Assigned ID: 900
----- Attempting Submission 1 (Fri Feb 24 23:18:58 GMT 2012) ---------- Attempting Submission 1 (Tue Jul 10 18:14:51 GMT 2012) -----As discussed in the proposal description, we use only 2 FP-POS per CENWAVE, because we
do not expect to obtain very high signal-to-noise ratio spectra from these observations and also,
for CENWAVE=1105, we do not cover a line of interest except in FP-POS=4 (we partially cover it
for FP-POS=3).
The target coordinates for this object are known to approximately 0.3", so we are justified in using
the ACQ/IMAGE and not doing an ACQ/SEARCHWPVS 007: Acceleration or Evolution in a Broad Absorption Line OutflowOutflowing gas, recognised through broad absorption lines, is an important component of AGN and quasars. Outflows remove angular momentum, enrich the intergalactic medium, and possibly play a key role in the evolution of galaxies. Yet outflow astrophysics remains poorly understood. Absorption line variability is a potentially valuable too, offering constraints on distance from the continuum emission region, density, and homogeneity and stability of the outflow.
Dramatic absorption-line variability has been observed in the Seyfert-luminosity AGN WPVS 007 (M_V=-19.7, z=0.02882). Observed to have a miniBAL with maximum velocity v_max~1000 km/s in an 1996 HST observation, it was discovered to have developed an additional BAL flow by the time of the FUSE observation in 2003. The BAL flow had a maximum velocity of 6,000 km/s, and the unambiguous presence of PV indicated that it is very optically thick. A third observation by HST COS in 2010 shows further dramatic variability, a shift of the BAL to higher velocities of ~8,000 km/s. Yet the absorption profile is similar to that observed in 2003, suggesting acceleration.
We propose two COS observations designed to reveal the origin of the dramatic variability in WPVS 007. WPVS 007 is an extreme object, but it may be key to understanding outflows, since its low luminosity for such a high-velocity outflow challenges acceleration mechanisms, and its small size means that we may be able to see, on human time scales, phenomena important in all quasars.We were awarded two observations of WPVS 007 using COS in the FUV
channel with the G140L grating that should be separated by an interval
of 6 to 10 months. We observed this object in 2010 as part of a Cycle
17 proposal, and we have been monitoring it with Swift UVOT since
2005. We base the exposure time estimates on these data.
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PROPERTIES OF WPVS 007:
The reddening of our Galaxy in the direction of WPVS 007 is 0.012
mag. The redshift is z=0.02882. The GSC II states that the best
optical magnitude is 13.6. This, however, is the integrated magnitude
for the galaxy which is resolved at this redshift. A better estimate
for the AGN is V=15.3, based on Swift UVOT monotoring. We estimate an
uncertainty in this value of 0.5 due to AGN variability. A more
relevant flux would be the continuum flux observed at 1500 Angstroms
of F(lambda)=1.0e-14 erg/s/cm^2/A from our 2010 COS observation. But
we also have a large amount of Swift monitoring data. Our 2010 HST
COS observation was made when the objects was near a maximum; the
magnitude in the UVW2 filter (central wavelength=1928 Angstroms) was
14.3. The historical maximum and minimum from our monitoring data
(beginning in 2005 and continuum through March 2012) are 14.16 and
14.88. Recently, it has been fainter (UVW2=14.77). So we will
investigate flux densities in the range 3.0e-15 to 1.0e-14
erg/s/cm^2/A.
The brightest line in the FUV is Lyalpha, and it will be present in
the spectrum for CENWAVE=1105. Using an approximate spectral model
based on the FOS spectrum of WPVS 007, but renormalizing it to the
flux observed during the 2010 COS observation, we find that the
brightest pixel (at Lyalpha) attains a count rate of only 0.09
counts/s (COS.sp.416496).
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OBSERVATION DETAILS:
Two observations of the object were awarded. There are no coordinated
observations so the first observation can be done at any time. We
request that the second observation be done between 6 and 10 months
after the first. WPVS 007 has an RA of 00:40, so it is in a
restricted RA region of the sky. However, because of its large
declination (-51), it has very good visibility. In addition, the
exposures that we request are short (two orbits per visit), so we
expect that it will not be extremely difficult to schedule.
