Need some help with QHY9 calibration

[hercule1939]

Hi,

I have had bad problems with astronomical image calibration with QHY9 images.
Background values gets below zero, no matter what offset I use, thats solvable by adding some
pedestal, but there was not this kind of problem before with older drivers.

The main problem is, that Flat frames doesn't work correctly!
I have used QHY9 a longish time and before I installed the new driver there was no problems.

I have uploaded some files to test.
Please, try to calibrate with those files and see if you'll abel to get them work.
I really want to figure out the reason for this behavior.

BIAS:
http://www.mediafire.com/?adndtymt02z

DARK:
http://www.mediafire.com/?znohjnx0lzn

FLAT:
http://www.mediafire.com/?2zygyhyvhvq

LIGHT:
http://www.mediafire.com/?2eknftnjjh5

All the files are single shots, the idea is just to see if it's possible to get them work right.
Exposure time is 1200s, trough the 7nm H-alpha filter with LX200GPS 12" @ f4.65

J-P Metsavainio

[janori]

Hi J-P

I think that your problem is in the dark-frame. The min_value of dark-frame is more bright than the min_value of the light-frame, and it's very strange. Are you sure that all master-frames (light, flats, bias and darks) are the same gain and offset? Why this data not appears in your fits-header?

After dark substraction, the min_value of image is negative ==> black image and no good correction

But calibrating only with bias and flats (no darks) the result is... acceptable

I suggest try to make a new dark-frame and test ¿¿¿???

Regards

[hercule1939]

Hi and thanks,

I have three sets of darks, just for the reason you mentioned, I tryed to add more offset and I had to shoot new darks to be able to test.
I might have send a wrong dark with the files. I have tested it with correct dark and  with same result!

I'll send a rights flat here tomorrow, sorry.

J-P

Ps.
I noticed the same ting with Fits header? I'm using MaximDL v5 and a plugin from QHY.

[hercule1939]

Hi,


I just took images of  a O-III channel Binned 3x3.
Calibration doesn't work for me!

I have shot all new calibration files. Gain 20, Offset 100 for all.
Master Bias, Dark and Flat are created in CCDStack.
I place links to the files here.
Please, can someone try calibrate those files.
I never have had any problems with a calibration with QHY9,
before I upgraded the Driver.
Images are taken in MaximDl 5.07.

Bias:
http://www.mediafire.com/?dumycnltt2x

Dark: (600s, -30degrees)
http://www.mediafire.com/?mon0rimymej

Flat:
http://www.mediafire.com/?5z2mwqdwyim

Light: (600s, -30degrees)
http://www.mediafire.com/?jddwelitkxm

I have made hunderts of images with no problems before, only changed thing is a driver.
Am I the only one here?

[MMys]

I'm not able to calibrate this. Does not work properly. There may be mistake in process of creation of masters.

Try to share unmodified Light, Bias, Dark and Flat as they saved from camera. One piece from each.

[hercule1939]

It's same with them, but I'll upload the images in few minutes.

J-P

Ok, here they are:
BIAS
http://www.mediafire.com/?3mmymeirwzw
FLAT
http://www.mediafire.com/?ggjdlxiezyu
DARK
http://www.mediafire.com/?vywiz3vmjmk
LIGHT
http://www.mediafire.com/?jddwelitkxm

All are unmodified camera Fits. Taken with Gain 20 and Offset 100, binned 3x3 in camera hardware.

[QiuHY]

Hello,

     I can not reach the link. Can you send me with other method? I will analyze the overscan area to find the problem.

Best regards,

[hercule1939]

Hi,

Liks work ok to me.
Please, give me a email address, so I'll mail them. Binned 3x3 filesize is about 2meg/file.

J-P

[QiuHY]

Hello,

        You can email to qhy9@qhyccd.com


Best regards,

[MMys]

You made mistake. Instead of flat, flat.fit contains light frame of pelican.

Calibration by it is perfect, ofcourse  . All is eliminated into perfecty flat image with hotpixel an cosmics only.

[ejcruz]

JP here are my results for Oiii data, it looks like you have an issue with your flats:

Here is the original light frame with just simple stretching:


Processed with Dark+Flat+Bias:


Processed with Dark+Bias:


Ooops looks like you posted the wrong Flat file, here it is stretched:


Cheers
Eddie

[hercule1939]

Sorry!

Here is the right Flar frame:
http://www.mediafire.com/?jddwelitkxm

New try, the right Flat here:
http://www.mediafire.com/?5z2mwqdwyim


Wrong again, can't be so difficult.
The correct one will be here in five minutes.

Here it is, now a correct Flat finally.
http://www.mediafire.com/?ytgyyn03inh
J-P

[ejcruz]

JP - just download and that link downloaded a light frame and not a Flat frame.

Cheers
Eddie

[hercule1939]

Should be fixed.
I have done too much astro photographing, my Brains are like jelly.

[MMys]

Calibration by flat does not work. Flat have shifted levels to some higher value. After subtraction of bias from flat, overscan remains at 5500 ADU. There is same mistake here. After 0.4sec of exposure, overscan of flat should be same as overscan of bias.

Light and flatfield images have overscan value about 6600 ADU, dark and bias have it about 1200 ADU.
There is something wrong in this. I should expect only slightly higher overscan value in Light and Dark due to dark current, but 6600 ADU is too much.