Trans-Neptunian Objects.

[Paul M]

2 minutes ago, Xilman said:

That said, I did manage to image six globular clusters in M31 so the time wasn't entirely wasted.

Absolutely.

This session was a shakedown after a long summer/autumn weather layoff. I'm still getting to know my RC250 scope! 

So there was no fail in that respect. I got a unexpectedly deep image, full of faint fuzzies that I'm still inspecting with Simbad and other online resources. And this is the stuff that interests me.

I do like big, beautiful images of the deep sky favorites, but image processing isn't my thing. I like the hunt, pulling resources together to identify things and dig deep for the oddball stuff. Cosmic Horseshoe being a particular object of interest that you pointed me towards.

I am still playing with the "Not !Gunk" image, it's quite attractive as a non-descript deep field. That's where I'm happiest! 

Here is the colour image:

 

[Xilman]

Have you checked with the MPC to see whether you picked up any asteroids unintentionally?

Not very likely, as most random fields contain at best an asteroid at mag fainter than 22 or, perhaps, as bright as 20 if you are particularly lucky.

Worth checking anyway. Once I was imaging Nereid and found a rather nice trail form (16095) Lorenball in the frame.

Paul (the other one)

[Xilman]

Just now, Xilman said:

Have you checked with the MPC to see whether you picked up any asteroids unintentionally?

Not very likely, as most random fields contain at best an asteroid at mag fainter than 22 or, perhaps, as bright as 20 if you are particularly lucky.

Worth checking anyway. Once I was imaging Nereid and found a rather nice trail form (16095) Lorenball in the frame.

Paul (the other one)

My apologies.  I did not examine your image closely enough. It appears that you have checked for other asteroids in the district.

[Paul M]

55 minutes ago, Xilman said:

My apologies.  I did not examine your image closely enough. It appears that you have checked for other asteroids in the district.

Yes, the image has asteroids down to mag 22 annotated by ASTAP. As you'd expect, none of them are detected. ASTAP uses MPC's MPCORB.DAT, master file, which I now know contains (229762), so there should have been a warning alarm going off in my head that it hadn't been picked up by annotation.

[Paul M]

Like a dog with a bone, I'm in this for the long run.

Lat night (this morning) was forecast to be and turned out to be a very good night. 

So I had another go at !Gunk, sorry, that's the only way I'll remember my tussle with this object. But remember it I will.

Another 30 x 300 sec, in a moonless sky, but more importantly, the right bit of sky!! I did have trouble with focus, Collimation seems to have been abruptly disturbed but at best focus the stars look ok, just ok.

I have an anxiety issue with flat calibration frames. So, from the warmth of my bed at 07:30, I used the twilit sky as a flat reference. It works well but, yet again, I've got some condensation on the sensor, I really should leave the camera cooled after the imaging run ends to avoid this. So there is still a residual watermark off center.

For consistency I used random processing routes. First is a stack and stretch, entirely from ASTAP. The annotation is from ASTAP to, which uses MPCORB.DAT as a reference file. So looking good so far as astrometrics are concerned:

At upper left it looks like some light leakage. I think it's from the neighbour's IR night vision security camera. But it looks to me like there is something in the middle of the box.

Although over the time range, the subject should be slightly elongated.

The above image goes down to mag 19.8 according to a photometric calibration. and !Gunk is 19. 2 or something.

Next exhibit is a stack form DSS, stretched in PS and annotated back in ASTAP.

 

 I'm going to claim a win. Cross referencing with DSS imagery, there are some bits an pieces in that area but I think they are fainter.

This is obviously the very limit of my urban sky.

I'm beginning to understand why Clyde Tombaugh wore his trousers so high, no explanation, just an understanding...

 

Edited December 6, 2023 by Paul M

[Xilman]

I am sure that's a success. Well above the noise level.

There are other things you could try to enhance the image.  Obvious ones are to stack on the calculated motion of the TNO so that its pixels are slightly less trailed (though the stars will be, of course) and to separate the RGB frames of each sub and then stack them as a monochrome image. Not only will that raise the SNR slightly but monochrome images are generally more resilient to extreme contrast enhancement measures.

Note that sky brightness is an important hindrance but it is certainly possible to image stellar objects which are fainter than the sky background. I've managed 10% of sky, or better. Professionals commonly achieve 1%. If it is not obvious how this is possible, it is most certainly worthwhile working out how it can be done.

You should be able to get below mag 20 if you really push your equipment and your software.

[Paul M]

4 hours ago, Xilman said:

  Obvious ones are to stack on the calculated motion of the TNO so that its pixels are slightly less trailed

Thanks Paul, I tried that already. ASTAP has that function available but my one attempt with this data so far didn't go right.

I've used it in the past with success so maybe worth another, less rushed attempt.

Anyway, other than play with the data already collected, I'll leave this one alone.

Upwards and onwards!

An obscure Jovian satellite next, maybe

[Xilman]

12 minutes ago, Paul M said:

Thanks Paul, I tried that already. ASTAP has that function available but my one attempt with this data so far didn't go right.

I've used it in the past with success so maybe worth another, less rushed attempt.

Anyway, other than play with the data already collected, I'll leave this one alone.

Upwards and onwards!

An obscure Jovian satellite next, maybe

Go for it. Nereid would also be a worthy target for you. Saturn has a whole bunch of accessible satellites too. Phoebe would be a nice and easy one for starters.