We note that three different proposals (PI Jerome Bouvier, PI David Barrado
and PI Ignacio Mendigutia) have been granted 3 hours of observing time for a combined
program. This is included in the present document. After reached an agreement, D.
Barrado and I. Mendigutia will execute a combined two hours program, and J. Bouvier
and his team will execute the remaining 1 hour. v4046sgr is the only OB of this
latter subprogram. In the following, the document is divided in two parts correponding
to the two sub-programs.
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Barrado & Mendigutia et al. (2 hours)
This proposal aims to test and compare different spectroscopic accretion tracers
(Brgamma, Pabeta, CaII triplet, Halpha, etc) measuring them from different epoch
X-Shooter spectra of V1121 Oph, as well as to charactherize the accretion rate variability
of this object. We need to derive absolute line fluxes. We aim to monitor V1121
Oph on hours, days and weeks timescales. The stars to be observed are:
V1121 Oph, RA:16 49 15.31 DEC:-14 22 08.63 (J2000), K5, V = 11.5 (target star)
HD 150869, RA:16 48 43.26 DEC:-67 04 59.60 (J2000), K5, V = 6.9 (veiling standard
star)
X-Shooter will be used in slit mode. We need three types of observations:
- target_high_res: V1121 Oph will be observed with slit widths of 1.0/0.4/1.5 ''
for the UVB/VIS/NIR arms, respectively. Using the same nomenclature as in the X-Shooter
exposure time calculator provided in the ESO web, we need Exp. time = 20 seconds
for each arm, Nexp = 4/4/1 for the UVB/VIS/NIR arms, and NDit = 4 for the NIR arm.
1x1 fast readout modes for UVB/VIS. A total of 764 seconds is required (including
the telescope offsets).
- target_low_res: V1121 Oph will be observed with a slit width of 5'' in all three
arms. Exp. time = 20 seconds, Nexp = 1 for all arms and NDit = 1 for the NIR arm.
2x2 fast readout modes for UVB/VIS. A total of 29 seconds is required. This type
of observation is needed since we are interested in obtaining absolute fluxes. It
will be used combined with the data of the spectrophotometric standard provided
by the ESO calibration plan. We need target_low_res to be done just before or just
after target_high_res.
- veiling_standard: HD 150869 will be observed with the same instrumental configuration
as in target_high_res. In this case however Exp. time = 1 second, being equal the
remaining parameters and readout modes. A total of 460 seconds is required (including
the telescope offsets). We will compare the accretion rates derived from the spectroscopic
tracers with those derived from the veiling, for which we need this standard to
be observed once during the X-Shooter SV campaigns.
We need the maximum number of target_high_res (and target_low_res) spectra as possible.
We estimate that to be 3 (+3), taking the overheads into account (obtained considering
the observations scheduled as in the "Time-Critical Aspects" and "Special Execution
Requirements" Sections), a total amount of 2 hours is needed.
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Bouvier et al. (1 hour)
Principal Investigator Email Address : jbouvier@obs.ujf-grenoble.fr
====================================
Estimated Total Execution Time (hours, including overheads) : 5 * 12 min = 60 min
(one 12 min spectra every night for 5 nights)
===========================================================
General Description
===================
We will obtain multiple Xshooter spectra of V4046 Sgr, a young
accreting T Tauri star, quasi-simultaneously with X-ray XMM
observations scheduled on 16-20 September, 2009. We aim at
investigating spectral variability in relation with X-ray emission
along the orbital period of this close binary system (P=2.42d,
cf. Stempels & Gahm, 2004). The goal is to obtain 1 spectrum per night
over 5 nights between September 25 to 30, 2009, in order to cover 2 full
orbital cycles at the most critical orbital phases including
quadratures and conjunctions (i.e., Phi=0., 0.24, 0.41, 0.50, and
0.83).
V4046 Sgr : RA(2000) 18h14m10.46s, Dec(2000)=-32d47m34.5s
Vmag = 10.5, Kmag=7.2
Xshooter set-up:
Slit mode : 0.8" UBV, 0.7" VIS, 0.6" NIR
Exposure time for the AB sequence (2 positions)
UBV : 2*(50s + 19s 1x1 fast readout) + 15s AB offset = 153s
VIS : 2*(30s + 24s 1x1 fast readout) + 15s AB offset = 123s
NIR : 4*(30s + 0.88s 1x1 fast readout) + 15s AB offset = 138.5s
Overheads : 570s per spectrum (pointing and acquisition)
Total per spectrum (exposure + overhead) = 153s + 570s = 723s
Total exposure time : 1 spectrum per night over 5 nights between
September 25 to 30, 2009 = 5*723s = 3615s
Note : we will rederive V4046 Sgr accurate ephemeris on the basis of
new photometry scheduled on early September 2009. By mid-september, we
will then be able to tell which 5 nights within the 6-night SV run
would optimize the orbital coverage of the system.