!  File:  4416C.PROP
!  Database:  PEPDB
!  Date:  22-FEB-1994:10:59:30

coverpage:

  title_1:         THE HOT STELLAR COMPONENT IN THE CENTERS OF M31 AND M32:
    title_2:       CYCLE3 HIGH
    sci_cat:       GALAXIES & CLUSTERS
    sci_subcat:    STELLAR POPULATIONS
    proposal_for:  GO
    pi_fname:      HENRY
    pi_mi:         C.
    pi_lname:      FERGUSON
    pi_inst:       UNIVERSITY OF CAMBRIDGE
    pi_country:    ENGLAND
    hours_pri:     11.64
    num_pri:       2
    foc:           Y
    off_fname:     DONALD
    off_lname:     LYNDEN-BELL
    off_title:     DIRECTOR
    off_inst:      8014
    off_addr_1:    THE OBSERVATORIES
    off_addr_2:    MADINGLEY ROAD
    off_city:      CAMBRIDGE
    off_zip:       CB3 0HA
    off_country:   ENGLAND
    off_phone:     (0223) 337548
! end of coverpage

abstract:

    line_1:        We propose to construct a far-UV color-magnitude diagram for the
    line_2:        point sources detected in FOC images of the centers of M31 and M32.
    line_3:        These data will be used, in conjunction with spectroscopy obtained
    line_4:        by the Hopkins Ultraviolet Telescope, to provide constraints
    line_5:        on the mix of stars responsible for the far-UV emission in old,
    line_6:        metal-rich stellar populations. Our inference from the existing HUT
    line_7:        and FOC data is that the resolved sources are mostly low-mass PAGB stars.
    line_8:        If so, our observations will provide the first direct estimates of
    line_9:        the PAGB star mass distribution, and will provide important insight
    line_10:       into the differences in the evolution of the stellar populations in
    line_11:       these two galaxies, the amount of mass-loss among the AGB progenitor
    line_12:       stars and evolution along the PAGB. By combining our observations
    line_13:       through different filters, we will be able to assess the emission-line
    line_14:       contribution and search for variability. Comparison with the HUT
    line_15:       data will allow a precise estimate of the contribution to the far-UV
    line_16:       light from PAGB stars of different mass, and will allow a more
    line_17:       precise determination of the spectral-energy distribution of the
    line_18:       remaining unresolved population.

!
! end of abstract

general_form_proposers:

  lname:           FERGUSON
    fname:         HENRY
    title:         PI
    mi:            C.
    inst:          UNIVERSITY OF CAMBRIDGE
    country:       UNITED KINGDOM
    esa:           Y

!

  lname:           KING
    fname:         IVAN
    mi:            R.
    inst:          UC-BERKELEY
    country:       USA

!

  lname:           DAVIDSEN
    fname:         ARTHUR
    mi:            F.
    inst:          JOHNS HOPKINS UNIVERSITY
    country:       USA

!

  lname:           STANFORD
    fname:         S. ADAM
    inst:          UC-BERKELEY
    country:       USA

!

  lname:           DEHARVENG
    fname:         JEAN-MICHEL
    inst:          CNRS LABORATOIRE D'ASTRONOMIE SPATIALE
    country:       FRANCE
    esa:           Y

!
! end of general_form_proposers block

general_form_text:

  question:        3
    section:       1
    line_1:        The FOC will be used in f/96 mode with the F275W and F175W filters
    line_2:        in zoom mode (0.022 X 0.044 arcsec pixels) to obtain images of
    line_3:        the M31 bulge and of M32 in the far UV. We strongly prefer to use
    line_4:        f/48 mode if it becomes available again for imaging.
    line_6:        We originally proposed to obtain photometry accurate to 10%
    line_7:        in the F150W and F220W filters to the detection limit of the
    line_8:        existing f/48 F175W image. This is not possible in the f/96 mode.
    line_9:        Instead, we aim to obtain F275W images sufficient to get
    line_10:       S/N ~ 10 on a T=20000K star with STMAG=21 in the F175W bandpass.
    line_11:       The additional shorter F175W exposures will be combined with
    line_12:       the existing f/48 F175W images to obtain nearly the same S/N,
    line_13:       and will also serve to test the calibration.
    line_15:       We wish to keep the orientation the same as the previous f/48
    line_16:       F150W observations, so that we do not lose stars off the corners
    line_17:       of the field.
    line_19:       Note that if the observations are to be carried out in f/48
    line_20:       mode, some of our requirements will change, and this could
    line_21:       potentially affect the scheduling of the observations. In
    line_22:       particular, the ORIENTations will likely be different, and
    line_23:       we would require DARK time for F150W observations.

