN 17350:2020 E
reserved worldwide for CEN national Members and for
CENELEC Members.
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EN 17350:2020 (E)
Contents Page
European foreword . 4
0 Introduction . 5
0.1 Document structure . 5
0.2 Verbal conventions . 5
1 Scope . 6
1.1 Purpose . 6
1.2 Applicability . 6
2 Normative references . 6
3 Terms, definitions, symbols and abbreviations . 6
3.1 Terms and definitions . 6
3.2 Symbols and abbreviations . 9
4 Overview — Context of the document . 10
5 General nature of the standard — Documentation within the format . 11
6 SCM structure and content . 11
6.1 General structure . 11
6.2 Nested logical segments in the format. 15
6.3 Auxiliary messages . 15
6.4 General rules . 15
6.5 OS Control Computer and OS Scheduler Inputs . 17
6.6 Quantization of Commands/Requests . 18
6.7 Parameter Types . 18
7 Detailed SCM Syntax . 19
7.1 Introduction: First-Level Structure . 19
7.2 Definition of the segment 'header' . 20
7.3 Definition of the segment 'metaData' . 21
7.4 Definition of the segment 'commonData' . 23
7.5 Definition of the segment 'command' . 23
7.6 Definition of the segment 'scheduleRequest' . 34
7.7 Macros . 46
8 Sequence higher level structures . 46
8.1 Higher Level logical structures (“sequence” segments) . 46
8.2 Handling of FITS header keywords — General expected behaviour in regard to
writing to FITS headers . 49
Annex A (informative) Commanding and Scheduling Message background . 50
Annex B (informative) Examples . 51
B.1 Commanding a Series of Observations . 51
B.2 Requesting Follow-up observations two hours apart . 54
Annex C (informative) Survey Strategy Types and Related Parameter Requirements —
Description of Survey Strategies . 59
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C.1 General . 59
C.2 Parameter Requirements for Survey Strategy Type 1 (vertical strip) . 61
C.3 Parameter Requirements for Survey Strategy Type 2 (horizontal strip) . 61
C.4 Parameter Requirements for Survey Strategy Type 3 (free mosaic) . 61
Annex D (informative) Handling of Filter Requests . 62
D.1 Filter specification. 62
D.2 Specifying narrowband filter types (wavelength value) . 63
Bibliography . 64
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EN 17350:2020 (E)
European foreword
This document (EN 17350:2020) has been prepared by Technical Committee CEN/CLC/JTC 5 “Space”,
the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2021, and conflicting national standards
shall be withdrawn at the latest by February 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
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0 Introduction
0.1 Document structure
Clause 2 provides an overview of the SCM.
Clause 3 describes the scope and general nature of the SCM.
Clause 4 describes the general format of the SCM standard.
Clause 5 describes the detailed syntax of SCM communications.
Clause 6 provides additional information about headers.
Annex A (informative) provides SCM background.
Annex B (informative) provides SCM examples.
Annex C (informative) describes the survey strategy types and related parameter requirements.
Annex D (informative) informs about the handling of filter requests.
0.2 Verbal conventions
The following conventions apply:
a) 'shall' implies a requirement;
b) 'should' implies a recommendation;
c) 'may' implies a permission; and
d) 'is', 'are', and 'will' denote factual statements.
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1 Scope
1.1 Purpose
The “Scheduling and Commanding Messages” (SCM) specifies a standard format for observing system
commanding and scheduling. This document aims to ease the planning and operation processes and to
reduce the efforts from researchers that use several different observing systems and/or simulation
software products.
The SCM establishes a common language for exchanging information on planning, scheduling, and
executing observations of celestial objects. In the end this will:
a) Facilitate interoperability and enable consistent warning between data originators who supply
celestial observations and the entities or researchers who use it; and
b) Facilitate the automation of observation processes.
