ROSAT Guest Observer Facility

ROSAT Status Report #53:

Mar 26, 1993






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[                    HINTS & POINTERS for PROS Users                   ]
[   26 MARCH 1993                                                #7    ]
[                                                                      ]
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1.0 PROS Patch 2.1.2 - new PSPC matrix
2.0 Indexes for PROS tasks - provided by E. Schlegel (NASA/GSFC)
3.0 QPMERGE - how to deal with observation segments processed separately
4.0 System Notes for SAOIMAGE and Post-Script output

1.0 PROS Patch 2.1.2 - new PSPC matrix :M. Conroy

Notification of this patch will be made to all registered sites. This patch installation does NOT require a re-build of PROS. It includes only updated calibration files, parameter files, scripts, and help files that require only an 'un-tar' for SUN systems, and one data file installation for non-Sun systems.

New features in PROS patch 2.1.2 - 3/22/93

XSPECTRAL

The latest PSPC detector response matrix and off-axis area file from MPE have been installed and are now the DEFAULT value in 'pkgpars'. (These files: dtmat_36, offar2_6, offar1_6, are equivalent to the 93jan12 file in XSPEC). Additionally, the default channels to fit have been changed from 2:34, to 3:34. The parameters and values are:

	ros_dtmat = "xspectraldata$dtmat_36.ieee"
	ros_offar = "xspecraldata$offar2_6.ieee"
	ros_pspc_cha = "3:34"

Please 'unlearn pkgpars' to activate this.

The previous versions of the calibration files are still available and can be recalled by users, if desired, by resetting the above parameters.

XDATAIO

RARC2PROS
This is a new script task to convert files retrieved from the ROSAT archive to PROS format. It recognizes either US or MPE format files and does all the necessary conversions (including a QPSORT) that are required by PROS. In addition the WCS parameters in the header are edited to correct the ~1 pixel error problem in the original FITS files.
RFITS2PROS
Support has been added for additional files for PSPC: EVRAT file (file 18) and the Aspect Quality (file 25). If they have been retrieved from tape and are available in the directory a *_evr.tab file and/or a *_qlt.tab file will be produced containing this info. (To retrieve them, just add the above file numbers to the list when running 't2d') These can be examined using the usual TABLES tasks, such as TPRINT,SGRAPH, etc.

2.0 Indexes for PROS tasks - provided by E. Schlegel (NASA/GSFC)

In the anonymous ftp directory /pub/pros/PUG, we have added a cross-indexing of PROS, STSDAS, and useful IRAF tasks. This is an ASCII file, roughly 39 pages long, called "indexes.asc"

3.0 QPMERGE - how to deal with observation segments processed separately

3.1 General
3.2 Spatial
3.3 Timing
3.4 Spectral

3.1 General - D. Harris

Most Rosat observations consist of more than one observation interval, "obi", and these have been merged in the SASS processing. However, when it became apparent that probable startracker problems produced misalignment (often on the scale of 15") for segments separated by 6 months (and in at least one case of an HRI observation which had 3 "observing seasons", the two segments separated by a year were correctly aligned but the 6 month segment was misaligned), MPE decided to no longer merge data taken from different "seasons".

When we (RSDC/SAO) learned of this decision, we realized that we would have to up the priority of coding the "qpmerge" tool which had been in the queu for some time. Our current plans (Mar 93) call for a basic version of qpmerge to be included in the May 93 general release of PROS (which will also have the ability to read the new FITS formatting of reporcessed data).

We need to emphasize that the first implementation of qpmerge will be rudimentary. It will require the same pointing position, but will allow spatial shifts of the time segments being merged. With this capability, one can use a point source in the field to serve as a guide for registration. It will NOT handle merging of offset POINTINGS (i.e. adjacent and overlapping fields).

3.2 Spatial - How to perform spatial analysis from multiple qpoe files (useful while waiting for the appearance of "qpmerge") D. Harris

If you do not need the qpoe file - i.e. you do not need spectral or timing information, IRAF has many image processing tools to shift and "merge" arrays. The simplest of these is imshift, but there are many others which regrid, perform registration, etc. For an HRI observation this can make a significant improvement in the final image by, for example, measuring the position of a point source on different time segments, and then aligning each array with imshift before adding them back together. NB: When combining the parts with IMCALC, use the component with the best absolute correspondence between pixel location and RA, DEC as the first term in the addition. This will ensure that the header information of the final file will correspond.

3.3 Timing - How to perform variability analysis from multiple qpoe files (useful while waiting for the appearance of "qpmerge") F. Primini

Timing analysis of an observation divided into multiple qpoe files will, in general, be difficult without QPMERGE. The observer can, in principle, run TIMSORT separately for each qpoe file, specifying source regions appropriate for the different files. Examination of the time series can be accomplished by the simple expedient of generating separate light curve table files for each qpoe file and appending them (in appropriate time order) with the TABLES task TMERGE. In fact, this may be preferable to generating a light curve plot from a merged qpoe file, since such a plot would be dominated by the (presumably large) gaps between qpoe files. However, such merged tables cannot be used in any subsequent quantitative analysis, such as coherent FFT's. Incoherent FFT's can be performed on multiple qpoe files by inputing an ASCII list of qpoe file names when prompted for input file (see section 8.8.4 of the PROS USERS GUIDE). However, no other timing tasks have the capability of handling lists of qpoe files.

