Orion nebula core with ASI178MM

ndb

Hello,

first deep-sky image with my new ASI178MM, uncooled for now.

Prime focus of 254-mm newtonian.

The Moon was in vicinity, almost in quarter. No filter.

Image is sized down.

Unfortunately DeepSkyStacker was not able to align and stack 4000 6-mpx, 14-bit images! Only 1000 frames here. the camera requires a powerful laptop :)

Nicolas

m42_2016-02-15_newt254_asi178mmc_1000x500ms.jpg

bdeclerc

You could try to stack using the latest Autostakkert beta - http://www.astrokraai.nl/software/latest.php

It won't have any problems with 4000 frames.

ndb

Thank you for the advice!

I guess the most efficient way is to acquire a SER file, like planetary imaging ?

For deep-sky imaging, I usually choose fits or tiff images in order to verify individual frames prior to stacking (in case of gusts and bad tracking).

Next time I'll try to acquire a SER file; I suppose that autostakkert will ignore blurred frames to achieve a correct alignment (something like 80% of good frames, "surface" mode).

bdeclerc

NDB wrote:
Thank you for the advice!

I guess the most efficient way is to acquire a SER file, like planetary imaging ?

For deep-sky imaging, I usually choose fits or tiff images in order to verify individual frames prior to stacking (in case of gusts and bad tracking).

Next time I'll try to acquire a SER file; I suppose that autostakkert will ignore blurred frames to achieve a correct alignment (something like 80% of good frames, "surface" mode).

Autostakkert can also read series of FITS or TIFF files, by dragging and dropping the directory they're in onto the program, so you don't really have to use .SER.

And you can configure Autostakkert to stack XX% of the total frames or an absolute number, so it'll drop the worst frames. For deepsky I usually let it perform the align & quality analysis, then drag the frames-slider back and forth until I find the first "bad" picture (usually in my series there are only a very small nr of those in deepsky) - then you select a single small align point on a star and let it stack. If you're suffering from field rotation there isn't yet a really good solution in AS2! but if you're well polar aligned, it works perfectly.

wargrafix

Its a great shot. Sharpcap does png. How bad is the amp glow?

ndb

Amp glow? I picked the ASI178 because the glow seemed lesser than in the ASI174. I noticed a faint glow with the 224MC, uncooled, in June, with 120-s exposures. But I didn't try long exposures with the ASI178. That's planned of course. When clear skies are back .

As for now, I've seen some limited flaws:

- In lunar imaging, I noticed small areas with columns in darkest areas of lunar maria, only after having very strongly increased lightness. Perhaps it is the classic bane of CMOS sensors with short exposures and bright enlightment; I have had similar problems with a conspicious offset of CMOS sensors to image the full Moon. The 178 is less prone to the phenomenon than the ASI120MM. Perhaps a better FPN neutralization when the sensor initializes, or a better homogeneity of amps and ADCs in the columns.

- In DSO imaging, some black, broad lines appear with 10-s exposures. I don't know where they come from, perhaps something like what I noticed when the antiblooming capacity of older Sony sensors was exceeded. It's too early to conclude about that.

- in planetary (and lunar) imaging, numerous, short-lived black points appear in the raw frames. They are randomly spread during acquisition and they totally disappear after stacking. Another mystery, looking like electromagnetic disturbances. No effect in the final images.

To BDECLERC:

oops, I unsuccessfully tried to drag & drop the series of files rather than the folder (I'm used to AviStack). I'll follow your advice about the renowned Autoskattert next time, BEFORE I clean up the disk. Thanks!

Nicolas