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Chandra Electronic Bulletin No. 47
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             |              CCC  XX   XX    OOO           |
Chandra      |             CC     XX XX    OO OO          | CXC
Electronic   |            CC       XXX    OO   OO         | Number 47
Bulletin     |             CC     XX XX    OO OO          | February
             |              CCC  XX   XX    OOO           | 2006
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Welcome to the Chandra X-ray Center's Electronic News Bulletin Number 47.

CXC Web site: http://cxc.harvard.edu

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1.  Update to Procedure for Charging Slew Tax on Raster Surveys in Cycle 8


Item 1. Update to Procedure for Charging Slew Tax on Raster Surveys in Cycle 8

The following text has been included as an erratum to the Cycle 8 Call for 
Proposals, and can also be found on the website under "CfP Errata"

Section 7.1 is  updated as follows:

An observing efficiency including slew and settle time will be used to 
determine the amount of time available for observations. To evaluate time 
required by a given proposal, a "slew tax" of 1.5 ksec will be added to each 
proposed target within the peer review process; this added time closely 
represents the average observatory slew and set-up
time required for each observation.
The Peer Review takes the slew tax into account 
along with the requested time when assessing the resources requested to 
accomplish a proposed research project. For a large set of short exposures 
this slew tax can substantially increase the "cost" in terms of time needed 
for a project.
Starting with Cycle 8, this policy is modified as follows:
For a series of contiguous or nearly contiguous pointings (maneuver from one 
observation to the next of less than or equal to 1 degree), with no change in
instrument set-up or observing mode, the slew tax for the first observation 
will remain 1.5ksec, while for observations 2 through n (where "n" 
is explained below) will be assessed at 0.5ksec. The series of pointings will
be assembled into one or more groups comprised of a set of closely spaced 
pointings with maximum exposure time per group of 30 ksecs, including the
slew tax. The value of "n" is the number of observations which can be 
done including the slew tax without exceeding 30 ksecs.
Thus proposals requesting more time than 30 ksecs (including slew tax) will 
be assessed slew tax in several groups, the first observation of which
will be charged 1.5ksec slew tax. Proposers should set the RPS flag
{\it Is this target part of a raster survey?"} to be "Y" (yes).
The formula for slew tax is included here to enable proposers to 
understand the total time which they are effectively requesting; however the 
time on target is all that the proposers should include in their proposal. The 
CXC will compute the slew tax and provide the information to the Peer Review.

Please note that observations taken 
as part of a raster survey are not constrained and therefore are not 
guarenteed to have the same (or similar) roll angle.  Proposers must 
also include a group or roll constraint if they wish to ensure the 
individual observations have roll angles within particlar tolerances.


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