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Questionnaire survey on standard stars

Questionnaire survey on standard stars. Topics of the survey: Basic info about polarimetric project Used instrument Requirements for science targets Information about used standard stars Interesting feedback: Thank you! 9 forms received (10 projects). Science topics: Solar system objects.

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Questionnaire survey on standard stars

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  1. Questionnaire survey on standard stars Topics of the survey: • Basic info about polarimetric project • Used instrument • Requirements for science targets • Information about used standard stars Interesting feedback: Thank you! 9 forms received (10 projects)

  2. Science topics: Solar system objects

  3. Science topics: stellar physics Science topics: extra-galactic

  4. Requirements and limitations Targets Autor Sensitivity Limitations n ins. cal, var. bckg. Comets, asteroids, Hadamcik, 0.1-0.3% x x Planets, limb Schmid 0.1-0.3% x x Comets Kiselev 0.03-0.1% x x Minor bodies, comets Rosenbush 0.01-0.03% x x x protopl.. Disks Hashimoto 0.3-1.0% x x Magnetic CVs Buckley 0.03-0.1% x x Herbig, Be stars Harrington 0.01-0.03% x x Ap-stars Zeeman Kochukov 0.01-0.03% x x x RL-AGN variab. Heidt 0.1-0.3% x

  5. Use of standard stars All programs (except 1) use 0-pol. and high-pol. standards All programs on circ. Polarization use circ-pol standards Use of 0-pol. standards • 6 calibration of instrument polarization • 3 check (circumstellar disks, planet limbs, AGN) • 1 not used (Zeeman pol.) Use of high pol. standards • 9: check (cal) 0 degr. polarization angle , efficiency-check • 3: cross talk check • 0: not used Use of circ. Pol standards • 5: Check-V • 3: Check-cross talk • 5: Not used (linear polarization)

  6. Properties of 0-pol standard stars Brightness of 0-pol. standards • 0: too faint • 8: O.K. • 3: too bright Distribution of 0-pol. standards • 2: good • 2: O.K. • 6: poor  Quality of 0-pol. standards • 1: high • 8: O.K.  • 0: poor

  7. Properties of high-pol standards Brightness of high-pol. standards • 1: too faint • 7: O.K. • 1: too bright Distribution of high-pol. standards • 1: good • 2: O.K.  • 8: poor Quality of high-pol. standards • 1: high • 8: O.K.  • 0: poor

  8. Properties of circ-pol standards Brightness of circ-pol. standards • 3: too faint • 0: O.K.  • 1: too bright Distribution of circ-pol. standards • 0: good • 1: O.K. • 3: poor Quality of circ-pol. standards • 0: high • 1: O.K.  • 2: poor

  9. References for standard stars • 3: Whittet et al.(1992) • 3: Tunschek et al. (1992) • 2: Schmidt et al. (1992) • 2: Heiles (2000) • 2: Angel and Landstreet (1970) circ. • 2: Hsu + Breger (1982) • 2: Serkowski – UKIRT-List • 2: FORS-list • 1: Michalsky 1976 • 1: slowly rot. AP stars (Zeeman-spect.)

  10. What should be improved with standard stars All types of standards • 3: higher accuracy • 4: less variable • 8: more standard objects • 2: fainter standards • 3: brighter (circ). standards • 1: R-band data missing

  11. Summary Survey gives some clear hints Main use of calibration targets • calibration of instrument polarization • check/cal. 0-degr angle, check efficiency • check V signal Main problems of standard stars • Distribution of 0-pol. and high-pol. is poor • Circular polarization standards are bad (all prop) Requirements • More standard stars • Higher accuracy, less variable

  12. What could be done? 1) Are there unpublished data on standard stars?  survey the archives  coordinate expertise within COST can the distribution of standards be improved? 2) elaborate the exact requirements for better instrument calibration with standard stars 3) Try to get new data if required

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