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This seems to confirm the centroiding problem. C offset is usually the safest location mode. Tom Richards > -----Original Message----- > From: > owner-vsnet-campaign-ccd-discussion@ooruri.kusastro.kyoto-u.ac.jp > [mailto:owner-vsnet-campaign-ccd-discussion@ooruri.kusastro.ky > oto-u.ac.j > p]On Behalf Of Marc Bos > Sent: Tuesday, July 15, 2003 9:04 PM > To: tom@woodridgeobsy.org > Cc: 'Taichi Kato'; > vsnet-campaign-ccd-discussion@ooruri.kusastro.kyoto-u.ac.jp; > vsnet-chat@ooruri.kusastro.kyoto-u.ac.jp > Subject: [vsnet-campaign-ccd-discussion 93] Re: [vsnet-chat 6702] RE: > (fwd) problems with AIP4win > > > Yes I was discribing an older version but now have rerun the > test with the > latest . However I would have expected the fisrt version to > be reliable but it > seems not. > > Since having made some comments about AIP4win, I have put the > latest version > through its paces, the aperture photometry that is. I > commented that when > comparing AIP4win results with those of Munipack 2.2 the > later showed less > scatter. 2 sets of stars between Mag 12.5 & 13 were measured > in 163 frame. > > I have rerun the data and come up with some results > > 1 ) The quality of the output data seems to dependent on the telescope > tracking > When all the images are aligned to remove tracking errors > like declination > drift > and periodic errors the results are as good as that of > Munipack 2.2 but not > the > same. However if you just let the apertures track on the > image the results > are > not as good > > The results from both reduction programs were close but not > the same, The > delta > magnitude of first pair of stars agreed to 0.01mag the > other pair to 0.02. > The SD for Munipack were 0.010 & 0.012 for AIP4win on the > aligned images 0.011 > & > 0.012 and on the nonaligned images 0.014 & 0.015 . > These were taken with a .3m SCT and a ST6b at medium resolution. > The best aperture for AIP4Win was 3pr and Munipack 2.5pr the > sky annulus for > both was set at IS 10pr OS 30pr (AIP4Win now lets u set the > inside sky > annulus) > > 2) One of the stars which I wanted to measure to include with > these results > would not let it self be measured either in the aligned data > set or the > unaligned data set. On close inspection of the image I could > see a fainter > star > about 5 pixels north of the target. The aperture insisted in > placing itself > between the two stars. Selecting the VCK tracing mode for > moving targets > fixed > this. > > Marc Bos > > Tom Richards wrote: > > > AIP4Win does allow you to set the inner sky annulus. > However it does have > > some problems with centroiding: I've noticed they show up > particularly if > > you're using it on moving objects, as you might expect. > This may give rise > > to the problems described in this thread. I find MaxIm far > better in this > > regard. > > > > Tom Richards >
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