1.2 Applicability
The SCM is applicable to ground-based activities related to the planning, scheduling, and execution of
the observations of celestial objects. It is used by planning software, scheduling software, telescope
commanding software. It is applicable for optical telescopes.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1.1
Observing System Command File
“observation plan”
data file which is used to control an observing system (OS), which contains absolute information on
actions the OS is due to perform, e.g. absolute times and sky coordinates for observations, and which is
read by an OS control computer that still processes part of their content (e.g. conversion of equatorial
coordinates to telescope hardware coordinates, execution of pre-defined standard routines for
calibration processes that are called by a single entry in the command file, etc.) and sends commands to
the hardware drivers
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3.1.2
Observing System Scheduler Input File
“scheduler request”
data file providing input to an observation scheduler
Note 1 to entry: Opposed to Observing system command files, these files usually do not contain absolute
information on when an OS is due to perform a certain action, but rather constraints that allow a scheduler to
flexibly allocate the requested actions. The scheduler, on the other hand, can write command files which are
subsequently passed on to an OS control computer.
3.1.3
Hardware Driver Input
commands that are produced by an OS control computer and are selectively sent to the according
hardware drivers, e.g. the telescope mount drivers, dome drivers, etc.
3.1.4
Near-Earth Object
NEO
Solar System objects whose orbit brings them into close proximity with the Earth, which all have a
6
perihelion distance < 1.3 astronomical units (the distance Sun - Earth, ~149,6x10 km), and which
include near-Earth asteroids (NEAs), near-Earth comets, a number of solar-orbiting spacecraft, and
meteoroids large enough to be tracked in space before striking the Earth
3.1.5
follow-up
term used in the NEO field, identical to 'tracking' in the SST field. It is a specific effort to obtain
observations of an interesting object at times subsequent its discovery, with the goal of improving the
knowledge of its orbit and the predictability of its future motion
Note 1 to entry: Follow-up telescopes are generally distinct from survey telescopes, and operate with a more
close supervision of an observer, which selects the targets in need of follow-up. Survey telescopes may also
observe known objects, thus providing follow-up observations, although these observations are often not the goal
of the project.
Note 2 to entry: 'Tracking' is used in the SST field and identical to 'follow-up' in the NEO field.
3.1.6
range
radial distance between an observer and an object at a given instant of time, which is one of the direct
observable that can be derived from a radar observation, by measuring the travelling time of a radio
wave reflected from the object's surface, and which, since ground-based optical astrometry does not
allow to directly determine radial distances, range measurements from radar are extremely powerful
for orbital determination
3.1.7
survey
project operating telescopes designed to detect unknown moving objects in the sky, some of which will
become new discoveries
Note 1 to entry: Surveys typically operate in a mostly automated way, and can detect and report measurements
for thousands of objects every night.
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3.1.8
sensor
in the SST field, complete observation system, i.e. an optical telescope together with its camera, or a
radar system
in the NEO field, detector, i.e. light-sensitive device in a camera (CCD or CMOS)
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3.2 Symbols and abbreviations
Table 1 — Symbols
n.a. not applicable
Table 2 — Abbreviations
ASCII American Standard Code for Information Interchange
ASCOM Astronomy Common Object Model
AstDyS Asteroids Dynamic Site
CCD Charge-Coupled Device
CCSDS Consultative Committee for Space Data Systems
CDM Conjunction Data Message
CMOS Complementary Metal–Oxide–Semiconductor
ESA European Space Agency
ESO European Southern Observatory
FITS Flexible Image Transport System
IAC Instituto de Astrofísica de Canarias
INDI Instrument-Neutral Distributed Interface
JSON JavaScript Object Notation
NEO Near-Earth Object
NEODyS Near-Earth Objects Dynamic Site
OCA Observatoire de la Côte d'Azur
OGS Optical Ground Station
OS Observing System
RTML Remote Telescope Markup Language
RTS2 Remote Telescope System 2nd Version
SCM Scheduling and Commanding Message
SSA Space Situational Awareness
SST Space Surveillance and Tracking
TBT Test Bed Telescope
TDM Tracking Data Message
TLE Two-line element
UTC Coordinated Universal Time
VLT Very Large Telescope
XML eXtensible Markup Language
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The SCM generally uses units that are part of the International System of Units (SI), either base, derived,
or non-SI units that are accepted for use within the SI. The following units are used in the SCM:
Table 3 — Unit conventions
deg decimal degrees
as seconds of arc (1/3 600 °)
m meter
mm millimetre
nm nanometer
s SI seconds
min minutes (60 SI seconds)
In order to simplify the standard and the interface to an observing system control computer or
scheduler, only one notation per parameter is foreseen.
