coverpage: title_1: THE BETA PICTORIS CIRCUMSTELLAR DISK (5202; 2nd visit) sci_cat: INTERSTELLAR MEDIUM sci_subcat: CIRCUMSTELLAR MATTER proposal_for: GTO/WF2 pi_title: DR. pi_fname: JOHN pi_mi: T. pi_lname: TRAUGER pi_inst: JPL pi_country: USA pi_phone: (818) 354-9594 hours_pri: 1.80 num_pri: 1 wf_pc: Y time_crit: Y pi_position: PROJECT SCIENTIST off_fname: JOHN off_mi: T. off_lname: TRAUGER off_title: PROJECT SCIENTIST off_inst: JET PROPULSION LABORATORY off_addr_1: 4800 OAK GROVE DRIVE off_addr_2: MAIL STOP 179-225 off_city: PASADENA off_state: CA off_zip: 91109 off_country: USA off_phone: (818) 354-9594 ! end of coverpage abstract: line_1: We propose new methods to examine the circumstellar disk around Beta line_2: Pictoris in order to determine its radial profile, and hence (in combination line_3: with IRAS data) to fix its albedo and temperature profile. These observations line_4: will extend previous extensive ground based coronagraphic observations, and line_5: models by members of the science team. The data will enable us to understand line_6: better the central clearing in the disk and whether it is caused by sublimation line_7: or possible planet formation. They will also constrain the geometric propertie line_8: of the disk including its inclination angle, vertical thickness and radial line_9: profile. Such observations limit models for the dynamics of the disk, includin line_10: its velocity dispersion and hence mass distribution, and radial mass transport line_11: mechanisms. If density waves or clear zones are observed, they will give line_12: indirect evidence for the presence of massive bodies (planets) in the disk. Th line_13: observations involve a combination of roll deconvolution, polarizers and PSF line_14: modelling in order to allow the central stellar image and associated scattered line_15: light to be subtracted. Ultraviolet observations will constrain the particle line_16: size distribution and the composition of the disk. The observations require the line_17: new capabilities in WFPC2 provided by the absence of bleeding across columns, line_18: as well as its UV capabilities. ! ! end of abstract general_form_proposers: lname: TRAUGER fname: JOHN title: DR. mi: T. inst: JPL country: USA esa: N ! lname: BURROWS fname: CHRISTOPHER title: DR. mi: J. inst: STSCI country: USA esa: Y ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The observations are designed to give the clearest possible image of the disk. line_2: In order to penetrate within the crucial 2 arcsecond radius where the disk is line_3: expected to disappear, but which is affected by the wings of the star image, line_4: similar exposures through polarizers will provide a differential measurement line_5: (the disk is about 30% polarized), as well as providing the first direct line_6: measurement of the polarisation of the disk from 1 to 5 arcsec. The total line_7: observation set is designed to take one orbit, and thus optimizes the use of line_8: HST time. The observations on Beta Pictoris are repeated at a different roll line_9: order to allow roll deconvolution. ! question: 3 section: 2 line_1: This novel technique avoids unpredictable scattered light and diffraction line_2: effects caused by the focal plane masking with the pyramid which have been line_3: proposed by the WFPC1 GTO team. It relies on the unique ability of the WFPC2 line_4: Loral CCDs to avoid bleeding across columns. This arises because the NPP line_5: inplant gives an effective well depth of 60000 electrons, but an inter-column line_6: well depth equivalent to 300000 electrons. We have found by simulation that line_7: exposures masked with the pyramid of other stars or of the same star with the line_8: telescope rolled but with the star off the edge of the CCD have very strong line_9: position dependences in the PSF. Hence it is virtually impossible to subtract line_10: them, because the absolute HST pointing is not easily controllable at the 1/20 line_11: arcsecond level with different guidestars. ! question: 4 section: 1 line_1: HST is needed because of its high angular resolution, high contrast images, UV line_2: sensitivity, and because of the unique WFPC2 NPP inplant that prevents bleeding line_3: across columns. We expect 1.0*10^7 electrons/sec through NF410M, 3.9e5 through line_4: NF255W, and 2.0e5 through NF160W. The disk has a surface brightness of about line_5: V=16mag/as^2 at six arcseconds. Beta Pictoris saturates the equivalent of 170 line_6: pixels per second through NF410M, but the bleeding is along the columns. With line_7: this filter, two four minute exposures yield a signal to noise of 12 per pixel line_8: in the disk six arcseconds from the star along the centerline, and still good line_9: signal to noise in the fainter outer regions. 