! Proposal 6259, submission 5 ! PI: BRANDT, JOHN ! Received Mon Feb 26 14:30:14 EST 1996 ! From: cora@hrssun.gsfc.nasa.gov ! Phase II proposal for GTO 6259. Completed by Cora Randall, 2/15/96, for ! observations of comet Hyakutake. ! Revised on 2/22/96 to shorten the time between certain sets of plasma ! exposures. ! Revised on 2/26/96 to explicitly add "comment" lines to the exposures ! which should follow immediately after the second track-51 command. Proposal_Information Title: IMAGING OF NEAR-NUCLEAR PLASMA IN COMETS Proposal_Category: GTO/HRS Scientific_Category: SOLAR SYSTEM Cycle: 5 Investigators PI_name: BRANDT, JOHN PI_Institution: UNIVERSITY OF COLORADO CoI_Name: STEPHEN LARSON CoI_Institution: UNIVERSITY OF ARIZONA Contact: CoI_Name: MALCOLM NIEDNER CoI_Institution: GSFC Contact: Y CoI_Name: CORA RANDALL CoI_Institution: UNIVERSITY OF COLORADO Contact: Abstract: We propose to carry out high-resolution imaging of the near-nuclear regions of comet Hyakutake to determine the structure and evolution of the plasma. These images will determine the nature of the comet's interaction with the solar wind, show the morphology of the comet's magnetic field, provide insight to mechanisms for disconnection events (DE's), and assist in determining the important mechanism for ionizing molecules in comets. The interaction of the solar wind with comets -- capture of solar magnetic field lines, formation of the plasma tail, formation of rays, activity including disconnection events, ionization of molecules -- is widely believed to follow a standard paradigm. None of the features of the paradigm have been verified for nuclear distances less than about 1000 km or with spatial resolutions comparable to the expected dimension of fine structure. This dimension is the Larmor radius of water ions; for this case, about 15 km. For a comet with a geocentric distance of 1 AU, each WFC-2 chip will cover about 55,000 km on a side, with a resolution of 72 km. Such an image would provide, by far, the most stringent test of our physical view of the comet/solar wind interaction. These observations require a comet of total visual magnitude 10 or less, the preferred target being a new comet of magnitude 7 or less. Questions Observing_Description: ORBIT 1 & ORBIT 2 & ORBIT 3 & ORBIT 4\\ GS Acquisition & GS Acquisition & GS Acquisition & GS Acquisition\\ Track 51 & Track 51 & Track 51 & Track 51\\ WFPC2 Alignment & WFPC2 Alignment & WFPC2 Alignment & WFPC2 Alignment\\ 785LP/0.23sec & 785LP/4sec & 785LP/30sec & 785LP/4sec\\ Readout & Readout & Readout & Readout\\ 785LP/4sec & 785LP/0.23sec & 785LP/4sec & 785LP/30sec\\ Readout & Readout & Readout & Readout\\ 785LP/30sec & 785LP/30sec & 785LP/0.23sec & 785LP/0.23sec\\ Readout & Readout & Readout & Readout\\ 439W/1sec & 622W/0.11sec & 439W/10sec & 622W/1sec\\ Readout & Readout & Readout & Readout\\ 439W/3sec & 622W/3sec & 439W/50sec & 622W/10sec\\ Readout & Readout & Readout & Readout\\ 439W/3sec & 622W/3sec & 439W/50sec & 622W/10sec\\ Readout & Readout & Readout & Readout\\ 439W/50sec & 622W/10sec & 439W/30sec & 622W/30sec\\ Readout & Readout & Readout & Readout\\ Track 51 & Track 51 & Track 51 & Track 51\\ WFPC2 Alignment & WFPC2 Alignment & WFPC2 Alignment & WFPC2 Alignment\\ 785LP/0.23sec & 785LP/4sec & 785LP/30sec & 785LP/4sec\\ Readout & Readout & Readout & Readout\\ 785LP/4sec & 785LP/0.23sec & 785LP/4sec & 785LP/30sec\\ Readout & Readout & Readout & Readout\\ 785LP/30sec & 785LP/30sec & 785LP/0.23sec & 785LP/0.23sec\\ Readout & Readout & Readout & Readout\\ 439W/1sec & 622W/0.11sec & 439W/10sec & 622W/1sec\\ Readout & Readout & Readout & Readout\\ 439W/10sec & 622W/1sec & 439W/1sec & 622W/0.111sec\\ Readout & Readout & Readout & Readout\\ 439W/10sec & 622W/1sec & 439W/1sec & 622W/0.11sec\\ Readout & Readout & Readout & Readout\\ 439W/50sec & 622W/10sec & 439W/30sec & 622W/30sec\\ Readout & Readout & Readout & Readout\\ We will acquire WFC images of a comet with 3 filters, as given in the table above. Our goal is to obtain temporal derivatives of the images in each of the filters. We will thus obtain multiple exposures with the same filter/exposure time combination, scheduling observations such that the time elapsed between identical exposures is on the order of 15 minutes. The exposure times and thus the scheduling strategy depend heavily on the predicted magnitude of the comet. We have outlined a strategy which is optimum for a total visual magnitude of 2, which is the predicted magnitude of comet Hyakutake on 1 April 1996. The time derivatives will be obtained with the F439W, F622W and F785LP WFPC2 filters. These derivatives will enable us to study the structure in $CO^{+}$, $H_{2}O^{+}$ and continuum, respectively. We are requesting 4 orbits for these observations. Because the amount of time which elapses between WFPC2 exposures is critical to the science which we have proposed, we request that all 4 orbits be executed within 1 day. In addition, the time elapsed between separate exposures within an orbit is critical. We have thus defined the specific exposure sequences in the table above. As can be seen from this table, we have chosen several different exposure times for each of the filters. This will enable us to account for poor predictability of the cometary brightness, and will vary the amount of plasma change occurring during and between similar exposures. SCIENTIFIC JUSTIFICATION Since Alfven's fundamental paper in 1957 [Alfven, 1957], the plasma tails of comets have been understood as usually attached to the heads of comets by their magnetic