9132( 3) - 05/16/01 14:48 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9132 Version: 3 Check-in Date: 16-May-2001 14:46:34 1.Proposal Title: Resolving the Puzzling Dark Mass Concentration in Abell 1942 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Thomas Erben Max-Planck-Institut fur Astrophysik CoI: Dr. Yannick Mellier Insitut d'Astrophysique de Paris N CoI: Prof. Peter Schneider University of Bonn N CoI: Prof. Richard Ellis California Institute of Technology N CoI: Dr. Ludovic van Waerbeke Institut d'Astrophysique de Paris N CoI: Dr. Francisco-Javier Castander Observatoire Midi-Pyrenees N CoI: Ms. Meghan Gray Institute of Astronomy, Cambridge UK N ------------------------------------------------------------------------------------ 5. Abstract Exhaustive ground-based studies have not resolved the physical nature of the highly significant gravitational lensing signal observed by Erben et al in the field of the rich cluster Abell 1942 (z=0.22). Independent lensing analyses of two optical datasets reveal a striking mass concentration ~eq7 arcmin south of the cluster centre with no obvious visible source counterpart. Placed at the redshift of the cluster the implied mass would be M(0.5h^-1mboxMpc) >= 1* 10^14M_\odot. The absence of an obvious excess of faint sources in suitably deep infrared images makes it highly unlikely that such a strong lensing signal can be caused by a projected background cluster of galaxies. Accordingly we must take seriously the possibility of either the detection of a new type of extragalactic object or some hitherto undiscovered uncertainty in the weak lensing mass reconstruction techniques. The former is of obvious importance but so would be the latter given the increasingly important role lensing plays in constraining the mass power spectrum. A modest HST allocation will significantly improve the precision and localised position of this puzzling signal enabling the first detailed examination of both possibilities. ------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 2] Observations Description ------------------------ The CFHT data delivered ~eq20 galaxies arcmin^-2 within 21.0 < I < 24.0. The faint limit is defined as that beyond which reliable object shapes cannot easily be ascertained from the ground. Although deeper ground-based images would readily yield higher surface densities, as such sources would be fainter and smaller, their shape cannot easily be measured accurately in typical conditions and are more affected by PSF abnormalities. This is particularly the case when a specific region is being studied (as opposed to the requirements for a statistical survey over wide fields). Dithered WFPC2 observations by many workers have demonstrated adequate precision in estimating galaxy shapes on WFPC2 fileds at surface densities of ~eq 100 galaxies arcmin^-2 (Seitz et al. 1996, Hoekstra et al.\ 1999). The latter work demonstrates the high superiority of WFPC2 images compared even to deep Keck images (Clowe et al. 2000). Whereas the gross features of both lensing-reconstructed mass maps are in very good agreement, the increased useful number density of galaxy images in the HST data allows for a highly improved mass reconstruction, in which the three cluster subcomponents are clearly identified, and a more accurate estimate of the total mass owing to the higher S/N-ratio. The S/N-ratio for the detection of the dark clump is expected to increase in two ways: the enhanced number density of galaxies used in the weak lensing analysis will reduce the noise by a factor ~ sqrt100/20~ 2, turning a 4.5Sigma detection into a ~ 10Sigma detection. Second, as the faintest galaxies measureable with WFPC2 will have a higher mean background redshift, the lensing signal will also increase. If the clump is at redshift z>= 0.8 this could be a significant effect, since the geometric factor D_ ds/D_ s depends very sensitively on the source redshift z_s (e.g., for a lens at redshift z_d=0.8, the lensing strength increases by a factor ~ 2 if z_schanges from 1 to 1.5). Together, these effects will increase significance relative to CFHT by a factor of >2.5-3. The outcome of these improvements will be a greatly improved mass reconstruction with consequent gains in the astrometric position of the feature and new information on whether it can be represented by a point mass. The dark mass concentration reveals a coherent lensing signal up to about 150'' from its center on the ground based images. To cover the full area out to 180'' with the WFPC2 camera we require a mosaic of six pointings as shown in Fig. refhstpointingfig. For every pointing we request six dither positions with 1100sec. each and half pixel shifts. This strategy follows the successful strategy for the HST proposal GO 7372 which yielded a mass map of unprecedented angular resolution for the high redshift cluster MS1054-03 (Hoekstra et al.