ctskymap

Generate sky map from event list(s).

Synopsis

This tool creates a sky map from either a single event list or event lists provided in an observation definition file. The tool will loop over all event lists that are provided and fill all events into a single sky map. Only events within an energy interval spanned by emin and emax are considered.

Optionally, the tool will subtract a background model from the sky map. The background subtraction method can be selected using the bkgsubtract parameter. By default, no background model is subtracted (method NONE). If IRF is selected, the background template that are shipped with the Instrument Response Functions will be used for background subtraction. If RING is selected, the background is estimated from a ring with the inner radius specified by the inradius parameter and the other radius specified by the outradius parameter. If a background template is available, that template will be used for weighting the counts in the ring. Otherwise, a constant background rate will be assumed.

ctskymap generates a FITS file comprising a sky map as primary extension. If a background subtraction method was selected, the FITS file will contain the additional extensions BACKGROUND and SIGNIFICANCE that contain the background map and a significance map, respectively. For the latter, the significance of the signal is computed for each sky map pixel.

General parameters

inobs [file]

Input event list or observation definition XML file.

caldb [string]

Calibration database (only required for IRF background subtraction if no response information is provided by inobs).

irf [string]

Instrument response function (only required for IRF background subtraction if no response information is provided by inobs).

(inmap = NONE) [file]

Input sky map file containing a COUNTS and an ACCEPTANCE extension. Such extensions are produce by a previous run of the ctskymap tool with the IRF or RING background method.

outmap [file]

Output sky map file.

emin [real]

Minimum energy in map (in TeV).

emax [real]

Maximum energy in map (in TeV).

(usepnt = no) [boolean]

Use pointing instead of xref/yref parameters?

nxpix [integer]

Size of the Right Ascension / Galactic longitude axis (in pixels).

nypix [integer]

Size of the Declination / Galactic latitude axis (in pixels).

binsz [real]

Pixel size (in degrees/pixel).

coordsys <CEL|GAL> [string]

Coordinate system (CEL - celestial, GAL - galactic).

proj <AIT|AZP|CAR|GLS|MER|MOL|SFL|SIN|STG|TAN> [string]

Projection method.

xref [real]

Right Ascension / Galactic longitude of image centre (J2000, in degrees).

yref [real]

Declination / Galactic latitude of image centre (J2000, in degrees).

Background subtraction configuration parameters

bkgsubtract <NONE|IRF|RING> [string]

Background subtraction method.

roiradius [real]

Source region radius for RING subtraction (in degrees).

inradius [real]

Inner background ring radius for RING subtraction (in degrees).

outradius [real]

Outer background ring radius for RING subtraction (in degrees).

iterations [integer]

Number of iterations for the automatic computation of exclusion regions. Sky map pixels with detection significance above the value specified by the threshold parameter will be defined as exclusion regions, and the RING background will be recomputed based on these exclusion regions. Since this will likely change the significance of the pixels, the procedure can be iteratively repeated, and the iterations parameter specifies how often the procedure should be repeated.

threshold [real]

Significance threshold above which pixels should be excluded for the background computation in the RING background method.

(inexclusion = NONE) [file]

Exclusion region file as either a FITS map or DS9 region file.

(usefft = yes) [boolean]

Specifies whether a FFT should be used for ring computation. If set to no the ring background will be computed directly. Direct computation is more accurate since the precise angular distances between pixels are taken into account, but FFT is faster, but less accurate since it assumes Euclidean distances between pixels.

Standard parameters

(publish = no) [boolean]

Specifies whether the sky map should be published on VO Hub.

(chatter = 2) [integer]
Verbosity of the executable:

chatter = 0: no information will be logged

chatter = 1: only errors will be logged

chatter = 2: errors and actions will be logged

chatter = 3: report about the task execution

chatter = 4: detailed report about the task execution

(clobber = yes) [boolean]

Specifies whether an existing output sky map file should be overwritten.

(debug = no) [boolean]

Enables debug mode. In debug mode the executable will dump any log file output to the console.

(mode = ql) [string]

Mode of automatic parameters (default is ql, i.e. “query and learn”).

(logfile = ctskymap.log) [string]

Name of log file.