9111( 11) - 02/19/02 11:20 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9111 Version: 11 Check-in Date: 19-Feb-2002 11:19:39 1.Proposal Title: The UV Light Echo of Shock Breakout During SN 1987A ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Arlin Crotts Columbia University in the City of New York CoI: Dr. Stephen Lawrence Hofstra University N CoI: Mr. Ben Sugerman Columbia University N CoI: Dr. William Kunkel Las Campanas Obs., Carnegie Observatories N ------------------------------------------------------------------------------------ 5. Abstract Light echoes (transient reflection nebulae) from SN1987A were discovered in the optical in 1988 and have been detected in the vacuum ultraviolet by IUE. The UV data would be the first ``direct'' observation of the hot spectrum emitted by a supernova shock destroying its progenitor star; unfortunately the large aperture and pointing instabilities of IUE make these data difficult to calibrate and interpret in great detail. The breakout signal has also been modified by the spectral reflectance of the echoing dust. We propose to confirm the UV detection and to disentangle the incident SN spectrum from the dust reflectance by observing the UV echo at two scattering phase angles and combining them with HST and ground-based data. Sampling two echoes at widely-spaced spectral points and two scattering angles will provide us with enough independent information to factor these separately. The resulting early UV spectrum of SN 1987A will allow a direct test of theoretical models of supernova shock propagation and breakout from a star, as well as provide an accurate input ionization spectrum for understanding the excitation and recombination of gas in the observed circumstellar nebulosity around SN1987A. This study will also strongly constrain the physical properties of interstellar dust in the Large Magellanic Cloud. ------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 2] Observations Description ------------------------ The proposed observations will require 16 orbits spread across 8 visits. We will use our well-sampled ground-based monitoring campaign to intensively monitor the light echoes in the R1170 and R430 complexes (X+95) starting a few months before the start of Cycle 10. When a bright, spatially condensed patch begins to develop in either ring (as happens 3--4 times per year), we will trigger our TOO alert for the corresponding first or second visit. Given the optical position of the echo, we can use Eq. 1 and the known delay time between the UV and optical maxima to accurately predict the future location of the UV echo. As the successful IUE proposals have shown, typical optically-bright patches persist for 60--80 days beyond their first appearance, allowing us to catch the UV echo still in the denser dust structure. We will attempt to select a target echo patch that allows a radial placement of the STIS slit with respect to SN 1987A to be scheduled within the TOO activation window, which will maximize the spatial information and movement of the echo within the aperture. Such an orientation is not a necessary condition for our observations, however, and primary emphasis will be on selecting targets with high surface brightness and compact structure. The first and second visits (3 orbits each) will use STIS to measure the UV spectrum of two bright echo patches and the underlying scattered stellar background, one each in the R1170 and R430 complexes. The third and fourth visits (1 orbit each) will use WFPC2 to perform broad-band optical surface photometry of the same patches, delayed in time by 90 +/-20 days. This delay matches the offset between the UV and optical maxima of SN 1987A, allowing us to image the optical echo reflecting from the same dust as the STIS UV data. The fifth and sixth visits are delayed by 12 or 18 months until Cycle 11, giving the UV and optical echoes time to propagate well beyond the target patches and rotating the slit into an orientation (anti-)parallel with the original. These second epoch STIS (6 orbits) and WFPC2 (2 orbits) observations allow us to measure the constant stellar background flux scattered from these dust patches. In order to optimize throughput and match the IUE observations in hand, the UV observations will be taken with STIS using the FUV-G140L grating and the 52*2 aperture. Figure 1 presents spectra of a previous bright echo patch, with and without the permanent LMC reflection signal, as derived from IUE