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 Betreff des Beitrags: Entdeckung - C/2021 O1 (Nishimura)
BeitragVerfasst: 26. Juli 2021, 06:39:12 AM 
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Registriert: 20. Januar 2013, 20:03:54 PM
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12 mag am 24. Juli.

Micha war beteiligt:
Code:
OC   Date        Reporter           Coma    Tail    PA          Exposures
D78  2021-07-23  H. Sato            1'.2                          2x20s
A71  2021-07-24  M. Jaeger          130"     300"   287          20x30s
:
Code:
Orbital elements:
    C/2021 O1 (Nishimura)                                                       
T 2021 Aug. 12.93249 TT                                 Rudenko                 
q   0.7965502            (2000.0)            P               Q                  
                   Peri.   72.64711     -0.33375951     -0.89292731             
                   Node    41.17165     +0.59156189     -0.44794502             
e   1.0            Incl.   27.31939     +0.73393401     -0.04501192             
From 46 observations 2021 July 21-24.                            


https://minorplanetcenter.net/mpec/K21/K21O47.html
(CBET 5004)

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Uwe Pilz, Fachgruppen Kometen und Astrophysik/Algorithmen.
Oft benutzte Instrumente: Swarovski SLC 7x50B, Fujinon 16x70 FMT-SX-2, TMB Apo 105/650, Skywatcher Evostar 120/900 ED, Ninja Dobson 320/1440


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BeitragVerfasst: 26. Juli 2021, 11:54:34 AM 
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Aktuell geht er gerade noch. Heute (26. Juli) habe ich versucht nachzustellen, wie er auf der Entdeckungsaufnahme ausgesehen haben muss. Bild mit Leica-Tele f-180/4 und Z50, im Newton zeigt er einen Schweif. Gruß Michael


Dateianhänge:
2021O120210726UT140gif.gif
2021O120210726UT140gif.gif [ 4.19 MiB | 1023 mal betrachtet ]
2021O1202100726UT138sec10x60.jpg
2021O1202100726UT138sec10x60.jpg [ 1.32 MiB | 1023 mal betrachtet ]
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BeitragVerfasst: 26. Juli 2021, 14:27:55 PM 
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die Auswertung von heute ergab 9m4 Koma 2,5' und Schweif 6' PW 293


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BeitragVerfasst: 26. Juli 2021, 21:05:56 PM 
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Gratulation! Eine fantastische Leistung!


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BeitragVerfasst: 27. Juli 2021, 09:09:05 AM 
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Registriert: 01. Juli 2018, 21:40:23 PM
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Hello All,

After more than a month of nothing but clouds and 6 inches of rain here in the desert I did not expect to have a night where one could see 50% of the sky and actually image some comets. Collected 48 images of Comet C/2021 O1 (Nishimura) on the morning of July 26, 9 of those images actually showed the comet clearly thru a 5 minute opening in the clouds. The images were all 30 seconds long.

So with the Moon 93% illuminated, the comet 7 degrees above the horizon and surrounded by clouds these images see a comet that is magnitude G=9.2, a 76" coma, but not the tail that Michael caught in his images.

Did I mention that living in the desert the last thing that I have had to worry about was dew on the telescope optics until this night when the humidity was 80%, a 1500 watt portable heater does a nice job of evaporating the moisture near a telescope, only a few times all night did I have any fogging on the optics after I started using the heater.

I hope all are well and safe from all the flooding that you have had in Germany.


Dateianhänge:
2021O1_20210726_1119_molason.jpg
2021O1_20210726_1119_molason.jpg [ 377.76 KiB | 936 mal betrachtet ]

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BeitragVerfasst: 27. Juli 2021, 09:25:12 AM 
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Well done Mike. I measured 9m4, coma 2,5' and tail 6' pa 293 on jul. 26 cs Michael


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BeitragVerfasst: 28. Juli 2021, 05:22:48 AM 
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Hello Michael,

Thank you, yes I see that your magnitude measurements are close to the 9.2 that I measured so one would assume that we are close to what the true comet magnitude might actually be, but it is tough to figure out with the comet so low above the horizon.