!

  question:        4
    section:       1
    line_1:        The stars we propose to observe are detectable only in the far-UV. The
    line_2:        integrated spectra of M31 and M32 have been measured by IUE
    line_3:        \acite{Johnson79; Welch 1982; Burstein 1988}.  M31 was observed by by
    line_4:        HUT \acite{Ferguson 1991 ApJ; Ferguson Davidsen submitted}.
    line_5:        Low-resolution far-UV images were obtained from a sounding rocket
    line_6:        \acite{BCHHOS85} and more recently from the UIT \acite{O'Connell 1991
    line_7:        Stellar; O'Connell 1992 ApJ}. No resolved sources were detected in
    line_8:        these images.  Far-UV images have been taken in 1991 with HST.
    line_9:        In the M31 F175W image \acite{King 1992 ApJ}, 137 sources were detected
    line_10:       in the $44 \times 44\arcsec$ FOC $f/48$ field of view.  Estimates from
    line_11:       this image suggest that resolved sources provide roughly 15\% of the
    line_12:       total flux at 1750\ang. More recent images were obtained at 1500\ang
    line_13:       with the F130LP+F150W filters \acite{Bertola 1992}. These images were
    line_14:       not as deep as expected, and the field of view was $22 \times
    line_15:       22\arcsec$, so fewer sources were detected.  Preliminary estimates from
    line_16:       these images suggest that the resolved sources contribute a much larger
    line_17:       proportion of the far-UV flux \acite{Buson 1992}.
    line_19:       While we expect the FOC calibrations now planned for Cycle 2 to resolve
    line_20:       much of the discrepancy about the contribution of the resolved sources
    line_21:       to the total far-UV flux, the wavelength coverage and depth of the
    line_22:       existing images is insufficient to constrain the temperature
    line_23:       distribution of the point sources and the amount of emission-line

!

  question:        4
    section:       2
    line_1:        contamination.  A color-magnitude diagram with a wide UV baseline will
    line_2:        provide the necessary constraints, and will allow for the first time a
    line_3:        direct estimate of the PAGB star mass distribution.
    line_5:        For comparison with the existing F175W image, there is are great
    line_6:        advantages to to carrying out these observations in f/48 mode if
    line_7:        it becomes possible to do so.

!

  question:        4
    section:       3
    line_1:        To measure the PAGB-star mass distribution (assuming that is what most
    line_2:        of the sources are), we will try to assign stars to evolutionary tracks
    line_3:        like those shown in Fig. 3.  To do this adequately for a large enough
    line_4:        sample, we desire photometric accuracy better than 0.1 mag down to an
    line_5:        ST magnitude $m = 21.0$. This should be sufficient to probe the mass
    line_6:        distribution down to the Schoenberner 0.546 solar-mass track, and should
    line_7:        allow detection to even lower masses.
    line_9:        It is not possible to achieve this desired sensitivity in f/96 mode
    line_10:       within the time allocated by the TAC. In f/96 mode, the best combination
    line_11:       of temperature discrimation and sensitivity can be obtained by using
    line_12:       the F275W and F175W filters. The F175W observations will serve to
    line_13:       calibrate and increase the S/N of the existing f/48 images. The F175W
    line_14:       images are not quite as deep as the F275W images.
    line_16:       The ingredients in the exposure time calculation are as follows:
    line_17:       Source spectral Energy distribution:
    line_18:       - We have used a Kurucz (1992) model atmosphere with T_eff = 20000K
    line_19:       and log(g) = 4.5.  For a source of this temperature detected at
    line_20:       1 count/s in the f/48 F175W filter, the count rate would be 1.25
    line_21:       and 3.02 in the f/96 F175W and F275W filters, respectively.
    line_22:       Diffuse UV background + redleak:
    line_23:       - For M31 we used a spectral-energy distribution compiled by

