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thespacedoctor / sherlock

The QUB Transient Classifier
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Seemingly obvious SN candidate classified as ORPHAN #121

Closed genghisken closed 3 years ago

genghisken commented 4 years ago

This object was classified as an ORPHAN by Sherlock.

There's definitely a PS1 source nearby and the PS1 imagery shows a clear galaxy. Curious to know how it got an ORPHAN classification.

https://star.pst.qub.ac.uk/sne/atlas4/candidate/1000749640184852800/

thespacedoctor commented 3 years ago

A search within 5 arcsec on the MAST archive on the PS1 DR1 mean objects tables yields a match:

But the same search on the stacked objects tables (same data we have in the Sherlock database) returns nothing!

The same is true for PS1 DR2. Note ndetections for this object is 2, so my take on this is that there was not enough PS1 data in this area to go into making a stack. I'm also not sure I would blindly trust PS1 mean object data with less than 3 detections.

Take-away here is that this is a catalogue issue and not a Sherlock algorithm issue.

On a positive note, running Sherlock with the NED flag switched on finds a match:

The transient is possibly associated with WISEAJ000749.68-184842.6; a 17.21 mag galaxy found in the NED catalogue. It's located 7.70" S, 1.00" W from the galaxy centre.