! File: 3312C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:02:38:09 coverpage: title_1: SPACECRAFT GLOW MEASUREMENT TEST-REVISED proposal_for: SV/OLT pi_fname: PIERRE pi_lname: BELY pi_inst: ST SCI pi_country: USA pi_phone: (301)338-4780 hours_pri: 6.00 num_pri: 1 wf_pc: Y time_crit: N ! end of coverpage abstract: line_1: Test Objective: line_3: Measure the broadband intensity and spectral distribution of HST line_4: induced glow (i.e., "shuttle glow") resulting from its passage line_5: through the ambient upper atmosphere. Determine the glow line_6: intensity dependence on the HST spatial orientation relative line_7: to the HST orbital parameters. This test will be repeated line_8: after 6 months to study outgassing effects. line_10: This is a revision of SV/OLT 2141 which failed early January line_11: due to a major frame timing error. ! ! end of abstract general_form_proposers: lname: LUPIE fname: OLIVIA inst: ST SCI country: USA ! lname: BELY fname: PIERRE title: P.I. inst: ST SCI country: USA esa: Y ! lname: PARESCE fname: FRANCESCO inst: ST SCI country: USA esa: Y ! lname: CLARKE fname: JOHN inst: MSFC country: USA ! lname: TOTH fname: BRUCE inst: STSCI country: USA ! lname: O'DELL fname: ROBERT inst: RICE UNIVERSITY country: USA ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: Test Description: line_3: The "spacecraft glow" effect in the HST environment could introduce line_4: a spurious background in the observations of all HST science line_5: instruments particularly for long exposures of very faint objects. line_6: At present, there is no mission constraint to limit observations when line_7: this effect may be present, that is, at times when the in-plane HST line_8: velocity vector points in the vicinity of the targets. This test line_9: is designed to measure the intensity and the wavelength characteristics line_10: of any S/C glow that may be present under this worst case condition. line_11: Because of the faintness of the phenomenon (predicted to be line_12: 25th magnitude per arc second square in the red), this OLT must line_13: be performed under minimum conditions of background and stray line_14: light illumination. All target and environmental constraints line_15: are described in detail in GF #5. ! question: 3 section: 1 line_1: To allow differentiation from the background and characterization line_2: of the glow with the attack angle (angle between the HST velocity line_3: vector and line of sight), 3 WFC 8-minute exposures will line_4: be obtained contiguously while in shadow. The first of the line_5: exposures must start as soon after target rise as possible. line_6: Note that the Dark requirement may be lifted on the 3rd line_7: observation if the last 1-2 minutes of that observation falls line_8: outside of shadow. line_10: The wavelength dependence of the glow will be measured by line_11: repeating the observations with different filters over 2 additional line_12: orbits. Because of the line_13: target faintness, a WF/PC bias and dark frame are required before and after line_14: each set of observations during each orbit. ! question: 3 section: 2 line_1: The LOS will be parallel to the HST velocity vector line_2: 4 minutes after the start of first observation of the second line_3: orbit. This requirement (described further in GF.5) allows line_4: the attack angle to be about equal to zero at the midpoint of the first line_5: observation of the second orbit, and near but equally displaced line_6: from zero during the first exposure of the other orbits. line_7: The pointing is fixed and the same for all measurements in this test. line_8: GYRO Tracking is acceptable and requested. ! question: 3 section: 3 line_1: **Attack Angle, Orbit Geometry, and Test Design** line_3: The velocity vector sweeps an angle of about 30.5 deg in 8 minutes. line_4: The angle between the