| Version |
$Revision: 1.4 $ |
| Last Update |
$Date: 2001/11/08 14:46:10 $ |
| HRC CCB Status |
not reviewed |
Number: HRC-R-003
Type: Restriction
Original Date: 1998 March 18
Subsystem: HRC
Subject: Bright Source observations with the HRC and an OTG
Source: HRC IPI input at OP05 comments review 1998 March 17
CRL Statement:
When the HRC is used in combination with either the LETG or HETG to view
sources for which the undispersed image is brighter than 200 count/sec,
the grating and/or a blocking shutter must be in place before the source
is acquired and should not be removed until after the slew to the next
target begins
CRL Rationale/Justification:
The HRC sensitivity to bright objects is derived from the HRC design. A
localized region on the HRC MCPs that receives a dose of more than 500
events per MCP channel undergoes a permanent reduction in gain of 10%;
increasing dose above this leads to further reduction in gain. The grating
and/or blocking shutter must be in place while these sources are on-axis
in order to disperse the x-rays from the image, thus reducing the local
rate.
CRL Impact:
The high counting rates (200 count/sec imaged) generated by bright
sources will permanently degrade HRC MCP performance in regions where the
source is imaged.
Recommended Action:
Incorporate into the Systems and Operations Procedures, with ASC providing
the inputs and into the OFLS.
$Log: hrc-r-004.html,v $
Revision 1.4 2001/11/08 14:46:10 juda
HTML "href" tag edits to convert to soft links
Revision 1.3 1998/06/17 16:24:06 juda
Updated restriction number to agree with TRW CARD (HRC-R-004? replaced with HRC-R-003)
Revision 1.2 1998/04/27 13:59:23 juda
Added Version table
Page created 1998 March 18
Dr. Michael
Juda
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Mail Stop 70
Cambridge, MA 02138, USA
Ph.: (617) 495-7062
Fax: (617) 495-7356
E-mail: mjuda@cfa.harvard.edu