26 replies to this topic

[han.k]

FYI, the free ASTAP program has two new features.

 

The first is "Track and Stack" for minor planets and comets. This new feature allows to compensate for the velocity of these objects and keeping them centered in the stack. This allows to improve the signal to noise ratio. The program can also extract the time and position and put them in a MPC1992 report line to check the object in the minor planet center MPCchecker. A video demonstration of the "track and stack" is available here.

 

Below a normal stack compared with "Track and Stack". For the 60 x 120 seconds stack the two minor planets are vague streaks. The obsolete remarks indicates that the MPCORB database is obsolete. That is why the two minor planets are out of the center of the annotation:

 

 

 

The manual for "Track and Stack" is here

 

The second change is the possibility to add a SIP 3th order polynomial to the solution. This improves astrometric measurements and also improves the stitching of a mosaic.

 

Feedback is most welcome.

 

Han

[Bob Denny]

Han this is really good!! I started my astro life as a Minor Planet guy back in 2001. I worked with the Hough Transform as a way to deal with streaked stars on a tracked target (NEO, comet). Did you use that scheme? In any case well done!

[han.k]

Hi Bob,

 

I have experimented with a Hough transform for streak detection but did not get a good result. So it was abandoned.

 

The track and stack algorithm is not complicated. The MPC orbital elements from the MPCORB.DAT file  are used to calculate the minor planet ra & dec position.  Using the image astrometrical solution the x, y positions of the imaged minor planets can be predicted. Then the x, y position differences are used to align on each minor planet and combine the images into a stack aligned for each minor planet position. This will improve the SNR greatly, allowing detections of very faint minor planets.

 

So without the MPC orbital information, it is not possible to align the images. Therefore, this routine is in principle not designed for discovering new minor planets or neo's. It can only help with followup observations. The minor planet center typically only requires followup observations of very faint objects of magnitude 21 or fainter. This is not achievable by the typical hobby astronomer. It can only be achieved by semiprofessional observers with a very good setup and very dark sky.

 

So for the moment it is a tool which hobbyist can use to observe/image faint solar objects including comets and is available for Windows, Linux and Mac. It is not a tool to make discoveries.

 

It would be nice to try out all possible minor planet movements (millions) instead of the calculated movements. So something like Tycho tracker does in the graphic card processor called syntactic tracking. But that is a significant undertaking for me and will not bring anything new compared with what Tycho Tracker achieves.

 

Han

[Bob Denny]

Ahh I misunderstood. Yes, My software uses MPC orbital elements NEOCP Ephemeris with interpolation and velocity, then does either track and stack or will send the RA and Dec rates to the mount so it will do "orbital tracking" resulting in the same thing while preserving the entire frame.  I entered astronomy software world back in 2001 when hunting for new asteroids was popular and I have a discovery tool as well). Then came LINEAR and others ha ha. 

 

Anyway your software is very cool to do it automatically with untracked images. 

Edited by Bob Denny, 08 March 2024 - 08:23 AM.

[Tapio]

Thank you Han for improving already excellent software.

 

Tried it with older datasets and got also the obsolete.

What should be done in that case?

[Sky King]

I am working through this. I got the "obsolete" also and downloaded the latest MPCORB and that fixed that. I also couldn't get the "Track and Stack" menu option, but I wasn't in the Blink tab. Finally got it to work and it aborted due to OSC images. I will try converting the OSC images to mono and try again. Cool feature! 

 

I got PiPP to convert color to mono fits, but now Astap won't read the header.   

 

Guess I should be using my ASI174mm or ASI183mm Pro. Will this "track and stack" comets?

 

Got it to work with some old data from the ASI183mm from 11-17-22, so the "obsolete" returned and too small to be visible. 

 

no_object, 2022-11-17, 20x300L, EQMod Mount, (CV), ZWO ASI183MM Pro(28378) 1999 JN24_average_stacked:

 

Edited by Sky King, 08 March 2024 - 03:37 PM.

[han.k]

Thank you Han for improving already excellent software.

 

Tried it with older datasets and got also the obsolete.

What should be done in that case?

A few month's epoch offset should be fine. The message comes if the epoch of the MPCORB.DAT files is 120 days off.  To my knowledge, there are no older (epoch) MPCORB.DAT files available for download. You can create them with the very last HNSKY program (2024.02,08). But it is probably better I create them and upload them for general use. The process used in HNSKY is called numerical integration. So you use the orbital positions of the planets to calculate a distortion vector for the minor planet and use that to integrate a correction over time. This is very accurate and you can go back 20 years or more (or to the future) with high accuracy. This feature was already a long time available, but I created now an export facility to export the numerical integration result to a file in MPCORB.DAT format. I added this because I faced the same problem as you did. The only problem it takes some time to process. A few year back takes maybe one hour computing for the 1.3 million objects. What is the epoch of your files?

