Frequently Asked Questions

Is there a User Manual for ADONIS?

What will the observer do during the observations?

How do I select the best lens scale?

How often should a sky frame be taken?

Can I change wavefront sensors during the night?

What should I prepare before the observations?

What should I bring to La Silla?

May I use an observatory car?

How can I check my email?

Is there a User Manual for ADONIS?:

There is no single document that is the official User Manual for Adonis. Instead all the information is available on these web pages. Observers should at least read the Observing page. There is also the COMIC User's Manual which has very detailed information on the software used to control both the SHARP and COMIC cameras.

What will the observer do during the observations?:

The observer will control the SHARP or COMIC detector. They will use the ADOCAM software to control the settings of the detector. These settings include exposure time, filters, exposure time and on/off mirror position. They must provide the telescope operator with source coordinates and advise them when sky frames are needed and what type of adaptive optic correction is required. The telescope operator will control the adaptive optics and the telescope.

How do I select the best lens scale?

For sufficient sampling criteria the FWHM of a diffraction limited point like star should be sampled by at least two pixels. This means selecting a suitable lens scale depends on the observered wavelength, the seeing, the desired field of view and on the flux. The available lens scales are 100, 50 and 35 marcsec/pixel.

**Diffraction limits**
Filter	Center Wavelength	Table 1. Diffraction limit [arcsec]
J	1.25	0.072
H	1.65	0.094
K	2.2	0.126
L	3.5	0.200
M	5.0	0.286

Table 1 lists the diffraction limit as a function of wavelength. It is clear the 100 marcsec/pixel lens does not provide adequate sampling in J and H band. Furthermore, the flux measured using the 100 marcsec/pixel lens will be roughly 9 times brighter than when using the 35 marcsec/pixel lens.

In summary, we recommend the following:

Pixel scale	Field of view	Recommended purpose
100 marcsec/pixel	25.6" x 25.6"	Search for new objects and mapping in J, H and K bands General Purpose for L and M bands.
50 marcsec/pixel	12.8"x 12.8"	General Purpose in J, H and K bands
35 marcsec/pixel	8.5"x 8.5´	Extraordinary seeing conditions

How often should a sky frame be taken?

The sky background is strong and variable in the near infrared. Therefore sky calibration is required using sky frames. Our experience shows that on average the sky is stable over 40 minutes in J- and H-band, 15 minutes in K-band and no more than 15 secs in L and M band. These numbers will be much smaller if the sky conditions are not stable (i.e. bad seeing, cloud, rapid transit of source).

Can I change wavefront sensors during the night?

The Reticon wavefront sensor is used for reference stars brighter than magnitude 8 (m_V<8) and the EBBCD wavefront sensor is used for reference stars between magnitudes 8 and 12 (8< m_V<12). There is no strict cuttoff at magnitude 8 for the reticon, instead its performance steadily degrades. It takes about 5 minutes to change wavefront sensors. This process involves remotely moving the MWS3 mirror and loading in the wavefront matrix solution. You can make this change as many times as you like throughout the night. However to increase your observing efficiency it is best to keep such changes to a minimum. Therefore you should group your list of sources according to their brightness above or below magnitude 8.

What should I prepare before the observations?

If you want to be well organized for your observations you should prepare:

A science target list which is grouped in such a way as to minimize changes between each wavefront sensor.
A list of targets to be used for the PSF objects. It is a good idea to select a "backup" PSF object incase your chosen PSF turns out to be a multiple star or a variable.
A list of standard stars.
Finding charts for all objects to be observed (including PSF and standard stars).

Note: Adonis does not use VLT compliant software. Therefore there are no "Observing Blocks" to prepare beforehand.

The Adonis support astronomer will give you an introduction to the instrument on the day of your first observing night. The introduction will start at 4pm and typically last 1.5 hours. After the introduction you may want to take some sky flats and/or have some dinner before your night observations begin.

What should I bring to La Silla?

Don't leave home without:

A torch. (Make sure you use it whenever you are walking outside at night, otherwise you run the risk of being hit by a car.)
A copy of the most important ESO contact addresses in Germany and Chile.
Reading the Guidelines for Visiting Astronomers.
Chocolate (for your friendly 3p6 support team).

You will be provided with a warm jacket to use during your visit. The telephone in your room can be used as an alarm clock.

May I use an observatory car?

During your ADONIS observing run you may use car number 137 each day between 4:00pm and the end of your observations the following morning. Please leave the keys in the car at all times and park it in the designated 3p6 observer parking space.

How can I check my email?

On the ground floor of the library building there is a User's room. THere you will find a number of machines which you can use for emailing and data reduction.