Getting back into imaging after a long break

[Gina]

Created a Superbias.  Now to calibrate the Flats.  With the short exposures and low gain I can't see the need for Dark subtraction but I guess applying the Superbias is worthwhile.  The Master Dark showed some variation when stretched.

Edited July 10, 2019 by Gina

[Gina]

Calibrated and Integrated the 3 sets of Flats (HA, OIII, SII).  Time for a break!

[Stub Mandrel]

Comment so I can follow this thread 🙂

[Gina]

Calibrated the Lights that I took with 2x binning - 2328 x 1760 pixels which is more than my monitor.  I also took some un-binned - 4656 x 3520.

Edited July 10, 2019 by Gina

[Gina]

Star Alignment next but I might leave that until tomorrow.  Tired from two late nights!

[Gina]

Had a read and it looked simple enough unless tweaking the settings and I remembered it a bit so I had a quick go but it rejected lots of subs, mostly OIII and SII leaving just 4 OIII and a single SII.  A lot of noise was left after calibrating the Light frames, particularly OIII and SII is worse so I guess it needs longer exposure subs. 

That's it for tonight.  Probably try tweaking the settings tomorrow after reading the book and see if I can recover more OIII and SII subs.

Edited July 10, 2019 by Gina

[Chriske]

10 hours ago, Stub Mandrel said:

Comment so I can follow this thread 🙂

That makes two of us...

[Gina]

Still recovering from two very late nights.  Seems I'm just not up to it.  If I can't get set up ready for unattended imaging by midnight or soon after I shall just have to give up and go to bed.  Have to adjust my activities to what I can manage without getting ill!.  Drat!  This getting old is not good!  Mind you there are plenty worse off than me - just got to be thankful for what I can do.

[Chriske]

At our age we need to make the best of it...

[Gina]

Definitely not well this morning.  Took my blood pressure and it's very low but I don't entirely trust electronic equipment.  Had to delay breakfast due to dizziness.  Now I feel a bit better and prepared and eaten breakfast (a bowl of porridge).  Plan to ring up the doctors' surgery later if I'm not a lot better - might do anyway.  I'll measure BP again when my breakfast has been mostly digested.

[Gina]

The screenshot below shows samples of the Calibrated Lights for the 3 filters.  I'm not sure the calibration has worked properly but it certainly seems the OIII and SII subs need longer exposures.  Exposures are Ha-45s, OIII-120s and SII-240s.  SII always seems weak but there is definitely some nebulosity showing amongst the noise.

[Gina]

Stretched the Ha image with CurvesTransformation and the calibration hasn't removed the problem round top edge and on the left.  This is noise and should have been removed with either Bias or Dark frames.

[Gina]

Here are stretched versions of Master Bias and Superbias.

[Gina]

Stretched 45s Master Dark.  To match the Ha Lights.  Plus stretched 120s and 240s Master Darks to match OIII and SII.

 

[Gina]

Stretched versions of the 3 sample calibrated lights.  Although rather noisy I feel sure Star Alignment has worthed on images like the OIII and SII samples in the past.  Anyway, calibration hasn't got rid of the amp glow and I'm sure it's supposed to.  Any thoughts very welcome.

[Gina]

I've posted on the INDI Forum asking about maximum image size for plate solving.

[Gina]

No reply as yet.

[Gina]

Had another go at StarAlignment reducing the Log (sensitivity) as suggested in the book but it was worse - much worse.  Only 18 of 28 Ha chosen and no OIII or SII.

[Gina]

Probably giving up for today unless I find an answer to this,

[Stub Mandrel]

How close are the temperatures for your darks?

And are you feeling better?

[Gina]

Darks were at -20°C whereas the lights were at -27°C.  Couldn't get the temperature lower for the darks - weather has been too hot.  Do you think this is the problem?

[Gina]

Yes, thank you.  Quite a lot better though still tired.

[Stub Mandrel]

2 minutes ago, Gina said:

Darks were at -20°C whereas the lights were at -27°C.  Couldn't get the temperature lower for the darks - weather has been too hot.  Do you think this is the problem?

Not if those figures are accurate.

[Gina]

They were what the camera said.

[symmetal]

5 minutes ago, Gina said:

Darks were at -20°C whereas the lights were at -27°C.  Couldn't get the temperature lower for the darks - weather has been too hot.  Do you think this is the problem?

I have a fairly powerful fan blowing over the camera this time of year to get the temperature down. I usually image at -30C for the ASI1600 and can reach this with an ambient of +15C using the extra fan. Mainly used for taking darks and when it's cloudy as the temperature is normally higher, but I used it when imaging the last couple of times as it could only reach -27C. Using the fan it easily reached -30C at 80% power. If imaging for any length of time you might need to move the fan every couple of hours. 

Alan