Multi-dimensional Data Access minimal requirements

[Arnold Rots]

That's (the rest frequency) something you specify on the spectral axis.

-------------------------------------------------------------------------------------------------------------
Arnold H. Rots                                          Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory                   tel:  +1 617 496
7701
60 Garden Street, MS 67                                      fax:  +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------------------------------------------



On Fri, Mar 7, 2014 at 10:42 AM, Peter Teuben <teuben at astro.umd.edu> wrote:

>  This does make sense if your spectral axis contains one line, but raw
> cubes
> from MUSE, or ALMA for that matter, often contain thousands of channels
> with many spectral lines.... it's good to have the doppler shift of the
> intended object in a header, but where is the decision which line to use as
> reference line?
>
>     Peter
>
>
> On 03/07/2014 10:27 AM, Arnold Rots wrote:
>
>     While appreciative of these requirements that are generally
> reasonable,
>  I have to register my strong objection to its leaving out the Doppler
> velocity
>  (Redshift) axis. I have said this over and over, and will keep repeating
> it:
>  if we don't properly distinguish between the redshift and the spectral
> axes,
>  queries and results will get confused and users annoyed.
>  Redshift or Doppler velocity constraints need to be added to Data
> Discovery
>  and to Simple Cutout.
>
>  Cheers,
>
>    - Arnold
>
>
> -------------------------------------------------------------------------------------------------------------
> Arnold H. Rots                                          Chandra X-ray
> Science Center
> Smithsonian Astrophysical Observatory                   tel:  +1 617 496
> 7701
> 60 Garden Street, MS 67                                      fax:  +1 617
> 495 7356
> Cambridge, MA 02138
> arots at cfa.harvard.edu
> USA
> http://hea-www.harvard.edu/~arots/
>
> --------------------------------------------------------------------------------------------------------------
>
>
>
> On Thu, Mar 6, 2014 at 7:14 PM, Gaudet, Severin <
> Severin.Gaudet at nrc-cnrc.gc.ca> wrote:
>
>> Hi all
>>
>>  During the Exec meeting two weeks ago, the topic of multi-dimensional
>> data access was discussed. The two main points from that discussion were:
>>
>>    - The Exec endorsed the CSP's recommendation for the minimum
>>    requirements (see below) for the first version of the necessary standards
>>    as defined by the CSP.
>>    - The Exec expressed their strong desire to see "RFC-ready" working
>>    drafts ready by the May InterOp.
>>
>>
>>  Practically speaking, the endorsement of the minimum requirements for
>> the first version of the multi-dimensional data access standards means:
>>
>>    - The preparation of the standards cannot be held up by discussion of
>>    "features" that are not necessary to meet the minimum standards
>>    - The WGs should be thinking in an agile sense where subsequent
>>    versions of a given standard with more "features" come rapidly after the
>>    first version.
>>
>>
>>  Here is my view of what standards need to be RFC-ready by the May
>> InterOp:
>>
>>    1. SIAv2 (query capability only)
>>    2. DataLink
>>    3. AccessData (for simple cutouts only)
>>
>>
>>  By implication, ImageDM,  the "get additional metadata" capability in
>> SIAv2 and other AccessData functions are not required to meet the minimum
>> requirements.
>>
>>  Just to be clear, this does not imply that work on
>> ObsCore/ImageDm/Observation data models or on complex AccessData services
>> is not required. To the contrary, after the initial versions of the
>> standards (SIA, DataLink, AccessData) are adopted, those will be the next
>> things required to meet the use cases that will be discussed in Madrid. The
>> request is to see RFC-ready standards (SIA, DataLink, AccessData) being
>> presented and discussed in May. Although SIAv2.0 will only be dependent on
>> the ObsCore, SIAv2.1 will certainly be dependent on "get additional
>> metadata" and thus on ImageDM and possibly AccessDatav1.1, ObsCorev1.1 or
>> v2.0.
>>
>>  Cheers
>> Séverin
>>
>>  --------------------------------------------------
>>
>>  Multi-dimensional Data Access minimal requirements:
>>
>>    - Data Discovery (Query)
>>       - A service shall be able to receive queries regarding its data
>>       collection(s) from a client, with the client placing one or more of the
>>       following constraints:
>>          - RA,Dec
>>          - Frequency/wavelength
>>          - Polarization states
>>          - Spatial size
>>          - Angular resolution
>>          - Integration time
>>          - Time of observation
>>       - A service shall return to the client a list of observations, and
>>       the corresponding metadata for each observation, meeting the user-imposed
>>       constraints.  In the event that the user places no constraints, the entire
>>       list of observations, and the corresponding metadata for each data set,
>>       shall be returned.  In the event that no data meet the user's constraints,
>>       the service shall indicate the absence of any matches.
>>    - Data Access
>>       - Once a user has the list of observations that satisfy the
>>       constraints, they select all or a subset of the observations and:
>>          - Download the complete science data for each of the selected
>>          observations (the service shall return the complete multi-dimensional
>>          science data and metadata for each selected observation) or;
>>          - Download simple cutouts of the science data for each of the
>>          selected observations (the service shall be able to extract and return a
>>          user-specified subset of the complete multi-dimensional science data and
>>          metadata for each selected observation).
>>        - Simple Cutout
>>       - For a simple cutout, the user-specified subset is restricted to
>>       be a contiguous interval within each dimension of the multi-dimensional
>>       science data. The user should *not* be allowed to specify subsets with
>>       "gaps" or resampling or anything like that.
>>          - Spatial: a circle (a coordinate and a radius)
>>          - Energy: one interval (from energy1 to energy2)
>>          - Time: one interval (from time1 to time2)
>>          - Polarization: a list
>>
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.ivoa.net/pipermail/dal/attachments/20140307/36571749/attachment-0001.html>