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 Kiselev Nikolay Comets, scattering and molecular emission Vis. Polarimetry Linear (+circ ) Hadamcik (Levasseur-Regourd) Comets, Asteroids scattering Vis. Polarimetry and imaging pol. linear Rosenbush Vera Asteroids, Moons, minor bodies Vis. Polarimetry, imaging pol., spec.pol, linear Comets, circular polarization (multiple scattering, chirality) Vis. Polarimetry, circular (+lin.) Schmid, Hans Martin Giant planets, limb polarization Vis. imaging pol. spec. pol. linear

Science topics: stellar physics David Buckley Magnetic CVs (polars) Vis. pol. spec.pol, circular+linear Kochukhov O. Zeeman spectropol. of magnetic stars Vis. Spec.pol (HR) circular+linear Harrington David Herbig and Be stars, scattering, pumping Vis. Spec.pol (HR) linear Hashimoto Jun Circumstellar disks, scattering IR, AO, imaging pol. linear Science topics: extra-galactic Heidt Jochen Radio-loud AGNs polarization var. Vis. Imaging. pol, linear

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

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)

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

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

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 2: poor

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.)

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

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

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