How do they take flats on big professional telescopes?

[tomato]

While participating in the Las Cumbres Observatory Educational Project, I have found out that one set of calibration frames supplied with the light frames taken with the 2 metre telescope at Siding Springs are called SkyFlats. It then occurred to me that taking flats with a twilight sky might be the way they are done with large professional scopes, given the practical difficulties of using very large light panels.

Can anyone confirm this or tell me I’m way off the mark.

Thanks

[alan potts]

A very big white T shirt too.

Alan

[Helen]

LCO take twilight flats at the end of each night but  other observatories use dome flats - some do have huge light panels for this purpose 😎

Helen

Ps what are you doing with LCO?  Is it FT? I work with the FT team 😉

[Davey-T]

I used to use a Sky Flats plug in for Maxim but really needs automating as the sky, at my location anyway, gets dimmer really quickly although this isn't apparent to the naked eye, so by the time you've done a load of flats the last one has lower ADU than the first one.

Dave

[Wiu-Wiu]

Flat panel of the 1.2 m Mercator Telescope on La Palma: 

 

(maybe not a huge one but still a professional scope...)

[DaveS]

The 2m Liverpool Telescope on La palma uses twilight flats.

[tomato]

Thanks for the replies, sounds like a SkyFlat is exactly what is says on the tin.

[Alien 13]

I have to admit I always wondered how they did this, I took some sky flats once without a diffuser and there were hundreds of stars visible. The question is why dont the big scopes image during the day as there would still be lots of targets?

Alan

[tomato]

10 hours ago, Helen said:

LCO take twilight flats at the end of each night but  other observatories use dome flats - some do have huge light panels for this purpose 😎

Helen

Ps what are you doing with LCO?  Is it FT? I work with the FT team 😉

Yes, it is the FT, accessed via Perton Library Astronomy Group which is affiliated to the Wolverhampton AS.