!

  question:        4
    section:       4
    line_1:        Burstein (1992); for M32 we used the IUE SED from Burstein (1988),
    line_2:        joined at 3300A to the "cold-E" 15Gyr model of Rocca-Volmerange &
    line_3:        Guiderdoni (1987). To normalize, we estimated the mean background
    line_4:        (after subtracting dark-count) within the central 15 arcsec diam
    line_5:        (3.2e-3 counts/pixel) for M31; 2.9e-3 counts/pixel for M32). Folding
    line_6:        through the SYNPHOT-generated response functions, gives 1.15e-3
    line_7:        counts/pixel in the F175W filter and 8.71e-3 counts/pixel with F275W
    line_8:        for M31. For M32, the background is 1.13e-3 and 1.30e-2, respectively.
    line_9:        Airglow + detector background:
    line_10:       - For 90 degree solar zenith angle, Fig. 41 of the FOC Instrument
    line_11:       Handbook gives 2.0e-2 counts/pixel with no filters. The resulting
    line_12:       rates using the filter transmissions at Ly-alpha from SYNPHOT are
    line_13:       2.0e-3 and 5.9e-7 through the F175W and F275W filters, respectively.
    line_14:       Detector background (dark count) was taken to be 6e-4 counts/pixel.
    line_16:       Exposure times were calculated using equation 1 of section 6.0 in the
    line_17:       FOC Instrument Handbook. While profile fitting will be used to do the
    line_18:       photometry in the real data, for our purposes here we computed the
    line_19:       exposure times for stars measured through apertures of the sizes given
    line_20:       in the different rows of Table 9, and chose the aperture with the
    line_21:       shortest exposure time. In the Table below, R_S_tot is the count rate
    line_22:       for a source with an ST magnitude of m_F175W = 21 in the f/48 F175W
    line_23:       filter, integrated over the entire PSF, R_B_tot is the total

!

  question:        4
    section:       5
    line_1:        background in counts/pixel, and R_S and R_B are the source and
    line_2:        background count rates in a 0.176 arcsec radius aperture.
    line_4:        RESULTS OF EXPOSURE TIME ESTIMATE
    line_5:        Galaxy Filter R_S_tot   R_B_tot    R_S    R_B    Exposure (sec)
    line_6:        M31    F175W  0.24      1.9e-3     0.11   0.57   16000
    line_7:        M31    F275W  0.58      9.3e-3     0.13   0.45   11000
    line_8:        M32    F175W  0.24      1.9e-3     0.11   0.54   16000
    line_9:        M32    F275W  0.58      1.4e-2     0.13   0.61   16000
    line_11:       We were granted 14.62 hours of spacecraft time by the TAC.
    line_12:       We must therefore shorten exposure times, and choose to do
    line_13:       so in the F175W filter, where we can get some S/N back
    line_14:       by combining with the existing f/48 images. We put more
    line_15:       time on M31 because the existing f/48 image is slightly
    line_16:       lower qualitiy than the M32 image due to defocussing in
    line_17:       the detector. The exposure times shown in the exposure
    line_18:       log section reflect these modifications of the exposure
    line_19:       times times shown in the above table.

!

  question:        5
    section:       1
    line_1:        For both the F175W and the F275W exposures, we wish to use the same
    line_2:        orientation as the previous FOC F150W observations. This is to
    line_3:        avoid losing stars off the corners of the field. The desired orientations
    line_4:        are 97D for M31, and 98D for M32. Our pointing positions are
    line_5:        chosen to be the same as those of the FOC F150W observations
    line_6:        (program ID 2719). Our f/96 22x22" field with thus include all
    line_7:        the stars in the F150W f/48 22x22" field. (The existing f/48
    line_8:        F175W images were taken in zoom mode, and completely include our
    line_9:        proposed f/96 field.)
    line_11:       Our orientation requirements and pointing positions would change
    line_12:       if we were allowed to use f/48 mode, because we would then like
    line_13:       to align the new images with the existing F175W images, rather
    line_14:       than the existing F150W image.

