10707( 4) - 05/09/05 11:55 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10707 Version: 4 Check-in Date: 09-May-2005 15:54:59 1.Proposal Title: First Mass Measurement of a Planet Found By Microlensing ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO/DD 13 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Andrew Gould The Ohio State University Research Foundation CoI: Dr. Andrzej Udalski Warsaw University N CoI: Dr. David P. Bennett University of Notre Dame N CoI: Dr. Bernard S. Gaudi Harvard University N CoI: Mr. Subo Dong The Ohio State University Research N Foundation ------------------------------------------------------------------------------------ 6. Abstract We will use ACS to determine the mass of the extra-solar planet found in the ongoing microlensing event OGLE-2005-BLG-071. This source will be imaged in V (F555W) and I (F814W) at two epochs, one "very soon" while the event is still significantly magnified, and the other after 5 months when it has returned to baseline. If the centroid does not move, this will demonstrate that the "blended light" detected in the event is "perfectly aligned" (within 15 mas, 1 sigma) with the source, and so is almost certainly the lens. V and I photometry will then permit an estimate of its mass and distance. Since the planet-star mass ratio is already known to be 0.007, this will yield a planet mass. Even if the HST images show that the blended light is not aligned with the source (and so is not from the lens), the HST observations will still strongly constrain the mass by helping to measure the "microlens parallax", which when combined with the "angular Einstein radius", determines the mass. Thus, the observations have a very high probability of success. The observations are time- critical because the first one must be taken while the event is still in progress. ------------------------------------------------------------------------------------ 10707( 4) - 05/09/05 11:55 - [ 2] Observations Description ------------------------ The target is an ongoing microlensing event with coordinates: (J2000.0): 17:50:09.77 -34:40:23.3 There will be two observations on ACS HRC, each taking one orbit. One orbit will be ``as soon as possible'' and the other on or after 1 October 2005. The protocol for the two orbits will be the same: 4 I band (F814W) exposures, each 3.75 min, each separated by dithers as indicated in Phase II form; then 4 V band (F555W) exposures, each 5.25 min, each separated by dithers as indicated in Phase II form. At the two epochs, the target will be (V, I)=(19.8, 18.2) [20 May] and (V, I)=(20.7, 18.9) [1 Oct]. This will yield S/N=549 and 395 for the two I-band measurements. This is more than adequate to centroid to 1 mas, but we expect the astrometry to be fundamentally limited by crowding, not S/N. The V images will have lower S/N=339 and 208. They will be of high enough S/N to check the centroid motion and in addition will permit precise photometry of any blended light that is not aligned with the source. Orbit 1 (ASAP) Orbit 2 (~1 Oct 2005) Guide Star Acq 6 min Guide Star Acq 6 min F814W overheads (1.8+2.4) 4.2min F814W overheads (1.8+2.4) 4.2min 4 x 3.75min exp 15 min 4 x 3.75min exp 15 min 3 x 20s dither 1 min 3 x 20s dither 1 min F555W overheads (1.8+2.4) 4.2min F555W overheads (1.8+2.4) 4.2min 4 x 5.25min exp 21min 4 x 5.25min exp 21 min 3 x 20s dither 1 min 3 x 20s dither 1 min----- -------------------------- ------------------------------- total 52.4 min total 52.4 min Real Time Justification ----------------------- First observation should be done as soon as possible. The precision obtained from these observations will degrade rapidly the more they are delayed. Details were given in the DDT proposal, which was approved. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 10707( 4) - 05/09/05 11:55 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 OGLE-2005- STAR, F3-F9 RA=17H50M9.7700S +/- 1", DEC=- J2000 V = 19.8+/-0.3 BLG-071 34D40'23.30" +/- 1" I mag: 18.2 [In 2nd visit (~1 Oct) source will be V=20.7 I=18.9] Coordinate Source: Other_Source: OGLE-III Comments: Distance to source is unknown, but is believed to be 1 or 2 kpc. 10707( 4) - 05/09/05 11:55 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-HRC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.15 Line_Spacing 0.098 Coordinate_Frame POS-TARG Pattern_Orient 19.89 Angle_Between_Sides 63.5 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 10707( 4) - 05/09/05 11:55 - [ 5] Visit: 01 Visit Priority: Visit Requirements: NUMBER OF GYROS 3; BETWEEN 15-MAY-2005:00:00:00 AND 15-JUN-2005:00:00:00 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 OGLE-2005-B ACS/HRC ACCUM HRC F814W CR-SPLIT=NO 1 225 S PATTERN 1 1 LG-071 ------------------------------------------------------------------------------------------------------------------------------------ 2 OGLE-2005-B ACS/HRC ACCUM HRC F555W CR-SPLIT=NO 1 315 S PATTERN 1 2 LG-071 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 1 none none none 1 N/A OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 2 none none none 1 N/A OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 3 none none none 1 N/A OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 4 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 1 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 2 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 3 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 4 none none none 1 N/A 10707( 4) - 05/09/05 11:55 - [ 6] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 01-OCT-2005:00:00:00 AND 15-JUN-2006:00:00:00 On Hold Comments: Additional Comments: Our "default option" is for the second visit to take place on or shortly after 16 Feb 2006 (when schedulability begins, assuming 2 Gyros) However, if 3 Gyros are operating on 1 Oct 2005, then it would be possible to observe our field at that time. This would be somewhat preferable to the above "default option". Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 OGLE-2005-B ACS/HRC ACCUM HRC F814W CR-SPLIT=NO 1 225 S PATTERN 1 1 LG-071 ------------------------------------------------------------------------------------------------------------------------------------ 2 OGLE-2005-B ACS/HRC ACCUM HRC F555W CR-SPLIT=NO 1 315 S PATTERN 1 2 LG-071 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 1 none none none 1 N/A OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 2 none none none 1 N/A OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 3 none none none 1 N/A OGLE-2005-BLG-071 1 ACS/HRC ACCUM HRC F814W 4 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 1 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 2 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 3 none none none 1 N/A OGLE-2005-BLG-071 2 ACS/HRC ACCUM HRC F555W 4 none none none 1 N/A 10707( 4) - 05/09/05 11:55 - [ 7] Summary Form for Proposal 10707 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements NUMBER OF GYROS 3; BETWEEN 15-MAY-2005 00 00 00 AND 15-JUN-2005 00 00 00 PATTERN 1 1 PATTERN 1 2 BETWEEN 01-OCT-2005 00 00 00 AND 15-JUN-2006 00 00 00 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names OGLE-2005-BLG-071 ------------------------------------------------------------------------------------------------------------------------------------