7842( 2) - 11/24/97 10:42 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7842 Version: 2 Check-in Date: 24-Nov-1997 10:40:33 1.Proposal Title: A High-Resolution Proper Motion Study of the Ionized Gas Near Sgr A* ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: SUSAN STOLOVY STEWARD OBSERVATORY CoI: Dr. Fulvio Melia University of Arizona N CoI: Dr. Farhad Yusef-Zadeh Northwestern University N CoI: Dr. Donald McCarthy University of Arizona N ------------------------------------------------------------------------------------ 5. Abstract We propose to observe the inner 0.5 pc (~12'' at the Galactic center distance) of the Galaxy in Paschen Alpha at high spatial resolution with Camera 1 of NICMOS in order to study the detailed morphology and transverse motion of ionized gas near Sgr A*. Proper motions in the ionized gas within 0.5'' of Sgr A* will be measured for the first time and will provide a measure of the influence of gravitational versus non- gravitational forces. Structures observed in the ionized gas as a result of wind-wind collisions, evidence of infall and outflow, as well as kinematic and spatial correlations to stellar proper motions (NICMOS proposal 7225) will yield unprecedented understanding of the environment of black hole candidate, Sgr A*. The two epochs proposed here to derive proper motions will be combined with observations from approved proposal 7320 to increase the time baseline of the proper motion measurement. ------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 2] Observations Description ------------------------ We desire to reach a dynamic range relative to the brightest nearby source of ionized emission, IRS 13, of at least 1000:1 in order to track faint emission sources near Sgr A* and to achieve sufficient signal/noise to effectively subtract the stellar background. IRS 13 has a point-source flux in Br Gamma of 2.5 * 10^-16 W m^-2 at the ~ 1 '' resolution image presented in Tamblyn et al. (1996). We estimate that its Pa Alpha flux will be 1.3 * 10^-15 W m^-2. A signal/noise of 15 will be achieved in 40 minutes for a source with a Pa Alpha flux 1000 times fainter than IRS13 with F187N and Camera 1. This will significantly improve upon the contrast in the ionized filaments and the faint emission near Sgr A* in the radio observations. An equal time needs to be devoted to observing the continuum with F190N. This translates to two orbits. The second epoch will require an additional two orbits. Dithering will be done to replace bad pixels. The orientations will be set to be offset by multiples of 90 degrees in order to fix the detectors axes on the sky and insure identical dithering patterns. The first epoch should be conducted early in 1998, ideally in February or March when the observing window opens for the Galactic Center. The second epoch should be executed approximately in October 1998, before the observing window closes. If the projected lifetime of NICMOS is extended to February 1999 when the Galactic Center comes back into the window (or later), the second epoch should be delayed as much as possible. In conjunction with the data from the 7320 proposal, which is currently scheduled for Sept./Oct. 1997, these two new epochs will provide approximate intervals of 6 months and 1 year. Although camera 2 is diffraction limited at 1.87 Mum , we choose to observe with camera 1 for several reasons: 1) a finer grid is desireable for the best measurement of proper motion without having to impose a finer grid in software to register images at different epochs and to mosaic dithered images, 2) the first epoch (proposal 7320) uses camera 1, and 3) if deconvolution is used, sub-sampling the PSF is desireable (in this case, 1.22 Lambda/D is 4.6 pixels). Real Time Justification ----------------------- Since this is a proper motion project, we request as much as a time delay between the 2 visits as possible. Thus, we have put timing constraints on the orbits to force the first visit to occur in the Spring and the other to occur in the Fall of 1998. We desire to have the orientation differ by 180 degrees between the 2 visits so that we can avoid interpolating pixels when comparing the datasets. We have constrained the orientation of the first orbit to be 270 and the second to be 90 degrees. NOTE: the choice of these particular angles does NOT constrain the scheduling much at all. The BETWEEN timing constraint also essentially matches the desired Spring and Fall windows. Calibration Justification ------------------------- Additional Comments ------------------- Note that the IRS16 sources will NOT saturate in the narrow-band filters in the integration times chosen. A source of flux of 0.2 Jy (that's brigher than any of the IRS16 sources) at 1.87 microns will saturate in 221 seconds. In order to strike a balance between spatial coverage and good QE on regions of interest, visit 1 has a PATTERN-ORIENT of 225 and visit 2 has a PATTERN-ORIENT of 135. Targets 2 and 3 are defined in order to get comparable (though not identical) spatial coverage. The aperture defined (NIC1) is at (162,100) in the detector x -y system. We are taking parallel exposures in Camera 2, and even in Camera 3 (which will be out of focus, but which will give us a diffuse Pa alpha detection). As it is out of focus, this is not in conflict with GTO proposal 7250 to map out Pa alpha in camera 3. ------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 3] Data Distribution Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GCPAA1 STELLAR CLUSTER RA=17H 45M 40.1S +/- 0.1S,DEC=- J2000 H = 19.5+/-1.0 29D 0' 27.9" +/- 0.1",PLATE- ID=067N Comments: This is the position of Sgr A*. We will place it at the defined aperture NIC1, which hopefully is in a portion of the array with reasonably good QE and flatness. 