!

  question:        6
    section:       1
    line_1:

!

  question:        7
    section:       1
    line_1:        Data will be reduced at Berkeley using the same procedures that were
    line_2:        used to analyze the F175W image. Source detection will be carried out
    line_3:        by eye and using DAOFIND. Photometry will be performed on the
    line_4:        un-deconvolved images using DAOPHOT.  Standard monte-carlo procedures
    line_5:        will be used to estimate completeness.
    line_7:        Both images will be deconvolved to look for extended emission that
    line_8:        might be indicative of planetary nebulae.
    line_10:       Color-magnitude diagrams and color-color diagrams will be be compared
    line_11:       to models constructed from theoretical evolutionary tracks, using
    line_12:       stellar model atmospheres to predict the far-UV fluxes.
    line_13:       Spectral-synthesis software developed by HF for analysis of the HUT
    line_14:       data has been modified to produce the evolutionary tracks shown on
    line_15:       Figs. 2 and 3 of this proposal. Modifications now underway for further
    line_16:       analysis of the HUT data and analysis of the proposed FOC data include
    line_17:       incorporating a realistic spread in metallicity, providing for
    line_18:       different enrichment of metals relative to helium, allowing different
    line_19:       mass-loss laws on the RGB and AGB, and incorporating improved non-LTE
    line_20:       model atmospheres for stars hotter than T_eff = 35000 K.  Improved
    line_21:       evolutionary tracks will be incorporated as they become available.
    line_23:       Software developed independently by JMD is being used to model the

!

  question:        7
    section:       2
    line_1:        luminosity function in the F175W image. The results from the separate
    line_2:        models will be compared in the near future.
    line_4:        A rough division of resonsibilities is as follows: HF is responsible
    line_5:        for coordinating the overall effort, IK and AS provide expertise on the
    line_6:        FOC and will be responsible for the initial data reduction and
    line_7:        photometry.  AFD provides expertise on the HUT data. HF and JMD are
    line_8:        responsible for modeling the resulting color-magnitude diagram,
    line_9:        although all will assist in its interpretation.

!

  question:        8
    section:       1
    line_1:

!

  question:        9
    section:       1
    line_1:        King and Deharveng are on the FOC IDT; Davidsen is on the FOS IDT.
    line_2:        The complete list of observations for these teams can be found in
    line_3:        documents readily available. The direct precursor to this proposal is
    line_5:        FOC-3105  UV IMAGING OF THE CENTERS OF M31 AND M32
    line_7:        Observations possibly related to this proposal include
    line_9:        SAO-3121, MORPHOLOGY OF FAINT GALAXIES - PART II
    line_10:       GTO-1277, IMAGING OF M31-GROUP GALAXIES
    line_11:       GTO-1278, SPECTROSCOPY OF THE CENTERS OF M31, M32, AND NGC 205
    line_12:       GTO-1279, STRUCTURE OF GLOBULAR CLUSTERS
    line_13:       GTO-1281, THE FAINT POPULATION IN BAADE'S WINDOW
    line_14:       GTO-3218, (continuation of 1279)
    line_15:       GTO-3219, (continuation of 1277)
    line_16:       GTO-3325, (continuation of 1279, 3218)
    line_17:       AUG-3684, IMAGING OF GLOBULAR CLUSTERS
    line_18:       AUG-3685, IMAGING OF HIGH-REDSHIFT FIELD GALAXIES AND CLUSTERS
    line_19:       AUG-3870, IMAGING IN THE M31 GROUP
    line_20:       GTO-4138, IMAGING OF NGC 4472
    line_21:       GO-3647   THE STAR-FORMING HISTORY OF ELLIPTICAL GALAXIES

!

  question:        9
    section:       2
    line_1:        The GO program is a Cycle-2 program of FOS spectroscopy with Ferguson
    line_2:        as PI and Davidsen among the Co-I's.
    line_4:        3105 revealed PAGB stars in the center of M31 and showed that they
    line_5:        account for only a small part of the UV upturn.  M32 (in 1277) went
    line_6:        into Crane et al., below, which found that none of the ellipticals
    line_7:        observed so far have isothermal centers.