10 min through nf160w or 5 min line_10: through NF255W both would give less well exposed images, but still a signal to line_11: noise of 10 at 2 arcseconds from the star. line_12: Figure 1 shows the expected WFPC2 HST PSF (the solid line marked PC2) line_13: compared to the present performance (the dashed line), and an 1 arcsecond line_14: atmospheric seeing profile. The disk surface brightness is plotted with an line_15: assumed arbitrary cutoff at 2 arcseconds (shown as the dotted line). The disk line_16: brightness is seen to be well below both the ground based stellar background line_17: and that presently accessible with the PC. On the other hand, it will be line_18: observable with a contrast exceeding unity all the way in to within 2 line_19: arcseconds with WFPC2. ! question: 5 section: 1 line_1: The basic observation set is repeated at a roll 90 degrees different from the line_2: first set. The scattered light from the instruments will remain stationary line_3: while the disk rotates. This allows instrumental scatter to be separated line_4: from the disk. The second visit includes three different roll angles to line_5: allow more differentiation between scatter and disk structures. ! question: 7 section: 1 line_1: In order to supress scattered light from the central star, we propose to first line_2: subtract model PSFs from the images. We have performed extensive PSF fitting, line_3: and have now refined the methods to the point that the models agree with the line_4: data with a mean pixel to pixel error of 15%. The models include spherical line_5: aberration, focus, other low order aberrations, spacecraft jitter, measured line_6: mirror figure errors, pixel registration, the full aperture function of the line_7: telescope, and misalignments in the PC camera. The residual errors are line_8: correlated, and look similar from star to star, hence they can be shifted and line_9: subtracted to further improve PSF subtraction. The parameters in the models line_10: include the PSF registration relative to pixel boundaries, so this method does line_11: not require that the stars and reference exposures be identically registered line_12: with respect to the pixel boundaries. Problems with the undersampled data line_13: which can be serious with a reference star image are automatically largely line_14: overcome, as only residual images need to be resampled. The current models line_15: fit PC1 data. However, there is every reason to expect that the fits to PC2 line_16: which should have no pupil misalignemnt or spherical aberration will be at line_17: least as good. line_18: Thus we would expect that a subtraction accurate to about 5% should be possible line_19: after the combination of modelling and reference image subtraction. This would line_20: give a residual contrast of about a factor of 20 where the disk turns over. The line_21: contrast outside 2.5 arcseconds is always about an order of magnitude even line_22: without subtraction. ! question: 8 section: 1 line_1: The orients assigned to the REQ_n keywords in the logsheet are line_2: selected to ensure that the disk is 90 degrees (+/- 180D) from line_3: its orientation in the first set of observations (which were taken line_4: at an orient of 90D). Observations should be taken at three different line_5: roll angles during the same visit. ! question: 10 section: 1 line_1: Members of the team have already written the relevant computer software to line_2: model the PSF, subtract the images, parameterize the disk, and fit it to line_3: thermal and mass equilibrium models. ! !end of general form text general_form_address: lname: TRAUGER fname: JOHN mi: T. title: DR. category: PI inst: JPL addr_1: Mail stop 179-225 addr_2: 4800 Oak Grove Drive city: Pasadena state: CA zip: 91109 country: USA phone: (818) 354-9594 ! lname: BURROWS fname: CHRISTOPHER mi: J. title: DR. category: CON inst: STScI addr_1: 3700 San Martin Drive city: Baltimore state: MD zip: 21218 country: USA phone: (410) 338-4935 ! lname: KRIST fname: JOHN mi: E. category: CON inst: STScI addr_1: 3700 San Martin Drive city: Baltimore state: MD zip: 21218 country: USA phone: (410) 338-5030 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: HD39060 name_2: BETA-PIC descr_1: A,124,904 pos_1: RA = 5H 46M 5.935S +/- 0.1S, pos_2: DEC = -51D 5' 1.75" +/- 0.1" equinox: 1950 pm_or_par: Y pos_epoch_bj: B pos_epoch_yr: 1950.00 ra_pm_val: 0.0005 dec_pm_val: 0.087 comment_1: EXPOSURE TIMES PROVIDE FOR A S-TO-N comment_2: OF 20 IN THE DISK AT FOUR ARCSECS. fluxnum_1: 