 

I am working through this. I got the "obsolete" also and downloaded the latest MPCORB and that fixed that. I also couldn't get the "Track and Stack" menu option, but I wasn't in the Blink tab. Finally got it to work and it aborted due to OSC images. I will try converting the OSC images to mono and try again. Cool feature! 

 

I got PiPP to convert color to mono fits, but now Astap won't read the header.   

 

Guess I should be using my ASI174mm or ASI183mm Pro. Will this "track and stack" comets?

I will look tomorrow into OSC images. Once stacked you can not convert them to colour. Conversion to colour should be done prior to (track and ) stacking. I will look for a fix the next days.

 

Han

 

 

[han.k]

Thank you Han for improving already excellent software.

 

Tried it with older datasets and got also the obsolete.

What should be done in that case?

I have uploaded some older MPCORB.DAT files here temporary. Try the once with the best match. If there is no reasonable match, tell me.
https://sourceforge....s/MPCORB_files/

[han.k]

I am working through this. I got the "obsolete" also and downloaded the latest MPCORB and that fixed that. I also couldn't get the "Track and Stack" menu option, but I wasn't in the Blink tab. Finally got it to work and it aborted due to OSC images. I will try converting the OSC images to mono and try again. Cool feature! 

 

I got PiPP to convert color to mono fits, but now Astap won't read the header.   

 

Guess I should be using my ASI174mm or ASI183mm Pro. Will this "track and stack" comets?

 

Got it to work with some old data from the ASI183mm from 11-17-22, so the "obsolete" returned and too small to be visible. 

 

no_object, 2022-11-17, 20x300L, EQMod Mount, (CV), ZWO ASI183MM Pro(28378) 1999 JN24_average_stacked:

 

no_object, 2022-11-17, 20x300L, EQMod Mount, (CV), ZWO ASI183MM Pro(28378) 1999 JN24_average_stacked.jpg

I have uploaded a new ASTAP development version (2024.03.08) for Windows. Download from this link. This new version will track and stack raw OSC images and create stack in colour. A second possibility is to use the bin2x2 button in tab Blink first/ This will produce a mono stack and will possible a little more accurate in position and reported magnitude.

 

The reason why you don't see a minor planet in the stack is most likely that the epoch of the database is a few years off. The minor planet will be just at another place. Download and use the  older MPCORB file dated 2022-06-12  from this link. It is not perfect, but I assume the minor planet will be visible in the stack.

 

Han

 

[Sky King]

I have uploaded a new ASTAP development version (2024.03.08) for Windows. Download from this link. This new version will track and stack raw OSC images and create stack in colour. A second possibility is to use the bin2x2 button in tab Blink first/ This will produce a mono stack and will possible a little more accurate in position and reported magnitude.

 

The reason why you don't see a minor planet in the stack is most likely that the epoch of the database is a few years off. The minor planet will be just at another place. Download and use the  older MPCORB file dated 2022-06-12  from this link. It is not perfect, but I assume the minor planet will be visible in the stack.

 

Han

Han,

That's about the nicest thing that's happened today! Thank You! You built a ASTAP for my color images! I can't get to mag 20, and I'm in Bortle 8. New to minor planet imaging, with a C8/Hyperstar I imaged from (1) Ceres to (9) Metis. But did them with a ASI678MC. I downloaded the ASTAP version linked and it just worked. (I didn't need the bin 2x2 button but will try it too.) Thanks! This is very cool!  

Al

 

 

 

 

[Sky King]

(2) Pallas

 

 

 

[Tapio]

I have uploaded some older MPCORB.DAT files here temporary. Try the once with the best match. If there is no reasonable match, tell me.
https://sourceforge....s/MPCORB_files/

Thank you. I tested with some files from last summer.

 

Back in the days I used HNSKY. Could use it again to do the transformation.

[Sky King]

One other point, Track and Stack does comets well. Here's 12P/Pons-Brooks from 3-3-24 and 3-6-24 with Track and Stack.   C8/Hyperstar, ASI533MC Pro, UV/IR filter.

 

3-3-24:

 

 

 

3-6-24

 

 

 

 

Edited by Sky King, 09 March 2024 - 02:46 PM.

