I record asteroid occultations of stars. I have a series of440 FITS frames that look at one star as an asteroid approaches and then occults that star.Examaning each frame with the Asteroid Annotation tool should show an asteroid moving through the frames toward the target. Instead looking at the first and last frame, the asteroid has not moved. Am I not applying the tool properly?
The occultation was predicted to occur at 02:34:32. I recorded from 2 min. before until 2min. after that time at an exposure of 0.5 sec. Examination of the light curve taken from theat series of FITS frames found an occulttion starting at 02:34:26.1 and ending at 02;34:34.7. I can send you the whole series. I have trimmed several frames from the beginning and end to make the series fit in 2G for WeTransfer.
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Today I ran a JPL Horizon ephemeris for (934) Thuringia centered on the 4 min. surrounding
2021 12 31, 02:34:29 at 10 sec intervals. Making a mark on the image at the coordinates of each ephemeride showed, as you stated, the marks fell on top of each other and the target star.
But the Asteroid Annottion tool put Thuringia at the far edge of the image. I don't believe thatis correct.
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The attached image is taken from the start of the sequence and annotated with a marker at the position of the star and several markers from ephemerides taken over the 4 min paeriod. They all fall on top of each other as you rightly pointed out. The marker at Tools> Asteroid annotation shows the correct asteroid but at a great distance from the positions of the ephemeres.
Here is points to the correct place. See attached screenshot the red marked points:
1) Check solution. The RA, DEC values of the solution should match. If not is the tolerance of the solver not above 0.007
2) Is the minor planet ephemerides of the last 2 months?
3) Check date of observation
4) Check location.
I record asteroid occultations of stars. I have a series of440 FITS frames that look at one star as an asteroid approaches and then occults that star.Examaning each frame with the Asteroid Annotation tool should show an asteroid moving through the frames toward the target. Instead looking at the first and last frame, the asteroid has not moved. Am I not applying the tool properly?
It should definitely move. One condition is that the recorderd time is different.
I haven’t looked to this routine for some time. I will check with my test sets.
Can you share a few images of your series with a significant time difference?
Han
Share in FITs format.
Sent several frames via WeTransfer.
No link yet. Can you send the Wetransfer link by personal message or just drop it here?
Asteroids move in my old test sets.
Han
I got the images. FOV is 0.2 degrees. They solve.
The asteroid move 26 arcsec/hour in Ra and 21 arcsec/hour in Dec. So about 33 arcsec/hour. See attached screenshot
Your pixelscale is about 1 arcsec pixel.
The time span is about 4 minutes or 1/15 of an hour. So the asteroid moves 33/15 is about 2 arcsecond or 2 pixels in the 4 minutes.
When I blink the images I can see some little movement. My conclusion is that the time span is just too short to see see significant movement.
To you have images much earlier or later?
Han
The occultation was predicted to occur at 02:34:32. I recorded from 2 min. before until 2min. after that time at an exposure of 0.5 sec. Examination of the light curve taken from theat series of FITS frames found an occulttion starting at 02:34:26.1 and ending at 02;34:34.7. I can send you the whole series. I have trimmed several frames from the beginning and end to make the series fit in 2G for WeTransfer.
Today I ran a JPL Horizon ephemeris for (934) Thuringia centered on the 4 min. surrounding
2021 12 31, 02:34:29 at 10 sec intervals. Making a mark on the image at the coordinates of each ephemeride showed, as you stated, the marks fell on top of each other and the target star.
But the Asteroid Annottion tool put Thuringia at the far edge of the image. I don't believe thatis correct.
?? Is the asteroid on attached image wrongly positioned?
What is the star position of the occulation?
JPL generates this for Amsterdam):
2022-Jan-13 01:36 m 05 31 23.13 +35 59 40.3 17.858 n.a. 2.17161819548005 12.1018042 149.0618 /T 9.5153 0.3970581 248.93771 49.260695 2.195 n.a.
2022-Jan-13 01:37 m 05 31 23.09 +35 59 40.1 17.858 n.a. 2.17162304941398 12.1026301 149.0611 /T 9.5155 0.3970186 248.93292 49.265385 2.193 n.a.
2022-Jan-13 01:38 m 05 31 23.06 +35 59 40.0 17.858 n.a. 2.17162790367840 12.1034522 149.0604 /T 9.5157 0.3969790 248.92813 49.270076 2.191 n.a.
2022-Jan-13 01:39 m 05 31 23.03 +35 59 39.8 17.858 n.a. 2.17163275827180 12.1042706 149.0596 /T 9.5159 0.3969392 248.92335 49.274768 2.190 n.a.
2022-Jan-13 01:40 m 05 31 23.00 +35 59 39.7 17.858 n.a. 2.17163761319268 12.1050851 149.0589 /T 9.5161 0.3968993 248.91858 49.279461 2.188 n.a.
2022-Jan-13 01:41 m 05 31 22.97 +35 59 39.5 17.858 n.a. 2.17164246843950 12.1058959 149.0582 /T 9.5163 0.3968592 248.91381 49.284155 2.186 n.a.
2022-Jan-13 01:42 m 05 31 22.94 +35 59 39.4 17.858 n.a. 2.17164732401074 12.1067029 149.0575 /T 9.5165 0.3968190 248.90906 49.288849 2.185 n.a.
This is the settup for a recording that did document an 8 sec. occultation
Star: UCAC4 664-034866
RA 05 13 32.1
Dec. 42 46 27.4
Asteroid: (934) Thuringia
Time: 2021-12-31 02:34:29 +- 4sec.
I recorded FITS frames from 02:32:29 to 02:36:29.
The attached image is taken from the start of the sequence and annotated with a marker at the position of the star and several markers from ephemerides taken over the 4 min paeriod. They all fall on top of each other as you rightly pointed out. The marker at Tools> Asteroid annotation shows the correct asteroid but at a great distance from the positions of the ephemeres.
Here is points to the correct place. See attached screenshot the red marked points:
1) Check solution. The RA, DEC values of the solution should match. If not is the tolerance of the solver not above 0.007
2) Is the minor planet ephemerides of the last 2 months?
3) Check date of observation
4) Check location.
Using an old MPCORB.DAT was the problem.
Thanks for solving my problem.