/***********************************************************************//**
* @brief Write time reference into FITS header
*
* @param[in] hdu FITS extension.
*
* Writes or updates the time reference information in a FITS header.
* Depending of whether the keyword "MJDREF" or the pair of keywords "MJDREFI"
* and "MJDREFF" exist already in the header, the method either writes the
* reference MJD as floating point value, or split into an integer and a
* fractional part. If nothing has been written yet, splitting into an
* integer and fractional part will be used as this preserves the highest
* possible accuracy.
*
* The following additional keywords are written:
* TIMEUNIT
* TIMESYS
* TIMEREF
*
* Nothing is done if the HDU pointer is NULL.
***************************************************************************/
void GTimeReference::write(GFitsHDU* hdu) const
{
// Continue only if HDU is valid
if (hdu != NULL) {
// Case A: use floating point reference MJD
if (hdu->hascard("MJDREF")) {
hdu->card("MJDREF", mjdref(), "[days] Time reference MJD");
hdu->card("TIMEUNIT", timeunit(), "Time unit");
hdu->card("TIMESYS", timesys(), "Time system");
hdu->card("TIMEREF", timeref(), "Time reference");
}
// Case B: use fractional reference MJD
else {
hdu->card("MJDREFI", mjdrefi(), "[days] Integer part of time reference MJD");
hdu->card("MJDREFF", mjdreff(), "[days] Fractional part of time reference MJD");
hdu->card("TIMEUNIT", timeunit(), "Time unit");
hdu->card("TIMESYS", timesys(), "Time system");
hdu->card("TIMEREF", timeref(), "Time reference");
}
} // endif: HDU was valid
// Return
return;
}
/***********************************************************************//**
* @brief Read LAT events from FITS file.
*
* @param[in] file FITS file.
*
* This method read the LAT event list from a FITS file.
*
* The method clears the object before loading, thus any events residing in
* the object before loading will be lost.
***************************************************************************/
void GLATEventList::read(const GFits& file)
{
// Clear object
clear();
// Get HDU (pointer is always valid)
const GFitsTable& hdu = *file.table("EVENTS");
// Read event data
read_events(hdu);
// Read data selection keywords
read_ds_keys(hdu);
// If we have a GTI extension, then read Good Time Intervals from that
// extension
if (file.contains("GTI")) {
const GFitsTable& gti = *file.table("GTI");
m_gti.read(gti);
}
// ... otherwise build GTI from TSTART and TSTOP
else {
// Read start and stop time
double tstart = hdu.real("TSTART");
double tstop = hdu.real("TSTOP");
// Create time reference from header information
GTimeReference timeref(hdu);
// Set start and stop time
GTime start(tstart);
GTime stop(tstop);
// Append start and stop time as single time interval to GTI
m_gti.append(start, stop);
// Set GTI time reference
m_gti.reference(timeref);
} // endelse: GTI built from TSTART and TSTOP
// Return
return;
}
/***********************************************************************//**
* @brief Print time reference
*
* @return String containing the time reference.
***************************************************************************/
std::string GTimeReference::print(void) const
{
// Initialise result string
std::string result;
// Append header
result.append("=== GTimeReference ===\n");
// Append information
result.append(parformat("MJD reference time")+str(mjdref())+"\n");
result.append(parformat("Time unit")+timeunit()+"\n");
result.append(parformat("Time system")+timesys()+"\n");
result.append(parformat("Time reference")+timeref()+"\n");
// Return
return result;
}
