6510( 6) - 06/10/97 11:14 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6510 Version: 6 Check-in Date: 10-Jun-1997 11:11:34 1.Proposal Title: The Spatially Extended Featureless Continuum Source of Cygnus A: Multicolor Imaging in Total Flux and Polarization ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle AGN GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: R. ANTONUCCI UNIVERSITY OF CALIFORNIA CoI: Anne Kinney Space Telescope Science Institute N CoI: Todd Hurt University of California, Santa Barbara N ------------------------------------------------------------------------------------ 6. Abstract We would like to obtain multicolor flux and polarization images of the powerful prototype Classical Double radio galaxy Cygnus A. Ground based data and several brief HST images show that the nuclear featureless continuum (FC) source is fully resolved spatially. From the proposed images and our HST UV spectrum, we hope to distinguish among emission mechanisms, test definitively whether the UV continuum is reflected light from a hidden quasar, and investigate the important new phenomenon of spatially extended but nonstellar and unpolarized optical emission. ------------------------------------------------------------------------------------ 6510( 6) - 06/10/97 11:14 - [ 2] Observations Description ------------------------ Unfortunately, Cygnus A is quite faint. The F342W post-CoStar FOC exposure (Fig. 1) indicates that the SE (featureless- continuum-emitting) nucleus has a total flux of only 2.6 * 10^-17 erg/sec cm^2Angstrom, spread out over a region approximately 1buildrel ''over.2 * 2buildrel ''over.2 in size. We can expect to get a high-resolution polarization map only in the hotter filter (F342W). For the F275W filter, we will get full resolution total flux images but the polarization will have to be binned up to ground-based resolution. Reflected off-nuclear light is generally highly polarized, \\\\\\\\\\\\\\\\gtwid10\\\\\\\\\\\\\\\\%. In the F342W filter, if the flux were smoothly distributed, the FOC simulator says that in a 0buildrel ''over.1 * 0buildrel ''over.1 box, through the polarizers, we'd get SNR=4.2 in 1 hour in the combined total flux image. I NOW MULTIPLY THIS BY 1.45^.5, BASED ON THE FORMAT -DEPENDENT SENSITIVITY, TABLE 11 OF THE FOC HANDBOOK, ADOPTING THE 512z x 512 FORMAT, RESULTING IN SNR=5.1. This is based on the flux and size of the FC source quoted above. For the error in fractional P, we invert and multiply by root 2 and scale according to exposure time and solid angle of binning. Specifically, in 5 hours, binning the Stokes maps by 0buildrel ''over.4, we'd get an error in P of 2.2\\\\\\\\\\\\\\\\%. Since the mirrors are generally localized (e.g. Capetti et al. 1995, ApJ, 446, 155 on FOC polarization imaging of NGC1068), the situation may actually be considerably better. The total flux SNR in 0buildrel ''over.1 bins will be 11.3. The other filter is taken to get full-resolution flux images for colors, and also to get wavelength-dependence of P. We will just expose long enough to get P in coarsely binned data. The F275W will have important new information in the flux images and gross binning in total flux in undesirable. The simulator corrected for Table 11 says we'll get SNR=5.4 in each 0buildrel ''over.1 * 0buildrel ''over.1 box in 5 hours. This corresponds to a polarization uncertainty of 2.6\\\\\\\\\\\\\\\\% in bins of one square arcsec. (For the flux at 2750Angstrom, we have extrapolated by F_nu\\\\\\\\\\\\\\\\proptoNu^- 1, and confirm that the result agrees with our spectrum.) For the red, we just need satisfactory archival total-flux images for subtraction purposes (see Sci. Just.). Macchetto's 1200 sec FOC/CoStar F430W or Westphal's 1800 sec PC2 F622W is suitable. For each filter (F275W and F342W), we would like a series of FOC polarization images, taking exposures with POL0, POL60, and POL120. Format should be 512z x 512, if it's correct that this gives an adequate 7"x14" field at highest sensitivity. The long axis should be within 30 degrees of the structural axis of Cygnus A, which is at 105 deg. The visibility period for our target is 54 min. We will acquire guide stars and take a single-polarization-filter image during an orbit for the rest of the available time (allowing 7 min imaging overhead). The result is 39.5 min available for the first orbit, and 41 min for succeeding ones (reduced guide- star acq time). In 2 sets of 3 orbits (for each polarizer) we accumulate ~4 hrs exp. in F275W; then in 3 sets of 3 we accumulate ~6 hours in F342W. Sets of 3 orbits at least should be continuous for minimizing polarization systematics. The very slightly lower exp time in POL0 than in POL60 and POL120 is fine, and can be compensated by a slight scaling in the reductions. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- Please check our reasoning carefully. ------------------------------------------------------------------------------------ 6510( 6) - 06/10/97 11:14 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Phys Dept, UCSB, Santa Barbara CA 93106 Ship Via: Email: __Diagnostic-Sum-Section__ Software-Version (Controller= ------------------------------------------------------------------------------------ 6510( 6) - 06/10/97 11:14 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CYGNUS-A GALAXY,RADIO GALAXY RA=19H 59M 28.47S +/- J2000 V = 15.1+/-.3 .05S,DEC=40D 44' 2.21" +/- F(3460)=5.0+/-2.0e-17 .5",PLATE-ID=003S 6510( 6) - 06/10/97 11:14 - [ 5] Visit: 01 Visit Requirements: ORIENT 109D TO 169D On Hold Comments: Additional Comments: Please check our ORIENT parameters: we want the long 14" axis of the FOV to be roughly along a true p.a. of 105D. The format must be 512z x 512 as we understand it, but that's not an option under APERTURE. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 46 M POL0 ------------------------------------------------------------------------------------------------------------------------------------ 2 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL60 ------------------------------------------------------------------------------------------------------------------------------------ 3 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL120 ------------------------------------------------------------------------------------------------------------------------------------ 4 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL0 ------------------------------------------------------------------------------------------------------------------------------------ 5 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL60 ------------------------------------------------------------------------------------------------------------------------------------ 6 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL120 ------------------------------------------------------------------------------------------------------------------------------------ 7 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL0 ------------------------------------------------------------------------------------------------------------------------------------ 8 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL60 ------------------------------------------------------------------------------------------------------------------------------------ 9 CYGNUS-A FOC/96 IMAGE 512X512 F342W, PIXEL=50x25 1 48 M POL120 ------------------------------------------------------------------------------------------------------------------------------------ 6510( 6) - 06/10/97 11:14 - [ 6] Visit: 02 Visit Requirements: ORIENT 109D TO 169D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CYGNUS-A FOC/96 IMAGE 512X512 F275W, PIXEL=50x25 1 46 M POL0 ------------------------------------------------------------------------------------------------------------------------------------ 11 CYGNUS-A FOC/96 IMAGE 512X512 POL60, PIXEL=50x25 1 48 M F275W ------------------------------------------------------------------------------------------------------------------------------------ 12 CYGNUS-A FOC/96 IMAGE 512X512 POL120, PIXEL=50x25 1 48 M F275W ------------------------------------------------------------------------------------------------------------------------------------ 13 CYGNUS-A FOC/96 IMAGE 512X512 POL0, PIXEL=50x25 1 48 M F275W ------------------------------------------------------------------------------------------------------------------------------------ 14 CYGNUS-A FOC/96 IMAGE 512X512 POL60, PIXEL=50x25 1 48 M F275W ------------------------------------------------------------------------------------------------------------------------------------ 15 CYGNUS-A FOC/96 IMAGE 512X512 POL120, PIXEL=50x25 1 48 M F275W ------------------------------------------------------------------------------------------------------------------------------------ 6510( 6) - 06/10/97 11:14 - [ 7] Summary Form for Proposal 6510 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PIXEL=50x25 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category AGN ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 109D TO 169D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F342W,POL0 F342W,POL60 F342W,POL120 F275W,POL0 POL60,F275W POL120,F275W POL0,F275W ------------------------------------------------------------------------------------------------------------------------------------ Target Names CYGNUS-A ------------------------------------------------------------------------------------------------------------------------------------