9490( 7) - 10/01/02 09:43 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9490 Version: 7 Check-in Date: 01-Oct-2002 09:42:34 1.Proposal Title: Stellar populations in M101: X-ray binaries, globular clusters, and more ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Kip Kuntz University of Maryland Baltimore County CoI: Dr. Pauline Barmby Smithsonian Astrophysical Observatory N CoI: Dr. Koji Mukai USRA/Laboratory for High Energy N Astrophysics, Goddard Space Flight Center CoI: Prof. John P. Huchra Smithsonian Astrophysical Observatory N CoI: Prof Jean P. Brodie University of California, Santa Cruz N CoI: Dr. Steve L. Snowden USRA/Laboratory for High Energy N Astrophysics, Goddard Space Flight Center CoI: Dr. William D. Pence Laboratory for High Energy Astrophysics, N Goddard Space Flight Center ------------------------------------------------------------------------------------ 5. Abstract Given our location in the disk of the Milky Way, it is often difficult to catalogue a complete population of objects in the Galaxy due to obscuration. M101 is the closest face-on Milky Way analogue and thus is the best system for studying stellar populations similar to those of the Milky Way. We propose a multi-purpose mosaic of ACS observations of M101 that will allow us to complete two major goals. 1) We will identify optical counterparts of M101's population of X-ray sources, resolving the mystery of M101's curious X-ray population and increasing the number of known High Mass X-ray Binaries (HMXB) to the point that statistical studies of those objects will be useful. 2) We will identify globular clusters in M101 and measure the luminosity and metallicity distribution of the M101 globular cluster system, which has not been previously studied. These measurements will improve our understanding of the variation in globular cluster populations as a function of galaxy type, and provide an important study of a spiral galaxy's globular cluster system for use in constraining galaxy formation/merger models. Given M101's closeness, an optical map of a substantial portion of the disk, when combined with high resolution data at other energies, will allow M101 to play a key role in further studies of galactic structure. ------------------------------------------------------------------------------------ 9490( 7) - 10/01/02 09:43 - [ 2] Observations Description ------------------------ We are proposing a mosaic of 16 pointings in three filters (BVI) of the nucleus and disk of M101. Because of the ACS/WFC overheads and the need for CR-SPLIT exposures, 12 minutes is the shortest practical exposure time for our project. Positions: The positions of the pointings are driven by the desire to cover the Chandra field (highest priority) and to extend the coverage over the bulk of the disk (lower priority). The aimpoint of the Chandra observation was placed near the nucleus, and sampled environments from the bulge to the outer disk (see Figure refpositions). In other galaxies, the surface density of globular clusters is proportional to r^-2, where r is the projected distance to the galaxy center. The fraction of the GCS covered by our observations will thus be r/r_ max, where r_ max is the (unknown) size of the GCS. If r_ max( M101)=2r_ max( MW) as the ratio of optical diameters suggests, then the ACS observations will cover about 40\ of the GCS. Filters: In order to provide the best comparison with previous research we will use the BVI filters (F435W, F555W, and F814W). As described in the justification, these filters will allow a clear discrimination between HMXB and background AGN, and will allow good characterization of the globular clusters. Exposure Times, X-ray Sources: Although we do not expect any of the HMXB to have B>25, V>25.3, and I>25.6, we would like to be able to detect AGN to >3Sigma at B=27 and I=26. Reaching such a limit assures the identification at the 95 of X-ray point sources not detected in the optical as being LMXB. The AGN detection limits are met by 15 minute exposures in B and 12 minute exposures in I, producing 3.8Sigma and 5.5Sigma detections respectively. These exposure times will provide 21Sigma (B), 13Sigma (V) and 6Sigma (I) detections of HMXB counterparts (assuming a standard O9V-star spectrum, but the slightly smaller flux typical of HMXB counterparts.) We have assumed CR-split=2, gain=1, and a galaxy surface brightnesses of B=23.0 arcmin^-2, V=22.6 arcmin^-2, and I=21.7 arcmin^-2 (Okamura et al.