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Hi,
Does anyone know what AMPLIST is a header of an image stands for. It says : readout order y,x , but I still don't understand what that is. :shock: Thanks

See "cl> help quadformat" for details.-Mike

Thanks,
It makes more sense now, It says it is the number of regions, does it mean the number of Data regions or both Data and Bias regions?

In general, a 'region' will contain both data and bias pixels. The number of regions is usually the number of amplifiers used to readout the data. This will also normally correspond to the number of extension in a MEF file. [Note I said normally, we're aware of formats (being considered if not yet readily available) where e.g. two amplifiers will be repacked into a single extension covering the whole CCD, but iraf won't handle these properly because of keyword conflicts.]-Mike

Thanks for the clarification, so AMPLIST is basically the number of amplifiers, right?

More correctly, the number of items in AMPLIST is the number of amplifiers used to readout the data. The actual labels are somewhat peculiar to the detector (e.g. the CTIO mosaic has labels "11 12 21 22" and not "1 2 3 4" because the first amplifier used to readout is identified as '11'). That label value is then appended to the ASEC, DSEC etc keywords to specify the pixel region.-Mike

oh, so an AMPLIST of 11 for CTIO means 1 amplifier, 12 meqans 2 amplifiers, 21 means 3 and 22 means 4?

No. The '11' is just the name. ConsiderAMPLIST = "fred bob jane jill"Four names means four amplifiers. So, AMPLIST="11" means 1 amplifier, AMPLIST="11 12" means two, and so on.

Oh, thank you so much, it makes perfect sense to me now