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  1. Data Management
  2. DM-34693

Investigate lack of solar system matches in ap_verify runs

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    Details

    • Type: Story
    • Status: Done
    • Resolution: Done
    • Fix Version/s: None
    • Component/s: ap_association, ap_verify
    • Labels:
      None

      Description

      DM-33821 found that we are not matching solar system objects to DIASources in either ap_verify_ci_hits2015 or ap_verify_ci_cosmos_pdr2.

      The starting point for the investigation should be identifying which solar system objects are detectable. ap_verify_ci_hits2015 has 416 objects in its caches, but according to SolarSystemAssociationTask only 5 appear in the restricted visit footprints (expect <~13, given that the search radius for the ephemerides is conservative). For ap_verify_ci_cosmos_pdr2, it's 1 object out of 594 in the caches (expect <~5). Until we know which objects are being considered for association, we can't evaluate e.g. the objects' magnitudes.

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        1. 2003_ss69.png
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        2. parallax.png
          parallax.png
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            Activity

            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            The five objects in the HiTS field are:

                   # Num          Name        Class    Mv  Err(arcsec)    Dg(ua)    Dh(ua)  Phase(deg)         ssObjectId  visitId
            77   227477    2005 WV185    MB>Middle   19.6        0.220  1.917858  2.869382        6.26  53569918513453402   411371
            9         -    2015 DL180     MB>Outer   21.4        0.740  2.118523  3.069327        5.82  43707620656988304   411420
            11    93419    2000 SS305    MB>Middle   20.1        0.226  2.151946  3.102871        5.74  44866635817748191   411420
            12   503735     2016 LG24     MB>Outer   21.3        1.491  2.169487  3.120478        5.69  15168997349454932   411420
            26   192000     2005 XW67    MB>Middle   19.1        0.173  1.583128  2.542704        6.93  26697415027480166   419802
            

            The object in the COSMOS field is:

                  # Num         Name       Class    Mv  Err(arcsec)    Dg(ua)    Dh(ua)  Phase(deg)        ssObjectId  visitId
            7   276537    2003 SS69    MB>Outer   20.1        0.266  1.993244  2.949244        6.07  4362913742843557    59160
            

            At first glance, all of these should be detectable and matchable.

            Show
            krzys Krzysztof Findeisen added a comment - - edited The five objects in the HiTS field are: # Num Name Class Mv Err(arcsec) Dg(ua) Dh(ua) Phase(deg) ssObjectId visitId 77 227477 2005 WV185 MB>Middle 19.6 0.220 1.917858 2.869382 6.26 53569918513453402 411371 9 - 2015 DL180 MB>Outer 21.4 0.740 2.118523 3.069327 5.82 43707620656988304 411420 11 93419 2000 SS305 MB>Middle 20.1 0.226 2.151946 3.102871 5.74 44866635817748191 411420 12 503735 2016 LG24 MB>Outer 21.3 1.491 2.169487 3.120478 5.69 15168997349454932 411420 26 192000 2005 XW67 MB>Middle 19.1 0.173 1.583128 2.542704 6.93 26697415027480166 419802 The object in the COSMOS field is: # Num Name Class Mv Err(arcsec) Dg(ua) Dh(ua) Phase(deg) ssObjectId visitId 7 276537 2003 SS69 MB>Outer 20.1 0.266 1.993244 2.949244 6.07 4362913742843557 59160 At first glance, all of these should be detectable and matchable.
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            We looked at this in pair coding with Eric Bellm, Kenneth Herner, and Clare Saunders. We didn't see an obvious calexp source for any of the three predicted objects in HiTS visit 411420, so we suspect that the bug is in SkyBotEphemerisQueryTask. It's not obvious at first glance how to verify its outputs, though.

            Show
            krzys Krzysztof Findeisen added a comment - - edited We looked at this in pair coding with Eric Bellm , Kenneth Herner , and Clare Saunders . We didn't see an obvious calexp source for any of the three predicted objects in HiTS visit 411420, so we suspect that the bug is in SkyBotEphemerisQueryTask . It's not obvious at first glance how to verify its outputs, though.
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            I found a bug: _decdms2decdeg does not work correctly for negative angles (e.g., -06 14 41.102 gets converted to -5.755249).

            However, this does not explain the COSMOS failure, since that one is at +2 degrees, and I checked the coordinate conversion by hand.

