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Virtis / Venus Express demo

Authors

S. Erard, B. Cecconi, P. Le Sidaner, F. Henry, R. Savalle, C. Chauvin

Change Log

VersionNameNotes
1Keyuan YinFirst converted
2Keyuan YinUpdated version below

Steps

Go to VESPA web site

  • Check "All VO" to access public data services
  • Enter search parameters:
    e.g.:
    Target_Name = Venus Dataproduct_type = cube
  • Add constraints/filters
    For instance:
    time_min = 3/6/2006 & time_max = 28/8/2006
    C2_max (= latitude) < 0 [in Location tab]
1

Service results

  • In line VVEx, click the "Display results" icon to get result list

You can also click "Advanced query form" to access specific parameters (local time...)

2

Query results

Result is a list of files matching the query

  • Click "Show all" to see other parameters
  • Hover the mouse to see thumbnails
  • Click to select one or more lines & click "Data selection" / Download
    to download files from the PSA
3

Displaying footprints

  • Select correct target

  • Click "Footprints" / Send GeoJSON to display bounding box in Mizar

  • Click "Footprints" / Send s_region to display footprint in Aladin

  • "GeoJSON" will open Mizar in a new browser tab and display the bounding box on a 3D sphere

  • "s_region" will launch Aladin and display a more precise footprint on a 3D sphere, here as a red contour (first load HIPS file of target manually to display background map) In both cases you can rotate, zoom in/ out, etc

4 5

Launch VO tools either from buttons or from your system
Favorite tools include:
Aladin and DS9: images and cubes
TOPCAT: tables & catalogues
CASSIS & SPLAT/Specview/VOspec: spectra

6

Analysing dataset

Click All Metadata / Send Table => TOPCAT will receive a description of all files
You can also select some lines & click Metadata selection

In TOPCAT, double-click table name to open it
Click menu buttons to get description of fields

7 8
  • Click Sky-plotting icon [or menu Graphics/Sphere plot (old) ]
    Select parameters c1min & c2min (= lon / lat min - this is not the entire cube footprints)
    => Spherical map
    In Form tab, select Mode = Aux with Local_time_min as parameter to get colors
    (coordinate -c1min should be used to get a correct plot in longitude; it is interpreted as a right ascension. Sphere plot from the Graphics menu uses c1min)
9
  • Click plane-plotting icon
    Select parameters C1min & C2min => Cylindrical map
    Some values are out of bound
    Select region of correct points
    (0/360 degree and -90/90 degree) with shift-drag andclick "Define subset"
    Call it "OK2"
10
  • continue: Click plane-plotting icon
    Select parameters time_min & C2min
    Select OK2 in Subsets tab
    Select Mode=Aux & C1min in Form tab => Coverage through time
    Clicking a point in any plot enlights it in other plots and tables => you can easily track outliers
11
  • In plane plot, click SizeXY option

In c1min vs c2min plot, define coordinates and sizes as in example.
This provides a rough approximation of the footprints in cylindral projection (the actual footprints are inside the boxes)

12

Analysing cubes

Select one line & click "Data Selection" / Send VIRTIS PDS cubes (use a VIRTIS-M cube, with name starting in VI or VV)

=> will send a cube to APERICubes

13

Visualization of spectral cubes

Validate all dialogues (and wait a bit)
Will open a new tab in your browser
Select channel 75 (O2 emission on night side)
Adjust contrast by clicking & dragging mouse over image
Click location in image
corresponding spectrum will plot below
You can also select a box region and move it on the image => average spectrum and box statistics

(with VOtools launched)
Check Samp status
(if not connected click "Register with SAMP HUB")
Click on a "Send... via SAMP" button
Images and cubes will display in Aladin
Spectra will display in TOPCAT, CASSIS, VOspec, Specview, etc
(PDS3 data have been read & converted to FITS files in a local IDL or GDL session)

14 15

Future developments to be implemented:

  • Geometry parameters: illumination angles, disk intercept, tangent altitude, etc
  • Cube footprints (KML / GoogleEarth type?) + mosaicking in a GIS or Aladin
  • Link to related geometry file
  • Bulk download from VESPA (on PSA side? Should accept a VOTable with URLs)
  • PDS3 reader/FITS converter (see APERICubes, currently a demo, & link to VESPA) Currently handles only M cubes, no geometry.
    All these points to be studied during Europlanet H2020

Spectral tools: TOPCAT

TOPCAT receives spectra from APERICubes, can overplot selections

  • Use Plane plot & check parameters
  • Click New line form to connect spectral channels
  • Click Add new plot to overplot spectra
16

Spectral tools: Specview

Specview receives spectra from APERICubes
Includes analysis functions

  • Click on Measure to perform continuum and band measurements
17
  • continue Click on "Line IDs" to query band line databases (from VAMDC)
    pick uprelevant ones
18

Spectral tools: CASSIS

CASSIS receives spectra from APERICubes, can overplot a selection of spectra and manipulate them

  • Click the Tools tab to combine spectra Spectra are resampled to a common wvl vector on the fly
    The Species tab accesses internal line databases (most of them related to the ISM) Includes LTE and RADEX modeling

  • Press shift to get info on mouse location Alt-drag to select a region (used in Fit tab) Alt-click to put markers

19

Spectral tools: VOSpec

VOSpec receives spectra from APERICubes, but does not recognize units

  • Select Wavelength in micron & Flux in W/m2/��m in input pannel
    Then uncheck "Log" in axes & reselect "W/m2/��m" in flux menu
  • Select "Line" to connect channels

Currently does not understand radiance ( W/m2/sr/��m) or reflectance - being discussed with ESA

20
  • continue Click Simple Line Access button
    Select area of interest
    Select spectral databases in new window
    Once loaded, lines are identified on mouse-over
  • Uses an older protocol which retrieves all lines in a given range => long and busy
    Databases mostly related to the ISM (atoms)

Fitting functions available in Operations menu

21

Future developments to be implemented:

  • Geometry parameters: illumination angles, disk intercept, tangent altitude, etc
  • Cube footprints (KML / GoogleEarth type?) + mosaicking in a GIS or Aladin
  • Link to related geometry file
  • Bulk download from VESPA (on PSA side? Should accept a VOTable with URLs)
  • PDS3 reader/FITS converter (see APERICubes, currently a demo, & link to VESPA) Currently handles only M cubes, no geometry.
    All these points to be studied during Europlanet H2020

VESPA to APERICubes connection (demo)
During the test phase:

  • Download library jsamp
    http://dev.lsstcorp.org:8081/nexus/content/repositories/ccs-maven2/org/astrogrid/jsamp/1.3.5/

  • Launch from terminal with options:
    java -jar jsamp-1.3.5.jar hub -web:norestrictmtypes & (this is currently required to handle the special file type)

  • Go to APERICubes page and register to the SAMP hub as previously

  • Go to VESPA page, select one VIRTIS file as previsouly

  • In menu SAMP selection as pick up cubes PDS VIRTIS (for the sake of the demo)

  • Validate dialogues (one in pop-up window + one in the browser)

  • Click Process SAMP cube in APERICubes page

  • Proceed as previously

22

Powerful searches on location

In Direct Query tab

  • Select service
  • Enter ADQL query on s_region footprint

Will return cubes with footprint intersecting or containing a polygon, circle, or point

23

VO functions

  • VESPA provides search functions to the PSA VVEx dataset
  • TOPCAT provides quick-look of table information
  • APERICubes will provide on-line visu & basic analysis functions to a single cube Will also provide conversion from PDS3 to VO format (FITS) & link with other VOtools
  • Aladin, Specview, CASSIS, etc can display images / cubes / spectra from APERICubes
24

Search other datasets
VESPA sends queries to several data services in parallel. In the long term it will access:

  • other VEx instruments => Cross correlate all VEx measurements with a single query
  • derived data / results of various analyses from VIRTIS (outside PSA)
  • reference data, other Venus missions, coordinated ground-based observations, lab spectra, simulations, etc
25

Possible extension to the Virtis VEx data service

22

References

Please refer this tutorial to PDF file uploaded on VESPA wiki and also the website

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