5901( 33) - 11/21/97 14:38 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5901 Version: 33 Check-in Date: 21-Nov-1997 14:37:13 1.Proposal Title: Imaging of Gravitational Microlens Source Systems and their Underlying Stellar Backgrounds ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 5 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Kem Cook Lawrence Livermore National Laboratory CoI: Alex Rodgers Mt. Stromlo and Siding Spring N Observatories CoI: Chris Stubbs U.C. Santa Barbara N CoI: Will Sutherland Oxford N CoI: Ken Freeman Mt. Stromlo and Siding Spring N Observatories CoI: Charles Alcock Lawrence Livermore National Laboratory N CoI: Robyn Allsman Lawrence Livermore National Laboratory N CoI: Tim Axelrod Lawrence Livermore National Laboratory N CoI: David Bennett Center for Particle Astrophysics/U.C.B N CoI: Kim Griest U.C. San Diego N CoI: Stuart Marshall U.C. Santa Barbara N CoI: Bruce Peterson Mt. Stromlo and Siding Spring N Observatories CoI: Mark Pratt U.C. Santa Barbara N CoI: Peter Quinn Mt. Stromlo and Siding Spring N Observatories ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain high spatial resolution images of fields containing the (currently) unresolved images of the source plus lens for a sample of recently detected microlensing events in the Large Magellanic Cloud and the bulge of the Milky Way. The deep images of the sources will provide first epoch images for comparison with later images to resolve the proper motion of the lensing object, if it is luminous. If the lens is not resolved on later images, this is strong evidence that the lenses are not members of the luminous stellar component of disk or near halo. These measurements cut to the heart of the dark matter controversy in the halo of the Milky Way. We also propose to determine the stellar luminosity function in these crowded fields to three magnitudes fainter than surveyed by our ground based search in order to determine the effect of blending and confusion on our microlens detection efficiency. ------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 2] Observations Description ------------------------ We propose to image 3 fields in the LMC and For all three fields we will determine the luminosity function to about V=24.5. For two fields fields in the LMC, we will collect deep F814W images as first epoch data to search for proper motion of (potentially) luminous lensing objects. The exposures necessary to determine the luminosity function consist of 3 x 450 second sets of exposures in V and R, and 3 x 30 second sets of exposures to tie to our ground based photometry. Using the data in the WFPCII Handbook and the 7 electron per ADU gain, and allowing for an increased sky brightness due to faint stars in the bar of the LMC of about 22 mag per square arcsec, allows us to predict an accuracy of about 0.03 mag in both bands at 24.5 and an accuracy of 0.04 in (V- R) . The LMC is in the continuous viewing zone and so orbits are 5760 seconds. Acquisition takes 720 second and the 12 readouts and 2880 seconds of exposure just fill the first orbit. The first epoch I exposure of the source star plus lens will require an unusual observing sequence. The source stars are about I=18.4 and will saturate in exposures of more than 500 seconds. We are trying to detect the presence of a 27th mag object a pixel or two away and so we must not saturate the source. The lens, if it appears in the future, must be distinguisable from the noise in the wings of the source. The source will be placed on the PC for maximum spatial resolution, but each source will need 35 x 500 seconds to allow a future 4 sigma detection above the shot noise in its wings in the worst possible position as estimated from the point spread functions given in the WFPCII handbook. The LMC series can be completed directly using 5 orbits. Real Time Justification ----------------------- We request that the telescope be dithered by a small amount between the exposures in each filter for a better determination of star centers, reduce photometric errors from quantum efficiency variations across pixels, and allow better cosmic ray identification. The Macho Collaboration continues to monitor about 40 million stars per night for evidence of microlensing. We are just establishing a relationship with CTIO to provide better time coverage and photometry of events identified in real time with our Australian system using the 0.9m. Ground based spectra of the source stars for the HST pointings will be collected at the CTIO 4m this October. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LMC-0534- EXT-STAR, A4-A9 V-IV RA=05H 34M 44.4S +/- 0.1S, DEC=- J2000.0 V=0.0 V = 19.2 7025 70D 25' 07" +/- 1.0" B-V = 0.6 Comments: This is a new target that the PI selected as of 4/97. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000.0 0.0 0.0 0.0 2 LMC-0517- EXT-STAR, F3-F9 RA=05H 17M 14.6S +/- 0.1S, DEC=- J2000.0 V=0.0 V = 20.1 7047 70D 46' 59" +/- 1.0" B-V = 0.6 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000.0 0.0 0.0 0.0 3 LMC-0515- EXT-STAR, A4-A9 V-IV RA=05H 14M 44.5S +/- 0.1S, DEC=- J2000.0 V=0.0 V = 19.6 6848 68D 48' 00" +/- 1.0" B-V = 1.2 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000.0 0.0 0.0 0.0 5901( 33) - 11/21/97 14:38 - [ 4] Visit: 01 Visit Priority: Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 LMC-0534-70 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,DITHER-TYPE=BOX 1 500 S 25 ------------------------------------------------------------------------------------------------------------------------------------ 12 LMC-0534-70 WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,DITHER-TYPE=BOX 1 500 S SAME POS AS 11 25 ------------------------------------------------------------------------------------------------------------------------------------ 13 LMC-0534-70 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,DITHER-TYPE=BOX 1 500 S SAME POS AS 11 25 ------------------------------------------------------------------------------------------------------------------------------------ 14 LMC-0534-70 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,DITHER-TYPE=BOX 1 30 S SAME POS AS 11 25 ------------------------------------------------------------------------------------------------------------------------------------ 15 LMC-0534-70 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,DITHER-TYPE=BOX 1 30 S SAME POS AS 11 25 ------------------------------------------------------------------------------------------------------------------------------------ 16 LMC-0534-70 WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,DITHER-TYPE=BOX 1 30 S SAME POS AS 11 25 ------------------------------------------------------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 5] Visit: 02 Visit Priority: Visit Requirements: CVZ 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 LMC-0517-70 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,DITHER-TYPE=LINE, 11 500 S POS TARG 0,0 47 DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.150 ------------------------------------------------------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 6] Visit: 03 Visit Priority: Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 LMC-0517-70 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 30 S POS TARG 0,0 47 DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.150 ------------------------------------------------------------------------------------------------------------------------------------ 12 LMC-0517-70 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 500 S POS TARG 0,0 47 DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.150 ------------------------------------------------------------------------------------------------------------------------------------ 13 LMC-0517-70 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 30 S POS TARG 0,0 47 DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.150 ------------------------------------------------------------------------------------------------------------------------------------ 14 LMC-0517-70 WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 500 S POS TARG 0,0 47 DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.150 ------------------------------------------------------------------------------------------------------------------------------------ 15 LMC-0517-70 WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 30 S POS TARG 0,0 47 DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.150 ------------------------------------------------------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 7] Visit: 04 Visit Priority: Visit Requirements: CVZ 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 LMC-0515-68 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,DITHER-TYPE=BOX 10 500 S POS TARG 0,0 48 ------------------------------------------------------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 8] Visit: 05 Visit Priority: Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 LMC-0515-68 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,DITHER-TYPE=BOX 1 30 S POS TARG 0,0 48 ------------------------------------------------------------------------------------------------------------------------------------ 12 LMC-0515-68 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,DITHER-TYPE=BOX 1 400 S POS TARG 0,0 48 ------------------------------------------------------------------------------------------------------------------------------------ 13 LMC-0515-68 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,DITHER-TYPE=BOX 1 30 S POS TARG 0,0 48 ------------------------------------------------------------------------------------------------------------------------------------ 14 LMC-0515-68 WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,DITHER-TYPE=BOX 1 400 S POS TARG 0,0 48 ------------------------------------------------------------------------------------------------------------------------------------ 15 LMC-0515-68 WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,DITHER-TYPE=BOX 1 30 S POS TARG 0,0 48 ------------------------------------------------------------------------------------------------------------------------------------ 5901( 33) - 11/21/97 14:38 - [ 9] Summary Form for Proposal 5901 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO DITHER-TYPE=BOX DITHER-LINE-SPACING=0.150 DITHER-LINE-STEPS=3 DITHER-TYPE=LINE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SAME POS AS 11 CVZ POS TARG 0,0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F675W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LMC-0534-7025 LMC-0517-7047 LMC-0515-6848 ------------------------------------------------------------------------------------------------------------------------------------