1 fluxval_1: V=3.9,TYPE=A5V fluxnum_2: 1 fluxval_2: B-V=0.2 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.100 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F555W num_exp: 2 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 1.200 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: WF2 sp_element: F555W,POLQ num_exp: 1 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 req_1: POS TARG 7.4, -13.2 comment_1: STAR WILL BE SATURATED. comment_2: WF2 APERTURE REQUIRED comment_3: FOR POS TARG. linenum: 1.300 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: POLQN33 sp_element: F555W,POLQN33 num_exp: 1 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 req_1: POS TARG 18.0, -0.1 comment_1: STAR WILL BE SATURATED. comment_2: WF2 APERTURE REQUIRED comment_3: FOR POS TARG. linenum: 1.400 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: POLQP15W sp_element: F555W,POLQP15 num_exp: 1 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 req_1: POS TARG -8.0, -20.9 comment_1: STAR WILL BE SATURATED. comment_2: WF2 APERTURE REQUIRED comment_3: FOR POS TARG. linenum: 1.500 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F255W num_exp: 1 time_per_exp: 10.0M s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 1.600 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F160BW num_exp: 1 time_per_exp: 30.0M s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 1.700 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F336W num_exp: 1 time_per_exp: 5.0M s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 1.800 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F439W num_exp: 1 time_per_exp: 1.0M s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 1.900 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F675W num_exp: 1 time_per_exp: 30.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 1.950 sequence_1: DEFINE sequence_2: IMAGES targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F814W num_exp: 1 time_per_exp: 30.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. linenum: 10.000 sequence_1: USE sequence_2: IMAGES req_1: CYCLE 4; req_2: SEQ 1.1-1.95 NO GAP; req_3: ORIENT 255D +/- 34D comment_1: OTHER POSSIBLE ORIENTS ARE comment_2: LISTED IN QUESTION 8. comment_3: THIS ORIENT SHOULD BE comment_4: +/- 90D, +/- 30D FROM THE comment_5: ORIENT IN LINENUM 11. ! linenum: 11.100 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1-FIX sp_element: F555W num_exp: 2 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. ! linenum: 11.200 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: WF2 sp_element: F555W,POLQ num_exp: 1 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 req_1: POS TARG 7.4, -13.2 comment_1: STAR WILL BE SATURATED. comment_2: WF2 APERTURE REQUIRED comment_3: FOR POS TARG. ! linenum: 11.300 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: POLQN33 sp_element: F555W,POLQN33 num_exp: 1 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 req_1: POS TARG 18.0, -0.1 comment_1: STAR WILL BE SATURATED. ! linenum: 11.400 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: POLQP15W sp_element: F555W,POLQP15 num_exp: 1 time_per_exp: 26.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 req_1: POS TARG -8.0, -20.9 comment_1: STAR WILL BE SATURATED. ! linenum: 11.600 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1-FIX sp_element: F439W num_exp: 1 time_per_exp: 1.0M s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. ! linenum: 11.700 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1-FIX sp_element: F675W num_exp: 1 time_per_exp: 30.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. ! linenum: 11.80 sequence_1: DEFINE sequence_2: IMAGES2 targname: HD39060 config: WFPC2 opmode: IMAGE aperture: PC1-FIX sp_element: F814W num_exp: 1 time_per_exp: 30.0S s_to_n: 1 fluxnum_1: 1 priority: 1 param_1: CLOCKS=YES param_2: ATD-GAIN=15 comment_1: STAR WILL BE SATURATED. ! linenum: 12.000 sequence_1: USE sequence_2: IMAGES2 req_1: CYCLE 4; req_2: SEQ 11.1-11.8 NO GAP; req_3: ORIENT 0D +/- 10D comment_1: ORIENT CAN BE 180D FROM THAT GIVEN. ! linenum: 13.000 sequence_1: USE sequence_2: IMAGES2 req_1: CYCLE 4; req_2: SEQ 11.1-11.8 NO GAP; req_3: ORIENT 20D +/- 10D FROM 12 comment_1: SAME VISIT AS LINE #12. comment_2: USED SAME GUIDE STARS AS #12. comment_3: MAXIMUM ANGLE FROM #12 comment_4: IS PREFERRED. ! linenum: 14.000 sequence_1: USE sequence_2: IMAGES2 req_1: CYCLE 4; req_2: SEQ 11.1-11.8 NO GAP; req_3: ORIENT -20D +/- 10D FROM 12 comment_1: SAME VISIT AS LINE #12. comment_2: USED SAME GUIDE STARS AS #12. comment_3: MAXIMUM ANGLE FROM #12 comment_4: IS PREFERRED. ! ! end of exposure logsheet ! No scan data records found