R. Tuffs et al.
20 December 2006
The Highly Processed Data Product was compiled by A. Moor and P. Abraham (Konkoly Observatory, Budapest, Hungary)
The authors present 124 ISOPHOT observations (184 measurements) of a sample of 63 galaxies later than S0 selected from the Virgo Cluster Catalogue of Bingelli, Sandage, & Tamman. Galaxies were observed in P32 mode with the C100/C200 detectors.
The data set consists on:
Supporting reference is: R. Tuffs et al., The Astrophysical Journal Supplement Series, Volume 139, Issue 1, pp. 37, 2002.
List of caveats related to P32 observing mode corrected in this work:
Data were reduced using algorithms specifically developed for the analysis of P32 observations. The most important functionality of these new procedures is the correction of the transient response behaviour of the Ge:Ga photoconductor detectors of ISOPHOT.
The final part of the transient correction procedures is a reassignment of the uncertainties in the photometry. This is done by examining the scatter in the solutions obtained for each chopper plateau and is a measure of the irreproducibility of the solution caused by imperfections in the detector model and/or glitch-induced stochastic undulations in the detector responsivity. This procedure yields a more representative measure of the true random uncertainty in the maps than uncertainties derived from the original fits to the integration ramps.
All of the listed sources were observed after revolution 94.
Flux extraction was performed by fitted two-dimensional Gaussians models to the maps. However, it was necessary to fit different combinations of models, according to the different morphologies encountered in the sample, such as single Gaussian fit, two Gaussian fit, multicomponent fit, and also a beam fit for pointlike sources. Based on the statistics given by the error analysis, we decided on a case-by-case basis which better fits the data.
This was done by subtracting a tilted plane obtained from a fit to the extremities of the map (external to the extent of the source). In principle, this should provide a better statistical measure of the source brightness near the map center than subtracting individual baselines from each map row.