\ 1999). This technique will allow us to increase the resolution of our images to 0.05'' per pixel and to get about 100 galaxies/arcmin^2 for reliable shape measurements. Because of its high sensitivity and to complement our optical V-, I- band and infrared data we propose to use the F702 broad-band filter throughout. Our team has extensive experience with both ground-based and HST- based lensing techniques. We have developed state-of-the-art lensing analysis techniques which are in widespread use on both ground and HST-based datasets (Mellier 1999, Bartelmann & Schneider 2000, Erben et al 2000). Real Time Justification ----------------------- The number density of faint objects for which we can reliably measure the shape is critical for the significance of our lensing signal (see above). Accordingly, it is important to ensure a LOW SKY background for the entire imaging campaign. None Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 OBJ-143823- UNIDENTIFIED, BLANK RA=14H 38M 11.35S +/- 1.0", J2000 R = 12.0+/-0.5 033248-POS1 FIELD DEC=03D 33' 31.61" +/- 1.0" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 2 OBJ-143823- UNIDENTIFIED, BLANK RA=14H 38M 15.96S +/- 1.0", J2000 R = 12.0+/-0.5 033248-POS2 FIELD DEC=03D 32' 22.61" +/- 1.0" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 3 OBJ-143823- UNIDENTIFIED, BLANK RA=14H 38M 20.57S +/- 1.0", J2000 R = 12.0+/-0.5 033248-POS3 FIELD DEC=03D 31' 13.61" +/- 1.0" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 4 OBJ-143823- UNIDENTIFIED, BLANK RA=14H 38M 29.79S +/- 1.0", J2000 R = 12.0+/-0.5 033248-POS4 FIELD DEC=03D 32' 22.61" +/- 1.0" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 5 OBJ-143823- UNIDENTIFIED, BLANK RA=14H 38M 25.18S +/- 1.0", J2000 R = 12.0+/-0.5 033248-POS5 FIELD DEC=03D 33' 31.61" +/- 1.0" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 6 OBJ-143823- UNIDENTIFIED, BLANK RA=14H 38M 20.57S +/- 1.0", J2000 R = 12.0+/-0.5 033248-POS6 FIELD DEC=03D 34' 40.61" +/- 1.0" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 9132( 3) - 05/16/01 14:48 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 135D TO 135D On Hold Comments: Additional Comments: Each visit is split into twelve exposures with 400 sec. exposure time each. The low exposure time is chosen to avoid blooming effects from a bright star right in the middle of our mosaic field. Each exposure is shifted from the previous by half pixel dithers (POS_TARG) to increase the final pixel resolution. CR-SPLIT=NO for all exposures as with 12 exposures per pointing there are enough single frames for cosmic ray rejection. LOW_SKY is selected as we need the largest depth reachable with our exposure time to measure accurately the shapes of faint objects. As we build a mosaic of 6 WFPC pointings, each exposure has to be taken with a fixed rotation angle (ORIENT). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.0 033248-POS1 ------------------------------------------------------------------------------------------------------------------------------------ 20 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.5 033248-POS1 ------------------------------------------------------------------------------------------------------------------------------------ 30 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 0.0 033248-POS1 ------------------------------------------------------------------------------------------------------------------------------------ 40 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS1 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 50 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS1 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 60 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.0, 033248-POS1 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 70 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS1 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 80 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS1 1.25 ------------------------------------------------------------------------------------------------------------------------------------ 90 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.25, 033248-POS1 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 100 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS1 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS1 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 120 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS1 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 5] Visit: 02 Visit Priority: Visit Requirements: ORIENT 135D TO 135D On Hold Comments: Additional Comments: Each visit is split into twelve exposures with 400 sec. exposure time each. The low exposure time is chosen to avoid blooming effects from a bright star right in the middle of our mosaic field. Each exposure is shifted from the previous by half pixel dithers (POS_TARG) to increase the final pixel resolution. CR-SPLIT=NO for all exposures as with 12 exposures per pointing there are enough single frames for cosmic ray rejection. LOW_SKY is selected as we need the largest depth reachable with our exposure time to measure accurately the shapes of faint objects. As we build a mosaic of 6 WFPC pointings, each exposure has to be taken with a fixed rotation angle (ORIENT). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.0 033248-POS2 ------------------------------------------------------------------------------------------------------------------------------------ 20 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.5 033248-POS2 ------------------------------------------------------------------------------------------------------------------------------------ 30 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 0.0 033248-POS2 ------------------------------------------------------------------------------------------------------------------------------------ 40 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS2 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 50 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS2 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 60 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.0, 033248-POS2 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 70 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS2 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 80 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS2 1.25 ------------------------------------------------------------------------------------------------------------------------------------ 