4 Overview — Context of the document
This document gathers the requirements described in the Proposal for a Telescope Commanding and
Scheduling Data Standard [2].
The basic application scenarios of the standard are illustrated in Figures 1 and 2, once for the
application as a scheduler input file and once for the application as an OS command file.
In the first case, the SCM file is created by a human operator or an automated planning tool and either
directly submitted to an observation scheduler or retrieved by it from a database. The scheduler creates
an observation schedule based on the targets and constraints provided in the SCM and sends
corresponding commands to the OS control computer. In case of an OS network it is also possible that a
central scheduler sends commands to several OSs. The scheduler can be located at the OS or work
remotely. The scheduler needs to be reasonably “smart” to interpret the constraints in the SCM and to
preferably calculate pointing coordinates from provided object ephemerides or retrieve information on
objects from online sources.
Figure 1 — Basic context of SCM used as a scheduler input file
It is well possible that the observation scheduler passes on the command to the OS control computer via
another SCM, as illustrated in Figure 2. The OS control computer in this case is likely to be allocated
somewhere close to the OS. It needs to be much less “smart” than the scheduler, assuming that in the
typical case it will already be provided by a simple coordinates and timing information.
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Figure 2 — Basic context of SCM used as OS command files
5 General nature of the standard — Documentation within the format
For individual images, the FITS (Flexible Image Transport System) standard allows the inclusion of a
considerable amount of information in the machine- and human-readable image header. There is thus
no need to duplicate this information in a separate file for observations of several images. The same
applies to information on used hardware in robotic OS networks where observation requests are not
submitted to individual OSs. The information on the OS used can also be written to the images' FITS
headers, as done in the Las Cumbres Observatory Global Telescope Network, for example. In case of
larger campaigns, however, it might be useful to have access to concise observation history in one file
(i.e. which observations have really been carried out, actual observation conditions, …). For the sake of
clearness, it is preferable to have this information in a single file, not interrupted by command or other
information.
To guarantee traceability from an image to the underlying command, the command message format
foresees the option to request the command message ID (and potentially also its location) to be written
into the image's FITS header.
6 SCM structure and content
6.1 General structure
6.1.1 General
An SCM file consists of at least one “observation block” which can be either a “command” or a “schedule
request”. The “header” element contains basic parameters of the message itself. All actual commanding
parameters for the OS are, in the basic case, included in a “command” element. In this element, the
camera to be used is specified, the path and filename where the resulting image file shall be saved are
detailed, information to be written into the image file’s FITS header can be passed on, and the physical
observation parameters are transferred. Hereby, coordinates are defined in decimal degrees, exposure
time in seconds. If more than one observation is desired, another “command” segment can be added at
the end of the file. Overlapping information can be defined for all “commands” in a “commonData”
segment.
The standard is described in an XML-based language. The logical layout of an XML document always
follows a tree structure. The higher-level structure of an SCM is shown in Table 4.