I always enjoy your gifs, they show the comet much better in some ways than a stacked image. So I created a gif from 10 images each 30 seconds long covering the time from 111920-112502 UT on the morning of July 26 with the last image showing the clouds moving back into the field of view. My gif does not show the comet tail but conditions were not ideal so it does not surprise me.

It was cloudy the morning of July 27 near the horizon and heading into July 28 the sky is cloud covered, I am hoping to get a few more images of the comet before it moves to close to the Sun's glare.

Hope you are having better luck, look forward to your images and gifs if you get a chance to image it again.


Dateianhänge:
2021o1_20210726_1118_molason_gif_crop75.gif
2021o1_20210726_1118_molason_gif_crop75.gif [ 3.25 MiB | 882 mal betrachtet ]

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:lol: Arizona
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BeitragVerfasst: 30. Juli 2021, 16:42:31 PM 
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Die Messungen von heute zeigen eine deutliche Abweichung von der Ephemeride. Am 30.7. war er nur noch 9m7 hell mit 3' Koma ohne Schweif auf den Grünaufnahmen mit 8"/2.0 und QHY600


Dateianhänge:
2021O120210730UT142sec4x50b.JPG
2021O120210730UT142sec4x50b.JPG [ 325.24 KiB | 765 mal betrachtet ]
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BeitragVerfasst: 31. Juli 2021, 08:14:11 AM 
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Hallo Michael,

hast Du ihn astrometriert? Wenn ja, kannst Du mir die Daten senden?

Hier eine neue Bahn mit der einen Beobachtung, die ich blinderweise nicht gesehen habe.
Code:
Orbital elements:  C/2021 O1
   Perihelion 2021 Aug 13.89030 +/- 0.0299 TT;  Constraint: e=1.0   Meyer
Epoch 2021 Jul 30.0 TT = JDT 2459425.5   Earth MOID: 0.1309   Ma: 0.0930
q   0.78726102 +/- 0.000247         (J2000 ecliptic)
H    9.5  G 0.15                    Peri.   74.37410 +/- 0.052
                                    Node    41.60269 +/- 0.014
e   1.0 +/- 0                       Incl.   27.57269 +/- 0.006
34 of 47 observations 2021 July 22-30; mean residual 0".66
CS

Maik


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BeitragVerfasst: 01. August 2021, 08:46:40 AM 
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cbet 5008 berichtet über Atrometrie, auch basierend auf Aufnahmen von Micha:
Code:
 
    2021 UT             R.A. (2000) Decl.       Mag.   Observer
    July 25.79789    6 57 02.65   +31 13 50.0   10.5   Yoshimoto
         25.80154    6 57 04.08   +31 13 51.6            "
         25.80559    6 57 05.67   +31 13 53.3            "
         26.06836    6 58 47.71   +31 15 33.4   12.8   Jaeger
         26.07063    6 58 48.60   +31 15 33.3   12.9     "
         26.07288    6 58 49.44   +31 15 35.5   12.7     "
         26.07833    6 58 51.65   +31 15 37.0   12.3     "
         26.08141    6 58 52.92   +31 15 37.3   12.3     "
         27.76235    7 09 52.12   +31 24 17.8          Kadota
         27.76542    7 09 53.33   +31 24 18.5            "
         27.76870    7 09 54.61   +31 24 19.2    9.7     "
         30.07253    7 25 10.95   +31 30 05.5   11.9   Jaeger
         30.07553    7 25 12.24   +31 30 03.5   12.3     "
         30.07807    7 25 13.25   +31 30 04.3   12.2     "

K. Yoshimoto (Kumage, Yamaguchi, Japan).  0.20-m f/8.0 Ritchey-Chretien
reflector + CCD.  Condensed coma 1'.8 in diameter and straight tail 4'.5
long in p.a. 290 deg.
M. Jaeger, E. Prosperi, and S. Prosperi (Stixendorf, Austria).  0.3-m f/4
reflector + CCD (July 26) and 0.2-m f/2.0 reflector + CCD (July 30).
K. Kadota (Ageo, Japan).  0.25-m f/5 reflector + CCD.




