STScI Logo

Hubble Space Telescope
WFPC2 STAN

+----------------------------------------------------------+
| STScI Analysis Newsletter (STAN) for ACS and WFPC2
| 10 December 2003
+----------------------------------------------------------+

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

+----------------------------------------------------------+

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

+----------------------------------------------------------+

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.

+----------------------------------------------------------+

3. Instrument and Data Handbooks

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

The ACS and WFPC2 Data Handbooks are also available from 
these 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.

+----------------------------------------------------------+

4. New versions of the ACS Exposure Time Calculators

New versions of the ACS Exposure Time Calculators were made 
available on September 10, 2003.
 
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.

+----------------------------------------------------------+

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

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

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.
The latest version of MultiDrizzle must still be 
downloaded and installed separately.

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

+----------------------------------------------------------+

6. Calibration plans and calibration proposals

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

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.

+----------------------------------------------------------+

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 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 on the ACS webpage.

+----------------------------------------------------------+

8. Recent Instrument Science Reports

For ACS...

Modelling the fringing of the ACS WFC and HRC chips

Flat Fields for Filter Wheel Offset Positions

Determination of Low-Frequency Flat-Field Structure from 
Photometry of Stellar Fields

On-orbit Calibration of ACS CTE Corrections for Photometry
                                           
Baseline Tests for the Advanced Camera for Surveys 
Astronomer's Proposal Tool Exposure Time Calculator
                           
The in-orbit wavelength calibration of the HRC G800L grism
                                
ACS WFC and HRC field-dependent PSF variations due to 
optical and charge diffusion effects

Elevated Temperature measurements of Hot Pixels
            
ACS Background Light vs. Bright Earth Limb Angle

Stability and Accuracy of HRC and WFC Shutters
                           
NUV Earth Flats 

For WFPC2...

WFPC2 Cycle 12 Calibration Plan

+----------------------------------------------------------+
| Need help? help@stsci.edu
+----------------------------------------------------------+
| To subscribe or unsubscribe to this STAN, send a message
| to majordomo@stsci.edu with a blank subject line and
| the following in the body: [un]subscribe acs_wfpc2_news
+----------------------------------------------------------+
| The Space Telescope Science Institute is operated by the
| Association of Universities for Research in Astronomy,
| Inc., under NASA contract NAS 5-26555.
+----------------------------------------------------------+