PIA FAQ: ======== Q-1) Can PIA reduce PHT37/38/39 data? There is a user who is complaing that ver5.0 does not handle PHT37/38/39 A-1) From version 6.4 upwards batch/AOT handling of P37/38/39 is included. If the option automatic AOT recognition is on, data corresponding to this AOT will be recognized and reduced accordingly. Also the interactive way to reduce this data is, however, possible. The FCS measurements can be interpolated for obtaining a responsivity for any of the source measurements. If instead of a linear interpolation the use of any of the two FCS measurements is desired, just obtain the responsivity from one of them and process all measurements interactively using "actual" responsivity. Q-2) Which platforms are necessary for running PIA? A-2) Unix (including Linux) as operating systems. IDL >= 5.0. Some problems with UNIX platforms other than SunOS/Solaris have occassionaly appeared and we solved them. From version 7.0 testing is performed for PIA running on SunOS/Solaris and Alpha/OSF. VMS is not further supported. Q-3) Is PIA running on IDL 5.0? A-3) Yes. From V7.0 PIA runs only on IDL 5.0 or higher. Q-4) Which is the PIA nomenclature for PHT C100/C200 pixels positioning on the sky? A-4) The positioning is as follows for a right handed coordinate system using Y- and Z-spacecraft coordinates. The Y-axis is giving the chopper axis. (Please take into account that the PIA main windows on the different levels use a left handed coordinate system to show the pixel positioning, thus 'Gods view') C200: ----------- +Z | 4 | 3 | ^ |-----|-----| | | 1 | 2 | | ----------- | | +Y<--------- C100: ----------------- +Z | 9 | 6 | 3 | ^ |-----|-----------| | | 8 | 5 | 2 | | |-----|-----|-----| | | 7 | 4 | 1 | | ----------------- | | +Y<----------- Q-5) Eg P32 maps: there are usually just a few integration ramps per chopper plateau. I understand that one can still do readout deglitching on per-ramp basis, but how is the second-stage deglitching (after ramp fitting) done with just a few signals per chopper plateau? A-5) Readout deglitching (single threshold method) can be applied if the number of read-outs per ramp is sufficiently large (by default > 12 used readouts, although this limit can be changed by the user: Test ramp deglitching). A two-thresholds algorithm can be used for readout deglitching, which is independent of the number of read-outs per ramp. Signal deglitching tries to cope with any number of signals >= 5. To increase the capability of the algorithm all signals from chopper plateaus with the same position (within a raster point) can be taken at once, thus increasing the statistics for a given chopper position. This option can be enabled/disabled by the test deglitching on the SRD level. Q-6) By running PIA I get always a bus error on the same place of the processing, losing all IDL windows. Is this a PIA bug? A-6) PIA leads to some divisions by zero when uncertainties have not been assigned. Normally this happens by values which are anyway discarded, thus not having any influence on the final result, and we are trying to get rid of them. The actually bug is given by an IDL version. Q-7) XPDMENU is no longer a part of IDL. But still used by PIA. A-7) There are certain IDL routines located under ...idl/lib/obsolete/ which are used by PIA. Please ask your system manager to install this lib too. We try nevertheless to avoid this problem by putting such routines into the support directory delivered with PIA. Q-8) When I do the "power calibration" (SCP to SPD) the SL spectrum suddenly disappears and I just have the 2.5-5.5 um spectrum at the end. A-8) We try to match the PHT pipeline as far as possible, and therefore separate the internal buffers from SPD level on, into SS and SL. From one SCP measurement you get one SS and one SL SPD measurement, respectively. Q-9) Is there an ftp site where I can get the PIA users manual ? (so pretty on www but very hard to print out for a serious read) A-9) The PIA users manual as the collection of html files and of postscript files is released with PIA. The best way of printing it is using a script/command file which sends everything in the right order to the printer. This is activated by "Print Users Manual" on Help button by the top PIA window. Q-10) this version of PIA has an option to use two fcs measurements and therefore interpolate between the measurements (correct for responsivity drifts). Our maps (produced with this version of the software) still have a responsivity drift. The sky is typically 50% higher after the galaxy has been mapped (recall we are doing P32 maps of nearby galaxies at 200um). Is the interpolated measurement really working or does it just do the job badly ? A-10) A linear interpolation between two very far away calibration measurements can work only in very few cases. We are trying to develop more fancy ways of modelling the long term responsivity drifts. A first approximation in version 6.4 giving the user the possibility of establishing graphically factors for correcting for long term drifts is already implemented. Q-11) Using PIA I cannot read the PHT products as stored in the CDRom containing my observations. What should I do? A-11) PIA works only with FITS files which are named in accordance with the official nomenclature (see IDPD), since its use allows for a preselection of files of different types. Conversion programs are available under the PIA homepage (see miscellaneous).