Verbesserte Elemente:

Code:
    T = 2021 Aug. 13.92185 TT        Peri. =  74.44011
                                     Node  =  41.60330 2000.0
    q = 0.7870368 AU                 Incl. =  27.57029
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.

(C) Copyright 2021 CBAT
2021 July 31 (CBET 5008) Daniel W. E. Green

_________________
Uwe Pilz, Fachgruppen Kometen und Astrophysik/Algorithmen.
Oft benutzte Instrumente: Swarovski SLC 7x50B, Fujinon 16x70 FMT-SX-2, TMB Apo 105/650, Skywatcher Evostar 120/900 ED, Ninja Dobson 320/1440


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BeitragVerfasst: 02. August 2021, 20:31:14 PM 
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Hallo,

meine Seite zu den Kometenentdeckern ist aktualisiert. Ich habe ein paar Bilder des Entdeckers erhalten. Die Geschichte zur Entdeckung muss noch von einem anderen japanischen Kometenentdecker in Englisch übersetzt werden.

https://www.cometchaser.de/discoverysto ... erers.html

Stefan


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BeitragVerfasst: 03. August 2021, 02:28:43 AM 
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Hello All,

Since my last images the clouds have lived above the Mountain Range where I have to try and image the comet, I have 100s of images of clouds. On the morning of 1 August 2021 a few holes opened up in the clouds which allowed several fairly decent 30 second images while it was still relatively dark. Then when bright twilight appeared the comet moved above the clouds and allowed for 20 uninterrupted images each 15 seconds long. All was clear in the night sky on 2 August 2021 except above the Mountain Range, so again a lot of cloud images, maybe a few to put together but they are very bad.

The results from 1 August 2021 show a comet at about magnitude 10 in the 30 second images and magnitude 10.6 in the bright twilight 15 second images. I have no idea how twilight, clouds and images 5 to 9 degrees above the horizon affect magnitude calculations so I will let those with better knowledge determine what my data generated by Astrometrica means for the comet magnitude.

From what one can see in the images the comet has a coma at least 1' wide and a tail at least 1' long at a PA of 298 degrees.


Dateianhänge:
2021O1_20210801_1120_molason.jpg
2021O1_20210801_1120_molason.jpg [ 405.2 KiB | 606 mal betrachtet ]

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BeitragVerfasst: 03. August 2021, 06:22:27 AM 
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Hello All,

Managed to find 7 out of 50 images to make a gif from the 30 second images collected on 1 August 2021. Clouds still appear in these images but one can still see some of the coma and tail. The information about the comet from 1 August 2021 is in the post above. The gif is 7x30 seconds from 1112-1134 UT. At 1112 UT the comet was only 3 degrees above the horizon.


Dateianhänge:
2021O1_20210801_1120_molason_gifcrop.gif
2021O1_20210801_1120_molason_gifcrop.gif [ 3.34 MiB | 590 mal betrachtet ]

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BeitragVerfasst: 04. August 2021, 12:01:16 PM 
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Hello All,

Found the comet under the clouds on the morning of 3 August 2021 at 4 degrees above the horizon, well technically just above the mountains. Found 8 good images out of 44 with the last 23 full of clouds and the first 7 images to low to show much. The comet is now showing less detail as it gets closer to the horizon. Can see a coma of about 1' and a tail at least 1' long. The magnitude is still about magnitude 10.


