S T A N / W F P C 2 - Number 7, June 1995

CONTENTS:

• WFPC2 ANALYSIS SOFTWARE
• LINEAR RAMP FILTER UPDATE
• WFPC2 SYNPHOT TABLES UPDATE
• RECENT PREPRINTS
• APPENDIX: WFPC2 Contacts

WFPC2 ANALYSIS SOFTWARE

by Brad Whitmore

We recently reviewed our plans for enhancements to STSDAS designed to benefit WFPC2 users. Here is a list of the "TOP FIVE" items we plan to work on in the near term. If you have comments on these, suggestions on improving the STSDAS' WFPC package or WFPC2-related tasks you have created and would like to share with the community, please contact whitmore@stsci.edu.

Top Five List:

1. WMOSAIC and METRIC update

• Insert new distortion and plate scale information.
• Allow both X,Y to RA,DEC and RA,DEC to X,Y conversion.

2. WFIXUP and FIXPIX update

• Allow flags to be set for which types of ``events'' to mask (e.g., saturated pixels, cosmic rays, traps, etc.) The default settings would not change.

3. Hot pixel tracking

• Provide a tool for using the hot pixel lists included on WWW.

4. Cosmic Ray Programs

• Add Rick White's new cosmic ray removal program.
• Modify GCOMBINE and CRREJ slightly (to allow images of differing exposure time, permit different cosmic ray rejection parameters for the PC and WF chips, and produce pixel mask files).

5. Analysis tools for dithered (offset) images

• Develop simple shift-and-add tools.
• Incorporate programs being developed at the European Coordinating Facility. (With future enhancement as time permits.)

LINEAR RAMP FILTER UPDATE

by J. Biretta and C. Ritchie

The first science images using the ramp filters and new wavelength/aperture mapping (TRANS) tables were taken on 23 June. The target appears to have been correctly positioned on the filter, and the images are quite excellent. Everything appears to be working properly.

Revisions to the spacecraft command system to allow the +15 degree rotation of the ramp filters have been completed. On 26 June the "interim" wavelength/aperture mappings were replaced by the "final" versions which include the +15 degree rotations. With these revisions, the ramp filters now provide continuous wavelength coverage from 3710 to 9762 Angstroms with no gaps.

WFPC2 SYNPHOT TABLES UPDATE

by S. Baggett

Synphot is a synthetic photometry package available in STSDAS. It's primary usage is to estimate exposure times for HST observations and to provide calibration information (eg., PHOTFLAM in the header of each image).

The WFPC2 synphot tables will be updated in early July. These updates will bring synphot into general agreement with results presented in Version 3.0 (June 1995) WFPC2 Instrument Handbook. In addition, other improvements determined after the Handbook went to press will also be included. These will be documented in an Instrument Science Report to be issued later in the month.

The new tables will be available via ftp to stsci.edu, in: cdbs/comp/wfpc2

A new README file will be posted along with these new files.

Note that the tables are in binary STSDAS format, readable with tasks in the IRAF/STSDAS ttools and synphot packages. The history and version of each new table is included in the table header, which can be viewed, for example, with tdump:

                   tdump wfpc2_f555w_003.tab | page

A new feature is that the time-variable photometric throughput is now included in the form of contamination tables. These tables list the decline in throughput as a function of Modified Julian Date (MJD) and wavelength. To have synphot take any contamination effects into account, just include the observation's MJD (provided in the header in the keyword EXPSTART) in the obsmode parameter and the expected countrate will be reduced appropriately.

For example, to compute expected countrate for a WF3, F218W observation of grw+70d5824 taken 20 days after the April 8,1995 (MJD=49835.0) decontamination:

calcphot "wfpc2,3,f218w,a2d15,cont#49835.0" 
spec=grw_70d5824_003.tab form=counts

Please note that the double quotes around the obsmode are required.

You can either read the Guide on-line as it has been written as an HTML document or download the PostScript version to print it locally. Hardcopies can be requested at help@stsci.edu.

RECENT PREPRINTS

We draw your attention to these papers, based on WF/PC and WFPC2 data, that will appear in the next few months. This list includes all preprints received by the STScI Library not yet published in the journals. Please remember to include our Library in your preprint distribution list.

"Hubble Space Telescope observations of circumnuclear 
star-forming rings in NGC 1097 and NGC 6951"  Barth, A.J.; 
Ho, L.C.; Filippenko, A.V.; Sargent, W.L.W.; AJ accepted

"Interaction of a stellar wind with clumpy stellar ejecta 
in A30"  Borkowski, K.J.; Harrington, J.P.; Tsvetanov, Z.; 
ApJ accepted

"Structural parameters of faint galaxies from pre-refurbishment 
HST medium deep survey observations"  Casertano, S.; Ratnatunga, 
K.U.; Griffiths, R.E.; Im, M.; Neuschaefer, L.W.; Ostrander, 
E.J.; Windhorst, R.A.; ApJ 11-10-95

"The contribution of late-type/irregulars to the faint galaxy 
counts from HST medium deep survey images"  Driver, S.P.; 
Windhorst, R.A.; Griffiths, R.E.; ApJ 11-1-95 

"The morphological mix of field galaxies to m(I) = 24.25 mag 
(b(j)~=26 mag) from a deep HST WFPC2 image"  Driver, S.P.; 
Windhorst, R.A.; Ostrander, E.J.; Keel, W.C.; Griffiths, R.E.;
Ratnatunga, K.U.; ApJ 8-10-95 

"Disk M dwarf luminosity function from HST star counts" 
Gould, A.; Bahcall, J.N.; Flynn, C., ApJ in press 

"Limits on the Hubble constant from the HST distance of M100"
Mould, J.R.; Huchra, J.; Bresolin, F.; Ferrarese, L.; Ford, 
H.C.; Freedman, W.L.; Graham, J.A.; Harding, P.; Hill, R.; 
Hoessel, J.G.; Hughes, S.M.; Illingworth, G.D.; Kelson, D.; 
Kennicutt, R.C.; Madore, B.F.; Phelps, R.; Stetson, P.B.; 
Turner, A.; ApJ accepted

"Galaxy clustering statistics of HST medium deep survey: WF/PC 
images"  Neuschaefer, L.W.; Ratnatunga, K.U.; Griffiths, R.E.; 
Casertano, S.; Im, M.; ApJ accepted

"HST imaging of the wind-blown lobe NGC 6165"  Scowen, P.A.; 
Hester, J.J.; Code, A.; Mackie, G.; Lynds, C.R.; O'Neil, E.J. 
Jr.; ApJ accepted

APPENDIX: Contacts

Any questions about the scheduling of your observations should be addressed to your PRESTO contact. Post-Observation queries should be addressed to your Contact Scientist. If you do not know who these persons are, they are listed at: http://presto.stsci.edu/public/propinfo.html.

Any questions or requests can be addressed to help@stsci.edu.

Comments, questions, requests for issues, additions or deletions to the mailing list, etc. can be e-mailed to help@stsci.edu.

The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.