deep sky sequencer and asteroids observation

[carlomuccini]

SUCCESS !!

Last night I took advantage of an almost clear sky to try a sequence of images of two bright asteroids.
I chose Pallas and Astraea because one is to the east and one is to the west.

The sequence included:

for each asteroid

GOTO the asteroid
1 second exposure
Sharpsolving
15 second exposure
Livestacking of 5 exposures
Saving

GOTO to the second asteroid and so on 10 times

The GOTO to the asteroid seemed to work well.
I'm attaching a photo of 10 shots of (2) Pallas.

(2) PALLAS, 2025-07-31, 12x24L, ASKAR V 80, (IR), ZWO ASI294MM Pro(2) Pallas.jpg (396.62 KiB) Viewed 2916 times

Carlo

[admin]

Hi Carlo,

thanks for the report - good to hear that it worked! Still waiting for some clear skies here to test this and a couple of other things out.

It would be cool to also include asteroids in the deep sky annotation, but we can't just have the whole MPCORB.dat file - too many to handle the calculations in any reasonable amount of time. Would it be any good to have a way to load (or paste in) a limited subset? Do you prepare or use a cut down version of MPCORB.dat just for the targets you are interested in? Since I don't really do asteroids myself, I don't know how people tend to work for this sort of imaging.

cheers,

Robin

[carlomuccini]

Hi

By aiming at the asteroid with the planetarium program or with the Sharpcap + Platesolve sequence, the asteroid is always exactly in the center and there's no need to note it.
If I want to image a single asteroid, I use the planetarium for the GoTo + sharpsolve and stop.

The Sharpcap sequence is fantastic for capturing the movement of multiple asteroids; for example, five 5-minute shots spaced 10 minutes apart for each asteroid. Manually, it's incredibly laborious; the sequence is trivial, especially considering that the sequencer correctly sets the asteroid's name. Perfect.

For asteroids, I download the MPCORB.DAT file and, using my own program, I indicate the 4, 5, 6, and 7 asteroids I'm interested in, creating a MPCORB.DAT reduced to just a few lines.
The original file is unmanageable by any program.

Asteroid selected.jpg (470.96 KiB) Viewed 2903 times

From today, I have another program that creates a ready-to-use .SCS sequence from the reduced MPCORB.DAT.
I tried, refined, and tested it just last night, and I'm very happy with it.

Generating SCS.jpg (254.56 KiB) Viewed 2902 times

Consider that anyone who wants to image an asteroid usually knows what they're doing and why. In opposition ? A NEA? Or a periodic check? and so on ..

Happy to be of assistance in any way

Carlo

[admin]

Hi Carlo,

I found myself thinking about this again and trying to come up with a way to include *some* MPC data in SharpCap so that you could find or annotate the most popular asteroids without needing to do tricks with making your own cut down MPCORB.DAT.

Eventually, I came up with the idea of filtering based on the highest brightness of the asteroid in the near future (currently I am working out the brightness up to 3 years ahead). If I cut the full MPC data set down so that I only include asteroids that hit magnitude 18 or above within the next 3 years, I end up with a fairly reasonable count of about 39000 targets. If I then cut down the data for those targets to the fields required to actually work with them (ie exclude stuff like observation history, perturbators, etc) then that amount of data can come down to not much more than 1Mb with appropriate packing and compression.

That sort of data quantity is manageable - loading it and calculation RA/Dec for each target is probably less than 1s or so (maybe a touch more on slower PCs). If I set a limiting magnitude of 17 rather than 18 then we are down to ~12000 targets, 16th mag limit gives only 4000.

So, I guess the piece of feedback I need from asteroid observers using SharpCap is how low (in terms of magnitude) do you go? 10th? 12th? 16th? further?

cheers,

Robin

[carlomuccini]

Your idea is interesting and also goes in the right direction.

In my opinion, there are two possible scenarios for imaging an asteroid.
The first is for "professional" use: I'm imaging a specific asteroid, probably of high magnitude: at least 18 or 19. In this case, the entire night is dedicated to it; so, just one GoTo, one plate solving, and a lot of imaging. There's no need to run any sequences, and there's no need to note the asteroid because I'm looking for it, and it's definitely at the center.

The second case is probably interesting for most users: the occasional search for an asteroid or, above all, the curiosity to know if there's an asteroid in the field of view.
In this case, annotation is very useful, but in my opinion, various filters can be applied in combination.

Number of asteroids: normally, the brightest ones fall within the first 100, which are likely to be the most randomly captured; however, it's certainly possible to manage the first 9,999 asteroids which are already "many".
The second filter is brightness; in a single frame, even in livestacking, it's difficult to exceed magnitude 15/16. Higher magnitudes correspond to special asteroids.
We can consider that with a 10cm lens and 10 minutes of exposure, the limiting magnitude is just over 16; and this could also be a limitation.

If for example we consider the following asteroids in the "middle" of the 9999
5025 Mecisteus mag. 18.3
5026 Mattes mag. 19.6
5027 Androgenos mag. 17.7
5028 Halaesus mag. 18.3

They're all already above 17/18, even 19a.
They probably "could be" in the field of view, but in reality they won't be visible because they're too faint.

Incidentally, last night I tried the two-asteroid sequence again using the updated MPCORB.DAT orbital data, and Sharpcap was very accurate.
I noticed a couple of anomalies and possible improvements, which I'll point out in a separate post.

Thanks for everything.

