6516( 4) - 01/09/97 16:19 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6516 Version: 4 Check-in Date: 09-Jan-1997 16:16:59 1.Proposal Title: SN 1991T: Reflections of Past Glory ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: BRIAN SCHMIDT MT. STROMLO & SIDING SPRING OBSERVATORIES CoI: Peter Garnavich Harvard N ------------------------------------------------------------------------------------ 6. Abstract We propose to image SN~1991T (host galaxy, NGC 4527) with the FOC to resolve a light echo inferred from ground based measurements. These observations will conclusively demonstrate (or repudiate) the presence of a light echo around SN~1991T. If demonstrated, measurements of the light echo's size and shape will enable us to map out the position and structure of dust in NGC~4527's disk, and combined with ground based velocity measurements, gain unique insight into the kinematics of the disk of a spiral galaxy other than the Milky Way. The light echo observations will also be helpful for determining the scale height of the SNe~Ia population --- a useful tool for understanding their progenitors. If a light echo is not seen, strong constraints as to the nature of SNe Ia explosions and their progenitors would be gained. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to image the area around SN~1991T using the FOC with the F430W filter. Ground observations have demonstrated that the light echo is quite bright, mB=21, peaks in flux at about 400nm, and has an apparent size less than 1 arcsec. A 1 orbit exposure approx 2200s should supply sufficient signal so as to determine the size and morphology of the ring, regardless of its size. The light echo has a precise position measured, and should be easily acquired within the 7 arcsec field of the FOC. One problem is that there will not be any bright stars in the field to determine the PSF (there may be some very faint stars in NGC 4527 which we resolve). Will use FOC images taken near the time of our observations to get a good estimate of the PSF. Real Time Justification ----------------------- None Calibration Justification ------------------------- Internal Flat during occultation time would be useful to accurately measure the geometric distortion in the FOC as suggested in "Status Update for Science Instruments: Faint Object Camera" Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6516( 4) - 01/09/97 16:19 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4527- EXT-STAR,SUPERNOVA TYPE RA=12H 31M 36.89S +/- B1950 V = 21.4+/-0.3 SN1991T IA,GALAXY,SPIRAL 0.3",DEC=2D 56' 28.7" +/- 0.3" B-V = 0.0+/-0.3 Comments: The source is extended by an unknown amount - it is less than 0.8" in diameter. 6516( 4) - 01/09/97 16:19 - [ 2] Visit: 01 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4527-SN1 FOC/96 IMAGE 512X512 F430W 1 2563 S 991T ------------------------------------------------------------------------------------------------------------------------------------ 6516( 4) - 01/09/97 16:19 - [ 3] Summary Form for Proposal 6516 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F430W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4527-SN1991T ------------------------------------------------------------------------------------------------------------------------------------