            Show
            krzys Krzysztof Findeisen added a comment - - edited I found a bug: _decdms2decdeg does not work correctly for negative angles (e.g., -06 14 41.102 gets converted to -5.755249). However, this does not explain the COSMOS failure, since that one is at +2 degrees, and I checked the coordinate conversion by hand.
            Hide
            ebellm Eric Bellm added a comment - - edited

            We should replace both of _decdms2decdeg and _rahms2radeg with calls to astropy.coordinates or similar. (Ah, this is already ticketed: DM-31934)

            Show
            ebellm Eric Bellm added a comment - - edited We should replace both of _decdms2decdeg and _rahms2radeg with calls to astropy.coordinates or similar. (Ah, this is already ticketed: DM-31934 )
            Hide
            kherner Kenneth Herner added a comment -

            Pushed a notebook covering today's pair coding session here: https://github.com/lsst-dm/ap_pipe-notebooks/tree/tickets/DM-34693/notebooks

            Show
            kherner Kenneth Herner added a comment - Pushed a notebook covering today's pair coding session here:  https://github.com/lsst-dm/ap_pipe-notebooks/tree/tickets/DM-34693/notebooks
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            I found 2003 SS69 in the COSMOS field! At least, I have a bright source that's moving in the right direction at just under the right speed (expected 2.5" trail (30.58"/h over 300 s), got 2.1") and doesn't show up in DSS/SDSS. It's 6-8 arcsec away from where it should be, consistent with the ephemeris being generated 14 minutes too late.

            Show
            krzys Krzysztof Findeisen added a comment - - edited I found 2003 SS69 in the COSMOS field! At least, I have a bright source that's moving in the right direction at just under the right speed (expected 2.5" trail (30.58"/h over 300 s), got 2.1") and doesn't show up in DSS/SDSS. It's 6-8 arcsec away from where it should be, consistent with the ephemeris being generated 14 minutes too late.
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            Final update for tonight: the detection statistics with DM-31934 are:

            HiTS
            Image 419802-10: 1/2 detected		2007 TC479, possible faint source
            					2017 OY31, off-center
            Image 419802-5: 0/1 detected		2013 TZ136, no obvious source
            Image 411371-56: 1/1 detected		2007 KX1, off-center
            Image 411371-60: 0/0 detected
            Image 411420-10: 0/0 detected
            Image 411420-5: 1/1 detected		2003 HH10, off-center
             
            COSMOS
            Image 59160-51: 0/1 detected		2003 SS69, far off-center
            Image 59150-50: 0/0 detected
            

            All the asteroids that I can identify in cutouts (now up to 200×200) are "behind" the predicted position and proper motion vector, so I think the next step is to look for a systematic error in the epoch.

            Show
            krzys Krzysztof Findeisen added a comment - - edited Final update for tonight: the detection statistics with DM-31934 are: HiTS Image 419802-10: 1/2 detected 2007 TC479, possible faint source 2017 OY31, off-center Image 419802-5: 0/1 detected 2013 TZ136, no obvious source Image 411371-56: 1/1 detected 2007 KX1, off-center Image 411371-60: 0/0 detected Image 411420-10: 0/0 detected Image 411420-5: 1/1 detected 2003 HH10, off-center   COSMOS Image 59160-51: 0/1 detected 2003 SS69, far off-center Image 59150-50: 0/0 detected All the asteroids that I can identify in cutouts (now up to 200×200) are "behind" the predicted position and proper motion vector, so I think the next step is to look for a systematic error in the epoch.
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            I've got it! The problem is parallax: by default, SkyBotEphemerisQuery computes ephemerides for Cerro Pachon. This gives a modest error for DECam data (Cerro Tololo) and a huge one for HSC data (Mauna Kea). So the solution is to use a custom config before we call SkyBotEphemerisQuery when maintaining the ap_verify datasets (geocentric observer isn't good enough; that's Obs=500 in the attached image). It's not a bug in the task itself.

            Show
            krzys Krzysztof Findeisen added a comment - - edited I've got it! The problem is parallax: by default, SkyBotEphemerisQuery computes ephemerides for Cerro Pachon. This gives a modest error for DECam data (Cerro Tololo) and a huge one for HSC data (Mauna Kea). So the solution is to use a custom config before we call SkyBotEphemerisQuery when maintaining the ap_verify datasets (geocentric observer isn't good enough; that's Obs=500 in the attached image). It's not a bug in the task itself.
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            FTR, the final results are:

            HiTS
            Image 419802-10: 1/2 detected		2007 TC479, not detected
            					2017 OY31
            Image 419802-5: 0/0 detected
            Image 411371-56: 1/1 detected		2007 KX1
            Image 411371-60: 0/0 detected
            Image 411420-10: 0/0 detected
            Image 411420-5: 1/1 detected		2003 HH10
             
            COSMOS
            Image 59160-51: 1/1 detected		2003 SS69
            Image 59150-50: 0/0 detected
            

            It's not clear why 2007 TC479 is missing, since it's not supposed to be particularly faint.