LOS and the velocity vector, line_5: at the mid-point of an 8 minute exposure is 0, 50, and 100 degrees line_6: for the 1st, 2nd, and 3rd exposures respectively, in an orbit. line_7: The horizon drop-off angle for the HST orbit is about 22.5 degrees. line_8: This means that for an LOS coincident with the velocity vector line_9: at the midpoint of an observation will intercept the earth's limb line_10: at the start of the observation if the exposure line_11: duration is longer than 11.5 minutes. For an 8 minute observation, line_12: the target LOS will be about 7 degrees above the earth's limb line_13: at the start of the observation. Note that the variation in line_14: the attack angle due to the orbital precession over four line_15: orbits is less than 2 degrees. ! question: 4 section: 1 line_1: Submitted as an Observatory Level Test ! question: 5 section: 1 line_1: The scheduling constraints on this test are line_2: listed in the following sections. line_3: The target will be described as a moving line_4: target but with a fixed pointing. ! question: 5 section: 2 line_1: *****Test Schedule Constraints: line_2: 1) Minimize scattered light from earth and moon: line_3: - Phase of moon: between new (- 2 days) or first quarter (+ 2 days). line_5: - Target observations taken during DARK TIME (spec. req). line_6: 2) Minimize zodiacal light - orbital velocity vector points line_7: furthest from the ecliptic (within +/- 10 degrees of plane). line_8: Limit observing times to those months of the year line_9: when this condition occurs (optimum months are Nov through line_10: January, May through July). line_13: 3) Minimize galactic background light by selecting those times when line_14: the velocity vector is >= 20 degrees from the galactic plane. line_15: 4) No data through the SAA line_16: 5) POINTING: First exposure in each non-int sequence to start line_17: as soon after target rise as possible within shadow. line_18: The target will be the direction of the velocity vector line_19: 4 (+/- 1) minutes after the START of this first observation line_20: of the Second orbit. This will be the pointing for all 4 orbits. line_21: 6) TRACKING: GYRO TRACK IS ACCEPTABLE AND REQUESTED. ! question: 5 section: 3 line_1: --- TEST PREREQUISITES: line_2: o Level 1 optical image quality not required. (lambda/8 is line_3: sufficient) line_4: o Mini-OFAD verification is desireable but not necessary line_5: o WF/PC UV Flood and pre-flash capabilities operational (SV/1431) line_6: o WF/PC cooled to nominal operating temperatures (SV/1431) line_7: o WF/PC preliminary focus setting established (OV/1482) line_11: --CAUTIONS:-- When the number of potential targets locations line_12: are sufficiently minimized or selected, we must make a line_13: brightness alert check of the candidate fields for protection of line_14: FOVs. ! question: 6 section: 1 line_1: Dark times are required for this OLT since the expected line_2: magnitude level of the S/C glow effect is extremely faint. line_3: Considerations of orbital geometry relative to the positions of line_4: the sun, moon, ecliptic plane and galactic plane and even the line_5: selection of an intrinsically dark portion of the sky as a line_6: target will all be required to insure meaningful measurements line_7: of the S/C glow. ! question: 7 section: 1 line_1: Real Time Data Analysis Requirements: line_2: Not anticipated at this time. line_3: Offline Data Analysis Requirements: line_4: For WF/PC Exposures: line_5: o Process each of the 12 frames for bias subtraction and line_6: normalization for relative sensitivity variation (flat line_7: fielding). line_8: o Select the image area which is common to the 9 frames line_9: o Determine a single mean flux for each of the WFC line_10: images. Because the image will be contaminated by field line_11: stars and extended sources, the mean (or modal) flux level line_12: for the image is most easily determined from the spatial line_13: intensity distribution function. For each image, construct line_14: a histogram of the number of pixels above a given count as line_15: a function of the count rate. Determine the mode of the line_16: major component of the distribution which is the background. line_17: The corresponding count rate defines the mean flux of the line_18: background portion of the image. line_19: o Add all remaining pixels in each individual frames together line_20: o Compare aggregated intensities of the last frame of each line_21: orbit (reference frames) relative to each other and against line_22: zodiacal light to calibrate (or verify) OTA and WF/PC line_23: throughput efficiency as a function of wavelength. ! question: 7 section: 2 line_1: o Compare the results of the repetition of the test after line_2: 6 months to those of the original test to obtain possible line_3: time dependence effects. ! !end of general form text general_form_address: lname: BELY fname: PIERRE category: PI inst: ST SCI ! lname: LUPIE fname: OLIVIA category: CON inst: ST SCI addr_1: 3700 SAN MARTIN DRIVE city: BALTIMORE state: MD zip: 21218 country: USA ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: GLOW-TAR pos_1: RA = 19H 00M 00S +/- 0.1S, pos_2: DEC = 0D 00' 00" +/- 0.1" equinox: J2000 comment_1: CYCLE 0 OBSERVATION fluxnum_1: 1 fluxval_1: SURF(V)=25 +/- 0.5 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 sequence_1: DEF sequence_2: CALIB1 targname: BIAS config: WFC opmode: IMAGE aperture: ALL sp_element: F850LP num_exp: 1 time_per_exp: 0 S priority: 1 param_1: SUM=2X2, param_2: PRE-FLASH=YES req_1: CYCLE 0 / 1-52; ! linenum: 2.000 sequence_1: DEF sequence_2: CALIB1 targname: DARK config: WFC opmode: IMAGE aperture: ALL sp_element: F850LP num_exp: 1 time_per_exp: 400S priority: 1 param_1: SUM=2X2, param_2: PRE-FLASH=YES ! linenum: 11.000 sequence_1: USE sequence_2: CALIB1 req_3: SEQ 11-52 WITHIN 7.0 H; req_4: SEQ 11-18 WITHIN 98 M; req_5: CALIB FOR 12; SEQ 11-18 NO GAP; ! linenum: 12.000 targname: GLOW-TAR config: WFC opmode: IMAGE aperture: ALL sp_element: F850LP num_exp: 3 time_per_exp: 400S priority: 1 param_1: SUM=2X2, param_2: PRE-FLASH=YES req_1: NON-INT; req_2: GUIDE TOL 6.0" comment_1: CRITICAL SCHEDULING REQUIREMENTS; comment_2: SEE GF QUESTION 5; FIRST EXPOSURE comment_3: SHOULD BE SCHEDULED IMMEDIATELY comment_4: AFTER SPACECRAFT ENTERS EARTH comment_5: SHADOW. PCS MODE GYRO. ! linenum: 18.000 sequence_1: USE sequence_2: CALIB1 req_1: CALIB FOR 12; ! linenum: 31.000 sequence_1: USE sequence_2: CALIB1 req_1: SEQ 31-38 WITHIN 98M; req_2: CALIB FOR 32; SEQ 31-38 NO GAP; ! linenum: 32.000 targname: GLOW-TAR config: WFC opmode: IMAGE aperture: ALL sp_element: F702W num_exp: 3 time_per_exp: 400S priority: 1 param_1: SUM=2X2, param_2: PRE-FLASH=YES req_1: NON-INT; req_2: GUIDE TOL 6.0" comment_1: CRITICAL SCHEDULING REQUIREMENTS; comment_2: SEE GF QUESTION 5; FIRST EXPOSURE comment_3: SHOULD BE SCHEDULED IMMEDIATELY comment_4: AFTER SPACECRAFT ENTERS EARTH comment_5: SHADOW. PCS MODE GYRO. ! linenum: 38.000 sequence_1: USE sequence_2: CALIB1 req_1: CALIB FOR 32; ! linenum: 51.000 sequence_1: USE sequence_2: CALIB1 req_1: SEQ 51-58 WITHIN 98M; req_2: CALIB FOR 52; SEQ 51-58 NO GAP; ! linenum: 52.000 targname: GLOW-TAR config: WFC opmode: IMAGE aperture: ALL sp_element: F555W num_exp: 3 time_per_exp: 400S priority: 1 param_1: SUM=2X2, param_2: PRE-FLASH=YES req_1: NON-INT; req_2: GUIDE TOL 6.0" comment_1: CRITICAL SCHEDULING REQUIREMENTS; comment_2: SEE GF QUESTION 5; FIRST EXPOSURE comment_3: SHOULD BE SCHEDULED IMMEDIATELY comment_4: AFTER SPACECRAFT ENTERS EARTH comment_5: SHADOW. PCS MODE GYRO. ! linenum: 58.000 sequence_1: USE sequence_2: CALIB1 req_1: CALIB FOR 52; ! ! end of exposure logsheet ! No scan data records found