! !__Proposal-Section__ !6128 ! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 6128,v 10.1 1995/07/18 17:25:25 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Christian Ready ! Phone: 410 338-4546 , E-mail: ready@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Date generated: Mon Dec 19 08:31:49 EST 1994 ! Proposal_Information ! Section 4 Title: Spatial Structure of the High Excitation Herbig-Haro Objects HH 80/81 Proposal_Category: GO Scientific_Category: Interstellar Medium Cycle: 5 Investigators PI_name: Steve Heathcote PI_Institution: Cerro Tololo InterAmerican Observatory CoI_Name: Bo Reipurth CoI_Institution: European Southern Observatory, La Silla Observatory Contact: ! Y or N (designate at most one contact) CoI_Name: Alex Raga CoI_Institution: Instituto de Astronomia, UNAM Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) Herbig-Haro outflows have in recent years been the subject of intense study, and it is now clear that they are an integral part of the star formation process and can provide insight into the very earliest stages of stellar evolution. They are also an excellent laboratory for the investigation of the physics of interstellar shock waves. We propose to use HST with the PC CCD of WFPC2 to study HH 80 and HH 81, the twin working surfaces at the terminus of a powerful jet driven by a luminous young star. As well as being the brightest known HH objects, HH 80 and HH 81 are unique in having a high excitation emission zone of considerable spatial extent. Because of their large, ~300km/s shock velocity and only modest, ~50 cm^-3 preshock density, the postshock cooling zone in these objects should be easily resolvable with HST. Narrow band filters will be used to obtain images in H Alpha, a high excitation line ([O III] 5007), and a low excitation line ([S II] 6717/31). We expect the emission regions for these species to be displaced by up to 0.2" in HH 80/81 offering the first opportunity to directly observe the stratification of high and low excitation/ionization lines in HH objects. The HH 80/81 system is the best known laboratory for performing this experiment. The high spatial resolution of HST is mandatory for its success. Questions ! Free format text (please update) Observing_Description: Images of the HH 80/81 complex will be obtained through three narrow band filters which isolate the key emission lines H-alpha (F656N), [O III] 5007 (F502N), and [S II] 6717,31 (F673N). These lines are amongst the brightest in the spectrum of HH 80/81, are at wavelengths where the sensitivity of WFPC2 is greatest, and their relative strengths are sensitive shock velocity diagnostics. These images will serve to map out the pattern of excitation within the various knots as well as providing information on their fine scale structure. The bright, isolated object HH 81 will be placed on the PC chip in order to obtain the finest possible sampling of its spatial structure. HH 80 will then fall on one of the adjacent WF chips. Sub-pixel dithering will be employed when taking the data so that image reconstruction techniques can be used to recover as much spatial resolution as possible in the bright core of HH80 where the S/N will be high. Conversely, the larger WF pixel size will aid in achieving adequate signal to noise in the very faint emission filaments in which HH80 is enveloped. Total integration times will be 5000S for F656N, 7500S for F673N and 10,100S for F501N. In these exposures we expect to achieve S/N ~40:1 in H-Alpha 25:1 in [SII] and 15:1 in [OIII] per PC pixel at the brightest point in HH81. For HH80A, which is of comparable brightness the S/N will be about a factor two greater for the larger WF pixels facilitating use of image restoration techniques. In the faintest knots in the HH complex S/N ~ 3:1 per WF pixel should be achieved in H-alpha and [SII]. Real_Time_Justification: None. Calibration_Justification: ! Move appropriate text from Real_Time_Justification None. Additional_Comments: A principal goal of the program is to detect small (~0.1") displacements between species of different excitation due to stratification in the cooling zone behind the HH shocks. The HH knots have large proper motions (0.1"/year for the fastest moving knot). To eliminate any confusion between displacements