Submillimeter Data for SINGS

1. George J. Bendo & Robert D. Joseph (A ''George's Adventures in Learning OpenOffice'' Presentation) Submillimeter Data for SINGS

2. Outline • Overview of JCMT and SCUBA • Basic data processing • Current archival data • Future observations

3. James Clerck Maxwell Telescope • 15 m submillimeter telescope • Located on Mauna Kea (elevation 4,090 m) • Began operating in 1987 • Operated by Joint Astronomy Center • UK controls most observing time; Canada, Netherlands, Hawaii also get shares • Instruments include bolometer array (SCUBA) and heterodyne receivers

4. More Views of the JCMT

5. SCUBA (Submillimeter Common-User Bolometer Array) • Two sets of bolometers that can observe the same field simultaneously • 91 element short wavelength (450 mm) array • 37 element long wavelength (850 mm) array • 3 longer wavelength (1.1, 1.35, 2.0 mm) bolometers flank the long wavelength array but are rarely used • Arrays can be used in three basic observing modes • Stare photometry • Jiggle map • Scan map

6. SCUBA bolometer arrays

7. SCUBA Processing Software Because the data comes in terms of bolometer signal measurements over time, special software is needed to process the data into intensity maps . The JAC has created the SURF package, which works with other Starlink packages and data in the NDF (N-dimensional Data File) format.

8. Basic SCUBA Processing(Steps for all observing modes) • reduce_switch Split data into individual bolometer signals • flatfield Flatfields the data • extinction Corrects the data for atmospheric extinction; also splits the data into short and long wavelength components • change_quality Remove ''bad'' bolometers (i.e. bolometers producing noisy data) • despike2, scuclip Remove data spikes

9. Example of JCMT Data before Rebinning

10. Jiggle Map / Stare PhotometryData Processing • remsky Remove background as well as systematic variations across image from sky noise • rebin Combines multiple data files and rebins the data in RA and declination

11. Scan Map Data Processing • scan_rlb Remove variations in offset from bolometer to bolometer • calcsky, remsky Remove background as well as systematic variations across image from sky noise • rebin Rebins the data in RA and declination for each individual scan • remdbm Combines all individual scans into a final image

12. Calibration • Planets (especially Uranus and Mars) favored • Secondary calibrators (mostly planetary nebulae) also used • JCMT documentation treats source calibration as though sources are similar to point sources but these instructions will be disregarded when calibrating SINGS data • Calibrator counts will be measured in 2' aperture to create calibration factor to apply to maps after processing

13. Final Maps • Images will be in fits format • Data will be calibrated in Jy • Beam sizes are approximately ~8” at 450mm and ~15” at 850mm • Image scales will be 1” / pixel (but scale can be adjusted) • Image artifacts may be present • Hexagonal image edges • Hot pixels (particularly around edges of pointings • Holes in images (where bolometers masked out) • Grainy sky-noise • Large scale background fluctuations in scan maps

14. Examples of SCUBA PSFs

15. SINGS data in SCUBA archive 24 SINGS galaxies found in SCUBA archives • 8 galaxies are non-detections • 8 galaxies are detections but contain no significant signal outside the nucleus • 8 galaxies contain detections of extended structure (although these structures are sometimes small)

16. Non-Detection (Jiggle Map of NGC 855)

17. Non-Detection (Scan Map of NGC 628)

18. Central Detection (Jiggle Map of NGC 2798)

19. Central Detection (Scan Map of NGC 4579)

20. Extended Source Detection (Jiggle Map of NGC 4826)

21. Extended Source Detection (Jiggle Map of NGC 7552)

22. Extended Source Detection (Jiggle Map of NGC 7331)

23. Extended Source Detection (Jiggle Map of NGC 4631)

24. Planned JCMT Observations • Proposed observations through R. D. Joseph at University of Hawaii • 9 shifts awarded as part of flexible observing • Proposal ranked 8 out of 16 • Requested conditions for observing 850 mm (450 mm possible but unlikely) • 5 shifts given high priority (observations likely) • 4 shifts given low priority (observations made only if weather is good) • Estimate that at least 12 - 13 galaxies can be observed • Data will consist of jiggle maps covering central 2.6' x 2.3'

25. Future Submillimeter Observations • JCMT • Most sensitive telescope at both 450 & 850 mm • Best at resolving and mapping moderately extended objects • Multiple wavelength observations possible • Difficult to apply directly; must apply through collaborators at institutions with access to telescope (but we will probably have future access through Hawaii)

26. Future Submillimeter Observations (continued) • HHST (Heinrich Hertz Submillimeter Telescope) • Scan mapping capabilities at 850 mm (but mapping mode is inefficient) • Easily accessible to Steward Observatory staff • Lower sensitivity (~5x) • CSO (Caltech Submillimeter Observatory) • Scan and stare mapping modes at 350, 450, & 850 mm • Easily accessible to Caltech staff • Optomized for 350 mm, which is exceedingly difficult; longer wavelength observations inferior to JCMT

27. Timeline Jan 2003 Finish processing archival data; check archives for new data Feb - Jul 2003 Observe targets with JCMT Mar 2003 Submit JCMT proposal for additional targets Sep 2003 Finish processing new JCMT data; submit JCMT proposal for additional targets