README web version of /home/usg/OPS/MTS/readme_xml/readme_77069200
Principal Investigator Email Address
Estimated Total Execution Time (hours, including overheads)
General Description
Asymptotic Giant Branch (AGB) stars are the highly evolved descendants
of 1-8 solar
mass main sequence stars. They lose mass at a high rate, and through the so-called
post-AGB phase evolve into planetary nebulae. The outflowing matter creates a dusty
molecular circumstellar envelope, in which both water vapour and water ice may be
present.
Using the Infrared Spectrometer And Array Camera (ISAAC), the primary objective
of this
proposal is to observe the 3 micron water ice feature in the spectra of a carefully
selected (post-)AGB stars, in order to study the ice formation process and the structure
of the ice
formation region around these stars. Some objects may additionally show broad continuous
absorption from high temperature (T>1000 K) gas-phase water located closer to
the star. Our
secondary objective is to observe this additional absorption when present.
We will use ISAAC in the following modes to observe the 3 micron band : SWS1-LR
(1.82-2.5
micron) and LWS3-LR (2.55-4.2 micron). The LWS3-LR data in principle covers the
complete 3
micron water ice/vapour feature, which is located in the 2.5-4.0 micron range. Still,
the
Earths atmosphere is opaque below 2.9 micron, so only part of the 3 micron feature
(2.9-4.0
micron) can be effectively observed. This complicates the shape determination of
the (broad)
3 micron feature. In order to still contrain the continuum, and hence the shape
of the 3
micron feature, the SWS1-LR data will be used. Finally, the 3 micron feature may
vary over
time. It is therefore important to make consecutive observations in the L and K
band where
possible (see the Special Execution Requirements section for details).
In case of any questions regarding the observations please ask CoI C. Dijkstra,
who prepared
the OBs on behalf of PI C. Dominik.
Email-address : dijkstrac@missouri.edu
Work Phone (USA) : 573-884-2278 (daytime)
Home phone (USA) : 573-814-5028 (evening, night)
Waiver Requests
Critical Observing Condition Constraints
MONTH PREFERENCE : june (also see the Time-Critical Aspects section)
MOON REQUIREMENT : there is no restriction
SEEING REQUIREMENT : the maximum acceptable seeing value in seconds of arc is 1.0.
This applies to all OBs, with the exception of the following
OBs
related to the observation of 53.8+20.2 and its standard stars:
231855 (OH 53.8+20.2 - L)
231847 (HD 140775 - L)
231850 (OH 53.8+20.2 - Ks)
231845 (HD 203769 - Ks)
For these OBs the seeing is constrainted to 1.5 seconds of arc.
This set of OBs must not be observed at seeing better than 1.0 seconds
of arc. The seeing constraint for these OBs has been relaxed on purpose,
because of the brightness of the target (53.8+20.2).
TRANSPARENCY REQUIREMENT (of the atmosphere) : photometric, a perfect night
Time-Critical Aspects
Special Execution Requirements
General remarks about the OBs.
------------------------------
1) The target stars in the finding charts are indicated with an open circle.
2) The slit postion is indicated with a solid line. We use a 0.3 arcsec wide slit,
which is smaller than the width of a pixel in the images.
3) For some science OBs, there is a reference object in the finding chart, indicated
by
a dashed circle. The reference object should be in the slit together with the
target
star. The provided position angles should put both the target and reference star
in
the slit. However, please check, making sure this is indeed the case!!! Where
applicable,
the User Comments in an OB will also say whether a reference star is present
in the field.
4) The standard stars needed for each science OB are mentioned in the Calibration
Requirements
sections of the science OBs.
Special procedure requests.
---------------------------
1) (IMPORTANT) Ideally, the following consecutive sequence of OBs is preferred.
a) start with an L-band Science OB (i.e. science target observation in the L-band),
b) followed by L-band Calibration OB (i.e. standard star observation in the L-band),
c) followed by an K-band science OB (i.e. science target observation in the K-band),
d) and finally a K-band Calibration OB (i.e. standard star observation in the
K-band).
A waiver has been granted for this procedure. It will provide good wavelength
coverage
to determine the shape of the broad 3 micron band, and minimize temporal variations
in
the shape of the 3 micron band.
