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2.3.3 Long-term stability

It appears that the effective area has not varied significantly since launch. Observations of the sources HZ43, Vega, A2256, and N132D at several epochs yield non-varying count rates (Table 3).



  
Table 3: Quantum Efficiency Monitor
Source Date of Observation Count Rate (counts s-1)
A2256 July 1, 1990 0.61 $ \pm$ 0.01
  August 3, 1992 0.62 $ \pm$ 0.01
     
HZ43 July 2, 1990 12.3 $ \pm$ 0.2
  December 11, 1991 12.0 $ \pm$ 0.2
  June 9, 1992 11.91 $ \pm$ 0.04
     
Vega March 20, 1991 0.10 $ \pm$ 0.01
  March 21, 1992 0.11 $ \pm$ 0.01
  Sept 18, 1992 0.10 $ \pm$ 0.01
  April 15, 1995 0.11 $ \pm$ 0.01
     
N132D 1990 July 3 4.43 $ \pm$ 0.09
  1990 July 4 4.50 $ \pm$ 0.13
  1991 February 9 4.54 $ \pm$ 0.01
  1991 December 11 4.49 $ \pm$ 0.09
  1992 June 10 4.40 $ \pm$ 0.04
  1992 August 3 4.21 $ \pm$ 0.05
  1992 September 17 4.57 $ \pm$ 0.05
  1993 April 17 4.46 $ \pm$ 0.04
  1994 January 10 4.40 $ \pm$ 0.04
  1994 March 10 4.39 $ \pm$ 0.06
  1994 June 15 4.56 $ \pm$ 0.04
  1994 July 15 4.53 $ \pm$ 0.05
  1994 August 15 4.54 $ \pm$ 0.06
  1994 September 15 4.49 $ \pm$ 0.06
  1995 February 11 4.40 $ \pm$ 0.04
  1995 March 11 4.51 $ \pm$ 0.04
  1995 October 20 4.54 $ \pm$ 0.06
  1995 November 20 4.51 $ \pm$ 0.04
  1996 January 20 4.59 $ \pm$ 0.05
  1996 February 20 4.34 $ \pm$ 0.04
  1996 April 20 4.23 $ \pm$ 0.05
  1996 May 20 4.45 $ \pm$ 0.07
  1996 June 20 4.10 $ \pm$ 0.04
  1996 August 20 4.63 $ \pm$ 0.05
  1996 September 20 4.43 $ \pm$ 0.05
  1996 December 27 4.36 $ \pm$ 0.05
  1997 March 5 4.30 $ \pm$ 0.09
  1997 April 5 4.19 $ \pm$ 0.04
  1997 October 5 4.23 $ \pm$ 0.04
  1998 March 15 4.26 $ \pm$ 0.06
Note: The count rate for A2256 is determined from the net emission within a 6' radius.


next up previous contents
Next: 2.3.4 Source Count Rates Up: 2.3 Effective Area Previous: 2.3.2 Off-axis Effective Area
rsdc@cfa.harvard.edu
1999-05-25