! Proposal 6526, submission 1 ! PI: Patrizia A. Caraveo ! Received Thu Feb 15 10:00:32 EST 1996 ! From: mignani@helios.ifctr.mi.cnr.it ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6526,v 5.1 1996/12/02 21:06:13 pepsa Exp $ ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6526,v 5.1 1996/12/02 21:06:13 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: Ready ! Phone: 410-338-4546 , E-mail: ready@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: archive-0364.caraveo.prop ! Date generated: Fri Dec 22 17:37:50 EST 1995 ! Proposal_Information ! Section 4 Title: Distance, Proper Motion and Colors of the Vela Pulsar. Proposal_Category: GO Scientific_Category: HOT STARS Cycle: 6 Investigators PI_name: Patrizia A. Caraveo PI_Institution: Istituto di Fisica Cosmica del CNR CoI_Name: Giovanni F. Bignami CoI_Institution: Istituto di Fisica Cosmica del CNR Contact: ! Y or N (designate at most one contact) CoI_Name: Roberto P. Mignani CoI_Institution: Istituto di Fisica Cosmica del CNR Contact: ! Y or N (designate at most one contact) CoI_Name: Lawrence Taff CoI_Institution: Dept. of Physics and Astronomy,JHU Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) PSR0833-45 is, with the Crab pulsar and PSR0540-69, one of the few Isolated Neutron Stars (INSs) associated with a SNR. Moreover, these are, so far, the only INSs known to pulsate in the optical domain. Although the optical counterpart of the Vela Pulsar has been identified since 1977, nothing is known about its UV emission beyond a limited, ground based point in the U band. Blueward of it, the FOC could easily measure, for the first time, the presumably non-thermal radiation of the pulsar. On the other hand, recent results in X and Gamma-ray domains have challenged the commonly accepted value of 500 pc for the source distance, suggesting the need for a significant downward revision. The distance to the Vela Pulsar is a quite important piece of information, since this object is used as a calibrator for SNRs. Thus, it seems worthwhile to address this point with a set of three high accuracy WFPC2 observations aimed at measuring (or set limit on) the parallactic displacem. ent of the Vela Pulsar optical cou nterpart. At 250 pc, for instance, Vela should show a parallactic displacement of 0.004", equivalent to 0.09 PC pixels, a value which, according to our experience, is certainly within the instrument capabality. These high accuracy observations would also yield a precise measure of the pulsar's proper motion. This is yet another open point in the complex Vela Pulsar phenomenology, since, although proper motion is certainly present, existing radio and optical observations yield conflicting results. Questions ! Free format text (please update) Observing_Description: We propose to do very accurate positioning of the PSR0833-45 optical counterpart exploiting the sharp angular resolution of the PC (0."0455/pixel) to perform relative astrometry. Since the source V and B mags are similar, about 23.7, we propose to use the PC associated with the "V filter" F555W. Using the WFPC2 exposure simulator available in STEIS, we estimate that a PC exposure of 2000 sec would be sufficient to detect the target with a high S/N. This one-orbit observation should be repeated three times (two visit in cycle 6 and one in cycle 7), scheduled six months apart when the parallactic displacement is expected to be maximum i.e. at days 7 and 191. Attached to one of these visits, we plan to get deep FOC exposures of the source using two near UV filters. The FOC should be used in the nominal "f/151" mode. According to FOCSIM, an exposure time of about 4500 sec in the F275W and F195W filters is required to detect the target with a high S/N. Thus, 4 orbits will be needed for the FOC pointings. Real_Time_Justification: The three PC observations should be scheduled at the time of the maximum parallactic displacement around days 7 and 191 of each calendar year. At those times the total parallactic displacment is a maximum, reaching 92\% of the theoretically largest values. The time constraint associated with these dates is +/- 1 week but as the maximum displacement only slowly falls off from the extreme values, +/- 3 weeks is possible too. Hence, this restriction is not very tight one. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number:01 Target_Name:STAR-0835-4510 Alternate_Names:PSR0833-45, VELA PULSAR Description:STAR,NEUTRON STAR Position: RA=8H 35M 20.67S +/- 0.019S, ! RA=0H 0M 0.00S +/- 0S DEC=-45D 10' 35.75" +/- 0.29" ! DEC=0D 0' 0.0" +/- 0" ! PLATE-ID=0000 Equinox: J2000 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux:V=23.6,B-V=0.2 ! Include at least V and B-V Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed !******************************************************************* Visits ! Section 6 Visit_Number:01 Visit_Requirements: ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling PCS MODE F ! GUIDing TOLerance ! DROP TO GYRO IF NECESSARY [NO REACQuisition] ! ORIENTation 0D TO 90D ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! SCHEDulability ! AFTER [BY [TO ]] ! AFTER ! BEFORE BETWEEN 30-JUN-97 AND 30-JUL-97 ! GROUP WITHIN