If for some reasons, during the above sequence, the observing conditions get
worse, or
to bad for this programme, and
i) you are observing an object in the L-band, please finish the L-band observations
(i.e. the science OB and the Calibration OB) and observe the K-band (science+Calibration
OBs) only when the weather improves again.
ii) you are observing an object in the K-band, please finish the K-band observations
(science+Calibration).
2) Generally, please observe calibration OBs observed immediately after the science
OBs, even
if weather conditions get worse. Also, where possible, please observe the science
targets
(+their associated standard stars) first in the L-band (which contains the 3
micron feature),
and then in the K-band.
Special Calibration Information
1) In each OB, in the "Instrument Comments" section, the magnitude of
the brightest object in the
field is for the Ks-band. For the star OH 13.1+5.0 values are given for the Ks
and J-band.
2) We request night-time calibration arcs for the L-band observations. An accurate
wavelength
calibration of the L-band spectra is needed in order to allow for the best possible
comparison
of the observed ISAAC spectra with the laboratory/theoretical spectra of water
ice and water
vapour.
2) We have a special calibration request for observation of the science star "PN
Vy 2-2".
There are some field stars close to this target star, which may potentially fall
on the slit,
yielding overlapping spectra while chopping/nodding. The position angle used
in the OBs for
PN Vy 2-2 should avoid this, but please ensure no overlap indeed occurs!!!
3) We provide our spectrophotometric calibration stars. These are all AOV stars.
Below we list
each science target, its calibration star, the magnitude of the calibration star
(B and V),
and the spectral type of the calibration star. We have seperate lists for the
K and L band
observations:
K band standards
----------------
Science star Calibration star | B V | sp. type
| (mags) |
IRAS 14429-4539 HD 128726 | 8.080 8.07 | A0V
OH 13.1+5.0 HD 157669 | 8.730 8.58 | A0V
OH 53.8+20.2 HD 203769 | 8.360 8.30 | A0V
OH 16.1-0.3 HD 172904 | 8.240 8.03 | A0V
OH 21.5+0.5 HD 169291 | 8.570 8.34 | A0V
OH 17.7-2.0 HD 169291 | 8.570 8.34 | A0V
OH 30.7+0.4 HD 181783 | 8.790 8.67 | A0V
OH 32.0-0.5 HD 181783 | 8.790 8.67 | A0V
PN Vy 2-2 HD 189920 | 9.470 9.44 | A0V
OH 55.0+0.7 HD 213030 | 8.810 8.72 | A0V
L band standards
----------------
Science star Calibration star | B V | sp. type
| (mags) |
IRAS 14429-4539 HD 129685 | 4.939 4.92 | A0V
OH 13.1+5.0 * d Sco | 4.822 4.79 | A0V
OH 53.8+20.2 HD 140775 | 5.601 5.57 | A0V
OH 16.1-0.3 * sig Ara | 4.552 4.57 | A0V
OH 21.5+0.5 * sig Ara | 4.552 4.57 | A0V
OH 17.7-2.0 * sig Ara | 4.552 4.57 | A0V
OH 30.7+0.4 HD 177406 | 5.948 5.95 | A0V
OH 32.0-0.5 HD 177406 | 5.948 5.95 | A0V
PN Vy 2-2 * lam Tel | 4.796 4.84 | A0V
OH 55.0+0.7 * 29 Vul | 4.800 4.82 | A0V
ToO Information
ToO Activators List
Is this a Pre-imaging run ?
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 ?
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?
If you have preferences which OBs should be executed first, did you make
use of the User Priority field in the OBs ?
If this is a run that requires coordinated observations with other facilities,
did you give proper instructions in the Time-Critical Aspects Section ?
If you submitted OBs for standard stars, did you use the provided StandardStar
templates ?
If you are using a specific offset pattern or position angle, did you
check carefully the definition in the manual ?
If you are doing spectroscopy, did you draw the slit on the Finding Charts
?
Did you enter the magnitude of the brightest star in the field-of-view
in the 'Instrument Comments' field of each OB ?
If you use the MoveToPixel acquisition, have you given clear instructions
on the FC and in the OB comment section as to how the field should be centered ?
Last creation of page: Tue Oct 6 15:40:14 2009
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