How can I contribute ?
The contribution to the CARA project is free, but some basic requirements are needed.
A telescope coupled with a CCD camera (no anti-blooming is highly preferred) with an image scale around 1-3 arcsec/pixel and at least one photometric filter (R or I Cousins / Bessel filters are suggested).
A sophisticated equipment is not specifically needed, but must be of enough quality and solidity to grant standard results and match the requirements to perform a basic scientific research (reproducible results).
It is asked observers to follow with care the whole CARA method. It requires first of all a proper pre-processing of images (dark frame subtraction and flat field correction) and then a data reduction according with the CARA guidelines and with the dedicated software.
The Af quantity measurements are very sensitive to image noise: insufficient S/N, bad pre-processing or inaccurate flat field correction, sky background gradient (strong moonlight, twilight, light pollution), as well as instrumental unwanted reflections or defects…. are all source of additional errors.
Please consider that we are not looking for spectacular impressive pictures, but for images suitable to be measured, that is to reproduce as closely as possible the shape and the light distribution of the true object in the sky. To get this result we don’t need sophisticated image processing to enhance or dim specific features (NOT photoshop-like techniques), but to reduce as much as possible the unwanted noise in the image. This is done with an accurate pre-processing (dark frame subtraction, flat field correction) and applying a rigorous standard method for observing. This implies that a part of the observing time can be devoted to the instrumental noise and not to the imaging of sky objects. On the other hand the reproducibility of the images and of the data is a basic need for photometry. Furthermore images need a long enough total exposure (usually obtained averaging many images) to get a high S/N. This reduces the number of object observed each night but grants to reach a good scientific grade quality in the images.
High performance (professional) CCDs, permanently mounted on an observatory instrument, can be “characterized”. This allows to use a “library of noises” without taking them each night and saving time. In this case a periodic (at least seasonal) check about the reproducibility of the noises is always recommended.
For further information feel free to contact us using che "Contact" form available in this site.