\ 1976). The ETC was used to translate the galaxy surface brightness to counts of 0.026, 0.038, and 0.077 e^- pix^-1 s^-1 in B, V, and I. The S/N values were calculated using the formula in the ACS Handbook, with the galaxy counts included in the background. Exposure Times, globular clusters: Our target for the globular cluster photometry is S/N=20, or 5\ the same method as for the X-ray sources but assuming a K0V spectrum: 12 minute exposures in V yield S/N=20 for point sources with V=24.65. The same magnitude limit yields S/N=14 for a 15-minute B exposure and S/N=30 for a 12-minute I exposure. The point-source magnitude limit must be corrected to account for the resolution of globular clusters in M101. We computed the correction factor by convolving King-model profiles with a tinytim ACS/WFC PSF and measuring the magnitude difference (in a 5 pixel square aperture) between the PSF and the GC profile. The magnitude correction depends on the assumed size and shape of the GC, but a value of 0.25 mag is appropriate for the typical Milky Way GC sizes and shapes used in Figure 2. The magnitude limit for M101 globulars is then V=24.4. Assuming that they conform to the universal globular cluster luminosity function (a Gaussian with peak M_V=-7.3 and dispersion Sigma=1.2 mag), the peak of the M101 GCLF should be at V=21.9. Our exposures will reach 2Sigma fainter than the peak and should include almost all M101 globulars in the field. Orbit Calculation: There are two CVZ opportunities for M101 in Cycle 11, with lengths of 17 and 9 orbits. In accordance with \S4.1.1 of the Call for Proposals, we have calculated the required orbits assuming CVZ use. For each pointing, we have assumed 15, 12, and 12 minute exposures, and for each exposure we have assumed a 6 and a 2.5 minute setup (i.e., 2 sub-exposures), plus 6 minutes for guide star acquisition, for a ``cost'' of 70.5 minutes per pointing. However, since we have requested CVZ observations, we also have to budget the time to slew from one pointing to the next (since we can't ``hide'' that time in the occultation). After consulting with Merle Reinhardt at the STScI, we have 9490( 7) - 10/01/02 09:43 - [ 3] budgeted 2 minutes for each slew. Thus we assume 73 minutes per pointing. If we assume CVZ, we will need 13 orbits for 16 fields. (Note that since this is a CVZ observation, and since each visit requires a fraction of an orbit, the ``Observing Summary'' has not attempted to show true distribution of orbits per visit.) Real Time Justification ----------------------- Because we are attempting to mosaic an extended area with the ACS, we will not be able simply to specify the central field and the offsets, as every observation will require the acquisition of new guide stars (as per the ACS handbook and Instrument Science Report ACS 2001-07). We have tentatively specified a grid of observations on the cover-page, but the positions of the individual exposures depends upon the roll- angle; the specified grid with the wrong roll-angle will not produce the required coverage for a mosaic. (The specified grid allows about a 100 pixel overlap between pointings.) We request observations in CVZ to ensure that all of the exposures are taken with (roughly) the same roll-angle so they may be mosaicked without significant inter-pointing losses. By requesting observations using the CVZ, all of the pointings can be made within a short period of time, and the roll-angle will remain roughly constant. There are no coordinated observations. Calibration Justification ------------------------- Additional Comments ------------------- The target positions were calculated assuming that the roll angle available during CVZ is 339.5+/-2.5. If the roll angle for the scheduled CVZ is significantly different, the target positions MUST BE RECALCULATED ------------------------------------------------------------------------------------ 9490( 7) - 10/01/02 09:43 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5457-1 GALAXY, SPIRAL, DISK RA=14H 3M 22.61S +/- 1", DEC=54D J2000 SURF-BKG(B) = 20.45+/-1.0 21' 27.98" +/- 1" SURF-BKG(V) = 19.72+/-1.0 SURF-BKG(I) = 19.15+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG Comments: The surface brightness is strongly variable. The uncertainty in the surface brightness encopasses the range likely to be found in this field. The Surface brightness profile is from Okamura, Kanazawa, and Kodaira (1976) PASJ, 28, 329. B-V=0.5 and B-I=1.3. 2 NGC5457-2 GALAXY, SPIRAL, DISK, RA=14H 3M 30.06S +/- 1", DEC=54D J2000 SURF-BKG(B) = 22.7+/-1.0 SPIRAL ARM 18' 31.08" +/- 1" SURF-BKG(V) = 22.2+/-1.0 SURF-BKG(I) = 21.4+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 3 NGC5457-3 GALAXY, SPIRAL, DISK, RA=14H 3M 49.57S +/- 1", DEC=54D J2000 SURF-BKG(B) = 23.4+/-1.0 SPIRAL ARM 20' 00.69" +/- 1" SURF-BKG(V) = 22.9+/-1.0 SURF-BKG(I) = 22.1+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 4 NGC5457-4 GALAXY, SPIRAL, DISK, RA=14H 3M 42.32S +/- 1", DEC=54D J2000 SURF-BKG(B) = 23.2+/-1.0 SPIRAL ARM 22' 59.34" +/- 1" SURF-BKG(V) = 22.7+/-1.0 SURF-BKG(I) = 21.9+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 5 NGC5457-5 GALAXY, SPIRAL, DISK, RA=14H 3M 20.60S +/- 1", DEC=54D J2000 SURF-BKG(B) = 22.7+/-1.0 SPIRAL ARM 24' 51.49" +/- 1" SURF-BKG(V) = 22.2+/-1.0 SURF-BKG(I) = 21.4+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 6 NGC5457-6 GALAXY, SPIRAL, DISK, RA=14H 2M 59.92S +/- 2", DEC=54D J2000 SURF-BKG(B) = 22.9+/-1.0 SPIRAL ARM 23' 43.48" +/- 2" SURF-BKG(V) = 22.4+/-1.0 SURF-BKG(I) = 21.6+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 7 NGC5457-7 GALAXY, SPIRAL, DISK, RA=14H 3M 02.15S +/- 1", DEC=54D J2000 