due to stratification and proper motion it is essential that all the images are as nearly contemporaneous as possible. We have had to split the program between two visits because of SAA avoidence constraints. We therefore require that these two visits are executed within 15 days, or less, of one another in order to limit the shift due to proper motion of the fastest moving knots to less than 0.1 PC pixel. We wish to use sub-pixel dithering in order to maximise spatial resolution, especially for the parts of the complex which fall on the WF chips, as well as to remove bad pixels. On the other hand because we are readout noise limited for the faintest knots, we will take only three, or four, rather long, exposures in each filter so that reliable correction of CR's is also important. As a compromise between these requirements, we will obtain exposures at only two telescope pointings differing by 0.75" (16.48 PC pixels, 7.53 WF pixels) along both the X and Y axes of PC1. The PC1-FIX position will be used for the first pointing, POS TARG 0.75, 0.75 (relative to PC1-FIX) for the second. For F656N and F501N two exposures will be taken at each of these telescope positions in order to simplify CR recognition. For F673N only three exposures will be obtained, two at one telecscope position, and one at the other. We have carefully chosen orients such that, with HH81 centred on PC1, the remainder of the HH complex falls entirely within the unvignetted field of one of the WF CCDs. Since the object has a complicated shape this was done by overlaying the WFPC-2 science apertures on an image. In drawing the aperturss, the PC1-FIX reference point was taken to be at pixel x=420.0, y=424.5, the offset angle from the PC1 +X axis to U3 was taken to be 45D, and the limits of the vignetted field were taken from the WFPC-2 instrument handbook version 2.0 page 14. The limits have been chosen conservatively to incorporate a margin for error of +/-2D in this procedure. There are three possible ranges of orientation, one for each WF chip. According to RPS2 the range (ORIENT 58.9D TO 106.9D) corresponding to placing HH80 on WF2 offers the largest window for scheduling (~5 months/year). The orients which place the object on WF4 can also be scheduled (~1 month window). Positioning on WF3 is only possible for a narrow range of orients which according to RPS2 cannot be scheduled. Consequently we have adopted the "WF2" range for ORIENT in the vist special requirements. However, the two alternative sets of roll angles are given in the visit comments. These alternatives may be used instead of that selected should it prove impossible to schedule the observations during the WF2 window. However, note that the same ORIENT must be used for both visits. As a last ditch backup, should it still proove impossible to schedule the observations, then data can be taken with HH81 falling on one WF chip (at the cost of reduced resolution) and HH80 on another, which allows use of two further different sets of spacecraft roll angles. In this event please contact the PI. Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: HH81 Alternate_Names: Description: ISM, Herbig-Haro Object, Bipolar Outflow Position: RA = 18H 16M 7.44S +/- 0.3", DEC = -20D 52' 23.5" +/- 0.3", PLATE-ID=067U Equinox: 1950 RV_or_Z: V = +250 RA_PM: -0.0008 ! Units are seconds of time per year Dec_PM: -0.040 ! Units are seconds of arc per year Epoch: 1990.6 Annual_Parallax: Flux: SURF-LINE(5007) = 8 +/- 1 E-15, W-LINE(5007) = 3.3 +/- 0.2, SURF-LINE(6563) = 22 +/- 1 E-15, W-LINE(6563) = 3.9 +/- 0.2, SURF-LINE(6717) = 5 +/- 1 E-15, W-LINE(6717) = 2.1 +/- 0.2, SURF-LINE(6731) = 8 +/- 1 E-15, W-LINE(6731) = 2.1 +/- 0.2, A(V) = 2.3 +/- 0.5 Comments: Coordinates are for HH81A which will be centred on the PC CCD The entire HH 80 complex will be included in the field of WF2. Flux data are for HH81A and give the MAXIMUM surface brightness in that knot. HH80A is of comparable brightness, the other knots of interest are up to 2 orders of magnitude fainter. ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ORIENTation 58.9D TO 106.9D !HH80 on WF2 ! ORIENTation 4.9D TO 18.9D !HH80 on WF3 ! ORIENTation 290.4D TO 333.9D !HH80 on WF4 ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND GROUP 1-2 WITHIN 15D ! PERIOD