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Hubble Space Telescope
ACS + WFPC2 STAN, 10 Dec 2003

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| STScI Analysis Newsletter (STAN) for ACS and WFPC2
| 10 December 2003
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CONTENTS:

1. HST Cycle 13 Phase I proposal deadline: 23 Jan 2004

2. ACS and WFPC2 instrument groups merged

3. Instrument and Data Handbooks

4. New versions of the ACS Exposure Time Calculators

5. Update on STSDAS, CALACS, and PyDrizzle/MultiDrizzle

6. Calibration plans and calibration proposals

7. ACS photometric zeropoints and transformations

8. Recent Instrument Science Reports

9. Recent publications

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1. HST Cycle 13 Phase I proposal deadline: 23 Jan 2004

See the HST Call for Proposals and related information at:

http://www.stsci.edu/hst/acs/proposing

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2. ACS and WFPC2 instrument groups merged

The ACS and WFPC2 instrument groups at STScI have merged,
which should be largely transparent to ACS and WFPC2 users.
This is the first joint ACS+WFPC2 STAN. The former acs_news 
and wfpc_news distribution lists have been merged into the 
acs_wfpc2_news list. The instructions for subscribing and 
unsubscribing from this new list are given at the end of 
this document.

The last WFPC2 STAN was issued in August 2003.
The WFPC2 STANs have been archived here:

http://www.stsci.edu/hst/wfpc2/documents/newsletters

The last ACS STAN was issued in March 2003.
The new ACS+WFPC2 STANs will be archived with the 
previous ACS STANs here:

http://www.stsci.edu/hst/acs/documents/newsletters

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3. Instrument and Data Handbooks

The ACS and WFPC2 Instrument Handbooks have undergone 
revisions to update for Cycle 13 .

The ACS and WFPC2 Data Handbooks are also available from 
their Web sites. Before the end of this year, we plan to
replace the pre-launch ACS Data Handbook with a revised
version. This new version will contain an updated and 
expanded discussion of the calibrations applied during 
pipeline processing, and demonstrates how to manually 
recalibrate data using the CALACS, PyDrizzle, and 
MultiDrizzle software. Additional chapters that discuss 
photometry, astrometry, polarimetry, and other applications 
in detail will be added in subsequent months.

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4. New versions of the ACS Exposure Time Calculators

New versions of the ACS Exposure Time Calculators were made 
available on September 10, 2003 and can be found here:

http://www.stsci.edu/hst/acs/software/etcs/ETC_page.html
 
The new ETCs were developed as part of the Astronomer's 
Proposal Tool (APT), but are available through a web 
interface with the same look-and-feel as the old CGI ETCs. 
In addition to the Imaging, Spectroscopic and Ramp Filter 
ETCs available under CGI, the APT version includes 
Coronographic and Coronographic-with-Ramp ETCs. We 
recommend the new APT versions for all users. Details 
about new features and improvements in the ETCs are 
available via the webpage above.

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5. Update on STSDAS, CALACS, and PyDrizzle/MultiDrizzle

The latest version of STSDAS was released on 20 Oct 2003:

http://www.stsci.edu/resources/software_hardware/stsdas

The version of CALACS in this STSDAS release is consistent 
with the version currently used in the calibration pipeline. 
This version of STSDAS also contains a self-consistent 
bundling of PyDrizzle, numarray, etc. These tasks requires 
PyRAF version 1.1, which was released simultaneously:

http://www.stsci.edu/resources/software_hardware/pyraf

The latest version of MultiDrizzle must still be 
downloaded and installed separately, see:
http://www.stsci.edu/resources/software_hardware/pydrizzle
(This link is no longer available.)

If you had a previously-installed MultiDrizzle, you will
need to reinstall it after installing STSDAS version 3.1
and PyRAF version 1.1.

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6. Calibration plans and calibration proposals

The current status and accuracy of the ACS and WFPC2 
calibrations are described in the respective Instrument 
Handbooks. Calibration plans are available for ACS and WFPC2. 