The principal lines of interest are PV, SiIV, and CIV. For this
object, with z=0.02882 and maximum blueshift velocity of the line of
approximately 11,000 km/s, these lines span 1111-1153, 1387-1440, and
1536-1594 Angstroms respectively. All settings described below will
partially or completely cover these wavelength ranges.
We conduct the observations differently than we did in 2010 in order
to obtain better wavelength coverage and to account for different
central wavelength availability (the 2010 observation was done using
CENWAVE=1230). After acquisition, we will devote the remainder of the
first orbit in each visit to CENWAVE=1280. We do not expect to attain
extremely high signal to noise ratios for this object, so we will use
two FP-POS only. We will use FP-POS=2 and FP-POS=3. Segment B will
be left on as it will cover PV.
The second orbit in each visit will use CENWAVE=1105. This time we
will use FP-POS=3 and FP-POS=4. These FP-POS are chosen to provide
short wavelength coverage, and FP-POS=4 should cover PV completely.
AQUISITION:
WPVS007 is in the GSC2 and therefore it has ICRS coordinates with
positional uncertainties of 0.3 arc seconds in RA and 0.33 arcseconds
in dec. These uncertainties are less than the nominal value of 0.4,
and therefore we do not have to do a ACQ/SEARCH. Rather, we will
start with an ACQ/IMAGE to acquire the object.
The flux density of the object was ~1.0e-14 erg/s/cm^2/A during the
2010 COS observation, and the spectrum was approximately flat.
However, our long-term Swift lightcurve shows that it was in a
relatively bright state during that observation, and 6 months later it
was a factor of ~3 fainter. So we will assume a flux density range of
0.3-1.0e-14 erg/s/cm^2/A account for variability. The COS Instrument
handbook Figure 8.3 indicates that we can use the PSA aperture and
MIRORB for this flux, and Table 8.3 indicates that we need a S/N of
40. Assuming a flat spectrum and a flux density of 3.0e-15
erg/s/cm^2/A, we use the COS ETC to determine the exposure time,
finding that 52 seconds will be adequate to produce the required
S/N=40 (Table 8.3; COS.ta.416441). We increase that value to 100
seconds.
The APT BOT estimates that the object should be too bright for this
acquisition. This is because the conservative assumptions made by the
BOT are not appropriate for this target. First, it uses the magnitude
given in the GSC2 of 13.6. That is the magnitude for the galaxy,
which is resolved at this redshift, rather than the target, which has
a magnitude closer to 15.3. Second, it assumes a OV star spectrum,
whereas the object is a modestly reddened AGN, nearly flat in Flambda
between 1000 and 6626 Angstroms. The continuum flux level is about
0.3--1.0e-14 erg/s/cm^2/A at 1500 Angstroms.
SCIENCE EXPOSURES:
All exposures are chosen to be TIME-TAG and FLASH is set to Yes.
For each visit, the remainder of the first orbit will be divided into
two exposures using CENWAVE=1280 using FP-POS=2 and FP-POS=3. The
exposure time for each of these exposures is 1008s. For a flux
density of 1.0e-14 erg/s/cm^2/A, the COS ETC gives a buffer time of
5245s. We conservatively set the buffer time to 800 seconds for each.
The second orbit is divided into two exposures using CENWAVE=1105
using FP-POS=3 and FP-POS=4. The buffer time is the same for this
setting, and so we use again a buffer time of 800s.AGN/QUASARS12false0.00.1falsefalsefalsefalseSUPPORTEDGALAXYSEYFERTWPVS007GSC1ID0803000885J2000J2000F(lambda)=0.3-1.0e-14 at 1500 Angstroms (> 7 years of Swift monioring and 2010 HST COS spectrum)COS/FUVSpectroscopicNoNoG140L1280COS/FUVSpectroscopicNoNoG140L1280/Users/leighly/Dropbox/proposals/hst/2012/wpvs007/OP-cache/phaseII_version2-v01.xmlTiming link suitability includes constraints ([02 After 01 by 180.0 to 300.0 days])The scheduling data was generated by CASM 20.2.CASM was run in Phase II mode.(Tic-Visit
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