field. The field itself is captured from the solar wind and generally has a bi-polar structure. The basic picture has been verified by in-situ measurements on comet Halley in 1985 and 1986. This picture can also be inferred from imaging data which exist on both large (about $10^{5}$ to $10^{6}$ km) and intermediate (about $10^{3}$ to $10^{4}$ km) scales. However, the critical small scale region around the nucleus (about 1000 km or less) is terra incognita. In addition, none of the near-nuclear regions have been imaged with the resolutions possible with HST. These resolutions are approximately ten times better than available from the ground. The basic morphology at these small scales is unknown, as are any changes with time. We may expect to see ray formation, evolution of rays, moving condensations, the structure of the ionosphere, and the shape of the extended plasma region. For example, at the time of disconnection events (DEs, see Figure 1), we expect dramatic changes in the magnetic field morphology and possibly in the heating of the near-nuclear plasma (ionosphere). The first exploration of this very important region in comets is possible because (1) experience with the Comet Levy observations with the WFPC on HST (the PI on this proposal was a CoI on the comet Levy program) shows that it is possible to achieve spatial resolutions approaching 0.1 arcsec in comet images; and (2) shift-difference or time-difference techniques have been demonstrated to be very effective in bringing out plasma structures in comets [Larson and Slaughter, 1992]. See, for example, Figure 2, in which a series of temporal derivatives of Comet P/Brorsen-Metcalf clearly depicts the formation of turning rays from a cloud of water ions, and their evolution into the central tail axis. Also, Figure 3 shows recovery of plasma structures for a test case where the ratio of continuum (dust) scattering and neutral gas emission to plasma emission is 50:1. GOALS Our primary goal for the observations proposed here is to test the standard paradigm for cometary interaction with the solar wind, which we have illustrated in Figure 4. The steady-state situation (Figure 4A) involves the capture, loading, and folding of solar-wind magnetic field lines of the same polarity. The resulting features are the usual plasma tail, folding tail rays (forming a bi-lobed magnetic structure), a magnetic pile-up region on the sunward side, condensations, an ionosphere, waves, and perhaps a region of enhanced ionization. The field lines are made visible by the molecular ions trapped on them, and generally we expect the flux tubes to be brighter near the nucleus. For the Disconnection Event situation, we depict magnetic field lines of different polarity being pressed into the comet, say, at a sector boundary. We believe that the merging and reconnection of fieldlines of opposite polarity at the nucleus causes the tail to disconnect as shown in Figure 4B. Other mechanisms for DEs have been proposed, and the HST observations proposed here could conclusively test our model (Niedner and Brandt, 1978). Many of the features of the steady-state situation are still visible, but the additional complication of opposite polarities can produce not only a disconnected tail, but perhaps could also produce increased wave activity and enhanced ionization. The site of the magnetic reconnection could be sunward or tailward. This general picture is consistent with the available imaging data, and with in-situ data (one pass by Giotto to within about 600 km of Halley's nucleus, two passes by the VEGA spacecraft to within 9000 km of Halley's nucleus, one pass by ICE to within 8000 km of comet Giacobini-Zinner, and one pass by the Giotto Extended Mission within 200 km of the nucleus of Grigg/Skjellerup). In a WFC2 image of a comet with a geocentric distance of 1 AU, each chip would cover about 55,000 km on a side, with a resolution of about 72 km (0.1 arcsec). The near-nuclear regions of cometary plasmas have never been systematically explorred with resolutions approaching this capability. A reasonable set of HST images as described here would provide a stringent test of the overall picture and many important details. In summary, straightforward imaging of plasma near cometary nuclei with HST resolutions promises great advances in our understanding of cometary plasma physics. The interaction of the solar wind with comets and the frequent occurrence of spectacular phenomena shows the importance of comets as plasma physics laboratories. Besides a critical test of the standard paradigm for interaction of the solar wind with comets, specific areas of progress that could result from this program are to: (1) Delineate the morphology of the near-nucleus plasma; (2) Determine the importance of ion-neutral coupling from the shape of the extended plasma region [Houpis and Mendis, 1981]; (3) Determine the areas of primary or enhanced ionization and constrain or determine the primary ionization mechanism; (4) Observe the evolution or formation of rays and/or condensations near the nucleus; (5) Observe the near-nuclear changes corresponding to the comet's cycle of plasma evolution; (6) Determine (or set an upper limit to) the diameter of the tail rays; the expected limit is the Larmor radius for 20 AMU ions (T=$10^{4}$ K and B=50 gamma), or about 15 km. PROPOSED TECHNIQUE In this section, we describe in more detail the procedures by which plasma structures are extracted from the data we propose to acquire with these HST observations. As explained in question 11, the spectral