Frequently Asked Questions

The Frequently Asked Questions (FAQ) page is a place where users can find the most common CIAO questions. The CXC Helpdesk also has a searchable database that allows users to look through all public Helpdesk questions.

General

Data Products

1. When was my observation performed?
   When was the file created?
   What version of data processing was used?
2. What does the CREATOR header keyword mean?
3. What was the aimpoint of the observation?
4. What ACIS gain file was used in the automatic processing?
5. What is the focal plane temperature for my observation?
6. Why are there sometimes multiple asol1.fits files for my observation?
   How do I treat these in my analysis?

Parameter Files

1. Why does the tool does not execute when I get the following error(s)?

   pget: parameter not found...

   parammatch : can't find parameter PARAMNAME in reference list
   parameter error?
             

2. Why should I delete my parameter files after upgrading CIAO?
3. How do I run multiple instances of a CIAO tool without clobbering the parameter file?
4. The tool is failing because ")sval" has somehow shown up in the parameter value.

Data Model

1. How do I change the MEM parameter when I get this error?

   # DMCOPY (CIAO3.3): WARNING: Creating large image: 134 MB. Current max set at 50 MB.
   Increase maximum using [opt mem=n] or increase blocking to reduce size.
   

2. How can I define a region around a single chip?
3. Why should I filter on sky coordinates rather than the CCD_ID column?

ARDLIB

1. Why am I getting an ARDLIB error about a bad pixel file from a different ObsID?

   ***ARDLIB error: Unable to find data file acisf01842_000N001_bpix1.fits[BADPIX7]
   

2. What does this warning mean?

   ***ARDLIB warning: Filename some_file.fits does not specify an extension. 
   Assuming the first "interesting" extension.
   

3. How can I tell CIAO to use a different HRMA effective area file?

Computer Environment

1. What is a shell?
   What shell am I using?
2. Why is the background of my smongo x11 window is changed to black if CIAO is running?

Miscellaneous

1. Which CALDB version is installed on my system?
2. What is the limiting file size for CIAO?
3. What is the maximum size region file that CIAO can process?

User Interface

ChIPS

1. How can I get better precision in ChIPS output?

   chips> 227.49334262014-0.0001363
   227.493
   

ds9

1. Can I use a newer version of ds9 than the one packaged with CIAO?
2. How do I build polygon regions in ds9?
3. How do I rotate a region in ds9?

Filtwin

1. Why am I getting the following error when I try to launch filtwin?

   FilterWindow has already been instantiated for this session.

Prism

1. Why am I getting the following repeated errors when launching prism?

   Warning: Cannot allocate colormap entry for "snow"
   Warning: Cannot allocate colormap entry for "cyan4"
   Warning: Type conversion failed
   

Tools

acis_process_events

1. Why hasn't the CALDBVER keyword been updated after I run this tool?
2. Why is my level 2 event file larger than the one from the pipeline?
3. What does this warning mean?

   # acis_process_events (CIAO3.3): The following error occurred 26941 times:
     dsAFEBADPCNTERR -- WARNING: Event island contains 1 or more bad pixels.
   

dmcopy

1. How can I specify the datatype of the output image?

dmextract

1. How do I extract many spectra with one command?
2. Why do I get a parse error with this region file?

   # Region file format: CIAO version 1.0	
   -rotbox(4055.375,4165.5674,4.6747966,4.4715447,63.400002)
   annulus(4059.5601,4163.4399,2.0325203,7.113821)
   

3. Why does dmextract convert arcseconds to arcminutes when I use pset?

dmstat

1. How can I calculate the centroid of counts in a region?

dmtcalc

1. Why is the column moved to the end of the table when I try to update it in place?

hrc_process_events

1. What does this warning mean?

   # hrc_process_events (CIAO3.3): The following error occurred 2482 times:
     dsHPEEVENTSEQERR -- WARNING: Out of sequence events discovered in hrc_evt1.fits.
   

2. What does this warning mean?

   # hrc_process_events (CIAO3.3): The following error occurred 224 times:
           WARNING: can't find a proper degap value for this raw coord. in hrc_evt1.fits.
   

mkwarf

1. What does this warning mean?

   Couldn't determine chip position for pixel: (1013.000000,0.000000)
   with value=1.000000. Skipping pixel
   

tg_create_mask

1. What if the extraction regions extend beyond the detector edge?

tg_resolve_events

1. What does this warning mean?

   # tg_resolve_events (CIAO3.3): The following error occurred 38950 times:
     WARNING: Event chip position is outside of valid range. 
     Grating coordinates not computed for this event.
   

2. What does this warning mean?

   # tg_resolve_events (CIAO3.3): The following error occurred 10000 times:
           dsTREUNKNOWNINCOLERR -- WARNING: Not loading data from
   			        unrecognized level 1.5 input column.
   

Scripts

S-Lang scripts

1. Why can't CIAO find my S-Lang scripts?

   sherpa> () = evalfile("lc_clean.sl")
   Error: cannot find or unable to open file as requested : lc_clean.sl
   

2. My script worked in CIAO 2.3. Why won't it work in CIAO 3?

fullgarf

1. Why do I get the following error?

   *** ERROR: aspect histogram acisf00459_ah4.fits[ASPHIST] contains no rows
   	  

2. Why do I get the following warnings?

   WARNING: OSIP file contains invalid data for the region
   512<=CHIPX<=768 608<=CHIPY<=640 at 0.1 keV.
   WARNING: OSIP file contains invalid data for the region
   512<=CHIPX<=768 608<=CHIPY<=640 at 0.277 keV.