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Table 4 — Higher-level structure of an SCM
- Header
- MetaData
- Project
- Contact
- Linked SCM
- Wait Constraint
- Common Data
- Camera
- Device
- Spectrograph
- Image Data
- Target
- Surey Strategy
- Exposure
- Observation
- Macros
- Command
- MetaData
- Camera
- Detector
- Chips
- Chip
- Windowing
- Binning
- Device
- Device
- Spectrograph
- Detector
- Device
- Grating
- FilterWheel
- Slit
- xyPosition
- Coordinates
- ImageData
- FitsHeader
- Target
- Coordinates
- Ephemerides
- OrbitalElements
- RaDecList
- TargetBrightness
- TrackRate
- CalibrationObservation
- Exposure
- Dithering
- Shutter
- Observation
- ScheduleRequest
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- MetaData
- LinkedBlock
- Camera
- Detector
- Chips
- Chip
- Windowing
- Binning
- Device
- Device
- Spectrograph
- Detector
- Device
- Grating
- FilterWheel
- Slit
- xyPosition
- Coordinates
- ImageData
- FitsHeader
- Target
- Coordinates
- Ephemerides
- OrbitalElements
- RaDecList
- TargetBrightness
- TrackRate
- SurveyStrategy
- Constraints
- AirmassConstraint
- DateTimeConstraint
- EclipticConstraint
- ExposureConstraint
- FieldOfViewConstraint
- GalacticPlaneConstraint
- InformationGainConstraint
- Interval
- MoonConstraint
- NightConstraint
- SunConstraint
- WaitConstraint
- Other Constraints
- CalibrationObservation
- Exposure
- Dithering
- Shutter
- Observation
6.1.2 XML document header
The header carries information on the format of the document, but also information necessary to check
the validity of the XML document (through the comparison with an XML grammar). It also lists the
document’s unique identification code.
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As Figure 3 shows, the third part of the document header appears in the form of attributes of the root
element (shown as red dots in the tree diagram). As the ASCII code of the header below shows, these
are written directly into the opening tag of the root element. The content of the attributes is added on
the right side in XML Notepad, or in the form attribute=”content” in ASCII format.
Figure 3 — XML document declaration and root element attributes
1 XML declaration. Defines the XML version and the character encoding.
2 Root element of the document (i.e. defining: “this is an SCM document”)
3 Root element attributes. Each has the following functions:
xmlns:xsi - defines the namespace used in the document. The
URL does actually point to the website, but is the
name of the namespace.
xsi:noNameSpaceSchemaLocation - Defines the location of the XML schema (the
grammar to be used for validation) for elements
that do not belong to any namespace (basically all
elements in an SCM)
id - Identification code for the document code. Shall
always be “ESA_SCM”.
version - Identifies the version of the SCM data format that
is used throughout the document.
Header in ASCII code:
6.1.3 Segment
Higher-level XML element that might contain child elements or other segments. For instance, the
segment “Header” only contains elements (COMMENT, CREATION_DATE, …) while segment
“commonData” containts other segments (camera, device, …) which, in turn, containts elements.
See Clause 7 for the description of each segment.
6.1.4 Observation Block
Smallest unit of an observation request/command. Are included in a Scheduling and Commanding
Message, with each Observation Block being represented by one XML element (with child elements).
Observation blocks are treated as impartible and are the smallest unit to which the status
“succeeded”/”not succeeded” can be assigned.
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6.1.5 Command
Single observation block used to command an action from an OS. Represented by an XML element called
“command” (with child elements).
6.1.6 Schedule Request
Single observation block used to describe an observation request to a scheduler. Represented by an
XML element called “scheduleRequest” (with child elements, see 7.6).
6.2 Nested logical segments in the format
The format uses nested XML elements, with the elements holding child elements being referred to as
“logical segments”. In the following description, not the entire hierarchical structure is displayed
graphically. Instead, elements are listed in tables with:
a) Logical segments of second level elements being indicated by an empty line before and after the
segment, and the segment being introduced with its name;
b) Logical segments within second or lower level elements being indicated by being indented. In this
case, all elements listed after the segment title are part of this particular segment until either a new
segment starts (indicated by a segment name on the same level) or the indent moves back to the
higher level.
Lower-level elements that are marked as mandatory but located within a logical segment that is not
mandatory are only mandatory if the optional, higher-level logical segment is used.