If possible, the observer should attempt to analyze the individual qpoe files separately, and merge the results. This may not be possible for tasks, such as epoch folding, which require a refence epoch. Such tasks typically use a time near the beginning of the observation as the reference time, and there is no facility at present for the observer to over-ride this. It is thus difficult to maintain relative phase between qpoe files. The situation is complicated for observations which span several months and for which barycentric corrections may be necessary. In applying such corrections, all photon times are referenced to an epoch near the beginning of the qpoe file. However, the observer can obtain ASCII lists of photon times with QPLIST, and compute the MJD for each photon, using non-IRAF tools such as AWK. The relevant formula is

MJD = XS-MJDRD + XS-MJDRF + (corrected photon time / 86400).

XXS-MJDRD and XS-MJDRF may be found in the qpoe header.

3.4 Spectral - How to perform spectral analysis from multiple qpoe files (useful while waiting for the appearance of "qpmerge") L. David

There is not a simple way to combine data from two qpoe files for spectral analysis. Here is what a user must do. To combine spectra of the same target from two different qpoe files, the user must first run "qpspec" on both qpoe files and create two _obs.tab files. There are a number of tasks in the "tables" package than can be used to combine these two tables into one spectrum. First, run "tmerge" in the append mode to combine the two tables. Second, use "tcalc" to calculate the total net counts and corresponding errors. Third, use tedit to edit the header part of the table and insert the correct exposure time and off-axis histogram.

Another, much simpler possibility, is to fit the two data sets simultaneously. The user must input as his "observed spectrum" when running "fit" the two data sets separated by a semi-colon. However, this will treat the data as two independent measurements and will not significantly improve the statistics.

4.0 Site-Specific System Support for SAOIMAGE and Post-Script output M. Conroy

4.1 SAOIMAGE

The PROS 2.1 release includes a task for invoking SAOIMAGE, xplot.ximtool. This task is used at SAO to start an SAOIMAGE window from the IRAF environment, and it's default settings assume that the 'IRAF/personal pipes' configuration has been implemented. To use at a site without these modifications, simply change the

ximtool.pipename="home$dev/imt1"

to

ximtool.pipename="dev$imt1"

The 'personal pipes' configuration is necessary to correctly handle situations where more than one IRAF session is using an SAOIMAGE display. Instructions on how to implement this configuration at you site is available from our anonymous ftp directory in:

pub/pros/extra/per_pipes

4.2 PostScript output for IRAF and SAOIMAGE

We have a script that will dump PostScript hardcopy from an SAOIMAGE window. This can be found in:

pub/pros/extra/ximage

The STSDAS group has implemented preliminary support for producing PostScript output files from any IRAF graphics task. We have implemented the necessary configurations at SAO. Complete details are included in the STSDAS newsletter, issue II, Summer 92, describing the system configurations needed to access this capability. However, it also requires an STSDAS package installation. So sites may install this capability locally, or access this support from the SAO/RSDC via remote login. (Please send us email to the address described below for further info.) This capability allows production of PostScript output files that can be printed on a PostScript printer, taking advantage of PostScript fonts. Alternatively, the PostScript file can be incorporated directly into TeX documents, via psfig, or easily converted to a format acceptable to FrameMaker.

ABOUT HINTS & POINTERS

As the provider of the PROS software package ("xray" in IRAF), the ROSAT Science Data Center (RSDC) at SAO distributes HINTS & POINTERS to PROS Users via email. When we find answers to often asked questions, or when we have implemented new software solutions to longstanding problems, we will send this information directly to our users. These messages will also be available via anonymous ftp*, but to receive the email version, you should register with us. If your username is the one associated with your site registration, you are already registered for "HINTS & POINTERS", but we encourage other users (even at the same sites) to register.

Mailings will be sent as the need arises, perhaps every month or so. If you would like to suggest items for future issues of H&P or add your name to our distribution list, please contact us at the following address:

**************************************************************************
Internet - rsdc@cfa.harvard.edu         RSDC    MS-3
DECnet   - CFA::RSDC (6699::RSDC)       Center for Astrophysics
UUCP     - ...!harvard!cfa!rsdc         60 Garden St. Cambridge MA 02138 USA
BITNET   - rsdc@cfa                     tel: (617) 495-7134  FAX: 495-7356
**************************************************************************

* to access our SAO anonymous ftp service:
    o   ftp -i sao-ftp.harvard.edu              # node address: 128.103.42.3
        [Name: anonymous]
        [Password: ]

   ftp> cd pub/pros/Hints

N.B.: you can also obtain your own copy of the PROS USERS GUIDE by
anonftp from subdir /pub/pros/PUG.

New Files in FTP (rosserv)

The IRAF/PROS/STSDAS cross-index files, are also available on the GSFC anonymous FTP under the pub/PROS_Info directory.

The C detector version of the January 1993 PSPC spectral response matrix is now available on the pub/PSPC_Info directory. The old matrices have been renamed to include the year of release. The ascii files have also been renamed accordingly. The matrices residing on the ftp account now are:

bytes date created name

504081 Dec  2 10:10 pspcb_92mar11.rsp
513662 Feb 19 16:00 pspcb_93jan12.rsp
504432 Dec  2 10:10 pspcc_92mar11.rsp
514450 Mar 26 15:16 pspcc_93jan12.rsp

and the ascii versions of these are:

bytes date created name

1191232 Mar 26 15:07 pspcb_92mar11.rsp_ascii
1486933 Feb 19 15:57 pspcb_93jan12.rsp_ascii
1191924 Aug 31  1992 pspcc_92mar11.rsp_ascii
1215494 Mar 26 15:17 pspcc_93jan12.rsp_ascii

Note: only copy the .rsp file directly if you will use it on a unix machine. The safest bet is to copy the .rsp_ascii ascii file over to your home machine and use mkrsp to make vax or unix versions of the response matrix as required. If there are any problems reading these files please contact the GSFC ROSAT GOF.

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This file was last modified on Tuesday, 14-Sep-1999 11:47:03 EDT

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