Dateianhänge:
2021O1_20210803_1122_molason.jpg
2021O1_20210803_1122_molason.jpg [ 418.76 KiB | 525 mal betrachtet ]

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BeitragVerfasst: 06. August 2021, 12:36:07 PM 
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Hello All,

Finally a morning with no clouds. Images of Comet C/2021 O1 (Nishimura) from the morning of 5 August 2021 at it's close approach to Earth at about 254 million km. The images were collected just above the mountains from 4 to 6 degrees above the horizon in morning twilight. In the twilight nothing other than the brighter part of the coma was visible. Astrometrica calculated the magnitude at G=9.0 and G=9.1 although not sure how accurate that is in the conditions the images were collected in and with the SNR at 2.8 and 4.2 for the 2 different group of image estimates.

I have images to process from the morning of 4 August 2021 but have not had the time to do so. The comet has become to low and faint in the morning twilight now to make any more attempts to image it, this morning maybe but it is cloudy. Now for some rest the next few nights.


Dateianhänge:
2021O1_20210805_1129_molason.jpg
2021O1_20210805_1129_molason.jpg [ 639.98 KiB | 434 mal betrachtet ]

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BeitragVerfasst: 07. August 2021, 11:44:58 AM 
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Hello All,

So in my last post showing images from 5 August 2021 of Comet C/2021 O1 (Nishimura) I mentioned that I had collected images of the comet on 4 August 2021. Below are those images and a gif which were collected under clear skies.

The gif is a collection of 12 images each 30 seconds long from 1124-1135 UT. Comparing this gif to the first gif that I put together of the comet back on 26 July 2021 above one can see what the visual affect on the comet has being lower to the horizon and instead of it being in fairly dark skies the comet in this gif is in skies at the beginning of twilight. All images in both gifs were 30 seconds long and according to calculations by Astrometrica the comet magnitude was about the same on both dates, G=9.0 and G=9.2. The only thing that I did to any of the images in these gifs was a dark subtraction and a flat field, so other than that the gifs show exactly what the camera showed me as raw images.

The images and the Astrometrica data show a different combination of images and times to see if the results will differ much by differences in the sky twilight, elevation above the horizon and how many images were used to generate the magnitude calculations. I did many different combinations and the results always showed a comet magnitude from G=8.9 to G=9.1, so it appears that the comet was G=9.0 according to Astrometrica. What one could see of the coma suggested it was at least 90" wide and that there was a very faint fan tail at a PA of approximately 280 degrees. All images collected were from 4 to 6 degrees above the horizon, just as the comet appeared above the mountain range.

After the attempted collection of images the past 11 mornings I have come to some conclusions about what the comet magnitude showed me using Astrometrica. On July 26 under relatively dark skies and getting some images thru a hole in the clouds the comet was magnitude 9.2. On August 1 and August 3 with thin clouds always present and with twilight conditions the comet magnitude was around magnitude 10. On August 4 and August 5 with no clouds but lower elevations and more twilight the comet was magnitude 9.0. It looks like the clouds made a big difference in the way that Astrometrica calculated the magnitude of the comet, a 1 magnitude difference unless the comet just happen to fade by a magnitude on August 1 and August 3 before brightening again.

So the question that I have to all the gentlemen and gentlewomen who understand how thin clouds, twilight and low elevations affect comet magnitudes, what do you make of the data that I have presented on this comet and it's magnitude? From this data what would you actually estimate the comet magnitude to be as it made it's close approach to Earth?

Thanks to all who might comment, feel free to make any suggestions, believe me, you can't hurt my feelings, I am just trying to learn.


Dateianhänge:
2021O1_20210804_1123_molason_gif12Icrop.gif
2021O1_20210804_1123_molason_gif12Icrop.gif [ 4.93 MiB | 386 mal betrachtet ]
2021O1_20210804_1124_molason.jpg
2021O1_20210804_1124_molason.jpg [ 474.85 KiB | 386 mal betrachtet ]

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BeitragVerfasst: 10. August 2021, 22:35:47 PM 
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Hallo,

mit der Hilfe von Shigemi Murakami konnte ich Kontakt mit dem Entdecker aufnehmen und jetzt gibt es auch eine Story zur Entdeckung dazu.


https://www.cometchaser.de/discoverysto ... erers.html

Gruß,
Stefan


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