De verwerking van VST-opnamen
Dit overzicht laat zien hoe de ruwe gegevens die door een telescoop zijn vastgelegd worden omgezet tot een verbluffende foto – in dit geval van de Vela-supernovarest, zoals gezien door de VLT Survey Telescope (VST).
1. De detector registreert het door de telescoop verzamelde licht. OmegaCAM, de camera van de VST, is uitgerust met 32 detectoren die een groot beeldveld bestrijken.
2. De ruwe beelden bevatten allerlei onvolkomenheden zoals dode pixels, schaduwen en helderheidsverschillen tussen de detectoren. Deze moeten worden gecorrigeerd voordat de beelden voor wetenschappelijke doeleinden kunnen worden gebruikt.
3. Astronomen corrigeren deze effecten met behulp van kalibratiegegevens. Dit proces van ruwe naar wetenschappelijk bruikbare gegevens wordt ‘datareductie’ genoemd.
4. Wanneer een hemelobject groter is dan het beeldveld moeten meerdere opnamen worden gemaakt, die tot een mozaïek worden samengevoegd. Hierdoor kunnen ook de marges tussen de detectoren worden opgevuld.
5. De helderheid van de achtergrond kan, door veranderingen in de maanfase en andere effecten, voor de verschillende delen van het mozaïek variëren, vooral als de deelopnamen tijdens verschillende nachten zijn gemaakt. Hiervoor kan worden gecorrigeerd door de overlappende delen van de diverse opnamen met elkaar te vergelijken.
6. Het resulterende mozaïek wordt visueel geïnspecteerd, en eventuele resterende onvolkomenheden worden gecorrigeerd. Het gaat hierbij bijvoorbeeld om de naden tussen de verschillende foto’s.
7. Astronomische detectoren maken geen kleurenfoto’s. In plaats daarvan worden afzonderlijke opnamen gemaakt door filters die licht van verschillende golflengten doorlaten. Aan deze opnamen worden verschillende kleuren toegekend, waarna ze worden gecombineerd tot een kleurenfoto.
8. Het eindresultaat.
Credit:ESO/M Kornmesser, VPHAS+ team. Acknowledgement: Cambridge Astronomical Survey Unit
Over de afbeelding
| Id: | eso2214c |
| Taal: | nl |
| Type: | Collage |
| Publicatiedatum: | 31 oktober 2022 14:00 |
| Gerelateerde berichten: | eso2214 |
| Grootte: | 5940 x 3401 px |
Over het object
| Naam: | Vela Supernova Remnant |
| Type: | Milky Way : Nebula : Type : Supernova Remnant |
Afbeeldingstypen
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