[han.k]

You can do the same using normal stacking, put the lights in tab light and select in tab alignment "emphemeris alignment".   Press "Analyse the selected file in tab images( lights)" and select the comet (for alignment). Then press the stack button  It works well for fast moving comets like 12P/Pons-Brooks. The annotations you can switch off under viewer menu "view". 

[Tapio]

You can do the same using normal stacking, put the lights in tab light and select in tab alignment "emphemeris alignment". Press "Analyse the selected file in tab images( lights)" and select the comet (for alignment). Then press the stack button It works well for fast moving comets like 12P/Pons-Brooks. The annotations you can switch off under viewer menu "view".

Do you think it should work also with images taken with alt-az mount?

[han.k]

Do you think it should work also with images taken with alt-az mount?

That is an interesting topic. The answer for minor planets is yes, For comets the answer is also yes but using the current version of ASTAP you have to do that in two steps.

 

The reason is that ephemeris alignment corrects for 1) minor planet shift and 2) flipped images but not for rotation.  Images taken with an alt-az mount will show a slow rotation between the images. That doesn't hurt for  point source like a minor planet but for a comet which has a tail you should compensate for the rotation. That can be fixed in the current ASTAP version but you have to stack in two steps:

 

1) Use the stack function "calibrate and align". This will convert your images such that the rotation is compensated.

2) Use "track and stack" in the blink tab on the new images from step 1)

 

 

I just realised I can modify the track and stack function to do that in once step using the image solutions. If you can share an image series taken with your alt-az mount I can proper test.it.

 

Note that standard stacking already compensates for any rotation or scaling.

 

Han

 

 

The calibration and alignment stack option for step 1)

[han.k]

Do you think it should work also with images taken with alt-az mount?

I released ASTAP version 2024.03.11. The mode "track and Stack" and ephemeris aligned stacking should work with images taken with an alt-az mounts or any other rotation drift.

[Sky King]

I released ASTAP version 2024.03.11. The mode "track and Stack" and ephemeris aligned stacking should work with images taken with an alt-az mounts or any other rotation drift.

 

Will version 2024.03.11 still work with color images like version 2024.03.08 does for track and stack?

 

Will this new version work with images from a tracking dob like the OrionXX12g? No need for short exposures or a rotator?  (Wow!)  Any special settings to change?

 

Thanks for all your efforts! 

[han.k]

Will version 2024.03.11 still work with color images like version 2024.03.08 does for track and stack?

Yes

 

Will this new version work with images from a tracking dob like the OrionXX12g? No need for short exposures or a rotator?  (Wow!)  Any special settings to change?

 

 

Yes. Rotation will be compensated. So even with rotation the stars will form straight streaks in the stack and both the comet center and comet tail should be sharp.

 

Track and stack will create images of 299x299 pixels by design since it was intended for minor planets. For a full size image stack just stack using the ephemeris alignment. Same routine.

 

 

Han
 

[han.k]

For the OrionXX12g, the stars should be reasonable sharp in the individual images. So I assume you have to find empirical the maximum exposure time for which this is true.

[han.k]

ASTAP version 2024.03.13 was released with some improvements.

[555aaa]

This sounds great, Han!  I have a bunch of comet subs I took with an alt-az direct drive mount and I'll have to try these with the new build. Your solver is so much better than the Astrometrica solver, I really want to ditch that one and use yours, which also doesn't need the horsepower of Tycho.

 

 - Bruce Van Deventer

[Sky King]

Regarding rotation, an interesting idea just came up regarding imaging comets rotating, for example. Any way of reordering ASTAP to catch this effect? 

[han.k]

ASTAP ephemeris stacking or" track and stack" will give a sharp stacked image of the comet center. But I assume you will need very good seeing to see that kind of details

[Sky King]

I like your posts in the rotating comet 12P thread. It is a complicated aspect of the comet, to say the least.

 

In ASTAP, to use the online query, Simbad, I get a pop-up that says "Install Open SSL. Required for AAVSO connections." Windows 11. How do I get this working?

 

I tried to image Pluto this morning. I used the comet/asteroid annotation tool but no Pluto. I am going up in aperture but likely need more accurate ephemerides. 

 

Edit: I definitely had the wrong setup. C8/ Hyperstar is at 390 focal length. I need more like 2000+ focal length and 14" aperture. On Astronomy Tools Jupiter is just a dot with this setup!

 

Thanks!

 

Edited by Sky King, 20 March 2024 - 11:04 PM.