1. The art of imaging with Hubble
Max Mutchler, 25 September 2008
DITHER
DRIZZLE

2. Advanced Camera for Surveys Wide Field Planetary Camera 2
(ACS) (WFPC2)

3. WF2 chip Wide Field Planetary Camera 2 (WFPC2)
PC1 chip
WF3 chip WF4 chip

4. WFPC2 pointing patterns
Small-scale dithers Large-scale mosaics
(at the pixel level) (at the detector level)

6. WFPC2
drizzling
cookbooks

7. WFPC2 drizzling cookbooks
Keep it simple and pragmatic; minimal explanations
Set of cookbooks for various pointing strategies and target placements (PC or WF chip/s)
Which files to de-archive; reference files (uref)
Some tangential issues: image registration; WF4 bias correction…34th row correction?
PyDrizzle and MultiDrizzle parameters (reasonable first pass)
Inspecting output, iterating, optimizing: what to look for, which key parameters to experiment with
Contact the Help Desk with questions

9. Training exercise
Basic work skills and habits: handling data, organizing/notes, scripting, sanity checks, filenaming conventions, version control, etc
Sub-sampled, compact dither box pattern; drizzled to half-scale
A test: new cookbooks, MultiDrizzle CR-rejection
Visually inspecting output: what to look for?
Trial-and-error iterations; experimenting (mainly with CR-rejection); knowing when to stop
More of a “functional” project, rather than a “science” project, but we’ll see how they inform each other; may include…
Photometry: verify rejections via more stringent comparison to Gilliland output (optional)
Photometry: drizzle both V-band and I-band images, make a color-magnitude diagram (CMD)
Results will help us advise GOs, review proposals…identify bugs?

10. WFPC2 chips

11. input
images

12. input
image 1
(single_sci)

13. input
image 2
(single_sci)

14. clean
drizzled
output
(drz_sci)

15. exposure
weight map
(drz_weight)

16. NGC 2440 at 0.10 arcsec/pixel (detector scale)

17. NGC 2440 at 0.06 arcsec/pixel (sub-sampling scale)