!

  question:        9
    section:       3
    line_1:        ``The Current Ability of HST to Reveal Morphological Structure in
    line_2:        Medium-Redshift Galaxies'', King, I.R., et al. (8 other authors),
    line_3:        Astron. J. 102, 1553, 1991.
    line_5:        ``Preliminary Analysis of an Ultraviolet HST FOC Image of the Center of
    line_6:        M31'', King, I.R., et al. (19 other authors), Ap. J. Letters, 397,
    line_7:        L35, 1992.
    line_9:        ``FOC Observations of Galaxy Cores'', Crane, P.C., et al. (19 other
    line_10:       authors), submitted to A. J.

!

  question:        10
    section:       1
    line_1:        HF is funded by an SERC rolling grant for observational astronomy,
    line_2:        through September 1993. Destination thereafter is likely STScI.
    line_3:        Computing facilities at Cambridge include four SUN-4 computers
    line_4:        dedicated to HST projects, with a total of 6 Gigabytes of disk storage,
    line_5:        and exabyte cartridge tape systems for off-line storage. Each SUN has
    line_6:        at least 24 Mb of core memory and three have i860 array processors to
    line_7:        speed up image deconvolutions. These machines operate within a larger
    line_8:        network of SUNs that can be used for HST data analysis as well.  An
    line_9:        extensive suite of software is installed on the SUNs, including IRAF,
    line_10:       STSDAS, FIGARO, VISTA, and MEMSYS5. These systems are maintained by an
    line_11:       in-house support staff funded by STARLINK.
    line_13:       The data reduction facilities used by members of the FOC GTO team at
    line_14:       Berkeley are available for this project. This includes four
    line_15:       SPARCstation IPC's with 3 gigabytes of disk space dedicated to HST
    line_16:       work.

!
!end of general form text

general_form_address:

  lname:           FERGUSON
    fname:         HENRY
    mi:            C.
    category:      PI
    inst:          University of Cambridge
    addr_1:        THE OBSERVATORIES, MADINGLEY ROAD
    city:          CAMBRIDGE
    zip:           CB3 0HA
    country:       UNITED KINGDOM
    phone:         (0223) 337548
    telex:         817297 ASTRON G

!
! end of general_form_address records

fixed_targets:

    targnum:       1
    name_1:        NGC224
    name_2:        M31
    name_3:        ANDROMEDA GALAXY
    descr_1:       E,301,910,913
    pos_1:         RA = 00H 42M 44.90S +/-1",
    pos_2:         DEC = +41D 16' 08.0" +/-1"
    equinox:       2000
    pm_or_par:     N
    acqpr_1:       EXT
    comment_1:     FLUX 2 IS ST MAG = 21, OUR DESIRED
    comment_2:     LIMIT FOR 10% PHOTOMETRY. FLUX 3
    comment_3:     CONVERTS THE OBSERVED F175W MEAN
    comment_4:     BACKGROUND OF 3.2E-3 CTS/S/PIX BACK
    comment_5:     TO A FLUX. THE BACKGROUND IN F/96
    comment_6:     F175W AND F275W ARE ESTIMATED IN
    comment_7:     QUESTION 4 OF THE GENERAL FORM.
    fluxnum_1:     1
    fluxval_1:     SURF(V)=15.75
    fluxnum_2:     2
    fluxval_2:     F(1750)=1.45E-17
    fluxnum_3:     3
    fluxval_3:     SURF-CONT-BKG(1750)=1.02E-16

!

