Yes, I know (and I am ashamed) so careless that I have this Blog. But I promised myself that that will change, so for the purpose of amending my attitude, I will try to write a while, at least once a week ... Even if I'm not able to fulfill my promise, at least I try ... Let us begin ... On Saturday March 19, I decided to do some tests with this technique has been called speckle interferometry and say that most know, is the solution to cancel the capricious dance of our atmosphere, allowing us to measure peer access closed, which is said closed ... Well, almost as closed as the theoretical resolution limit of the instrument employee permits. So I'll try to explain, what if you gave my first experience "speckleriana" and the conclusions that I arrived after 3 hours of hard work .... This is my chronicle particular comment ... Date: March 19, 2011 Time: 2011.214 Start Time: 20:50 UT End Time: 23:50 UT Temperature: 12.9 º C and 11.9 º C Humidity: Between 86% and 89% Wind: Calm Moon : Fill (perigee) the equipment used in this first test session with the speckle interferometry method consists of a SC LX200R telescope of 254mm aperture f/10 equatorial mounted and is fitted after microfocuser a Vixen Flip Mirror in apart from one eye 20mm grid is inserted an HR16 Atik CCD with a 1392x1040 pixel chip of 6.45 x6, 45 microns, which is attached a Celestron Barlowx2. For these initial tests do not use any type of filter photometric or cutting. The objective of this session is to try shooting the pair to 1352 whose components had magnitudes 9.42 and 11.48 in 1991 an angle of 40 º and separation 1.1 "... The reason for the choice of this pair, are based on the following reasons: - During the observation time, the constellation Uma where is located the pair, is located in the most optimal situation for the observation from the OANL. - It's a couple that, as regards magnitude, begins to be in the top of my opening, using speckle technique means. (The diameter of the target mark to the maximum quantities that can work with exposure times as short as those used in interferometry) Why start with the easy? Let's find out the limits of work as far as magnitudes are concerned, I said ... - The separation seemed affordable to the team, whose theoretical resolution limit is 0.46 "... (That means about three pixels of separation for this pair ....) Also should compensate a little added difficulty of magnitudes. Although at first I would have liked to use the same Florent Losse method used for calculating the calibration constants in the end I did it with a combined ... And, the calculation of the rotation angle of the camera is simple to calculate, taking a few simple traces stellar engine stopped. Another thing is to calculate the pixel scale ... To do this correctly you should spend some more time, doing shots of various parts of the sky, the primary focus first and then work settings and to describe accurately the focal length , something unthinkable for SC (and expressly discouraged by Florent) ... so I decided to use the traditional method using pairs of calibration. Determined a rotation angle of -1.06 º camera based on averaging the angles obtained by Drift Analysis function, from stellar traces some of the stars near the work area. Here you have a sample image. This is the trace of Dubhe (alpha Uma), one of the stars used for determining the rotation angle of the camera.
To determine the pixel scale, have taken pictures of double calibration STF 1603 (AP83.28 th Sep 22.31) and STF 1349 (AP Sep 19.22 165.62 º). And as you know I'm a little curiosón, I thought ... Why not try to make Reduc reduction to calculate the pixel level, first through the traditional method of reduction, after using an autocorrelation (in the purest style speckleriano ") and compare the results obtained using both methods? Well, in that I got, and here are the results ... Traditional Reduction ... ... ... ... 0.1886 "/ pixel reduction Autocorrelation ... 0.1887" / pixel As you can see, the results differ by 1 ten thousandth of a second of arc ... Incredible No? The results (by the traditional method ...) were averaged, obtaining for the optical configuration used, a scale of 0.1886 "/ pixel, which means working with a focal length of 7203mm (f/28.5) ... which is almost triple the original focus of the instrument! I am sure that when you clean a little technical, it is not mission impossible to increase this focus. Perhaps adding a further Barlow current optical system or projection images are acquired eye. For you to see them, here are some pictures interferometric STF 1603, one of the pair used to calibrate the pixel scale ... This individual takes, you can see the symmetry of the diffraction spots on both stars. In
some of the best shots ... Where can guess the pair!