Science program on a moving target
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Please communicate about this program to: boehnhardt@mps.mpg.de
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SCIENCE PROGRAM: Spectroscopy of the Oort Cloud comet C/2006 P1 McNaught, in 7 different
wavelength
ranges in order to determine the gas production of H2O, HCN, NH3, C2H2, C2H6, CH3OH,
H2CO, CO,
the D/H ratio and the ortho-para ratio for H2O, NH3, C2H2.
PRIORITY: 3 priority levels for the comet OBs are defined as indicated in the OB
name (last digit,
_1 being highest priority).
OBJECT INFORMATION: C/2006 P1 is a MOVING TARGET located far in the south. The comet
displays a
diffuse coma with a central brightness peak of <2" FWHM that can be used for
AO correction.
The comet RA/DEC changes from 23h30m/-70d in early April to 08h00/-85d in late May
2007, the total
brightness of the comet drops from 7.5 to 9.5mag. In the OBs we use as reference
RA/DEC = 00h00/-75d.
In April 2007 the comet is a late morning sky object with a nightly visibility window
increasing
from 1h to 2h. In May 2007 two nightly visibility windows exist, one in the evening
increasing
from 0.5 to 6h and one in the morning decreasing from 2 to less than 0.5h. The exact
position
and tracking rates for the comet for the respective observing epochs are to be taken
from the
attached ephemeris.
Instrument setup: for the comet 0.3arcsec slit width is used, for the standard star
0.3 and 0.8arcsec,
in all cases in parallactic setting. The reference wavelengths used differ from
the standard set listed
in the manual.
AO INFORMATION: Please try to close the AO loop on the central brightness peak in
the coma despite
the fact that the comet is positioned low in the sky. Any AO support will improve
the SNR
in the comet spectra.
IF THE AO LOOP CANNOT BE CLOSED, PLEASE RUN THE OB IN OPEN LOOP AND PROVIDE US WITH
A BRIEF IMMEDIATE
FEEDBACK.
In case the AO loop cannot be closed routinely (for instance since the central coma
peak is too wide),
we intend to modify the OBs for non-AO observations.
OBSERVING STRATEGY: Please perform the OBs according to user priority. Given the
relatively short nightly
observing windows, it may not be possible to execute many OBs per night. Hence,
the program has to be
split over several nights, ideally not so far apart from eachother.
CALIBRATIONS: Apart from the usual calibration data according to the CRIRES calibration
plan, we ask for
observations of 1 flux and telluric stars twice during the whole program. BS7950
will serve both needs.
This star should be measured once with 0.3arcsec slit at high airmass of about 2.5
and once with slit 0.8 arcsec at airmass of
about 1.8, i.e. only two nighttime calibration OBs are required. All spectral setups
foreseen for the
comet will be measured in a single OB. An important requirement for achieving good
calibration results is
that a CAL OB is performed for CLR sky conditions at high airmass and during a night
when also a comet OB
is executed.
Some information on the flux and Telluric star: ID=BS7950 Spectrum=A1V L=3.67mag
SNR~100
OB NAMING CONVENTION: The OB names of the comet contain - apart from MOV and the
object name -
the central wavelength, the molecular species to be measured and the user priority
(3 levels,
level 1 being highest priority) at the end.
EPHEMERIS FILE: The ephemeris provides in 1min time steps for the daily visiblity
window of the comet
at Paranal
* RA and DEC (hh mm ss.ss, sdd mm ss.s): R.A. and DEC
* velocities in RA and DEC (arcsec/s): dRAcosD and d(DEC)/dt
* airmass: a-mass
* total vis. brightness (mag): T-mag
* distance comet-moon (deg): T-O-M
* moon phase (%): Illu%
Cook instructions for OB execution:
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- select OB according to user priority
- check requirement for environmental conditions (CLR, moon phase/distance)
- in OB enter RA and DEC from target ephemeris that are closest in time to the
expected start time of the OB
- in OB enter differential velocity in RA and DEC from target ephemeris that
are closest in time to the expected start time of the OB
- perform preset, AO and slit acquisition; if AO cannot be close, work in open loop
- perform spectroscopy
- check whether flux calibration OB is executed, if not try to get it done as well