            There's still a systematic offset between the predicted and observed positions that's smaller than the 2" matching radius. Fixing that has been deferred to DM-34906 (possibly with a larger data set).

            Show
            krzys Krzysztof Findeisen added a comment - - edited FTR, the final results are: HiTS Image 419802-10: 1/2 detected 2007 TC479, not detected 2017 OY31 Image 419802-5: 0/0 detected Image 411371-56: 1/1 detected 2007 KX1 Image 411371-60: 0/0 detected Image 411420-10: 0/0 detected Image 411420-5: 1/1 detected 2003 HH10   COSMOS Image 59160-51: 1/1 detected 2003 SS69 Image 59150-50: 0/0 detected It's not clear why 2007 TC479 is missing, since it's not supposed to be particularly faint. There's still a systematic offset between the predicted and observed positions that's smaller than the 2" matching radius. Fixing that has been deferred to DM-34906 (possibly with a larger data set).
            Hide
            krzys Krzysztof Findeisen added a comment - - edited

            Thanks for agreeing to do this, Ari Heinze, and sorry for the mix-up!

            A brief summary, since I understand you're still getting oriented with the Stack:

            • ap_association#150 has the code changes done to fix this issue. It's about 80 lines between the bugfixes and the unit tests.
            • ap_pipe-notebooks#70 is a scratch notebook used for debugging. You can see a render of the notebook if you select "View File" from the upper right corner of the diff display. Notebook reviews tend to be fairly informal, since it's hard to make line comments and they aren't held to the DM coding standards anyway.
            • obs_subaru#419 and obs_decam#222 add centralized config files that are automatically detected and loaded by the pipeline framework (which is why you won't find them explicitly mentioned in the code or pipelines). The task being configured is one of the two being fixed in ap_association.
            • ap_verify_ci_hits2015#40, ap_verify_hits2015#45, and ap_verify_ci_cosmos_pdr2#29 are special, self-contained datasets for ap_verify. The primary change is to the input data (which needed to have their coordinates fixed), but the supporting pipelines are updated so that they actually use the configs added to obs_subaru or obs_decam, as appropriate.

            For ap_association, there are a large number of unrelated but partially overlapping changes, so I recommend looking at the changes one commit at a time to keep them straight.

            Show
            krzys Krzysztof Findeisen added a comment - - edited Thanks for agreeing to do this, Ari Heinze , and sorry for the mix-up! A brief summary, since I understand you're still getting oriented with the Stack: ap_association#150 has the code changes done to fix this issue. It's about 80 lines between the bugfixes and the unit tests. ap_pipe-notebooks#70 is a scratch notebook used for debugging. You can see a render of the notebook if you select "View File" from the upper right corner of the diff display. Notebook reviews tend to be fairly informal, since it's hard to make line comments and they aren't held to the DM coding standards anyway. obs_subaru#419 and obs_decam#222 add centralized config files that are automatically detected and loaded by the pipeline framework (which is why you won't find them explicitly mentioned in the code or pipelines). The task being configured is one of the two being fixed in ap_association . ap_verify_ci_hits2015#40 , ap_verify_hits2015#45 , and ap_verify_ci_cosmos_pdr2#29 are special, self-contained datasets for ap_verify . The primary change is to the input data (which needed to have their coordinates fixed), but the supporting pipelines are updated so that they actually use the configs added to obs_subaru or obs_decam , as appropriate. For ap_association , there are a large number of unrelated but partially overlapping changes, so I recommend looking at the changes one commit at a time to keep them straight.

              People

              Assignee:
              krzys Krzysztof Findeisen
              Reporter:
              krzys Krzysztof Findeisen
              Reviewers:
              Ari Heinze
              Watchers:
              Ari Heinze, Eric Bellm, Ian Sullivan, Kenneth Herner, Krzysztof Findeisen
              Votes:
              0 Vote for this issue
              Watchers:
              5 Start watching this issue

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