13466( 9) - 24-Mar-2014 17:56:37 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13466 Version: 9 Check-in Time: 24-Mar-2014 17:56:37 STScI Edit Number: 4 Title Determining the Mass of Proxima Centauri through Astrometric Microlensing ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Kailash C. Sahu Space Telescope Science Institute Y CoI: Dr. Howard E. Bond The Pennsylvania State University N CoI: Dr. Jay Anderson Space Telescope Science Institute N CoI: Dr. Martin Dominik University of St. Andrews N ------------------------------------------------------------------------------------ Abstract We propose to determine the mass of our nearest neighbor, Proxima Centauri, using the novel technique of astrometric microlensing. Proxima is a dM6e star, with an estimated mass of about 0.12 Msun, lying at a distance of 1.3 pc and having a large proper motion of 3.8 arcsec/yr. In a reprise of the famous 1919 solar eclipse that verified general relativity, Proxima will pass in front of a pair of 18th-magnitude background stars in 2015, affording us two independent opportunities to measure the relativistic deflection. The first passage will occur in May 2015 (impact parameter 1.5 arcsec), and the second in June 2015 (impact parameter 1.4 arcsec). As Proxima passes in front, it will cause a relativistic deflection of the background stars' images by ~0.5 milliarcsec, an amount readily detectable with HST/WFC3. The gravitational deflection angle depends only upon the distances and relative positions of the stars, and the mass of the lens (Proxima). Since the distance to Proxima is well known from accurate parallax measurements, and the relative stellar positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of a single, isolated star. We anticipate better than 10% accuracy for the mass determination. The mass of Proxima is of special interest because it is the nearest M dwarf, representing the most common type of star in the Galaxy, for which the mass-luminosity relation is still uncertain at present. ------------------------------------------------------------------------------------ Observations Description ------------------------ The first epoch observations will be taken in a few different filters (F475W, F555W, F606W, F814W) to better characterize the spectral type of the source. Subsequent observations will be taken mainly in 2 filters (F606W and F814W). We will obtain one short (0.5 sec) exposure to get an unsaturated image of Proxima, in order to register its position. The other exposures will be of 90 to 200 sec durations, so that the source stars will have a S/N & 300 in each exposure. We can obtain about 10 such exposures in each orbit, at 2 dither positions, which would be adequate to achieve the astrometric accuracy required for the project. Real Time Justification ----------------------- 13466( 9) - 24-Mar-2014 17:56:37 - [ 2] Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 13466( 9) - 24-Mar-2014 17:56:37 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PROXIMA-CEN- STAR, K V-IV RA=14H29M34.3300S +/- 0.1", J2000 V = 18.4 +/- 0.2 SOURCE DEC=-62D40'33.98" +/- 0.1" Reference Frame: ICRS Comments: This object was updated to the SOURCE that Proxima-Cen is going to lens. At present, the source and proxima-cen are separated by about 10.5 arcsec, and this separation will slowly decrease to 1.5 arcsec in 2015. ------------------------------------------------------------------------------------------------------------------------------------ 13466( 9) - 24-Mar-2014 17:56:37 - [ 4] Visit: 01 Visit Requirements: ORIENT 326.12D TO 326.12 D; BETWEEN 25-MAR-2014 AND 15-APR-2014; VISIBILITY INTERVAL 59 M 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W BLADE=A, FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 9; SEQ -SOURCE S C-SUB S) 1-10 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 170 S (170 SAME POS AS 1 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 15, 10 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F606W FLASH=8 1 170 S (170 SAME POS AS 3 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 5 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 13.0 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 6 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 170 S (170 SAME POS AS 5 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 7 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F606W FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 5 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 8 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F606W FLASH=8 1 170 S (170 SAME POS AS 7 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 9 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 5.4, 9 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 10 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 170 S (170 SAME POS AS 9 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ PROXIMA-CEN-SOURCE 1 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 2 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 3 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB 13466( 9) - 24-Mar-2014 17:56:37 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ PROXIMA-CEN-SOURCE 4 WFC3/UVI ACCUM UVIS2-2K F606W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 5 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 6 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 7 WFC3/UVI ACCUM UVIS2-2K F606W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 8 WFC3/UVI ACCUM UVIS2-2K F606W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 9 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 10 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB 13466( 9) - 24-Mar-2014 17:56:37 - [ 6] Visit: 02 Visit Requirements: ORIENT 158D TO 162 D; BETWEEN 17-OCT-2014 AND 23-OCT-2014; VISIBILITY INTERVAL 51.3 M 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12, BLADE=A 1 0.5 S (0.5 POS TARG 14.4, 9; SEQ -SOURCE S C-SUB S) 1-10 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 POS TARG 14.4, 9 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 13.0 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 3 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 5 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 5 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 6 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 5 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 7 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 8 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 8 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12, BLADE=A 1 0.5 S (0.5 POS TARG 4.0, 9 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 9 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 8 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 10 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12, BLADE=A 1 0.5 S (0.5 SAME POS AS 8 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ PROXIMA-CEN-SOURCE 1 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 2 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 3 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB 13466( 9) - 24-Mar-2014 17:56:37 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ PROXIMA-CEN-SOURCE 4 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 5 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 6 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 7 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 8 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 9 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 10 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB 13466( 9) - 24-Mar-2014 17:56:37 - [ 8] Visit: 03 Visit Requirements: ORIENT 326.12D TO 326.12 D; BETWEEN 25-MAR-2014 AND 15-APR-2014; VISIBILITY INTERVAL 59 M 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W BLADE=A, FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 9; SEQ -SOURCE S C-SUB S) 1-11 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 1 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 15, 10 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 3 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 5 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 13.0 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 6 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 5 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 7 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12 1 0.5 S (0.5 POS TARG 10.4, 5 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 8 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 7 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 9 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 10 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 10 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=12, BLADE=A 1 0.5 S (0.5 POS TARG 5.4, 9 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 11 PROXIMA-CEN WFC3/UVI ACCUM UVIS2-2K2 F555W FLASH=8 1 200 S (200 SAME POS AS 10 -SOURCE S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ PROXIMA-CEN-SOURCE 1 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB 13466( 9) - 24-Mar-2014 17:56:37 - [ 9] 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 | ------------------------------------------------------------------------------------------------------------------------------------ PROXIMA-CEN-SOURCE 2 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 3 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 4 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 5 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 6 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 7 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 8 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 9 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 10 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB PROXIMA-CEN-SOURCE 11 WFC3/UVI ACCUM UVIS2-2K F555W none none none none 1 N/A S 2C-SUB 13466( 9) - 24-Mar-2014 17:56:37 - [ 10] Summary Form for Proposal 13466 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-2K2C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BLADE=A, FLASH=12, FLASH=8 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 17-OCT-2014 AND 23-OCT-2014, BETWEEN 25-MAR-2014 AND 15-APR-2014, ORIENT 158D TO 162 D, ORIENT 326.12D TO 326.12 D, POS TARG 10.4, 13.0, POS TARG 10.4, 5, POS TARG 10.4, 9, POS TARG 14.4, 9, POS TARG 15, 10, POS TARG 4.0, 9, POS TARG 5.4, 9, SAME POS AS 1, SAME POS AS 10, SAME POS AS 3, SAME POS AS 5, SAME POS AS 7, SAME POS AS 8, SAME POS AS 9, SEQ 1-10 NON-INT, SEQ 1-11 NON-INT, VISIBILITY INTERVAL 51.3 M, VISIBILITY INTERVAL 59 M ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W, F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PROXIMA-CEN-SOURCE ------------------------------------------------------------------------------------------------------------------------------------