observations. With these data as inputs, we used the STIS Spectroscopic ETC to produce the simulated spectra shown in Figure 3. Plotted are the net counts per pixel (no binning) expected from the SN echo (dotted line) and the combination of the echo + LMC background + geocoronal emission + dark current (solid line), for a total exposure of 8500 seconds (3 orbits). Figure 4 presents a simulated extraction of the echo signal, obtained by subtracting the LMC background to be obtained in the third visit. The data have been binned by 82 pixels along the dispersion (to match the spectral resolution of the 2"\ wide slit) and by 10 pixels along the slit. Our simulations indicated that this combination of exposure time and binning provides a signal-to-noise ratio S/N >= 3 for 1150- 1650Angstrom, and was an optimal compromise between spatial resolution and total orbits required. Calculations were performed with the ``average'' settings for the geocoronal emission in the ETC; if the actual emissions are near maximum the error bars for the three affected pixels in Figure 4 could increase by a factor of 3. Note that the UV flash is extremely narrow, only a light-day or two thick, and much narrower than the STIS pixel scale. Any spatial extent of the light echo along the radial direction is due to the line-of- sight depth of the echoing dust cloud, and there is no penalty for binning the spectrum--all dust is reflecting the same brief period when the SN was UV-bright. The orbital programs for the four STIS visits (1, 2, 5, & 6) will be identical. The same ground-based optical images used to locate the echo target will provide a bright, nearby, isolated star to use for acquisition. A blind slew will position the echo patch in the 2"\ wide aperture. For the 58 minute visibility period, the orbital budget will run as follows: Orbit 1: Guide star acquisition (6 min); Point source target acquisition on nearby star (6 min); Slew to science target (1 min); two 20 min STIS-FUV-G140L spectra (45 min). Orbits 2 & 3: Guide star re- acquisition (5 min); two 25 min STIS-FUV-G140L spectra + overheads (53 min). \medskip The S/N achieved in three orbits is high, but this serves as a safety margin against a suitable echo patch being fainter than in 1995. A patch half as bright would require nearly four times the exposure to reach the same S/N. In order to obtain optical information at the same spatial scale as the STIS observations and with similar bandpasses as our ground- based monitoring campaign, the optical observations will be taken with WFPC2 through the ``standard'' BVRI filters. Images of the echo patch observed with IUE in 1995 showed an average surface brightness of 20.5 magnitudes arcsecond^-2 in V. Using this as the normalization for a strongly-reddened hot star, we used the WFPC2 ETC to estimate exposure times necessary to achieve S/N>~3 per PC pixel through the VRI filters. The exposures are short enough that two images in each will be sufficient to screen for cosmic rays. Guide star acquisition is accurate enough to place the echo centrally on the PC CCD. The programming for the single-orbit WFPC2 visits (3, 4, 7, & 8) will be identical: \medskip Orbit 1: Guide star acquisition (6 min); 2 F555W 2 minute exposures, filter change, overheads (11 min); 2 F675W 3 minute exposures, filter change, overheads (13 min); 2 F814W 3 minute exposures, filter change, overheads (13 minutes); 2 F439W 5 minute exposures, filter change, overheads (15 min). \medskip If any of the observations are scheduled during a CVZ period, extra time will be added to the spectra and F439W exposures to improve S/N. Real Time Justification ----------------------- All observations are time-critical, but according to comparatively lax constraints. Since we do not know when the targets will appear within the 4 arcmin radius search area, the first two visits are classified as Target of Opportunity. The first STIS observation of a given patch (visits 1 & 2) must occur within about 45 days after the alert that a bright echo patch is observed, and the WFPC2 imaging (visits 3 & 4) must then occur between 70 and 110 days afterwards. The second STIS & WFPC2 epochs for a given patch (visits 5 & 6) can occur anytime after notification that the bright echo patch has faded in the optical, but would be best taken 12 or 18 months after the first STIS data, in order to place the slit in a parallel orientation on the sky and retain the maximum amount of spatial information. Either way, visits 5 & 6 will need to be scheduled for Cycle 11. Due to the timing uncertainty of TOO observations, and the desire to use approximately repeat the aperture PA of visits 1 & 2 in visits 5 & 6, we have not requested CVZ orbits. The WFPC2 imaging does have the most relaxed timing constraints, however, and could possibly be scheduled in a CVZ window, which would allow us to expand the F439W exposures and improve the S/N. Ground-based observations of the optical echoes from which our TOO targets will be selected are performed by one of the co-Is roughly 8-10 times per year, all year long, except during June-August. These data will be monitored closely beginning several months before the start of Cycle 10, searching for compact echo clumps to trigger the TOO criteria as early as possible. Typically there are 3--4 suitable targets in each complex per year. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LMC-SN1987A- EXT-MEDIUM, REFLECTION RA=5H 35M 18.20S +/- 0.05S, DEC= J2000.0 V=+290 SURF(V) = 20.5+/-1.0 ECHO1-FIELD NEBULA -69D 11' 53.59" +/- 0.1", PLATE- B-V = -0.1+/-0.1 ID=06B0 E(B-V) = 0.17+/-0.02 SURF-CONT(1500)=1.5+/-0.5e-17 SURF-CONT-BKG(1500)=3.0+/-0.5e-17 Coordinate Source: GSC_SURVEY_PLATE Comments: Preliminary wide-field positioning exposure for echo patch #1, observed about 1 week ahead of visit 3 in order to most favorably position STIS aperture. Note that this observation has been modified since original proposal. 2 LMC-SN1987A- EXT-MEDIUM, REFLECTION RA=5H 35M 57.07S +/- 0.05S, DEC= J2000.0 V=+290 SURF(V) = 20.5+/-1.0 ECHO2-FIELD NEBULA -69D 16' 47.16" +/- 0.1", PLATE- B-V = -0.1+/-0.1 ID=06B0 E(B-V) = 0.17+/-0.02 SURF-CONT(1500)=1.5+/-0.5e-17 SURF-CONT-BKG(1500)=3.0+/-0.5e-17 Coordinate Source: GSC_SURVEY_PLATE Comments: Preliminary wide-field positioning exposure for echo patch #2, observed about 1 week ahead of visit 4 in order to most favorably position STIS aperture. Note that this observation has been modified since original proposal. 5 LMC-SN1987A- EXT-MEDIUM, REFLECTION RA=5H 35M 19.82S +/- 0.05S, DEC= J2000.0 V=+290 SURF(V) = 20.5+/-1.0 ECHO1 NEBULA -69D 12' 13.92" +/- 0.1", PLATE- B-V = -0.1+/-0.1 ID=06B0 E(B-V) = 0.17+/-0.02 SURF-CONT(1500)=1.5+/-0.5e-17 SURF-CONT-BKG(1500)=3.0+/-0.5e-17 Coordinate Source: GSC_SURVEY_PLATE Comments: Target-of-Opportunity light echo patch #1, located in the R1170 dust complex of Xu, Crotts, & Kunkel (1995). Initial coordinates selected from WF3 chip F170W and F555W imaging from Visit 1, then transferred to GSC_Survey_Plate ID=06B0. This dust complex is also part of the N157C superbubble surrounding the cluster LH90. This target will use the STIS F25QTZ and F25SRF2 apertures at PA near 25 degrees E of N on the sky (ORIENT=U3=70 D, V3=250 D). 7 LMC-SN1987A- EXT-MEDIUM, REFLECTION RA=5H 35M 56.95S +/- 0.05S, DEC= J2000.0 V=+290 SURF(V) = 20.5+/-1.0 ECHO2 NEBULA -69D 16' 54.76" +/- 0.1", PLATE- B-V = -0.1+/-0.1 ID=06B0 E(B-V) = 0.17+/-0.02 SURF-CONT(1500)=1.5+/-0.5e-17 SURF-CONT-BKG(1500)=3.0+/-0.5e-17 Coordinate Source: GSC_SURVEY_PLATE Comments: Target-of-Opportunity light echo patch #2, located in the R430 dust complex of Xu, Crotts, & Kunkel (1995). Initial coordinates selected from WF4 chip F170W and F555W imaging from Visit 2, then transferred to GSC_Survey_Plate ID=06B0. This target will use the STIS F25QTZ and F25SRF2 apertures at PA near 25 degrees E of N on the sky (ORIENT=U3=70 D, V3=250 D). 9111( 11) - 02/19/02 11:20 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 8 LMC-SN1987A- EXT-MEDIUM, REFLECTION RA=5H 35M 18.09S +/- 0.05S, DEC= J2000.0 V=+290 SURF(V) = 20.5+/-1.0 ECHO1- NEBULA -69D 11' 47.86" +/- 0.1", PLATE- B-V = -0.1+/-0.1 FOLLOWUP ID=06B0 E(B-V) = 0.17+/-0.02 SURF-CONT(1500)=1.5+/-0.5e-17 SURF-CONT-BKG(1500)=3.0+/-0.5e-17 Coordinate Source: GSC_SURVEY_PLATE Comments: Follow-up wide-field exposure for echo patch #1, to be observed about 90 days after visit 3 in order to image the optical echo at the same location as the UV echo. The coordinates presented here are optimized to reimage two of the WF chips exactly, given a 90.0 degree rotation between this visit and Visit 1, i.e. at ORIENT=U3=151D+/-2D. 9 LMC-SN1987A- EXT-MEDIUM, REFLECTION RA=5H 35M 56.90S +/- 0.05S, DEC= J2000.0 V=+290 SURF(V) = 20.5+/-1.0 ECHO2- NEBULA -69D 16' 47.06" +/- 0.1", PLATE- B-V = -0.1+/-0.1 FOLLOWUP ID=06B0 E(B-V) = 0.17+/-0.02 SURF-CONT(1500)=1.5+/-0.5e-17 SURF-CONT-BKG(1500)=3.0+/-0.5e-17 Coordinate Source: GSC_SURVEY_PLATE Comments: Follow-up wide-field exposure for