ICWG June 2006

                                       NOTES

                                      from the

                               FORUM on STANDARD CANDLES 
                   
	Date  	: 15 June 2006
	
	Participants	: Plenary Session


	REPORT ON STANDARD CANDLES WORKING SESSION
	------------------------------------------

	Haberl summarised the discussion of the Standard Candles Working Session.
	Refer to the minutes of the Working Session for details.

	During this forum the list of candidate standard candle sources compiled
	during the Working Session was augmented by the addition of the isolated
	neutron star PSR0656 and the supernova remnants PSR1509 and 0540-69. These
  	have consequently been added to the list of candidate standard candles
	recorded in the minutes of the Working Session.

	H. Marshall asked about the usage of stars as line standards. R. Smith 
	urged the consideration of Procyon as a key source extending calibration
   	beyond 30 Angstrom.  The matter of stellar line standards had been
	discussed in the Working Session and it had been decided that such 
	standards fell outside the scope of the standrad candles session, belonging
	more in the session on calibration sources in general.  

	U. Briel remarked that all the candidate standard candles listed were 
	potentially too bright for future missions, like Xeus, for example.  It was
	remarked that one possible way to deal with this situation might be to have 
	a "grey filter", a "pinhole", that could allow a controlled attenuation of 
	such sources. Kaastra remarked that Xeus can be defocussed, which might 
	offer one means of attenuating flux peaks. Smith	replied that Chandra can 
	also be defocussed, but it is not something that would be done routinely, 
	or indeed ever!

	Rothschild remarked on the desirability of finding other sources going 
	up to higher energies.
  	
	It was asked whether the ICWG should advocate regular observation of the
	identified set of targets by the various missions.  The minutes
	of the Working Session record the usage of these targets by the missions
	represented at the session.
	

	U. Briel remarked that all the candidate standard candles listed were 
	potentially too bright for future missions, like Xeus, for example.  It was
	remarked that one possible way to deal with this situation might be to have 
	a "grey filter", a "pinhole", that could allow a controlled attenuation of 
	such sources. Kaastra remarked that Xeus can be defocussed, which might 
	offer one means of attenuating flux peaks. Smith	replied that Chandra can 
	also be defocussed, but it is not something that would be done routinely, 
	or indeed ever!

	Rothschild remarked on the desirability of finding other sources going 
	up to higher energies.
  	
	It was asked whether the ICWG should advocate regular observation of the
	identified set of targets by the various missions.  The minutes
	of the Working Session (above) record the usage of these targets by the
 	missions represented at the session.