Frank's Astro Blog

NGC3628 Hamburger-Galaxie Diese Galaxie im Sternbild Löwe ist schätzungsweise 34 Millionen Lichtjahre entfernt und hat einen Durchmesser von etwa 145.000 Lichtjahren. Für uns erscheint sie als Edge-On-Galaxie, also genau in Kantenlage. Zusammen mit den Galaxien Messier 65 und 66 bildet sie das sogenannte Leo-Triplett. Wie immer ohne Filter aus der Stadt, Bildausschnitt: 31.9 x 21.3 arcmin Objektdaten:  Helligkeit: 9.44mag Größe: 11.04' x 3.44' Meridian: 55.4° für München 07.04.2026: Meridian um 23:30 MESZ München; Mond: 75,74%,  098° Aufnahmedaten: Capture: Omegon veTEC 571C  an 8" EdgeHD auf AVX Guiding: ZWO ASI 120MM mini an 60x240mm  260x 60sec = 4h20min für Stack 2.100mm f/10 an APS-C, Binning 1x1, ohne Filter 5000x3333px, runtergerechnet auf 1588x1080px SiriL, finish PS

let us define what are the use of darks, flats and biases. master dark removes both the thermal signal and the bias of the image . Attention, it does not remove the noise. Indeed, none of the master files remove noise, because the latter, with its random nature, will instead be added to the image. the master flat flattens the image by removing the vignetting and the possible dusts present on the sensor . The utility of the bias is more difficult to grasp. However, it is there to remove , as its name indicates, a level of offset that has been added by the manufacturer to avoid having negative values when processing the image by the camera and therefore to avoid losing information. DSLR manufacturers, most of the time, define a value that is a power of 2: 512, 1024, 2048 … while for astronomical cameras, it can be any value. Taking a bias image must be done at the fastest possible speed, to avoid adding signal and thermal noise that would interfere with the processing. However, a bi...