echo patch #2, to be observed about 90 days after visit 4 in order to image the optical echo at the same location as the UV echo. The coordinates presented here are optimized to reimage two of the WF chips exactly, given a 90.0 degree rotation between this visit and Visit 2, i.e. at ORIENT=U3=151D+/-2D. 9111( 11) - 02/19/02 11:20 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ON HOLD On Hold Comments: Target of Opportunity 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 LMC-SN1987A WFPC2 IMAGE WF3 F170W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 1800.0 -ECHO1-FIEL D ------------------------------------------------------------------------------------------------------------------------------------ 12 LMC-SN1987A WFPC2 IMAGE WF3 F555W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 300.0 S -ECHO1-FIEL D ------------------------------------------------------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ON HOLD On Hold Comments: Target of Opportunity 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 ------------------------------------------------------------------------------------------------------------------------------------ 21 LMC-SN1987A WFPC2 IMAGE WF4 F170W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 1800.0 -ECHO2-FIEL D ------------------------------------------------------------------------------------------------------------------------------------ 22 LMC-SN1987A WFPC2 IMAGE WF4 F555W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 300.0 S -ECHO2-FIEL D ------------------------------------------------------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 7] Visit: 03 Visit Priority: Visit Requirements: VISIBILITY INTERVAL 55 M On Hold Comments: Additional Comments: Target of Opportunity visit for SN 1987A light echo patch #1, in the R1170 dust complex. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 32 LMC-SN1987A STIS/F ACCUM F25QTZ MIRROR 1 525.0 S MAX DUR 525.0 S -ECHO1 UV-MAM A Comments: First of two dithered F25QTZ images. ------------------------------------------------------------------------------------------------------------------------------------ 33 LMC-SN1987A STIS/F ACCUM F25QTZ MIRROR 1 1050.0 MAX DUR 1050.0 S POS TARG -ECHO1 UV-MAM 0.4934, 0.4934 A Comments: Second of two dithered F25QTZ images. Dithered (20, 20) FUV-MAMA pixels from Exposure #32. ------------------------------------------------------------------------------------------------------------------------------------ 34 LMC-SN1987A STIS/F ACCUM F25SRF2 MIRROR 1 383.0 S MAX DUR 383.0 S -ECHO1 UV-MAM A Comments: First of two dithered F25SRF2 images. ------------------------------------------------------------------------------------------------------------------------------------ 35 LMC-SN1987A STIS/F ACCUM F25SRF2 MIRROR 1 766.0 S MAX DUR 766.0 S POS TARG -ECHO1 UV-MAM 0.4934, 0.4934 A Comments: Second of two dithered F25SRF2 images. Dithered (20, 20) FUV-MAMA pixels from Exposure #34. ------------------------------------------------------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 8] Visit: 04 Visit Priority: Visit Requirements: VISIBILITY INTERVAL 55 M On Hold Comments: Additional Comments: Target of Opportunity visit for SN 1987A light echo patch #2, in the R430 dust complex. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 42 LMC-SN1987A STIS/F ACCUM F25QTZ MIRROR 1 2890.0 MAX DUR 2890 S -ECHO2 UV-MAM A Comments: First of three dithered F25QTZ images. ------------------------------------------------------------------------------------------------------------------------------------ 43 LMC-SN1987A STIS/F ACCUM F25QTZ MIRROR 1 3085.0 POS TARG 0.4934, 0.4934 -ECHO2 UV-MAM MAX DUR 3085 S A Comments: Second of three dithered F25QTZ images. Dithered (20, 20) FUV-MAMA pixels from Exposure #42. ------------------------------------------------------------------------------------------------------------------------------------ 44 LMC-SN1987A STIS/F ACCUM F25QTZ MIRROR 1 3085.0 POS TARG -0.4934,-0.4934 -ECHO2 UV-MAM MAX DUR 3085 S A Comments: Third of three dithered F25QTZ images. Dithered (-20, -20) FUV-MAMA pixels from Exposure #42. ------------------------------------------------------------------------------------------------------------------------------------ 45 LMC-SN1987A STIS/F ACCUM F25SRF2 MIRROR 1 3065.0 MAX DUR 3065 S -ECHO2 UV-MAM A Comments: First of two dithered F25SRF2 images. ------------------------------------------------------------------------------------------------------------------------------------ 