6718( 5) - 10/28/96 11:36 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6718 Version: 5 Check-in Date: 28-Oct-1996 11:34:38 1.Proposal Title: The Missing Mass of the Crab Nebula ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle INTERSTELLAR MEDIUM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: PETER LUNDQVIST STOCKHOLM OBSERVATORY CoI: Roger Chevalier University of Virginia N CoI: Robert Fesen Dartmouth College N CoI: Claes Fransson Stockholm Observatory N CoI: Jesper Sollerman Stockholm Observatory N CoI: George Sonneborn Goddard Space Flight Center N ------------------------------------------------------------------------------------ 6. Abstract The Crab Nebula, along with its central pulsar and its explosive origin in SN 1054, plays a crucial role in our understanding of the link between supernovae and pulsar formation and activity. Yet, there are fundamental uncertainties in the nature of the event that have not been settled in more than two decades of investigation. The observed mass in the nebula and pulsar is less than half of the expected initial stellar mass and the observed energy is only a few percent of the typical supernova energy. Resting on the assumption that the ``missing mass'' is in a high velocity envelope around the observed nebula, we propose to search for this fast shell by taking an FOS spectrum of the Crab pulsar in the region of the C IV Lambda1550 line. According to time-dependent ionization calculations this line should produce a detectable broad, blueshifted absorption if the shell is present. Our spectrum will also narrow significantly the gap of the pulsar spectrum between the optical/UV and X-ray range. ------------------------------------------------------------------------------------ Observations Description ------------------------ To search for the C IV absorption line, expected to be of width ~ 5000 km/s, we will use the FOS/BL G130H disperser. (G160L is more sensitive but has flat- field problems around 1550 Angstrom.) To reach an optical depth of 0.1 at 3 Sigma for the predicted absorption line a S/N = 15 is required. At 1240 Angstrom we estimate a S/N = 8 for the continuum. The pulsar continuum is therefore expected to be traced with good signal-to-noise over the full range of the FOS. We will use the 1.0 aperture to maximize the signal throughput. Initial target acquistion using a four stage ACQ/PEAK is broken up into A+B1+C1+F1 target acquisition pointing patterns. This can be done during the first orbit. In the remaining five (5) orbits, we can then observe the target for a total of 12,100 seconds. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6718( 5) - 10/28/96 11:36 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CRAB-PULSAR STAR,PULSAR RA=05H 31M 31.47S +/- 0.02S, 1950.0 V = 16.4+/-0.3 DEC=+21D 58' 55.4" +/- 0.1", B-V = 0.5 PLATE-ID=000M 6718( 5) - 10/28/96 11:36 - [ 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 CRAB-PULSAR FOS/BL ACQ/PEA 4.3 MIRROR SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3, 1 5.0 S ONBOARD ACQ FOR 2 K SCAN-STEP-Y=1.204 Comments: 1 OF 4 STAGES FOR ACQ/PEAK TARGET ACQUISITION A+B1+C1+F1 SEQUENCE ------------------------------------------------------------------------------------------------------------------------------------ 2 CRAB-PULSAR FOS/BL ACQ/PEA 1.0 MIRROR SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2, 1 7.5 S ONBOARD ACQ FOR 3 K SCAN-STEP-X=0.602, SCAN-STEP-Y=0.602 ------------------------------------------------------------------------------------------------------------------------------------ 3 CRAB-PULSAR FOS/BL ACQ/PEA 0.5 MIRROR SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 1 9 S ONBOARD ACQ FOR 4 K SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 4 CRAB-PULSAR FOS/BL ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 1 15 S ONBOARD ACQ FOR 5 K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 ------------------------------------------------------------------------------------------------------------------------------------ 5 CRAB-PULSAR FOS/BL ACCUM 1.0 G130H 1 12100 S ------------------------------------------------------------------------------------------------------------------------------------ 6718( 5) - 10/28/96 11:36 - [ 3] Summary Form for Proposal 6718 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.204 SCAN-STEP-Y=0.602 SCAN-STEP-Y=0.29 SCAN-STEP-Y=0.17 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4 ONBOARD ACQ FOR 5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names CRAB-PULSAR ------------------------------------------------------------------------------------------------------------------------------------