90 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.25, 033248-POS2 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 100 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS2 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS2 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 120 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS2 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 6] Visit: 03 Visit Priority: Visit Requirements: ORIENT 135D TO 135D On Hold Comments: Additional Comments: Each visit is split into twelve exposures with 400 sec. exposure time each. The low exposure time is chosen to avoid blooming effects from a bright star right in the middle of our mosaic field. Each exposure is shifted from the previous by half pixel dithers (POS_TARG) to increase the final pixel resolution. CR-SPLIT=NO for all exposures as with 12 exposures per pointing there are enough single frames for cosmic ray rejection. LOW_SKY is selected as we need the largest depth reachable with our exposure time to measure accurately the shapes of faint objects. As we build a mosaic of 6 WFPC pointings, each exposure has to be taken with a fixed rotation angle (ORIENT). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.0 033248-POS3 ------------------------------------------------------------------------------------------------------------------------------------ 20 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.5 033248-POS3 ------------------------------------------------------------------------------------------------------------------------------------ 30 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 0.0 033248-POS3 ------------------------------------------------------------------------------------------------------------------------------------ 40 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS3 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 50 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS3 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 60 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.0, 033248-POS3 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 70 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS3 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 80 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS3 1.25 ------------------------------------------------------------------------------------------------------------------------------------ 90 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.25, 033248-POS3 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 100 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS3 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS3 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 120 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS3 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 7] Visit: 04 Visit Priority: Visit Requirements: ORIENT 135D TO 135D On Hold Comments: Additional Comments: Each visit is split into twelve exposures with 400 sec. exposure time each. The low exposure time is chosen to avoid blooming effects from a bright star right in the middle of our mosaic field. Each exposure is shifted from the previous by half pixel dithers (POS_TARG) to increase the final pixel resolution. CR-SPLIT=NO for all exposures as with 12 exposures per pointing there are enough single frames for cosmic ray rejection. LOW_SKY is selected as we need the largest depth reachable with our exposure time to measure accurately the shapes of faint objects. As we build a mosaic of 6 WFPC pointings, each exposure has to be taken with a fixed rotation angle (ORIENT). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.0 033248-POS4 ------------------------------------------------------------------------------------------------------------------------------------ 20 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.5 033248-POS4 ------------------------------------------------------------------------------------------------------------------------------------ 30 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 0.0 033248-POS4 ------------------------------------------------------------------------------------------------------------------------------------ 40 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS4 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 50 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS4 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 60 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.0, 033248-POS4 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 70 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS4 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 80 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS4 1.25 ------------------------------------------------------------------------------------------------------------------------------------ 90 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.25, 033248-POS4 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 100 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS4 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS4 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 120 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS4 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 8] Visit: 05 Visit Priority: Visit Requirements: ORIENT 135D TO 135D On Hold Comments: Additional Comments: Each visit is split into twelve exposures with 400 sec. exposure time each. The low exposure time is chosen to avoid blooming effects from a bright star right in the middle of our mosaic field. Each exposure is shifted from the previous by half pixel dithers (POS_TARG) to increase the final pixel resolution. CR-SPLIT=NO for all exposures as with 12 exposures per pointing there are enough single frames for cosmic ray rejection. LOW_SKY is selected as we need the largest depth reachable with our exposure time to measure accurately the shapes of faint objects. As we build a mosaic of 6 WFPC pointings, each exposure has to be taken with a fixed rotation angle (ORIENT). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.0 033248-POS5 ------------------------------------------------------------------------------------------------------------------------------------ 20 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.5 033248-POS5 ------------------------------------------------------------------------------------------------------------------------------------ 30 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 0.0 033248-POS5 ------------------------------------------------------------------------------------------------------------------------------------ 40 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS5 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 50 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS5 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 60 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.0, 033248-POS5 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 70 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS5 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 80 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS5 1.25 ------------------------------------------------------------------------------------------------------------------------------------ 90 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.25, 033248-POS5 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 100 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS5 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS5 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 120 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS5 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 9] Visit: 06 Visit Priority: Visit Requirements: ORIENT 135D TO 135D On Hold Comments: Additional Comments: Each visit is split into twelve exposures with 400 sec. exposure time each. The low exposure time is chosen to avoid blooming effects from a bright star right in the middle of our mosaic field. Each exposure is shifted from the previous by half pixel dithers (POS_TARG) to increase the final pixel resolution. CR-SPLIT=NO for all exposures as with 12 exposures per pointing there are enough single frames for cosmic ray rejection. LOW_SKY is selected as we need the largest depth reachable with our exposure time to measure accurately the shapes of faint objects. As we build a mosaic of 6 WFPC pointings, each exposure has to be taken with a fixed rotation angle (ORIENT). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.0 033248-POS6 ------------------------------------------------------------------------------------------------------------------------------------ 20 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.0, 0.5 033248-POS6 ------------------------------------------------------------------------------------------------------------------------------------ 30 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 0.0 033248-POS6 ------------------------------------------------------------------------------------------------------------------------------------ 40 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS6 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 50 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.5, 033248-POS6 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 60 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.0, 033248-POS6 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 70 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS6 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 80 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS6 1.25 ------------------------------------------------------------------------------------------------------------------------------------ 90 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 1.25, 033248-POS6 0.75 ------------------------------------------------------------------------------------------------------------------------------------ 100 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS6 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.25, 033248-POS6 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 120 OBJ-143823- WFPC2 IMAGE WFALL F702W CR-SPLIT=NO 1 400 S LOW-SKY POS TARG 0.75, 033248-POS6 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 9132( 3) - 05/16/01 14:48 - [ 10] Summary Form for Proposal 9132 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFALL ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 135D TO 135D LOW-SKY POS TARG 0.0, 0.0 LOW-SKY POS TARG 0.0, 0.5 LOW-SKY POS TARG 0.5, 0.0 LOW-SKY POS TARG 0.5, 0.25 LOW-SKY POS TARG 0.5, 0.75 LOW-SKY POS TARG 1.0, 0.25 LOW-SKY POS TARG 0.75, 0.75 LOW-SKY POS TARG 0.75, 1.25 LOW-SKY POS TARG 1.25, 0.75 LOW-SKY POS TARG 0.25, 0.5 LOW-SKY POS TARG 0.25, 1.0 LOW-SKY POS TARG 0.75, 0.5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F702W ------------------------------------------------------------------------------------------------------------------------------------ Target Names OBJ-143823-033248-POS1 OBJ-143823-033248-POS2 OBJ-143823-033248-POS3 OBJ-143823-033248-POS4 OBJ-143823-033248-POS5 OBJ-143823-033248-POS6 ------------------------------------------------------------------------------------------------------------------------------------