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.
|Table 1. Diffraction limit|
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 (mV<8) and the EBBCD wavefront sensor is used for reference stars between magnitudes 8 and 12 (8< mV<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:
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:
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.