Carlo

[Jean-Francois]

Hello,

Interesting discussion. Here some comments or ideas for the tool ...

Two kind of observers will use the asteroid tool.
One is already an asteroid observer and is looking for one or more asteroids, most of the time for scientific work.
The other is more or less a deep sky observer and is only curious.

Concerning the MPCORB.DAT file ... yes, it could be large, but it does not need to be downloaded every day.
The first several 10'000 asteroids are well known and the orbital parameters does not change (if yes, then only in arcsecond or part of it).
Note that the asteroid observer uses other programs that already use the MPCORB.DAT file. So I think that it is not necessary to have it several time.
But, it is a but ... I use for example the following software ... Prism, Cartes du Ciel and Occult. All three use the MPCORB.DAT file.
Carte du Ciel or Prism allows to use a local file. That is good for using the same database. The download and the preparation of the file need only few seconds. It is possible to compile the data with some conditions, for example the magnitude of the asteroids. The 1'456'988 asteroids of the MPCORB.DAT file (from today) can be reduced on the fly during the compilation.
In other words ... the programs does not use the MPCORB.DAT file directly, but a compilation of it.
Carte du Ciel seems to calculate the position of the asteroids in advance.

SharpCap can have the same process. At least to allow to select a local file (MPCORB.DAT downloaded for Occult or other software).
In addition, it could be possible to compile the MPCORB.DAT with some limit (typ. the magnitude).
Robin, I can do some image captures showing the processes in Prism and Cartes du Ciel .

Concerning the view of the asteroid with the Deep Sky Annotation tool ... yes, it will be a plus to see the asteroids (and comets) with the annotation. If it is possible to see the PGC or HyperLeda22 catalogues (2'424'088 galaxies in the HyperLeda22 !), then it will be fine to see the asteroids too.

A sequence is "good" ... but the script is "better"
So, you can think to add some script functions for the process and view of the asteroids (and comets).

Regards,
Jean-Francois

[admin]

Hi folks,

thanks for the feedback. Based on that, I think a good cut-off for 'built in' asteroids will be about 15th magnitude - that seems to give just over 2000 (mostly with low numbers, a handful of smaller, high number, ones that maybe come close to the earth at some point in the next 3 years). That seems reasonable to include with the default lists of targets in SharpCap for casual use.

I am definitely planning to have the ability to add a local user file to allow further asteroids to be loaded. However, I don't think I can get away with the HyperLeda approach of allowing millions of objects to be loaded from that file, since the calculations for each MPC line are much more complex than just reading a fixed RA and Dec figure from a text file. I was thinking of having a cut off - maybe reading the first 10000 entries in any user-specified file to avoid tha application becoming bogged down if someone dumps the whole MPCORB.DAT file there.

On the scripting side, the only thing I am seeing that I could add is the ability to calculate the RA/Dec position and magnitude from the elliptical orbit parameters in an MPCORB line - is that what you were thinking about Jean-Francois?

cheers,

Robin

[carlomuccini]

Hi

Yesterday evening was a beautiful evening and despite the almost full Moon I took advantage of it to test the sequence on 4 asteroids: (2) Pallas (30) Urania (89) Julia (129) Antigone.

Sharpcap worked very well in a completely automatic way, resuming in a 5-minute livestacking cycle for each asteroid.
Below is the part of the sequence used for each asteroid in the 5 cycle
I only had one "problem" with the stretching I had set on Pallas, but with the other asteroids near the Moon, I got a completely white screen. It's not a practical problem because I saved in FITS16, but all that light in front of me is annoying. I should insert an autostretching command into the sequence, but I don't know how/where.

Thank you

Carlo

PRESERVE CAMERA SETTINGS
SET EXPOSURE TO 2
MOUNT GOTOMPCORB "00003 5.19 0.15 K2555 172.45499 247.85974 169.82992 12.98651 0.2559473 ..... (3) Juno 20250804"
MOUNT SOLVEANDSYNC
END PRESERVE
SET EXPOSURE TO 15
DELAY 2
LIVE STACK FOR 4 FRAMES SAVING AS FITSRawStack16Bit COUNTING Stacked FRAMES
LIVE STACKING STOP

[admin]

Hi,

there is a 'Live Stack Apply Auto Stretch' step, but it doesn't fit nicely with the use of the 'Live stack for <N> frames then save as' step, since the latter does all the stacking inside one step.

You could try something like...

Code: Select all

    LIVE STACKING START
    LIVE STACK FOR 1 MORE FRAMES THEN PAUSE
    LIVE STACKING AUTOSTRETCH
    LIVE STACK FOR 3 MORE FRAMES THEN PAUSE
    LIVE STACKING SAVE FITSRawStack16Bit 
    LIVE STACK SAVE AND CLOSE

in place of the current one line 'LIVE STACK FOR 4 FRAMES...' line. That will stack the first frame, then auto stretch, then continue with the next 3 before saving. I think it should work.

cheers,

Robin

[cyrille.de.brebisson]

Hello,

Well, I did not think when I started this post that it would lead to that much discussion!

On my side, I ended up using Prim to shoot my asteroids because I had some experience doing so on the club's telescope and I did the shoot before Robin could add all these features in sharpCap...

The good news is that I was able to get an observatory code

I will be doing a presentation at the club next fall on that process and will make sure to include these new sharpcap features in the list of the reasons for using it !

Thanks again for the great work.
Cyrille