Return to Home Page
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 > > > (fwd) problems with AIP4win > > > > The following message is from Marc Bos in response to my finding. > > Forwarded here with permission. He is now on these lists, > > and follow-up > > message to these lists will reach him. > > > > === > > > > Normally I don't follow the discussions on VSnet but your > > comments about > > AIP4Win were forwarded to me . I have also found problems with this > > software and therefor don't use it . I prefer DAOPHOT II in > > the form of > > Munipack 2 by Rudolf Novac and his collaborators. When comparing the > > output of both these packages I find that the scatter in the > > comparison > > data is consistently higher for AIP4Win by about 40% . Part of the > > problem could be that AIW4Win dose not allow one to set a > > value for the > > inner sky annulus, so effectively you could be including some of the > > stars light in the sky back ground subtraction. Also, how dose the > > software deal with fractions of pixels, hot pixels and stars > > in the sky > > annulus .I know that DAOPHOT dose it very well. Just some thoughts on > > the matter. I'll keep using DAOPHOT untill something better > > comes along > > but I can't see that happening in a hurry. > > > > Kind regards > > Mrac Bos > > > > Mt Molehill Observatory > > Otahuhu, AKL > > New Zealand > >
Return to the Powerful Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
