! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /spectre/data1/aroman/proposals/6841.prop ! Generated by PREPROCESSOR, version 6.0j ! Date: Fri Jan 26 12:48:46 EST 1996 Proposal_Information Title: The Nucleus of Comet H-M-P Proposal_Category: GO/DD Scientific_Category: Solar System Cycle: 5 Investigators PI_Name: Michael F. A'Hearn PI_Institution: University of Maryland CoI_Name: Harold A. Weaver CoI_Institution: Applied Research Corporation Contact: N CoI_Name: Philippe Lamy CoI_Institution: Laboratoire d'Astronomie Spatiale Contact: N Abstract: The WFPC2 will be used for photometry and colorimetry of the nucleus of comet 45P/Honda-Mrkos-Pajdusakova during its remarkably close approach to Earth in early February 1996. Questions Observing_Description: These observations should be scheduled during the first week of February 1996 in order to catch the comet near its minimum geocentric distance. Ideally they would be coincident with a ground-based observing run which we have requested on Feb 3-5 (UT) although shifting one or two days beyond either end is possible without too much degradation in the interpretation. Since the comet will have an apparent geocentric motion of about 0.16 arcsec/sec, GS selection might be problematic. We emphasize that the primary scientific objective of this program requires the full spatial resolution capabilities of HST. Thus, we cannot tolerate any target drift that results in image smear of more than the rms jitter associated with FINE-LOCK tracking (i.e., more than 7 mas rms). However, if the gyro drift is roughly at its nominal value (of 1 mas/sec), then we estimate that we can tolerate single GS tracking (which would permit rotation about the selected GS) for exposure times of 20 sec or less. So we would consider using single GS tracking if a pair of GSs cannot be found to support these observations. Our program uses two orbits with the second being a repeat of the first in order to search for temporal variability and/or possible color changes with rotational phase. We hope to take images through the R (F675W), U (F336W), B (F439W), I (F814W), V (F555W), and R (F675W again) filters during each orbit. The specific sequence of observations is: Orbit no. 1: 2 F675W images with exp times of 3 sec and 10 sec 2 F336W images with exp times of 140 sec and 400 sec (exp times can be adjusted) 2 F439W images with exp times of 40 sec and 120 sec 2 F814W images with exp times of 3 sec and 10 sec 2 F555W images with exp times of 4 sec and 12 sec 2 F675W images with exp times of 3 sec and 10 sec Orbit no. 2 is simply a repeat of orbit no. 1. Since it is unlikely that the same pair of GSs will support both orbits, we have structured our program as requiring two separate visits. However, you can restructure the program if that would provide more efficient scheduling. In any case, we want to use consecutive orbits. We estimate that the above activities will require about 53 mins, which means that the visibility window is tightly packed. If all 12 exposures cannot fit in one orbit, then you should adjust the exp times for the F336W filter to make a fit. The general approach in CR splitting is to increase our dynamic range (because the magnitude of the nucleus is so uncertain by splitting the exposure in roughly a 3:1 ratio but this can be changed in order to increase the total observing time available, particularly in the F336W observations. As these observations are TIME-CRITICAL, we request that you contact the PI immediately to resolve any issues that arise during scheduling. Real_Time_Justification: Calibration_Justification: Additional_Comments: Fixed_Targets Solar_System_Targets Target_Number: 1 Target_Name: COMET-45P Description: COMET 45P-HONDA-MRKOS-PAJDUSAKOVA Level_1: TYPE=COMET,Q=0.5320503,E=0.8242449,I=4.24877,O=89.15246,W=326.05550,T=25-Dec-1995:23:45:20.0,EQUINOX=J2000,EPOCH=29-Dec-1995 Level_2: Level_3: Window: Flux: B-V = 0.75+/-0.2 V = 13.7+/-2.5 Comments: Magnitude of nucleus is very uncertain. Magnitude of coma in any pixel is faint compared to nucleus. Target_Number: 2 Target_Name: COMET-45P-2 Description: COMET 45P-HONDA-MRKOS-PAJDUSAKOVA Level_1: TYPE=COMET,Q=.05320503,E=.8242432,I=4.24869,O=89.15214,W=326.05763,T=25-Dec-1995:23:38:41.0,EQUINOX=J2000,EPOCH=29-Dec-1995 Level_2: Level_3: Window: Ephem_Uncert: 10 KM Flux: V = 13.7+/-2.5 B-V = .75+/-.2 Comments: Magnitude of nucleus is very uncertain. Magnitude of coma in any pixel is faint compared to nucleus. Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: BETWEEN 03-Feb-1996:09:36:00.0 AND 07-Feb-1996:09:36:00.0 On_Hold_Comments: Visit_Comments: All exps should be completed within one orbit. Exposure_Number: 11 Target_Name: COMET-45P Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 14.0S Special_Requirements: Comments: Exposure_Number: 12 Target_Name: COMET-45P Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F336W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 600.0S Special_Requirements: MIN DUR 30% EXPAND Comments: Exposure_Number: 13 Target_Name: COMET-45P Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 160.0S Special_Requirements: Comments: Exposure_Number: 14 Target_Name: COMET-45P Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 14.0S Special_Requirements: Comments: Exposure_Number: 15 Target_Name: COMET-45P Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 16.0S Special_Requirements: Comments: Exposure_Number: 16 Target_Name: COMET-45P Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 14.0S Special_Requirements: END ORBIT Comments: Visit_Number: 02 Visit_Requirements: BETWEEN 03-Feb-1996:09:36:00.0 AND 07-Feb-1996:09:36:00.0 On_Hold_Comments: Visit_Comments: All exps should be completed within one orbit. Exposure_Number: 21 Target_Name: COMET-45P-2 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 14.0S Special_Requirements: REQ EPHEM CORR HMPFIX Comments: Exposure_Number: 22 Target_Name: COMET-45P-2 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F336W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 600.0S Special_Requirements: REQ EPHEM CORR HMPFIX MIN DUR 30% EXPAND Comments: Exposure_Number: 23 Target_Name: COMET-45P-2 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F439W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 160.0S Special_Requirements: REQ EPHEM CORR HMPFIX Comments: Exposure_Number: 24 Target_Name: COMET-45P-2 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 14.0S Special_Requirements: REQ EPHEM CORR HMPFIX Comments: Exposure_Number: 25 Target_Name: COMET-45P-2 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 16.0S Special_Requirements: REQ EPHEM CORR HMPFIX Comments: Exposure_Number: 26 Target_Name: COMET-45P-2 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.25,ATD-GAIN=7 Number_of_Iterations: 1 Time_Per_Exposure: 14.0S Special_Requirements: REQ EPHEM CORR HMPFIX END ORBIT Comments: Data_Distribution ! 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