From pds-webserver created by rfrenchseti: SETI/pds-webserver#20
Hi. I was just wrapping up my task of helping Jeff Cuzzi with his brightness calibration, and I ran into what may be a problem with our metadata.
We’ve been focusing on the image N1493555099, which is from Rev 007, observation LATPHASE001. Jeff likes to use solar hour angle instead of inertial longitude, so I was looking at the subsolar longitude as an essential part in making that conversion. I thought I would direct Jeff to OPUS to find values of subsolar longitude when he needs them, when I noticed that the values in OPUS for this parameter do not agree with mine.
My code calculates the subsolar longitude as 171.772 degrees. I created this code years ago, in concert with Joe Spitale when he was creating the code that calculates the metadata values that were used by the Cassini Imaging Team. The Imaging Team metadata now resides at the Imaging Node, so it is not a surprise that the value in that database is a very similar 171.782 degrees, as you can see here:
https://pds-imaging.jpl.nasa.gov/search/?fq=ATLAS_MISSION_NAME%3Acassini&fq=OBSERVATION_ID%3A*007RI_LATPHASE001*&fq=ATLAS_INSTRUMENT_NAME%3Aiss&q=*%3A*
Actually, the Imaging Node does not have several of the nice features that we have. To get the display I want, do the following:
1) Select List View
2) Select the Results pulldown menu and choose a value greater than 100
3) Select the “Add field to sort by” pulldown menu and choose RINGPLANE_SUBSOLAR_LONGITUDE
4) Textsearch on N1493555099 to find the entry in question.
Furthermore, Jeff and his student Nadim are using solar hour angles for this image that closely correspond to the ones I am calculating, so we have three different people calculating the same value for subsolar longitude, and OPUS to the contrary.
This is not a weekend-urgent issue, but it may be something to address next week.
Matthew S. Tiscareno, Senior Research Scientist
SETI Institute, 189 Bernardo Avenue #200, Mountain View CA 94043
jnspitale
commented
1 month ago
From pds-webserver created by rfrenchseti: SETI/pds-webserver#20
Hi. I was just wrapping up my task of helping Jeff Cuzzi with his brightness calibration, and I ran into what may be a problem with our metadata.
We’ve been focusing on the image N1493555099, which is from Rev 007, observation LATPHASE001. Jeff likes to use solar hour angle instead of inertial longitude, so I was looking at the subsolar longitude as an essential part in making that conversion. I thought I would direct Jeff to OPUS to find values of subsolar longitude when he needs them, when I noticed that the values in OPUS for this parameter do not agree with mine.
Here is the OPUS metadata entry for the image in question: https://tools.pds-rings.seti.org:8080/#/instrument=Cassini+ISS&CASSINIspacecraftclockcount1=1493555099&CASSINIspacecraftclockcount2=1493555100&qtype-CASSINIspacecraftclockcount=any&cols=opusid,instrument,planet,target,time1,observationduration&widgets=CASSINIspacecraftclockcount,instrument,planet,target&order=time1,opusid&view=detail&browse=gallery&cart_browse=gallery&startobs=1&cart_startobs=1&detail=co-iss-n1493555099 Text searching on “sub-solar” yields the following relevant entries: Sub-Solar IAU West Longitude (degrees): 151.427 Sub-Solar J2000 Longitude (degrees): 302.359 If I understand correctly, the IAU West Longitude is measured from Saturn’s (rotating) prime meridian, but the J2000 Longitude should be what we want.
My code calculates the subsolar longitude as 171.772 degrees. I created this code years ago, in concert with Joe Spitale when he was creating the code that calculates the metadata values that were used by the Cassini Imaging Team. The Imaging Team metadata now resides at the Imaging Node, so it is not a surprise that the value in that database is a very similar 171.782 degrees, as you can see here: https://pds-imaging.jpl.nasa.gov/search/?fq=ATLAS_MISSION_NAME%3Acassini&fq=OBSERVATION_ID%3A*007RI_LATPHASE001*&fq=ATLAS_INSTRUMENT_NAME%3Aiss&q=*%3A* Actually, the Imaging Node does not have several of the nice features that we have. To get the display I want, do the following: 1) Select List View 2) Select the Results pulldown menu and choose a value greater than 100 3) Select the “Add field to sort by” pulldown menu and choose RINGPLANE_SUBSOLAR_LONGITUDE 4) Textsearch on N1493555099 to find the entry in question.
Furthermore, Jeff and his student Nadim are using solar hour angles for this image that closely correspond to the ones I am calculating, so we have three different people calculating the same value for subsolar longitude, and OPUS to the contrary.
This is not a weekend-urgent issue, but it may be something to address next week.
Matthew S. Tiscareno, Senior Research Scientist SETI Institute, 189 Bernardo Avenue #200, Mountain View CA 94043