2 GCPAA2 STELLAR CLUSTER RA-OFF=-0.2287S+/- .001S,DEC- J2000 H = 19.5+/-1.0 OFF=-2.0"+/- .01",FROM 1 Comments: This is 3''W, 2''S of target 1. To be used in visit 1. 3 GCPAA3 STELLAR CLUSTER RA-OFF=0.07622S+/- .001S,DEC- J2000 H = 19.5+/-1.0 OFF=-2.5"+/- .01",FROM 1 Comments: This is 1''E, 2.5''S of target 1. To be used in visit 2. 7842( 2) - 11/24/97 10:42 - [ 5] Visit: 01 Visit Priority: Visit Requirements: SCHED 30% ORIENT 270D TO 270D BETWEEN 20-Feb-1998 AND 10-May-1998 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 GCPAA1 NIC1 MULTIAC NIC1 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 11-12 WITH 10 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=225 Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 11 GCPAA1 NIC2 MULTIAC NIC2 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 12 GCPAA1 NIC3 MULTIAC NIC3 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 20 GCPAA1 NIC1 MULTIAC NIC1 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 21-22 WITH 20 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=225 Comments: continuuum ------------------------------------------------------------------------------------------------------------------------------------ 21 GCPAA1 NIC2 MULTIAC NIC2 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 22 GCPAA1 NIC3 MULTIAC NIC3 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 30 GCPAA2 NIC1 MULTIAC NIC1 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 31-32 WITH 30 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=225 Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 31 GCPAA2 NIC2 MULTIAC NIC2 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 32 GCPAA2 NIC3 MULTIAC NIC3 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 40 GCPAA2 NIC1 MULTIAC NIC1 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 41-42 WITH 40 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=225 Comments: continuuum ------------------------------------------------------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 41 GCPAA2 NIC2 MULTIAC NIC2 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 42 GCPAA2 NIC3 MULTIAC NIC3 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 7] Visit: 02 Visit Priority: Visit Requirements: SCHED 30% ORIENT 90D TO 90D BETWEEN 01-Oct-1998 AND 26-Oct-1998 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 GCPAA1 NIC1 MULTIAC NIC1 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 11-12 WITH 10 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=135 Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 11 GCPAA1 NIC2 MULTIAC NIC2 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 12 GCPAA1 NIC3 MULTIAC NIC3 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 20 GCPAA1 NIC1 MULTIAC NIC1 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 21-22 WITH 20 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=135 Comments: continuuum ------------------------------------------------------------------------------------------------------------------------------------ 21 GCPAA1 NIC2 MULTIAC NIC2 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 22 GCPAA1 NIC3 MULTIAC NIC3 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 30 GCPAA3 NIC1 MULTIAC NIC1 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 31-32 WITH 30 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=135 Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 31 GCPAA3 NIC2 MULTIAC NIC2 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 32 GCPAA3 NIC3 MULTIAC NIC3 F187N 18700 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 40 GCPAA3 NIC1 MULTIAC NIC1 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13, 1 DEF PAR 41-42 WITH 40 CUM PATTERN=SPIRAL-DITH,NUM-POS=6, OFFSET=SAM,DITH-SIZE=1.0965, PATTERN-ORIENT=135 Comments: continuuum ------------------------------------------------------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 41 GCPAA3 NIC2 MULTIAC NIC2 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM Comments: Pa alpha ------------------------------------------------------------------------------------------------------------------------------------ 42 GCPAA3 NIC3 MULTIAC NIC3 F190N 19000 SAMP-SEQ=STEP32,NSAMP=13 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 7842( 2) - 11/24/97 10:42 - [ 9] Summary Form for Proposal 7842 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC1 NIC2 NIC3 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=STEP32 NSAMP=13 PATTERN=SPIRAL-DITH NUM-POS=6 OFFSET=SAM DITH-SIZE=1.0965 PATTERN-ORIENT=225 PATTERN-ORIENT=135 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 30% ORIENT 270D TO 270D BETWEEN 20-Feb-1998 AND 10-May-1998 PAR 11-12 WITH 10 PAR 21-22 WITH 20 PAR 31-32 WITH 30 PAR 41-42 WITH 40 SCHED 30% ORIENT 90D TO 90D BETWEEN 01-Oct-1998 AND 26-Oct-1998 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F187N F190N ------------------------------------------------------------------------------------------------------------------------------------ Target Names GCPAA1 GCPAA2 GCPAA3 ------------------------------------------------------------------------------------------------------------------------------------