regions chosen for WFC exposures are the red $H_{2}O^{+}$ (0,8,0) band at 6190 \ang and the traditional blue $CO^{+}$ (2,0) band at 4262 \ang. Based on experience with ground-based detectors and the comet Levy HST observations, the exposures will be short; on the order of seconds to minutes. The WFC filters including these bands are F622W and F439W. We will also obtain continuum images with the WFC filter F785LP (the same filter used in the Weaver et al. [1992] study of comet Levy). Shift-difference or temporal-difference techniques will be our primary approach for extraction of cometary ion features. Using these techniques, we will determine the morphology of the near-nuclear plasma in one or more molecules (e.g., $H_{2}O^{+}$ and $CO^{+}$). One of us (SM Larson) has considerable experience with these techniques. Separation of the plasma structures from the continuum (dust) reflection and neutral gas emission could be approached in three generic ways: (1) Straight imagery (wavelength chosen for maximum contrast) with no other provision for continuum extraction might produce an image with sufficient contrast to identify the plasma structures. Such an approach might be successful for a comet with a low dust-to-gas ratio. (2) A separate continuum image could be obtained for subtraction from the image containing plasma plus continuum. This approach can work effectively only if the two images can be aligned and if the continuum image is not contaminated with plasma emission. While this approach can be effective, we prefer to use primarily the following well-established (and more generally applicable) approach. (3) Shift-difference techniques have been used for years and are effective for our needs. This is a standard, time-proven technique with many published results. Basically, the latter technique works because the continuum emission varies slowly over distance (or time) while the plasma emission varies rapidly over distance (or time). Subtraction of a slightly shifted image from an original involves subtraction of a continuum very nearly equal to the original (thus removing the continuum), and subtraction of a plasma emission very different from the original (thus emphasizing it). See Figures 2 and 3 for an illustration of this technique. Because the same instrumental configuration is used for both images in the shift-difference method, problems generally are minimal. Problems with shift-difference techniques could arise if they involve continuum images with dust structure. In this case, a pure continuum image would be needed. Therefore, we have adopted a hybrid strategy which uses shift-difference as the primary approach for efficiency, and the straightforward continuum subtraction as the secondary approach for certainty. In addition, the capability to perform the image processing two independent ways provides a valuable check. An integral part of our program is extensive ground-based observational support. This will have two parts: (1) A spectroscopic phase to confirm plasma emission in the comet (at facilities of the Lunar and Planetary Laboratory, University of Arizona); (2) An imaging phase that covers the comet before and during the HST observations at intermediate scales (at facilities of the Lunar and Planetary Laboratory, University of Arizona), and at large scales by a network of wide-field instruments that form the ULYSSES Comet Watch (UCW). The processed images will be analyzed for determination of detailed morphology, dynamics and comparison with the standard paradigm. These results will be placed in the context of the images (obtained by us) at intermediate and large scales. The solar wind conditions at the comet will also be determined. Thus, we expect that a sequence of HST images should lead to a major, detailed comparison of theory with observations, and to a more complete physical understanding of near-nuclear plasma phenomena in comets. REFERENCES H. Alfven, 1957. Tellus 9, 92. J.C. Brandt, 1982. In ``Comets'', Ed. L.L. Wilkening, U. Arizona Press, Tucson, 519. J.C. Brandt, 1990. In ``Comet Halley: Investigations, Results, Interpretations,'' Ed. J. Mason, Ellis Horwood, New York, 33. H.L.F. Houpis and D.A. Mendis, 1981. Ap.J. 243, 1088. S.M. Larson and C.D. Slaughter, 1992. In ``Asteroids, Comets, Meteors 1991'', LPI, Houston, 337-343. H.A. Weaver, et al. (including J.C. Brandt), 1992. Icarus 97, 85. SPECIAL REQUIREMENTS: This is a TOO proposal, since we require a reasonably bright comet showing plasma emission. New comets are in general brighter than periodic comets, and are thus more likely to be suitable candidates for this proposal. New comets which would be suitable for this proposal are discovered approximately once per year. It is likely that we would be able to notify the STScI a month in advance of the optimum time for executing these observations. This is also a time-critical proposal, since it should be executed at a time when the comet is near its maximum brightness. Real_Time_Justification: Calibration_Justification: Additional_Comments: Fixed_Targets Solar_System_Targets Target_Number: 1 Target_Name: HYAKUTAKE Description: COMET HYAKUTAKE Level_1: TYPE = COMET, Q=0.2306484, E=0.9996884, I=125.12570, O=187.95688, W=130.10377, T=01-MAY-96:06:24:41, EPOCH=03-MAY-96, EQUINOX=J2000 Ephem_Uncert: 10000 KM Acq_Uncert: 20" Flux: V = 10 B-V = 0.8 V-R = 0.4 Comments: V-mag is for 0.7 arcsec diameter aperture. Elements are from Hal Weaver (obtained from Don Yeomans via Mike A'Hearn) and must be updated prior to final scheduling. Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: BETWEEN 01-APR-96 AND 03-APR-96; GUID TOL 2"; SCHED 100%; On_Hold_Comments: Exposure_number: 10 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 SEQ 10-23 NON-INT Comments: Exposure_number: 11 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 12 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 13 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 14 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 3.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 15 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 3.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 16 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 50.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD PRECEDE 2ND TR-51 Exposure_number: 17 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD SUCCEED 2ND TR-51 Exposure_number: 18 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 19 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 20 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 21 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 22 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 23 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 50.0S Special_Requirements:REQ EPHEM CORR HY1; END ORBIT Comments: ! END OF FIRST ORBIT !============================================================================ Exposure_number: 30 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 SEQ 30-43 NON-INT Comments: Exposure_number: 31 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 32 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 33 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.11S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 34 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 3.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 35 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 3.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 36 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD PRECEDE 2ND TR-51 Exposure_number: 37 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD SUCCEED 2ND TR-51 Exposure_number: 38 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 39 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 40 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.11S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 41 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 42 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 43 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 END ORBIT Comments: ! END OF SECOND ORBIT !============================================================================ Exposure_number: 50 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 SEQ 50-63 NON-INT Comments: Exposure_number: 51 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 52 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 53 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 54 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 50.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 55 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 50.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 56 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD PRECEDE 2ND TR-51 Exposure_number: 57 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD SUCCEED 2ND TR-51 Exposure_number: 58 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 59 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 60 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 61 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 62 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 63 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 END ORBIT Comments: ! END OF THIRD ORBIT !============================================================================ Exposure_number: 70 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 SEQ 70-83 NON-INT Comments: Exposure_number: 71 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 72 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 73 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 74 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 75 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 10.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 76 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD PRECEDE 2ND TR-51 Exposure_number: 77 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 4.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: SHOULD SUCCEED 2ND TR-51 Exposure_number: 78 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30.0S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 79 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F785LP Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.23S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 80 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 1S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 81 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.11S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 82 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 0.11S Special_Requirements:REQ EPHEM CORR HY1 Comments: Exposure_number: 83 Target_Name: HYAKUTAKE Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F622W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_iterations:1 Time_Per_Exposure: 30S Special_Requirements:REQ EPHEM CORR HY1 END ORBIT Comments: ! END OF FOURTH ORBIT !============================================================================ Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: PI_Address Ship_Via: UPS Recipient_Email: