Posted by
chrismlt on
Feb 24, 2016; 12:52pm
URL: http://astroimagej.170.s1.nabble.com/sn-2016adj-tp356p357.html
Karen,
Sorry to have to ask this, once more:-(
The images linked in the previous post by my friend André were taken with the 2m Faulkes South Telescope, Siding Spring.
We were trying to do some photometry on the SN2016adj, which is located inside the Centaurus A Gx.
It appears that, for some reason, in the last of the 3 images, the centroid can't be set to the target.
The SN is the small star very near a bright star, some distance to the right of the center of the galaxy (it looks like a bright double star).
When trying to put an aperture to this star, the centroid stick to the nearest bright star. The only way to go through this is to disable centroid detection, which is not totaly satisfying.
More, the same centroid trouble is to be found in some images taken with a 1m tel.
Here is a link to one of the faulty images :
http://dl.free.fr/getfile.pl?file=/I3dVuNtoIt seems the centroid detection is false when the targeted star flux is small vs that of the near bright star.
By the way, the astrometrical plate solving, which I tried for testing purpose failed for all of the one-meter-telescope images. AIJ seems to be not able to find enough stars for submission success, no matter the setting entered in the « Astrometry settings » screen ; plus, many hot pixels were detected as stars (this can be controled by adjusting the noise tolerance well above 1 : 5 to 10 seems better). Fortunately those images where already plate solved at the observatory, so it don't really matters here. Anyway do you have any advice to deal with this, should this happening for other non-solved images, as to detect more efficiency the field stars before submission ?
Thank you so much,
Sincerely,
Christophe