Does anyone know how Maxim DL computes ensemble photometry? I would like to know if this software gives all stars in an enseble the same weight as AIP4WIN does. I would also like to know if Maxim DL excludes some percentage of pixels from the computation of the sky background. I can recall that AIP4WIN excludes the brightest and faintest pixel values from the sky annulus (+/- 20%) so that it can reliably compute the value of the sky background in case of intrusion of unwanted stars in the sky annulus with the single exception of the most crowded star fields.
Finally I would like to know where I can find equations to transform instrumental magnitudes, obtained with an ensemble, into the standard system. I am using the Sarty's equation to apply the transformation coefficients of my system but I am using the traditional approach with one comp and one check star at the moment.
Thank you for your help
Gianluca
Hello Gianluca
The last time I looked at the ensemble from Maxim, which was maybe 10 years ago, it scales the photometry so that the sum of the magnitudes in the ensemble are a constant approx = n * comp mag, where n is the number of comp stars in the ensemble.
Maxim does exclude some pixels in the sky anulus to get rid of outliers, but their algorithm is proprietary and the details are not disclosed.
Transforming with an ensemble is a topic for Arne to discuss.
I would suggest that you post the other 2 questions to the Maxim Discussion Group on Yahoo or post a Ticket with the Maxim Support, just to make sure things have not changed recently.
Gary