README web version of /home/usg/OPS/MTS/readme_xml/readme_75042500
Principal Investigator Email Address
Estimated Total Execution Time (hours, including overheads)
General Description
The aim of these observations is to image the nova shell of the unique
helium nova V445 Puppis at the highest possible resolution in order to determine
the distance to this object via its expansion parallax. We expect
a maximum radius of the shell in 2005 April of 2.5" (if the nova is at a 700 pc
distance), ie. ~90 pixels with the S27 objective. A jitter box width of 12" should
be sufficiently wide. The total integrated magnitude of V445 Pup 2005 January is
K=13.0 mag, but note that the object is extended (it has an expading asymmetric
nova shell). A lower limit for DIT of 15 s was chosen to avoid saturation if V445
Pup was observed under excellent seeing conditions (< 0.4") and if all of the
light is due to the central point source in the nova. This is a conservative lower
limit as the central point source is subjected to heavy extinction by the shell.
The brightest star in the 120"x120" field of view around V445 Puppis in the V-band
(see the attached V-band finding chart) is GSC2S1011002475 at V=10.4 mag (K=10.0
mag). The brightest star in the K-band is GSC2S101100238439 at K=9.9 mag.
We do require a PSF OB (see special calibration information for details).
Waiver Requests
Critical Observing Condition Constraints
In the NAOS PS tool I have specified the worst possible conditions (airmass
1.4, seeing 0.6) under which this observation is possible. This will give a SR of
12.5% on target (and 22.5% on the reference star). Given the relative faintness
of the AO reference star (V = 15.5 mag), the AO performance will improve considerably
with good seeing conditions. The preferred conditions (airmass 1.2, seeing 0.4)
will result in a SR of 26.3% on target (and 30.6% on the reference star), a very
big improvement over the (worst possible) correction specified in the AO config
file.
To summarise: this observation will benefit enormously from excellent seeing conditions
(seeing < 0.4") but the programme is still feasible for seeing conditions better
than 0.6".
Thin cirrus conditions are not a problem.
Time-Critical Aspects
During P75, V445 Puppis is visible only in April/May and September. This
OB (075.D-0425(A)) is scheduled for April
whereas 075.D-0425(B) marks a second (identical) exposure in September. We would
prefer run 075.D-0425(A) to be scheduled as soon as possible during Period 75, ie.
in early April, so to keep the airmass to a minimum (< 1.4)
and provide the longest possible baseline between 075.D-0425(A) and 075.D-0425(B).
Special Execution Requirements
Special Calibration Information
We require a PSF OB (specified in the PSF_V445 Puppis NACO OB) for which
we have chosen GSC2S101100238599 as the AO reference star (V=15.4 mag, compared
to V=15.5 mag for the AO reference star for V445 Pup). The chosen PSF star is 25.5"
away from the PSF AO reference star (compared to 23.9" for V445 Pup and its AO reference
star) and is GSC2S101100238567. Both the PSF star and the AO reference for this
star are indicated on the finding chart of V445 Pup. The nova shell of V445 Puppis
will most likely have fine structure; in order to retrieve this fine structure and
to remove the central point source, a reasonably good PSF is needed for image deconvolution.
The DITs and NDITs for the PSF OB are smaller (2s x 10) are smaller than the DITs
and NDITs for the prime target (15s x 11). We do not require equal exposure times
of target and PSF. The target is an extended source and large DIT*NDIT*NEXPO is
needed to get S/N in the outer regions of the shell; the PSF on the other hand is
fairly
bright (K=12.2 mag). The total brightness of the target V445 Puppis (even though
it is extended) is K=13.0 mag.
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 have PSF reference star OBs, do the names of those OBs begin with
PSF_ ?
If there are Finding Charts attached to your OBs, is the field-of-view
of at least one of these charts 2' x 2' (with clearly labelled field orientation)
?
Have you clearly marked and labelled your wavefront reference objects
R1, R2, R3, ... (as specified in the NAOS Preparation Software) on your Finding
Charts ?
Have you specified the magnitude of the brightest object in the field-of-view
for each OB ?
Are there objects in any of your fields (including standard stars) which
are brighter than the limits specified in the User Manual and on NACO web Pages
?
If the previous answer is yes, have you given a list of OBs and a justification
for the brightness limit violation in the general description field ?
Last creation of page: Tue Oct 6 15:40:07 2009
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