Need some help with QHY9 calibration

[hercule1939]

Yes, I noticed the same thing.

Gain, Offset and download speed value was same all the time.
It's like there is a some "random element" in settings.

I can't understood this behavior at all.

J-P

[janori]

Hi J-P

As you know, I also have problems with qhy9 image calibration, always with flat-frames
I have found a provisional solution that consists on adding up a pedestal to the flat-frame for a good correction

Image calibrated=(light-dark)/(flat+pedestal-bias)

In your bin3x3 images the pedesatal is aprox 40000adu for good result (try it)
In my bin1x1 images the pedesatal is aprox 10000adu

I don't understand why this happens

Regards

[hercule1939]

Hi,

I have noticed that too, thank you.
However, that's not an exact method.
It'll be close, but just close. I need a exact one, so do those, who do photometry and similar stuff.
There is something wrong in a driver and it should be fixed soon enough.

J-P

Ps.
QiuHY, did you get my files?

[aevans]

I'm having the exact same problem.  And though I can experiment with an offset of the flat file levels, it is close but not ideal.

For the record, I have tried doing the flat extraction with DeepSkyStacker and manually (so to speak) in Photoshop.

[QiuHY]

Hi,

I have noticed that too, thank you.
However, that's not an exact method.
It'll be close, but just close. I need a exact one, so do those, who do photometry and similar stuff.
There is something wrong in a driver and it should be fixed soon enough.

J-P

Ps.
QiuHY, did you get my files?

Hello,

        I have got the files, Just anaylze. I found the overscan area is :

light = 6600ADU,
dark = 1240ADU
bias =  1240adu
flat =  6800adu


        Seems the light and flat is a group and has similar offset  and the dark and bias is another group with similar offset. Are you sure you capture these four images with the same offset gain , download speed and temperature etc?



Best regards,

[hercule1939]

Hi,

I have tryed to confirm, that I used right settings. For some reason, there is not anymore QHY imaging information in FITs header.
I remember, that it used to be there, least with QHY8.

I'm positive that Gain, Offset and temperature are same all the time.
How ever, there might be a possibility, that the download speed has changed, I red somwhere here, that the Lowest
speed is not supported with a Green board, I still use a Green one.
I might have changed the speed to "normal" in new driver for that reason.

I will test again in near future.
Can a download speed explane so great difference in ADU?

J-P

[QiuHY]

Hello,

         Which software do you use? The last software should have the informations of gain, offset etc.
The download speed will effect the ccd signal levels.

Best regards,

[hercule1939]

Hi,

MaximDL v5.07 and a Plugin from QHY.

J-P

[QiuHY]

Hello,

         Finally we have found out why you meet this problem. Please see another topic discuss this:http://qhyccd.com/ccdbbs/index.php?topic=1810.0

This is due to the "ccd chip" temperature is not reach the stablize value.  The temperaure display on software is the temperature on tempterature sensor of the test point on KAF8300 ccd. But in fact this test point kodak gives has some distance to the real ccd chip. So you need wait a little more time after the temperature give come into stable and capture the bias image. Another way is add some offset value for it.

Best regards,