We welcome all comments on the planned STScI calibration 
programs (to help@stsci.edu). Also, GOs are encouraged to 
consider the submission of Cycle 13 Calibration Proposals 
to take the instrument calibrations beyond the levels 
planned at STScI. Anyone planning the submission of such a 
proposal should consult the policies at 
http://www.stsci.edu/hst/proposing/documents/cp/3_Proposal_Categories7.html
(This link is no longer available.)
and is advised to discuss their plans with the ACS+WFPC2 
Branch at STScI (email to help@stsci.edu) at least two 
weeks prior to the proposal deadline.

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7. ACS photometric zeropoints and transformations

On December 10, 2003 we delivered improved Detectors Quantum 
Efficiency (DQE) curves and filter throughput curves to the 
ACS pipeline. A detailed description of the new curves will 
soon be presented in an Instrument Science Report (ISR) 
(De Marchi et al, in preparation). The new files can be 
downloaded at the ACS reference files web page:

http://www.stsci.edu/hst/acs/analysis/reference_files/synphot_tables.html

The new curves reproduce the observed count rate of 
spectrophotometric standard stars with an accuracy better 
than 1% in all broad band filters, and ~ 1% for narrow band 
filters. This is an improvement of 1-2% with respect to the 
curves that were previously used by the ACS pipeline.

The new files will automatically be used for the calibration 
of any data retrieved from the HST Archive after December 10, 
2003. The calibrations only affect the "photometry  keyword"  
section in the header of the SCI extensions of the 
calibrated FITS file. The new zeropoints and the new values 
of the keywords are available at the following web page:

http://www.stsci.edu/hst/acs/analysis/zeropoints

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8. Recent Instrument Science Reports

For ACS...

Modelling the fringing of the ACS WFC and HRC chips
http://www.stsci.edu/hst/acs/documents/isrs/isr0312.pdf

Flat Fields for Filter Wheel Offset Positions
http://www.stsci.edu/hst/acs/documents/isrs/isr0311.pdf

Determination of Low-Frequency Flat-Field Structure from 
Photometry of Stellar Fields
http://www.stsci.edu/hst/acs/documents/isrs/isr0310.pdf

On-orbit Calibration of ACS CTE Corrections for Photometry
http://www.stsci.edu/hst/acs/documents/isrs/isr0309.pdf
                                           
Baseline Tests for the Advanced Camera for Surveys 
Astronomer's Proposal Tool Exposure Time Calculator
http://www.stsci.edu/hst/acs/documents/isrs/isr0308.pdf
                           
The in-orbit wavelength calibration of the HRC G800L grism                 
http://www.stsci.edu/hst/acs/documents/isrs/isr0307.pdf
                                
ACS WFC and HRC field-dependent PSF variations due to 
optical and charge diffusion effects
http://www.stsci.edu/hst/acs/documents/isrs/isr0306.pdf

Elevated Temperature measurements of Hot Pixels
http://www.stsci.edu/hst/acs/documents/isrs/isr0304.pdf
            
ACS Background Light vs. Bright Earth Limb Angle
http://www.stsci.edu/hst/acs/documents/isrs/isr0305.pdf

Stability and Accuracy of HRC and WFC Shutters
http://www.stsci.edu/hst/acs/documents/isrs/isr0303.pdf
                           
NUV Earth Flats 
http://www.stsci.edu/hst/acs/documents/isrs/isr0302.pdf

For WFPC2...

WFPC2 Cycle 12 Calibration Plan
http://www.stsci.edu/instruments/wfpc2/Wfpc2_isr/wfpc2_isr0303.pdf

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9. Recent publications
http://www.stsci.edu/hst/acs/documents/pub_2003_12.pdf
(This document is no longer available.)

The papers listed above are based on data from WF/PC, 
WFPC2 and/or ACS. The list includes all papers received and 
identified by the STScI Library during the current year. 
Please include our Library in your preprint distribution 
list. This listing was generated with STEPsheet:
http://stepsheet.stsci.edu/

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| Inc., under NASA contract NAS5-26555.
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