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Tracking asteroids and Ceres

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#1 jrkirkham

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Posted 23 October 2020 - 10:19 PM

Has anyone spent much time tracking asteroids or Ceres? If so what telescopes have worked best for you?



#2 astro_1

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Posted 24 October 2020 - 12:01 AM

This summer I was trying just that. Asteroid Pallas with an ES127 and QHY174 at 30 second exposures every 20 minutes. Needed to spread that out even more to see movement.

 



#3 Napp

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Posted 24 October 2020 - 12:22 AM

The size of the telescope needed to visually track asteroids depends on the brightness of the asteroids to be tracked.  For the brightest asteroids only a pair of binoculars is needed.



#4 jrkirkham

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Posted 24 October 2020 - 09:31 AM

I was thinking about a C11 with a .63x focal reducer, but that might have too small of a field of view with 1764mm focal length.

I also thought of my 80 ED. It has a shorter focal length, but the aperture is small.

I thought about using a Canon DSLR to record the star fields.

I didn't know how long to go between exposures. If 20min is too short I wonder what a better attempt might be, possibly an hour? Or would I perhaps need to go out on several different nights?

 

Hmmm, I just realized I've never listed my equipment so people would know what I have to choose from. I'll have to fix that.



#5 Tapio

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Posted 24 October 2020 - 10:03 AM

Planetarium software will tell the movement of asteroids.

#6 Redbetter

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Posted 25 October 2020 - 02:12 AM

Has anyone spent much time tracking asteroids or Ceres? If so what telescopes have worked best for you?

Any telescope for Ceres and Vesta.  In their closer oppositions I can find those two naked eye in dark sky for a few weeks or months. Pallas, Iris, and Eros can also become bright enough to be seen naked eye.   The primary difficulty for asteroids in the telescope is identifying vs. field stars.   



#7 Mike McShan

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Posted 29 October 2020 - 06:03 PM

Tonight, magnitude 8.1 Flora will be about 5' from Gamma Ceti. It should be visible in fairly small scopes. Take a look around 0400 UTC,.

 

Clear skies, Mike


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#8 ButterFly

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Posted 10 November 2020 - 01:08 AM

AstDyS-2 for the not so close ones (slow moving).  These can often be big and bright.

 

NEODyS-2 for the near Earth ones that are faster moving.  These are usually much more dim and not as big (one would hope!).  They can move very fast.

 

These are good sites that gives predictions for today (or for a future date, top right corner dorp down) with searches for apparent magnitude and speed.  On most sites, the absolute magnitude is given for asteroids, which is defined as the brightness if it were 1 AU from the observer AND the sun.  That's not very helpful information for what its apparent magnitude is tonight, nor for how fast it's moving.

 

For several nights this month, I was following around 1999 AP10, which was as bright as 13th mag and moving over 2 deg/day.  I have been using a night vision device on a 15" to follow things as dim as 16-17th mag that move very quickly. 

 

SkySafari is absolutely terrible with near Earth asteroids.  The mpcorb files it pulls do NOT include the NEA lists.  For the big slow moving ones, it's fine.  The sites above can generate ephemerides, and it's very accurate if you use an observatory code that is nearby to your observing site.  They also generate mag 18 charts that you can use in the field.  Stellarium lets you chose which files to update from and which asteroids in those files to import the elements of.  Get to know the "update solar system" feature well.

 

First step is to check how deep you can see with your setup, either visually or photographically, or both.  Limit your searches to those mags.  You can also limit by speed, entering a value in degrees per day (2 deg/day is detectable in a few minutes at the eyepiece).  For conversions, to go from degrees per day to arcseconds per second (or arcminutes per minute, or degrees per hour, same values!), divide by 24.  To go from degrees per day to arcseconds per minute (or arcminutes per hour), multiply by 2.5.  That will let you know how long to observe or photograph to detect motion in a single viewing period.  So 2 degrees per day is the same as 5 arcseconds per minute.

 

A C11 should get to at least 17th mag photographically with shorter exposures.  Hunt down those fast moving NEAs.  Once they are digital, calculating orbits is the next step!


Edited by ButterFly, 10 November 2020 - 01:11 AM.

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#9 Zorbathegeek

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Posted 10 November 2020 - 04:59 AM

I love star hopping to find asteroids. I've used my 6" dobsonian to find objects down to 9th magnitude from my urban location. I have a 10" with which I can find objects down to about 10.5 magnitude under city skies. I only ever use a 25mm eyepiece for star hopping.  all of the bright asteroids with opposition dates and daily magnitudes. After observation I record in my log, when the asteroid was first discovered, mean diameter and any other interesting (to me) details. I get a kick each time I find an asteroid that's smaller than any I've viewed before. I also keep an eye on the "Bright NEO" page, also to be found on Gideon van Buitenen's site, for tiny objects - although these are very rarely within my magnitude range.

 

Ray.


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#10 jrkirkham

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Posted 10 November 2020 - 09:35 AM

Thank you all. This is very helpful.




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