46 LMC-SN1987A STIS/F ACCUM F25SRF2 MIRROR 1 3085.0 POS TARG 0.4934, 0.4934 -ECHO2 UV-MAM MAX DUR 3085 S A Comments: Second of two dithered F25SRF2 images. Dithered (20, 20) FUV-MAMA pixels from Exposure #44. ------------------------------------------------------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 9] Visit: 05 Visit Priority: Visit Requirements: ORIENT 149.00D TO 153.00D AFTER 03 BY 70 D TO 110 D On Hold Comments: Additional Comments: This imaging visit must follow 70 to 110 days after Visit 03, in order for the light echo from SN 1987A's optical maximum to move outwards to the position of the UV maximum sampled by the STIS spectra in Visit 03. The ORIENT restriction and coordinate shift guarantee maximal overlap with two of the WF chips. This visit consists of three CR-SPLIT pairs of F555W, F675W, and F814W WF3 images. If extra orbital visibility becomes available upon scheduling, the extra time should be added to the F814W exposure(s). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 51 LMC-SN1987A WFPC2 IMAGE WF3 F555W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 600.0 S -ECHO1-FOLL OWUP ------------------------------------------------------------------------------------------------------------------------------------ 52 LMC-SN1987A WFPC2 IMAGE WF3 F675W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 570.0 S -ECHO1-FOLL OWUP ------------------------------------------------------------------------------------------------------------------------------------ 53 LMC-SN1987A WFPC2 IMAGE WF3 F814W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 600.0 S -ECHO1-FOLL OWUP Comments: If there is extra time in the orbit upon scheduling, the CR-SPLIT exposures in this filter should be expanded. ------------------------------------------------------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 10] Visit: 06 Visit Priority: Visit Requirements: ORIENT 149.00D TO 153.00D AFTER 04 BY 70 D TO 110 D On Hold Comments: Additional Comments: This imaging visit must follow 70 to 110 days after Visit 04, in order for the light echo from SN 1987A's optical maximum to move outwards to the position of the UV maximum sampled by the STIS spectra in Visit 04. The ORIENT restriction and coordinate shift guarantee maximal overlap with two of the WF chips. This visit consists of three CR-SPLIT pairs of F555W, F675W, and F814W WF3 images. If extra orbital visibility becomes available upon scheduling, the extra time should be added to the F814W exposure(s). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 61 LMC-SN1987A WFPC2 IMAGE WF3 F555W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 600.0 S -ECHO2-FOLL OWUP ------------------------------------------------------------------------------------------------------------------------------------ 62 LMC-SN1987A WFPC2 IMAGE WF3 F675W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 570.0 S -ECHO2-FOLL OWUP ------------------------------------------------------------------------------------------------------------------------------------ 63 LMC-SN1987A WFPC2 IMAGE WF3 F814W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 600.0 S -ECHO2-FOLL OWUP Comments: If there is extra time in the orbit upon scheduling, the CR-SPLIT exposures in this filter should be expanded. ------------------------------------------------------------------------------------------------------------------------------------ 9111( 11) - 02/19/02 11:20 - [ 11] Summary Form for Proposal 9111 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF3 WF4 F25QTZ F25SRF2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-TOLERANCE=0.1 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ON HOLD VISIBILITY INTERVAL 55 M MAX DUR 525.0 S MAX DUR 1050.0 S POS TARG 0.4934, 0.4934 MAX DUR 383.0 S MAX DUR 766.0 S POS TARG 0.4934, 0.4934 MAX DUR 2890 S POS TARG 0.4934, 0.4934 MAX DUR 3085 S POS TARG -0.4934,-0.4934 MAX DUR 3085 S MAX DUR 3065 S ORIENT 149.00D TO 153.00D AFTER 03 BY 70 D TO 110 D ORIENT 149.00D TO 153.00D AFTER 04 BY 70 D TO 110 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F170W F555W MIRROR F675W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LMC-SN1987A-ECHO1-FIELD LMC-SN1987A-ECHO2-FIELD LMC-SN1987A-ECHO1 LMC-SN1987A-ECHO2 LMC-SN1987A-ECHO1-FOLLOWUP LMC-SN1987A-ECHO2-FOLLOWUP ------------------------------------------------------------------------------------------------------------------------------------