6.3 Auxiliary messages
For unrestricted control of the OS and custom operation, the SCM provides an open string element, the
AUXILIARY_MESSAGE. It is primarily foreseen to providing additional data that is not foreseen to be
transmitted in an SCM. It can, however, also be used for a variety of other applications, such as to
provide custom scripts to a local scheduler or to pass OS specific commands directly through to the
control level below the local scheduler / OS control computer directly interfaced by SCMs.
AUXILIARY_MESSAGEs can generally be added at any location in an SCM and may contain any Unicode
characters. The characters &, <, >, “, and ‘ need to be escaped with the following entities: & with & ,
< with < , > with >
...
SLOVENSKI STANDARD
oSIST prEN 17350:2019
01-julij-2019
SCM - Obrazec za časovno razporejanje in vodenje - Standardizirani format
SCM - Scheduling and Commanding Message - Standard
Raumfahrt - Überwachung der Weltraumlageerfassung - Planungs- und Kommando-
Nachricht
SCM - Message de planification et de commande - Norme
Ta slovenski standard je istoveten z: prEN 17350
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
oSIST prEN 17350:2019 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 17350:2019
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oSIST prEN 17350:2019
EUROPEAN STANDARD
DRAFT
prEN 17350
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2019
ICS 49.140
English version
SCM - Scheduling and Commanding Message - Standard
SCM - Message de planification et de commande - Raumfahrt - Überwachung der Weltraumlageerfassung
Norme - Planungs- und Kommando-Nachricht
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/CLC/JTC 5.
If this draft becomes a European Standard, CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal
Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any
alteration.
This draft European Standard was established by CEN and CENELEC in three official versions (English, French, German). A
version in any other language made by translation under the responsibility of a CEN and CENELEC member into its own
language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.Recipients of this draft are invited to submit, with their comments, notification
of any relevant patent rights of which they are aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2019 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. prEN 17350:2019 E
reserved worldwide for CEN national Members and for
CENELEC Members.
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prEN 17350:2019 (E)
Contents Page
European foreword . 4
0 Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, symbols and abbreviations . 6
3.1 Terms and definitions . 6
3.2 Symbols and abbreviations . 7
4 Overview — Context of the document . 9
5 General nature of the standard — Documentation within the format . 10
6 SCM structure and content . 10
6.1 General structure . 10
6.1.1 General . 10
6.1.2 XML document header. 12
6.1.3 Segment . 13
6.1.4 Observation Block . 13
6.1.5 Command . 13
6.1.6 Schedule Request . 14
6.2 Nested logical segments in the format. 14
6.3 Auxiliary messages . 14
6.4 General rules . 14
6.4.1 Delay times . 14
6.4.2 Unforeseen/unknown delays in direct commanding (“command” segments). 15
6.4.3 Check of validity . 15
6.4.4 Default behaviour in case of erroneous input . 15
6.4.5 Significance of element order . 16
6.4.6 Exchange of SCM files . 16
6.4.7 Time specification . 16
6.4.8 Leading and trailing empty spaces in XML elements . 16
6.4.9 Case Sensitivity . 16
6.4.10 Commenting . 16
6.5 OS Control Computer and OS Scheduler Inputs . 16
6.6 Quantization of Commands/Requests . 17
6.7 Parameter Types . 17
7 Detailed SCM Syntax . 18
7.1 Introduction: First-Level Structure . 18
7.2 Definition of the segment 'header' . 19
7.3 Definition of the segment 'metaData' . 20
7.4 Definition of the segment 'commonData' . 22
7.5 Definition of the segment 'command' . 22
7.5.1 General . 22
7.5.2 metaData segment . 23
7.5.3 Camera segment . 23
7.5.4 Device segment . 24
7.5.5 Spectrograph segment . 25
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7.5.6 ImageData segment . 26
7.5.7 Target segment . 26
7.5.8 CalibrationObservation segment . 30
7.5.9 Exposure segment . 31
7.5.10 Shutter Segment . 32
7.5.11 Observation segment . 32
7.6 Definition of the segment 'scheduleRequest' . 33
7.6.1 SCM scheduleRequest segment . 33
7.6.2 MetaData segment . 34
7.6.3 Camera segment . 35
7.6.4 Device segment . 35
7.6.5 Spectrograph segment . 35
7.6.6 ImageData segment . 35
7.6.7 Target segment . 35
7.6.8 SurveyStrategy segment . 35
7.6.9 Constraints segment . 38
7.6.10 CalibrationObservation segment . 46
7.6.11 Exposure segment . 46
7.6.12 Observation segment . 46
7.7 Macros . 46
8 Sequence higher level structures . 47
8.1 Higher Level logical structures (“sequence” segments) . 47
8.2 Handling of FITS header keywords — General expected behaviour in regard to
writing to FITS headers . 49
Annex A (informative) Commanding and Scheduling Message background . 51
Annex B (informative) Examples . 52
B.1 Commanding a Series of Observations . 52
B.2 Requesting Follow-up observations two hours apart . 54
Annex C (informative) Survey Strategy Types and Related Parameter Requirements —
Description of Survey Strategies . 59
C.1 General . 59
C.2 Parameter Requirements for Survey Strategy Type 1 (vertical strip) . 61
C.3 Parameter Requirements for Survey Strategy Type 2 (horizontal strip) . 61
C.4 Parameter Requirements for Survey Strategy Type 3 (free mosaic) . 61
Annex D (informative) Handling of Filter Requests . 62
D.1 Filter specification. 62
D.2 Specifying narrowband filter types (wavelength value) . 62
Bibliography . 64
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European foreword
This document (prEN 17350:2019) has been prepared by Technical Committee CEN/CLC/JTC 5 “Space”,
the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
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0 Introduction
0.1 Document structure:
Clause 2 provides an overview of the SCM.
Clause 3 describes the scope and general nature of the SCM.
Clause 4 describes the general format of the SCM standard.
Clause 5 describes the detailed syntax of SCM communications.
Clause 6 provides additional information about headers.
Annex A (informative) provides SCM background.
Annex B (informative) provides SCM examples.
Annex C (informative) describes the survey strategy types and related parameter requirements.
Annex D (informative) informs about the handling of filter requests.
0.2 Verbal conventions:
The following conventions apply:
a) 'shall' implies a requirement;
b) 'should' implies a recommendation;
c) 'may' implies a permission; and
d) 'is', 'are', and 'will' denote factual statements.
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1 Scope
1.1 Purpose:
The “Scheduling and Commanding Messages” (SCM) specifies a standard format for observing system
commanding and scheduling. This document aims to ease the planning and operation processes and to
reduce the effors from researchers that use several different observing systems and/or simulation
software products.
The SCM establishes a common language for exchanging information on planning, scheduling, and
executing observations of celestial objects. In the end this will:
a) Facilitate interoperability and enable consistent warning between data originators who supply
celestial observations and the entities or researchers who use it; and
b) Facilitate the automation of observation processes.
1.2 Applicability:
The SCM is applicable to ground-based activities related to the planning, scheduling, and execution of
the observations of celestial objects. It is used by planning software, scheduling software, telescope
commanding software. It is applicable for optical telescopes.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
Observing System Command File
“observation plan”
data file which is used to control an observing system (OS), which contains absolute information on
actions the OS is due to perform, e.g. absolute times and sky coordinates for observations, and which is
read by an OS control computer that still processes part of their content (e.g. conversion of equatorial
coordinates to telescope hardware coordinates, execution of pre-defined standard routines for
calibration processes that are called by a single entry in the command file, etc.) and sends commands to
the hardware drivers
3.1.2
Observing System Scheduler Input File
“scheduler request”
data file providing input to an observation scheduler.
Note 1 to entry: Opposed to Observing system command files, these files usually do not contain absolute
information on when an OS is due to perform a certain action, but rather constraints that allow a scheduler to
flexibly allocate the requested actions. The scheduler, on the other hand, can write command files which are
subsequently passed on to an OS control computer.
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3.1.3
Hardware Driver Input
commands that are produced by an OS control computer and are selectively sent to the according
hardware drivers, e.g. the telescope mount drivers, dome drivers, etc.
3.1.4
Near-Earth Object
NEO
Solar System objects whose orbit brings them into close proximity with the Earth, which all have a
perihelion distance < 1.3 astronomical units (the distance Sun - Earth, ~149.6x10^6 km), and which
include near-Earth asteroids (NEAs), near-Earth comets, a number of solar-orbiting spacecraft, and
meteoroids large enough to be tracked in space before striking the Earth
3.1.5
follow-up
specific effort to obtain observations of an
interesting object at times subsequent its discovery, with the goal of improving the knowledge of its
orbit and the predictability of its future motion
Note 1 to entry: Follow-up telescopes are generally distinct from survey telescopes, and operate with a more
close supervision of an observer, which selects the targets in need of follow-up. Survey telescopes may also
observe known objects, thus providing follow-up observations, although these observations are often not the goal
of the project.
Note 2 to entry: 'Tracking' is used in the SST field and identical to 'follow-up' in the NEO field.
3.1.6
range
radial distance between an observer and an object at a given instant of time, which is one of the direct
observable that can be derived from a radar observation, by measuring the travelling time of a radio
wave reflected from the object's surface, and which, since ground-based optical astrometry does not
allow to directly determine radial distances, range measurements from radar are extremely powerful
for orbital determination
3.1.7
survey
project operating telescopes designed to detect unknown moving objects in the sky, some of which will
become new discoveries
Note 1 to entry: Surveys typically operate in a mostly automated way, and can detect and report measurements
for thousands of objects every night.
3.1.8
sensor
complete observation system, i.e. an optical telescope together with its camera, or a radar
system.
detector, i.e. light-sensitive device in a camera (CCD or CMOS)
3.2 Symbols and abbreviations
Table 1 — Symbols
n.a. not applicable
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Table 2 — Abbreviations
ASCII American Standard Code for Information Interchange
ASCOM Astronomy Common Object Model
AstDyS Asteroids Dynamic Site
CCSDS Consultative Committee for Space Data Systems
CDM Conjunction Data Message
ESA European Space Agency
ESO European Southern Observatory
FITS Flexible Image Transport System
IAC Instituto de Astrofísica de Canarias
INDI Instrument-Neutral Distributed Interface
JSON JavaScript Object Notation
NEO Near-Earth Object
NEODyS Near-Earth Objects Dynamic Site
OCA Observatoire de la Côte d'Azur
OGS Optical Ground Station
OS Observing System
RTML Remote Telescope Markup Language
RTS2 Remote Telescope System 2nd Version
SCM Scheduling and Commanding Message
SSA Space Situational Awareness
SST Space Surveillance and Tracking
TBT Test Bed Telescope
TDM Tracking Data Message
TLE Two-line element
UTC Coordinated Universal Time
VLT Very Large Telescope
XML eXtensible Markup Language
The SCM generally uses units that are part of the International System of Units (SI), either base, derived,
or non-SI units that are accepted for use within the SI. The following units are used in the SCM:
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Table 3 — Unit conventions
deg: decimal degrees
as: seconds of arc (1/3 600 °)
m: meter
mm: millimetre
nm: nanometer
s: SI seconds
min: minutes (60 SI seconds)
In order to simplify the standard and the interface to an observing system control computer or
scheduler, only one notation per parameter is foreseen.
4 Overview — Context of the document
This document gathers the requirements described in the Proposal for a Telescope Commanding and
Scheduling Data Standard [2].
The basic application scenarios of the standard are illustrated in Figures 1 and 2, once for the
application as a scheduler input file and once for the application as an OS command file.
