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Looking for a fast moving comet/asteriod that passed by about 1982?

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#1 opticsguy

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Posted 28 July 2021 - 05:56 PM

Looking for information about fast moving comet/asteroid that passed by about 1982?

 

I remember observing this object with my almost new Celestron C-8.   What I remember most was how fast this object was moving. Staring at the comet could not see it moving but if I took my eyes away for a short moment and then viewed again, the comet had moved.  

 

Anyone remember this event and could supply more information?  Not sure what year this was, 1979? 80? 81? 82? or ???



#2 MisterDan

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Posted 28 July 2021 - 06:13 PM

...maybe?...

 

https://www2.jpl.nas..._1983_1023.html



#3 Richard O'Neill

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Posted 28 July 2021 - 06:23 PM

"Staring at the comet could not see it moving but if I took my eyes away for a short moment and then viewed again, the comet had moved."

 

 How long was your 'short moment'?  Moved compared to what?

 

  Since you were observing with a early C-8 the apparent positional shift could have been attributed to the telescope's spur gear drive which allowed an image to oscillate back and forth within the field of view over a relatively short period of time (don't now recall the actual period).

 

  The only way you could have known for sure would have been to note a comet's position relative to background stars and watch for movement, not judged by the position in the field of view in a typical C-8 of that period.

 

 In those days, C-8 spur gear drives were notoriously frustrating for photographers who were required to continuously adjust a  variable speed drive's frequency to keep an object centered on a guide scope's cross hair. Ask me how I know. wink.gif


Edited by Richard O'Neill, 28 July 2021 - 06:25 PM.


#4 *skyguy*

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Posted 28 July 2021 - 06:26 PM

It could be comet C/1983 H1 (IRAS-Araki-Alcock) ...

 

I visually observed it on May 10, 1983 when it was moving about 30 degrees a day. It passed close to the Big Dipper bowl stars ... Dubhe and Merak ... around 11PM and its motion ... using the two stars as a reference ... could easily be seen within a minute or so. I looked like a huge circular cloud and knowing this was the closest pass to the Earth of a comet in 200 years, was somewhat disconcerting. It was easy to see why ancient peoples were terrified when a bright comet appeared in the night sky. 


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#5 DrAstro

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Posted 28 July 2021 - 07:03 PM

very good notes/memory.

 

I loaded up Stellarium with the comet info and set that date....bingo!

high in the north, near the bowl of the dipper as you recall.

stellarium estimates the mag to be 1.5, did you recall it being that bright?

 

see the attached file. the date is in UT time, so it is the night of the 10th.

 

stellarium-003sm.png



#6 spaceoddity

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Posted 28 July 2021 - 07:21 PM

Wow! I never knew a comet could move so fast that you can see the position change with a minute at the eyepiece. That is way cool. Hope we get decent comet to look at soon. Last years comet was pretty cool. Best one I've seen yet in the 12 years I've been in this hobby. 



#7 opticsguy

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Posted 28 July 2021 - 07:27 PM

Yes, this would be the one!!!   thankyou.

 

Yes, a very fast moving comet, nothing to do with spur gears.  I remember warm weather, clear skies, scope set up outside my house with street lights a block away.  Very memorable event (Yes, I did forget the year  :-)  )


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#8 *skyguy*

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Posted 28 July 2021 - 08:41 PM

very good notes/memory.

 

I loaded up Stellarium with the comet info and set that date....bingo!

high in the north, near the bowl of the dipper as you recall.

stellarium estimates the mag to be 1.5, did you recall it being that bright?

 

Knowing the distance between Dubhe and Merak was about 5º, I estimated the comet's diameter was about 1/3 that distance .... around 1.5º or a little bigger. Visually, it was very faint and it looked like a faint, round cloud slowly drifting across the sky (no nucleus). Magnitude 1.5 isn't going to be visually bright when spread across such a large area.

 

I've seen a number of comets over the years ... however, this little known comet will always be favorite. Mainly because it was so unique, but also because I just started getting into astronomy that year.


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