    targnum:       2
    name_1:        NGC221
    name_2:        M32
    descr_1:       E,303,910
    pos_1:         RA = 00H 42M 41.71S +/- 1",
    pos_2:         DEC = +40D 51' 54.1" +/- 1"
    equinox:       2000
    comment_1:     FLUX 2 IS ST MAG = 21, OUR DESIRED
    comment_2:     LIMIT FOR 10% PHOTOMETRY. FLUX 3
    comment_3:     CONVERTS THE OBSERVED F175W MEAN
    comment_4:     BACKGROUND OF 2.9E-3 CTS/S/PIX BACK
    comment_5:     TO A FLUX. THE BACKGROUND IN F/96
    comment_6:     F175W AND F275W ARE ESTIMATED IN
    comment_7:     QUESTION 4 OF THE GENERAL FORM.
    fluxnum_1:     1
    fluxval_1:     SURF(V)=15.77
    fluxnum_2:     2
    fluxval_2:     F(1750)=1.45E-17
    fluxnum_3:     3
    fluxval_3:     SURF-CONT-BKG(1750)=9.2E-17

!
! end of fixed targets

! No solar system records found

! No generic target records found

exposure_logsheet:

    linenum:       1.000
    targname:      NGC224
    config:        FOC/96
    opmode:        IMAGE
    aperture:      512X1024
    sp_element:    F175W
    num_exp:       1
    time_per_exp:  9199S
    priority:      3
    param_1:       PIXEL=50X25
    req_1:         CYCLE 3;
    req_2:         ORIENT 97D +/- 5D;
    comment_1:     ORIENT REQUIRED TO KEEP SAME STARS AS
    comment_2:     PREVIOUS F150W OBSERVATION. IT IS
    comment_3:     PERMISSIBLE TO INCREASE ORIENT BY
    comment_4:     90D OR 180D. WOULD LIKE TO HAVE AT
    comment_5:     LEAST THREE SUBEXPOSURES READ OUT
    comment_6:     IF SCHEDULING ALLOWS.

!

    linenum:       2.000
    targname:      NGC224
    config:        FOC/96
    opmode:        IMAGE
    aperture:      512X1024
    sp_element:    F275W
    num_exp:       1
    time_per_exp:  11396S
    priority:      1
    param_1:       PIXEL=50X25
    req_1:         CYCLE 3;
    req_2:         SAME ORIENT FOR 2 AS 1
    comment_1:     ORIENT REQUIRED TO KEEP SAME STARS AS
    comment_2:     PREVIOUS F150W OBSERVATION. IT IS
    comment_3:     PERMISSIBLE TO INCREASE ORIENT BY
    comment_4:     90D OR 180D. WOULD LIKE TO HAVE AT
    comment_5:     LEAST THREE SUBEXPOSURES READ OUT
    comment_6:     IF SCHEDULING ALLOWS.

!

    linenum:       3.000
    targname:      NGC221
    config:        FOC/96
    opmode:        IMAGE
    aperture:      512X1024
    sp_element:    F175W
    num_exp:       1
    time_per_exp:  4599S
    priority:      4
    param_1:       PIXEL=50X25
    req_1:         CYCLE 3;
    req_2:         ORIENT 98D +/- 5D;
    comment_1:     ORIENT REQUIRED TO KEEP SAME STARS AS
    comment_2:     PREVIOUS F150W OBSERVATION. IT IS
    comment_3:     PERMISSIBLE TO INCREASE ORIENT BY
    comment_4:     90D OR 180D. WOULD LIKE TO HAVE AT
    comment_5:     LEAST THREE SUBEXPOSURES READ OUT
    comment_6:     IF SCHEDULING ALLOWS.

!

    linenum:       4.000
    targname:      NGC221
    config:        FOC/96
    opmode:        IMAGE
    aperture:      512X1024
    sp_element:    F275W
    num_exp:       1
    time_per_exp:  16000S
    priority:      2
    param_1:       PIXEL=50X25
    req_1:         CYCLE 3;
    req_2:         SAME ORIENT FOR 4 AS 3
    comment_1:     ORIENT REQUIRED TO KEEP SAME STARS AS
    comment_2:     PREVIOUS F150W OBSERVATION. IT IS
    comment_3:     PERMISSIBLE TO INCREASE ORIENT BY
    comment_4:     90D OR 180D. WOULD LIKE TO HAVE AT
    comment_5:     LEAST THREE SUBEXPOSURES READ OUT
    comment_6:     IF SCHEDULING ALLOWS.

!
! end of exposure logsheet

! No scan data records found