SURF-BKG(B) = 22.1+/-1.0 SPIRAL ARM 20' 36.80" +/- 1" SURF-BKG(V) = 21.6+/-1.0 SURF-BKG(I) = 20.8+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 8 NGC5457-8 GALAXY, SPIRAL, DISK, RA=14H 3M 9.05S +/- 1", DEC=54D J2000 SURF-BKG(B) = 22.9+/-1.0 SPIRAL ARM 17' 28.24" +/- 1" SURF-BKG(V) = 22.4+/-1.0 SURF-BKG(I) = 21.6+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 9 NGC5457-9 GALAXY, SPIRAL, DISK, RA=14H 3M 38.87S +/- 1", DEC=54D J2000 SURF-BKG(B) = 25.1+/-1.0 SPIRAL ARM 15' 45.84" +/- 1" SURF-BKG(V) = 23.6+/-1.0 SURF-BKG(I) = 22.8+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 10 NGC5457-10 GALAXY, SPIRAL, DISK, RA=14H 2M 41.90S +/- 1", DEC=54D J2000 SURF-BKG(B) = 24.3+/-1.0 SPIRAL ARM 19' 13.46" +/- 1" SURF-BKG(V) = 23.8+/-1.0 SURF-BKG(I) = 23.0+/-1.0 Coordinate Source: GUIDE_STAR_CATALOG 9490( 7) - 10/01/02 09:43 - [ 5] Visit: 01 Visit Priority: Visit Requirements: CVZ ORIENT 334D TO 340D On Hold Comments: Additional Comments: Because this is a mosaicking program, other orientations are acceptable only if the PI is notified and the target coordinates recalculated. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5457-1 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC5457-1 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC5457-1 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5457-2 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M GS ACQ SCENARIO SINGLE C ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5457-2 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M NEW ALIGNMENT C ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC5457-2 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5457-3 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC5457-3 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 32 NGC5457-3 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M NEW ALIGNMENT C ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5457-4 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M GS ACQ SCENARIO SINGLE C ------------------------------------------------------------------------------------------------------------------------------------ 41 NGC5457-4 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 42 NGC5457-4 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 9490( 7) - 10/01/02 09:43 - [ 6] Visit: 02 Visit Priority: Visit Requirements: CVZ ORIENT 340D TO 347D On Hold Comments: Additional Comments: Because this is a mosaicking program, other orientations are acceptable only if the PI is notified and the target coordinates recalculated. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5457-7 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC5457-7 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC5457-7 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5457-8 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5457-8 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M NEW ALIGNMENT C ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC5457-8 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5457-9 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M GS ACQ SCENARIO SINGLE C ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC5457-9 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 32 NGC5457-9 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M NEW ALIGNMENT C ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5457-10 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 41 NGC5457-10 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 42 NGC5457-10 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 9490( 7) - 10/01/02 09:43 - [ 7] Visit: 03 Visit Priority: Visit Requirements: CVZ ORIENT 334D TO 340D On Hold Comments: Additional Comments: Because this is a mosaicking program, other orientations are acceptable only if the PI is notified and the target coordinates recalculated. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5457-5 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC5457-5 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC5457-5 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5457-6 ACS/WF ACCUM WFC F435W CR-SPLIT=2,GAIN=2 1 15 M C ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5457-6 ACS/WF ACCUM WFC F555W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC5457-6 ACS/WF ACCUM WFC F814W CR-SPLIT=2,GAIN=2 1 12 M C ------------------------------------------------------------------------------------------------------------------------------------ 9490( 7) - 10/01/02 09:43 - [ 8] Summary Form for Proposal 9490 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 GAIN=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ ORIENT 334D TO 340D GS ACQ SCENARIO SINGLE NEW ALIGNMENT CVZ ORIENT 340D TO 347D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F435W F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5457-1 NGC5457-2 NGC5457-3 NGC5457-4 NGC5457-7 NGC5457-8 NGC5457-9 NGC5457-10 NGC5457-5 NGC5457-6 ------------------------------------------------------------------------------------------------------------------------------------