This page lists noteworthy items and issues about the CIAO 4.2 release. For the full list of known issues please review the:

• CIAO bug list
• CIAO Frequently Asked Questions page

---

Installing & Starting CIAO

CALDB 4.2.0 Required

CALDB 4.2.0 is required in order for CIAO 4.2 to work correctly.

Solaris: Untarring the CIAO Software

Solaris users must use GNU tar to unpack the tarfiles. If native Solaris tar is used, some of the smoketest filenames will be truncated.

Installing on Mac OSX 10.6 (Snow Leopard)

Snow Leopard is not an officially supported platform for CIAO 4.2, but a user-submitted workaround allows CIAO to run.

Users installing CIAO on Snow Leopard with ciao-install should follow the special installation instructions.

Conflicts with Other Software Packages

There are some known conflicts between CIAO and other software or system libraries and tools. Issues not covered in this "Watch Out" page are listed on the "Other Software Packages" bug page.

---

Data Caveats

Source Detection and Cosmic-Ray Afterglows

CIAO users who are trying to detect sources of about 10 counts or less should be aware of potential confusion with cosmic-ray afterglows that have not been removed from the data.

The Cosmic-Ray Afterglows why topic explains the limitations of the current tools and describes analysis tips to help eliminate more of the afterglows.

Incorrect Exposure Time from Merged Event Files

When multiple event files that have different ranges of exposure numbers (expno column) are merged, the output file will have more than one GTI block for each chip. This causes incorrect exposure values later in the analysis, as the CIAO tools cannot use multiple GTI blocks for a single chip.

Further details and a workaround to this problem are available on the dmmerge bug page.

---

Analysis

CTI_APP Header Keyword is Required

CIAO 4.2 and CALDB 4.2 require that ACIS event files have a CTI_APP header keyword to indicate whether the CTI correction has been applied. The older CTI_CORR keyword is no longer used.

Follow the instructions in the ACIS CTI_APP Keyword Required section of the ACIS CTI Correction why topic to learn how to check for the keyword and add it if it is missing.

The analysis may produce incorrect results without issuing an error if the keyword is missing.

Specifying Aspect Solution Files

The aspect solution files (pcad..._asol1.fits) are used as inputs to several of the CIAO tools - e.g. acis_process_events, asphist, and tg_resolve_events.

If there is a single aspect solution file, it can be provided directly to the tool:

unix% pset asphist infile=pcadf245733620N002_asol1.fits

In many cases, there will be more than one aspect solution file for an observation. Then all the files must be provided in chronological order. (The time is in the filename, so "ls" lists them in chronological order.) This may be done as a comma-separated list:

unix% pset asphist infile="pcadf063874624N002_asol1.fits,pcadf063875522N002_asol1.fits,pcadf063902942N002_asol1.fits"

The list of aspect solution files may also be given as a stack. Any number of files can be specified in the stack, one:

unix% cat pcad_asol1.lis
pcadf245733620N002_asol1.fits

unix% pset asphist infile=@pcad_asol1.lis

or more than one:

unix% cat pcad_asol1.lis
pcadf063874624N002_asol1.fits
pcadf063875522N002_asol1.fits
pcadf063902942N002_asol1.fits

unix% pset asphist infile=@pcad_asol1.lis

Note that an at symbol ("@") is used before the filename to indicate that it is a stack file.

---

Website Issues

Printing from Firefox on Mac OS X

A software bug in Firefox 3.6 on Mac OS X platforms causes some of the CIAO webpages to not print properly to the printer or to PDF file. For multiple-page documents, only the first page is printed.

Pages print correctly from Safari. The bug is fixed in the Firefox 4 Beta release.