Principal Investigator Email Address
dsilva@tmt.org
Estimated Total Execution Time (hours, including overheads)
23.4 hours
General Description
HISTORY:
Version 1: 7 Feb 2007 - original
HIGHLIGHTS:
(1) Number of Stars in Period 79 sample: 29 + 3 telluric absorption
standards. Number of OBs per star: 2 (DIC1 and DIC2), except where noted below.
(2) "Filler" program: stars can be observed in any order under any conditions.
Please try to observe at seeing better than 2 arcsecs.
(3) Please try to observe the DIC1 and DIC2 OBs for each star on the same night.
(4) Please observe one (1) telluric star every other month. Please separate
the telluric star observations by approximately one (1) month. Please
observe the telluric stars at airmass ~ 1.5.
(5) The execution time of most OBs is much less than one (1) hour. A few OBs have
execution times as long as 80 minutes.
(6) Some of the cooler stars (spectral types KM) are probably variable.
Please confirm that the TiO peaks in these objects are not saturated.
(8) For stars with V < 9 *or* in crowded fields, finding charts have been
attached. The desired stars are in the center of the finding chart. These
stars are:
CD -62 1346
CD -69 1618
HD 195434
SAO 180855
OVERVIEW:
Title: HST Next General Spectral Library: A UVES Followup (The Final Chapter)
The Next Generation Spectral Library (NGSL) was an HST Snapshot project to
use STIS to obtain spectra spanning the HR diagram in four separate metallicity
bins.
This library will be used mainly to model the integrated spectral energy
distributions of unresolvable stellar systems. During HST Cycles 10 - 13,
Gregg et al. (including Silva) obtained STIS spectra for 382 stars in four
metallicity bins. These STIS spectra have spectral range 170 -- 1030 nm,
with resolution ~1000 at all wavelengths.
The goal of this on-going UVES "filler"
programme is to obtain followup high-resolution spectra with UVES for the 240 stars
visible from Paranal. To date, UVES spectra for 221 stars have been obtained and
processed.
These UVES spectra will be used to verify the stellar atmospheric
parameters of the NGSL stars, to construct high-resolution synthetic stellar
population models, and as a comprehensive reference library for stellar atmosphere
modelers. This program complements and extends the Paranal Observatory
Program (POP), primarily by providing a metal-poor extension. Analogous with the
NGST STIS data, these new UVES data will be made public immediately.
For each star, two UVES setup are used: DIC1 (346+580) and DIC2 (437+860).
We wish to obtain R ~ 48000 at all wavelengths. To achieve this, the following
slit widths (in arcsecs) are used: (346, 437, 580, 860) :: (1.0, 1.0, 0.90, 0.90).
Our Signal-to-Noise (SNR) goals are 100 - 250 per pixel (or greater) at all wavelengths.
Using UVES ETC 2.8.6, extensive simulations as a function of magnitude and spectral
type
were executed using a Slit = 1.0 arcsec and Full Moon. Exposure times have been
selected
to achieve maximum possible SNR without saturation at 0.5 arcsec seeing and Airmass
= 1.
For redder stars (KM), care was taken to avoid saturation at TiO peaks.
Of course, since this is a "filler" programme, most observations will be done at
higher airmass and worse seeing. At constant airmass, SNR will will decrease by
factor of 1.5 (approximately) if seeing changes from 0.5 to 2.0, as summarised here:
Airmass = 2
Seeing
--------
0.5 2.0
346 150 100
437 400 267
580 (AFG) 300 200
580 (KM) 250 167
860 (AFG) 300 200
860 (KM) 350 167
For constant seeing, SNR will change by 1.14 in the blue and not
change in the red as airmass changes from 1 to 2, as summarised here:
Air=1 Air=2
----- -----
346 140 100
437 115 100
580 106 100
860 100 100
Most OB execution times are much less than one (1) hour. A few OBs
have execution times as long as 80 minutes. Star co-ordinates and proper
motions have been extracted from Simbad. All co-ordinates and proper motions are
for
equinox and epoch 2000.
Some of the OBs have NEXPOBLUE and/or NEXPORED set to 2 or 3. Multiple
exposures are used to reach SNR goals and/or improve cosmic ray rejection.
In particular, no individual exposure time is longer than 45 minutes (2700 secs).
Waiver Requests
WAIVER 71.B-0529A.01: permission granted to omit finding charts for bright, isolated stars where identification during acquisition is unambiguous. We have assumed this wavier continues for Period 79. Using DSS cut-outs, a 3x3 arcmin box around each star has been examined. Finding charts have been provided for four (4) stars fainter than V = 9. See General Discussion section for more details and lists of affected stars.
Critical Observing Condition Constraints
Nothing special here.
Time-Critical Aspects
TELLURIC TARGETS: as explained in Special Calibrations section, three (3) telluric absorption OBs have been submitted - one star for April, June, and September. The names of these OBs start with CAL_TELLURIC XXX where XXX is the month. Their Time Intervals have been set appropriately. SCIENCE TARGETS (DIC1+DIC2 TOGETHER): as noted in the General Discussion, each object needs to be observed in two settings: DIC1 (346+580) and DIC2 (437+860). Whenever possible, please execute both settings for a single object on a single night. Objects can be variable (especially the cooler stars), so it would be good to get complete wavelength coverage at the same phase. TARGETS WITH DEC > +20: There are a small number of objects with Dec > +20. These have more narrow time windows when airmass < 2.5 than the rest of the sample.
Special Execution Requirements
SCIENCE TARGETS (DIC1+DIC2 TOGETHER): as noted above, each object needs to be observed in two settings: DIC1 (346+580) and DIC2 (437+860). Whenever possible, please execute both settings for a single object on a single night. Objects can be variable (especially the cooler stars), so it would be good to get complete wavelength coverage at the same phase.
Special Calibration Information
Attached Flats have been requested for all observations to obtain the best possible flat-field correction. This is particularly important for fringe-correction in the red. Ideally, each OB would be followed by an observation of a hot star to measure the current telluric absorption strength. In practice, this is too time consuming for a project where random stars will be observed on random nights. Using data from previous runs, tests have demonstrated that telluric absorption can be corrected at the ~ 2% level even using observations widely separated in time. Therefore, a different B star will be observed in DIC1 and DIC2 every other month to measure telluric absorption. This yields three (3) stars and six (6) OBs. IMPORTANT: please observe these stars at Airmass ~ 1.5.
ToO Information
ToO Activators List
Is this a Pre-imaging run ?
false
Pre-imaging Requirements
Source(s) of Pre-imaging
Pre-imaging sources not listed above
Do all your OBs comply with the instrument-specific requirements listed on the instrument-specific Phase 2 web page ?
If this is a pre-imaging run, did you select PRE-IMAGING for the Observing Category for each Observing Template ?
N/A
Do all your finding charts comply with both the general and instrument-specific Phase 2 Web Pages ?
If you submitted OBs for standard stars, did you specify the magnitude and spectral type of all standard stars in the OBs ?
Have you included OBs for any calibrations that you need but which are not part of the Calibration Plan ?
If you are observing Moving Targets, have you attached suitable ephemeris files to your OBs?
N/A
If you have preferences which OBs should be executed first, did you make use of the User Priority field in the OBs ?
N/A
If this is a run that requires coordinated observations with other facilities, did you give proper instructions in the Time-Critical Aspects Section ?
N/A
If you need secondary guiding, are there suitable objects within 30 arcsec from your target ?
N/A