In the first case, the SCM file is created by a human operator or an automated planning tool and either
directly submitted to an observation scheduler or retrieved by it from a database. The scheduler creates
an observation schedule based on the targets and constraints provided in the SCM and sends
corresponding commands to the OS control computer. In case of an OS network it is also possible that a
central scheduler sends commands to several OSs. The scheduler can be located at the OS or work
remotely. The scheduler needs to be reasonably “smart” to interpret the constraints in the SCM and to
preferably calculate pointing coordinates from provided object ephemerides or retrieve information on
objects from online sources.
Human
operator
creates
SCM
OS control
reads
Observation
commands
computer
scheduler
scheduleRequest
Planning
creates
tool
Figure 1 — Basic context of SCM used as a scheduler input file
It is well possible that the observation scheduler passes on the command to the OS control computer via
another SCM, as illustrated in Figure 2. The OS control computer in this case is likely to be allocated
somewhere close to the OS. It needs to be much less “smart” than the scheduler, assuming that in the
typical case it will already be provided by a simple coordinates and timing information.
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Observation
OS
creates
scheduler
commands
SCM
Human
reads OS control commands
creates
Camera
operator
computer
command
Planning creates
…
commands
tool
Figure 2 — Basic context of SCM used as OS command files
5 General nature of the standard — Documentation within the format
For individual images, the FITS (Flexible Image Transport System) standard allows the inclusion of a
considerable amount of information in the machine- and human-readable image header. There is thus
no need to duplicate this information in a separate file for observations of several images. The same
applies to information on used hardware in robotic OS networks where observation requests are not
submitted to individual OSs. The information on the OS used can also be written to the images' FITS
headers, as done in the Las Cumbres Observatory Global Telescope Network, for example. In case of
larger campaigns, however, it might be useful to have access to concise observation history in one file
(i.e. which observations have really been carried out, actual observation conditions, …). For the sake of
clearness, it is preferable to have this information in a single file, not interrupted by command or other
information.
To guarantee traceability from an image to the underlying command, the command message format
foresees the option to request the command message ID (and potentially also its location) to be written
into the image's FITS header.
6 SCM structure and content
6.1 General structure
6.1.1 General
An SCM file consists of at least one “observation block” which can be either a “command” or a “schedule
request”. The “header” element contains basic parameters of the message itself. All actual commanding
parameters for the OS are, in the basic case, included in a “command” element. In this element, the
camera to be used is specified, the path and filename where the resulting image file shall be saved are
detailed, information to be written into the image file’s FITS header can be passed on, and the physical
observation parameters are transferred. Hereby, coordinates are defined in decimal degrees, exposure
time in seconds. If more than one observation is desired, another “command” segment can be added at
the end of the file. Overlapping information can be defined for all “commands” in a “commonData”
segment.
The standard is described in an XML-based language. The logical layout of an XML document always
follows a tree structure. The higher-level structure of an SCM is shown in Table 4.
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Table 4 — Higher-level structure of an SCM
- Header
- MetaData
- Project
- Contact
- Linked SCM
- Wait Constraint
- Common Data
- Camera
- Device
- Spectrograph
- Image Data
- Target
- Surey Strategy
- Exposure
- Observation
- Macros
- Command
- MetaData
- Camera
- Detector
- Chips
- Chip
- Windowing
- Binning
- Device
- Device
- Spectrograph
- Detector
- Device
- Grating
- FilterWheel
- Slit
- xyPosition
- Coordinates
- ImageData
- FitsHeader
- Target
- Coordinates
- Ephemerides
- OrbitalElements
- RaDecList
- TargetBrightness
- TrackRate
- CalibrationObservation
- Exposure
- Dithering
- Shutter
- Observation
- ScheduleRequest
- MetaData
- LinkedBlock
- Camera
- Detector
- Chips
- Chip
- Windowing
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- Binning
- Device
- Device
- Spectrograph
- Detector
- Device
- Grating
- FilterWheel
- Slit
- xyPosition
- Coordinates
- ImageData
- FitsHeader
- Target
- Coordinates
- Ephemerides
- OrbitalElements
- RaDecList
- TargetBrightness
- Track
...
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