9445( 2) - 02/14/02 11:15 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9445 Version: 2 Check-in Date: 14-Feb-2002 11:12:16 1.Proposal Title: Gravitational Microlensing in the NGC 3314A-B Galaxy Pair ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: David Bennett University of Notre Dame CoI: Dr. Sun Hong Rhie University of Notre Dame N CoI: Dr. William Keel University of Alabama N CoI: Dr. Ian Bond University of Auckland N CoI: Dr. Philip Yock University of Auckland N ------------------------------------------------------------------------------------ 5. Abstract Determining the composition of the dark matter that dominates the masses of galaxies is an important unsolved problem, and the results of the MACHO Collaboration suggest that some of Milky Way's dark matter may be in the form of very old white dwarfs. However, some have argued that the excess of microlensing events seen by MACHO are due to a larger than expected microlensing rate for lens stars in the LMC itself or its tidal debris. We propose to address this question by detecting microlensing events in the line-of-sight galaxy pair NGC 3314 A & B. The large line-of-sight distance between these galaxies gives an optical depth that is 3-4 orders of magnitude larger than if the source stars and lenses were in the same galaxy, and the fact that the background galaxy is a spiral ensures that there will be a sufficient number of bright, non-variable source stars. Our proposed observations should have the sensitivity to detect microlensing by both ordinary stars and dark matter in NGC 3314A (the foreground galaxy). If there are dark matter microlensing events to be found, they can be clearly distinguished from stellar microlensing events because they will occur outside the visible disk of NGC 3314A. If baryonic dark matter is detected in NGC 3314A, we will be able to map its radial density variation. ------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 2] Observations Description ------------------------ We plan to use only single orbit visits so as to maximize number of visits and the the range of microlensing event time scales that we'll be sensitive to. We do not plan any filter changes during each visit, but we will get some color information by using the ACS WCF F606W filter in 1/4 to 1/3 of the visits. The majority of the visits will use the ACS WCF F475W filter since this offers the best sensitivity for our target stars which are typically highly magnified early B main sequence stars. In order to maximize our resolution, we plan to employ a 2* 2 square dither pattern of 0.5 pixel steps for each set of images (Lauer 1999). This will not give us the full Nyquist sampling in the F475W filter on the WFC, but a more complicated dither patter would cost too much observing time for our faint targets. We plan to use an image differencing technique similar to those proposed by Tomaney & Crotts (1996), Alard & Lupton (1998) and Lauer (1999) to analyze our data. (Our version has been developed by CoI Ian Bond.) One difficulty with this is that we will not be able to take all of the HST data with the same spacecraft orientation because the same orientation can only be maintained for a month or so. We plan to deal with this by ensuring that our data is taken at roll angles that are multiples of 30 degrees, so that there will be only 3 different orientations of the square pixels on this sky. We will also try to ensure that a large number of images over our two year program are taken at each orientation. This will result in relatively large data sets with each orientation that we can use to remove any orientation-specific systematic photometry errors. Finally, we also plan a time series of observations that will start with a slow tempo of observations every 2 weeks or so, and then increase toward the middle of the season to a rate of a couple visits per week. The tempo of observations will then decrease again in a mirror image of the first half of the observing season. There are several advantages of this plan. First it allows us to get reasonable sampling for events of different durations which is important because the durations are not well constrained in advance. It also allows us to schedule the bulk of the observations with telescope pointing far from the bright limb of the Earth which will decrease the background light levels and increase our photometric sensitivity. It is necessary to have two seasons of observations because the longest events are likely to last a year or so. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- This proposal requested time series observations to look for microlensing events which have an uncertain timescale. Therefore, it will be very useful to have the observations begin as early as possible, so that we have the longest possible baseline. For this reason, we have requested that the first two visits take place in April or May, 2002. ------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC3314 GALAXY, SPIRAL RA=10H 37M 12.81S +/- 1", DEC=- J2000 B = 13.11 27D 41' 3.59" +/- 1" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 2 NGC3314-UP GALAXY, SPIRAL RA=10H 37M 12.81S +/- 1", DEC=- J2000 B = 13.11 27D 40' 40" +/- 1" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 3 NGC3314- GALAXY, SPIRAL RA=10H 37M 13.56S +/- 1", DEC=- J2000 B = 13.11 UPLEFT 27D 40' 54" +/- 1" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 9445( 2) - 02/14/02 11:15 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 90D TO 90D BEFORE 20-May-2002 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 90D TO 90D BEFORE 01-Jan-2003 AFTER 01 BY 8 D TO 15 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 7] Visit: 03 Visit Priority: Visit Requirements: ORIENT 135D TO 135D BEFORE 01-Jan-2003 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 NGC3314-UPL ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 EFT C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UPL ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 EFT C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 8] Visit: 04 Visit Priority: Visit Requirements: ORIENT 270D TO 270D BEFORE 01-Jan-2003 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 9] Visit: 05 Visit Priority: Visit Requirements: ORIENT 315D TO 315D 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 NGC3314-UPL ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 EFT C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UPL ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 EFT C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 10] Visit: 06 Visit Priority: Visit Requirements: ORIENT 0D TO 0D AFTER 01-Jan-2003 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 NGC3314 ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314 ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 11] Visit: 07 Visit Priority: Visit Requirements: ORIENT 45D TO 45D BETWEEN 01-Mar-2003 AND 23-Mar-2003 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 NGC3314 ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314 ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 12] Visit: 08 Visit Priority: Visit Requirements: ORIENT 45D TO 45D BETWEEN 28-Mar-2003 AND 28-Apr-2003 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 NGC3314 ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314 ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 13] Visit: 09 Visit Priority: Visit Requirements: ORIENT 90D TO 90D BETWEEN 07-Apr-2003 AND 20-Apr-2003 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 14] Visit: 10 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 09 BY 4 D TO 8 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 15] Visit: 11 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 10 BY 4 D TO 8 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 16] Visit: 12 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 11 BY 2 D TO 4 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 17] Visit: 13 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 12 BY 2 D TO 4 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 18] Visit: 14 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 13 BY 4 D TO 8 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 19] Visit: 15 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 14 BY 4 D TO 8 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 20] Visit: 16 Visit Priority: Visit Requirements: ORIENT 90D TO 90D AFTER 15 BY 8 D TO 15 D 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 NGC3314-UP ACS/WF ACCUM WFC2-FI F475W CR-SPLIT=NO 1 520 S PATTERN 1 10 C X ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3314-UP ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=NO 1 540 S PATTERN 1 20 C X ------------------------------------------------------------------------------------------------------------------------------------ 9445( 2) - 02/14/02 11:15 - [ 21] Summary Form for Proposal 9445 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC2-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 90D TO 90D BEFORE 20-May-2002 PATTERN 1 10 PATTERN 1 20 ORIENT 90D TO 90D BEFORE 01-Jan-2003 AFTER 01 BY 8 D TO 15 D ORIENT 135D TO 135D BEFORE 01-Jan-2003 ORIENT 270D TO 270D BEFORE 01-Jan-2003 ORIENT 315D TO 315D ORIENT 0D TO 0D AFTER 01-Jan-2003 ORIENT 45D TO 45D BETWEEN 01-Mar-2003 AND 23-Mar-2003 ORIENT 45D TO 45D BETWEEN 28-Mar-2003 AND 28-Apr-2003 ORIENT 90D TO 90D BETWEEN 07-Apr-2003 AND 20-Apr-2003 ORIENT 90D TO 90D AFTER 09 BY 4 D TO 8 D ORIENT 90D TO 90D AFTER 10 BY 4 D TO 8 D ORIENT 90D TO 90D AFTER 11 BY 2 D TO 4 D ORIENT 90D TO 90D AFTER 12 BY 2 D TO 4 D ORIENT 90D TO 90D AFTER 13 BY 4 D TO 8 D ORIENT 90D TO 90D AFTER 14 BY 4 D TO 8 D ORIENT 90D TO 90D AFTER 15 BY 8 D TO 15 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F475W F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC3314-UP NGC3314-UPLEFT NGC3314 ------------------------------------------------------------------------------------------------------------------------------------