README web version of /home/usg/OPS/MTS/readme_xml/readme_82015700

Principal Investigator Email Address

```
ngibson07@qub.ac.uk
```

Estimated Total Execution Time (hours, including overheads)

```
5.0
```

General Description

This OB will be used to observe WASP-4 during a secondary transit of the
system, i.e. when the planet passes behind it's host star. This is expected to produce
a dip in the lightcurve of about 0.1% - 0.3% in flux and thus requires extremely
high precision photometry from the ground. We will observe the target for ~5 hours
so that we have excellent coverage both before and after the transit in order to
properly normalise the curve and evaluate the systematics. In terms of photons statistics
this should easily be possible from the ground (after binning the in and out of
transit data), but the challenge in observations of this type is to minimise the
systematics.

These observations are of course time critical, as the OB must coincide with the
secondary transit of WASP-4. Details are in the "Time-critical Aspects" part of
this readme.

Target acquisition will be done with the HAWKI_img_acq_MoveToPixel template for
very precise pointing, so that the field can be checked prior to the science template
being executed. The main reason for needing very precise pointing is to avoid a
nearby bright star falling onto the chip. This star is clearly indicated on the
attached finding chart (K~6.9), which is a NIR DSS image showing the desired field
of view of HAWK-I (Field centre: RA 23 34 27 DEC -42 02 23). It is also essential
that the target star and the main companion stars (each marked with a circle) do
not fall to close to the edges of the chips at any point in the jitter box (35 arcsec)
and therefore need to be >> ~20 arcsecs from the edge of the chips.

The science images will be taken using the HAWKI_img_obs_AutoJitter template in
the NB2090 filter. An exposure time of 10s will be used and 6 images will be taken
at each offset position as we cannot move the telescope more than once per minute.
The observations will then consist of 229 random offsets in a 35 arssec box with
1 minute of integration time at each, resulting in 1374 images over a ~5 hour period.

The observations were planned assuming a seeing of 0.8 arcsec, so that the brightest
star in the field (K = 9.6) does not exceed the linearity limit of the chip. If
the seeing is better than 0.8 arcsec during the observations, we request that badAO
be used in order to defocus the PSF to a FWHM of ~1.0 arcsec.

Waiver Requests

Waiver ID: 082.C-0157A.01

As our observations require coverage of a secondary transit ~5 hours needs to be
 spent continuously observing the same target. This is to ensure not only the full
 transit is sampled but also that sufficient out-of-transit data is available to
 normalise the lightcurve and to properly characterise the systematics. This was
 justified in our phase 1 proposal.

A waiver was therefore submitted to ESO on 28th July via email to request permission
 to submit OBs that take longer than 1 hour to complete. This was granted with waiver
 ID 082.C-0157A.01 on the 29th July.

Critical Observing Condition Constraints

We expect the observations to be limited by systematics in the instrument,
 therefore we did't request a photometric night as our minimum conditions. We would
 of course prefer a clear night but will specify it as Thin Cirrus as specified in
 the phase 1 proposal which may still produce useful results using relative photometry.
 As we would like to defocus the telescope anyway, seeing is not important to us
 and no seeing constraints are applied. The moon and airmass have already been checked
 for each of the time constraints given and so no constraints are applied for them
 either.

Time-Critical Aspects

These observations must coincide with the secondary transit, and therefore
 the observing blocks must be executed within one of the following time windows.
 These are (as provided in the OB):

2008-10-03T00:15:00 - 2008-10-03T05:45:00
2008-10-07T00:30:00 - 2008-10-07T06:00:00
2008-10-11T01:00:00 - 2008-10-11T06:30:00
2008-10-15T01:15:00 - 2008-10-15T06:45:00

Each OB lasts ~5 hours. Each of these windows however last 5.5 hours each. This
 is intended to give a bit of flexability as any 5 hour block in these time windows
 will still provide excellent coverage of the secondary transit event. The earlier
 periods are preferred due to favourable altitude and moon conditions, but all are
 still good enough for our observations.

Special Execution Requirements

```
None
```

Special Calibration Information

Extra calibrations were requested at phase 1 which accounted for 1 hour
 of the total 6 hours awarded to this proposal. Apart from a standard sequence of
 twilight flats in the NB2090 filter, if operationally possible we request observations
 of a second sequence of flats in one of the following few nights. These would prove
 very usful for our programme. We also request 40 extra darks of 10s exposure time
 as the standard calibrations of 10 exposures / DIT-NDIT are not sufficient for our
 needs. These extra calibrations are required for ultra precise photometry, so that
 no significant extra noise is added at the reduction stages.

ToO Information

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ToO Activators List

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Is this a Pre-imaging run ?

```
false
```

Pre-imaging Requirements

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Source(s) of Pre-imaging

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Pre-imaging sources not listed above

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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 ?

```
N/A
```

Have you included OBs for any calibrations that you need but which are not part of the Calibration Plan ?

```
N/A
```

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 submitted OBs for standard stars, did you use the provided StandardStar templates ?

```
N/A
```

If you are using a specific offset pattern or position angle, did you check carefully the definition in the manual ?

```
N/A
```

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 15:40:26 2009
If you have comments, please contact usd-help@eso.org