Hello friends!
not want you to think that in previous entries I have not given more details keep it to myself ...
If not ... What purpose would the creation of this blog on double stars? ...
The fact is that as me about other things sometimes make the mistake of thinking that everyone who reads what I write, it is as clear as me, so I usually do not get into the details. But I can not forget that this blog is open to anyone and that not everyone have to have double experience and therefore know how to interpret what they mean all data that is displayed next to the measures. It is true that what the doubles player, that we already have on hand, we may seem basic. For which there is "bundled" with double everything that is exposed may seem meaningless gibberish.
Although subsequent entries will go out in more detail all aspects of the methodology followed for the study of double, in this I will explain in simple (and hopefully entertaining ...) which means each of the data that you will go see in the measurements for each pair ...
My usual working methods, perform 100 passes through light sockets of each system (c'mon, what would be 100 pictures of the lifetime) plus another 50 shots Darks (or dark shots while the integration of light) to calibrate the former. Thus subtracted from the light sockets, thermal noise CCD's unfortunately all introduced in the images. Once
made the shots, the next step is to reduce (measure them) which I do whenever I can with the NR software, which we must thank the great doubles player and friend, Florent Losse. Once reduced images, the program generates data files (log), which are those that will see the different entries on measurements and whose concepts, as I said earlier, I will describe below:
for clarity from the data obtained in the measurement of the images for the couple STF 2917 AB which I also left an instant.
-=-= STF 2917 AB =-=-
Date: 2009,786
Location: Barcelona OANL
Conditions: Seeing 4 / 5 - 99%
Luna Instrument: SC 0.25 m.
f/13 Camera: QHY-5 (pixels: 5.2 x 5.2) 1.0 sec.
"/ pixel: 0.71583
Delta Matrix:
-3.86 70.8 (sigma theta: 0.38) Med: 70,935
4694 (sigma rho: 0.042) Med: 4,682
Deltamed = 0.31 Nb: 28
calibration Pairs: STF 2687 STF 2691 STF 2922.
Well folks, because here I go ...
Date: 2009.786
Location: Barcelona OANL
Conditions: Seeing 4 / 5 - 99%
Luna Instrument: SC 0.25 m.
f/13 Camera: QHY-5 (pixels: 5.2 x 5.2) 1.0 sec.
This block of data points out general information on the date they were made shots in years and fraction of year, the place of observation, the conditions of the night, the team used the camera and the size of their pixels as well as the integration time of each of the images used astrometry for that particular double.
"/ pixel: 0.71583
This concept points to the pixel scale, or whatever it is, the piece of sky covered by each pixel in the image.
This value depends on two things:
- of the focal length provides the optical configuration used and in my case is a prime focus 3200mm.
- Y pixel size in my case (QHY-5) is 5.2 x 5, 2 microns.
A longer focal length and smaller pixel size, higher resolution (or less arc seconds per pixel resolution) ... and vice versa. This value multiplied by the number of pixels between the center (photocentric) of each of the components of the pair determines the distance you are from each other in arc seconds. Delta
Matrix: -3.86
This value indicates the "clumsy" we have been aligning the X axis (horizontal) camera with blue Ecuador. Come on, which points in ° (degrees) the correction that we apply the angle measured in our images for the software to accurately place the North in them.
The two concepts above are what we usually call "calibration constants" and calculated using calibration star to theta and rho parameters well known and stable, or using software such as Astrometrica, which measure very accurately the position of all stars of a photo using precision astrometric catalogs.
70.8 (sigma theta: 0.38) Med: 70,935
parameter theta indicates the position angle of the secondary to the primary (hence that is called astrometry relative) taking as 0 degrees North and increasing the value to the East. 70.8
Here is the sum value of each of the values \u200b\u200bof theta (angle position) obtained As each image, divided by the number of images.
Come on, what would be the average!
The value of Sigma Theta: 0.38 points the standard deviation value between the total of measures. A lower value of sigma, the more reliable the measure. Med
: 70,935 indicates the median of all measurements, ie the central value of the series of measures. The closer this value is the value of the average accuracy.
4694 (sigma rho: 0.042) Med: 4,682
rho parameter indicates the angular distance between the two components (arcsec). In this case 4.694 is the distance between the components "A and B "and ... if we consider that each pixel covers an area of \u200b\u200b0.71583", then the centers of the two stars are separated in the image by 6.5 pixels. Sigma parameters rho and Med have the same interpretation that theta data.
Deltamed = 0.31
Notes the difference of magnitudes between the two components. Keep in mind that reducing gives an approximation. But yes, pretty good. In this case that as the main WDS has a magnitude of 8.28 and 8.56 secondary, its magnitude difference is 0.28 so the approach to the value that gives us Reduc 0.31 is pretty good.
Nb: 28
this figure indicates the total number of images and individual measures were used to calculate the final bill. In this case, the ultimate measure of this pair is the average of 28 individual measures. Peer
calibration : STF 2687 STF 2691 STF 2922
Shown are pairs of calibration used for that particular session and that are responsible for the determination of the "famous" calibration constants.
information I hope you find it useful .....
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