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14 Apr 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT #3340

PERIOD COVERED: DOYS 101-103

Part 2 of 6

ACS 9294

Observations of the Host Galaxy of 3C 273

The highly luminous flat-spectrum QSO 3C 273 {z=0.158, V=12.8,
M_V~-26.4} will be imaged with the WFC in the [O III]5007 and H-alpha
emission lines with the narrow-band filters FR601N and FR782N,
respectively. Off-band images in F475W and F850LP will also be
acquired to accurately subtract the underlying galaxy continuum.
Combined with the broad-band HRC coronagraphic images from the ERO
program 8992, these new images will offer the most complete and
detailed view yet of the host galaxy and environment of this QSO.

ACS 9656

Stability of the ACS CCD: geometry, flat fielding, photometry

A moderately crowded stellar field, located ~6' West of the centre of
the cluster 47 Tuc, is observed repeatedly {every three weeks with
the WFC, every other month with the HRC} in various filters, spending
1 orbit per epoch. Different filters will be used every time, so that
over the course of the year all filters will have been employed at
least twice. The most common filters will be checked more frequently.
The same field has been observed in the course of the SMOV phase and
the positions and magnitudes of the most prominent stars have been
accurately measured. Although the field is neither a proper
astrometric nor a proper photometric standard one, the positions and
magnitudes of the objects in it can be used to monitor any local and
large scale variations in the platescale and sensitivity of the
detectors. It should be noted that for the filters which have already
been used during the SMOV phase it will be sufficient to take one
single image, without CR-SPLIT, since the exposure time is always
short {20-30 sec} and there will be so many stars that the few of
them which are affected by cosmic rays can be discarded as outliers
in the photometry. For narrow and medium band filters not exercised
on this target in the SMOV phase, however, a baseline will have to be
set. This expenditure of time will apply to the current cycle only.
At variance with the approach used in SMOV, there is no need for
large telescope slews to place the same objects on opposite sides of
the detectors, thence allowing the programme to remain compact and
efficient. All exposure level parameters are set to their default
values, except for the amplifier gain of the WFC exposures in the
F606W band, which will be collected with the gain value of 2 for the
WFC for compatibility with the SMOV observations. The exposure time
is typically 30 seconds for the WFC, 60 sec for the HRC. No attempt
will be made to attain a predefined or the same orientation on the
sky amongst different epochs. Typically, for the WFC, five exposures
will be accommodated in one orbit. For the HRC, about 10 exposures
can be fitted within one orbit 

ACS 9454

The Nature of the UV Continuum in LINERs: A Variability Test

LINERs may be the most common AGNs, and the signposts of accretion
onto the massive black holes present in most galaxies. However, the
LINER spectrum is the result of UV excitation, and, in at least some
LINERs, a nuclear cluster of hot stars, rather than an AGN, dominates
the energetics in the UV. Thus, it is still unknown if the UV
continuum, or the optical emission lines it excites, have anything to
do with an AGN. The demographics and accretion physics of low-
luminosity AGNs hinge on this question. We propose to search for
variability in a sample of 17 LINERs with compact UV nuclei.
Variability can reveal an AGN component in the UV continuum, even
when its light is not dominant. We will test systematically the
handful of non-definitive reports of UV variability, and potentially
quantify the AGN contribution to the UV emission. Variability in all
or most objects will be strong evidence that LINERs mark dormant AGNs
in most galaxies. Alternatively, a general null detection of
variability will suggest that, even in LINERs with additional AGN
signatures, the UV continuum is stellar in origin. Contemporaneous
monitoring with the VLA/VLBA of 11 objects which have radio cores
{five of which we already know are radio-variable} will reveal the
relations between UV and radio variations. The UV-variable objects
will be targeted for future, better-sampled, monitoring. 

ACS/WFC/HRC 9445

Gravitational Microlensing in the NGC 3314A-B Galaxy Pair.

The Advanced Camera for Surveys (WFC and HRC) was used to determine
the composition of the dark matter that dominates the masses of
galaxies which is an important unsolved problem.

ACS/WFC/HRC 9696

Hubble Heritage observations of NGC 3370

Hubble Heritage proposes to observe NGC 3370 in conjunction with GO
program 9351 {PI Adam Riess} to use the combined data to produce a
three color image.

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS
QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for
low-z {z<1.65} metal absorption lines and found over 200 large rest
equivalent width MgII-FeII systems. Previously, we empirically showed
that such systems are good tracers of large neutral gas columns,
with ~50% being classical damped Lyman alpha {DLA} systems
{N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined
subset of 79 of them to search for DLAs with 0.47 * Origin: SpaceBase(tm) Pt 1 -14.4- Van BC Canada 604-473-9358 (1:153/719.1)

SEEN-BY: 633/267 270

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