PDA

View Full Version : Comet 73P/Schwassmann-Wachmann 3 Fragment B, 2006/4/19 UT



Dave Mitsky
2006-Apr-19, 08:15 AM
A fellow ASH member and I were able to observe Comet 73P/Schwassmann-Wachmann 3 Fragment B from the Naylor Observatory last night. I'd already located the C fragment the previous night. After a few minutes of searching with an 18" f/5 Obsession, we tracked down B to the north of Psi Bootis.

Fragment B was rather ghostly looking and was obviously fainter than C, with a well-defined if somewhat dim tail. The ASH 17" f/15 classical Cassegrain provided a good view at 162x. I could see the B fragment through the scope's 5" f/5 finder and a 13mm Ploessl.

Earlier we observed the C fragment through another member's 10" f/10 Meade LX200, the 17" classical Cassegrain, and the 18" Obsession. The C fragment was visible through the Obsession's finder scope, a 66mm Williams Optics refractor.

I had to leave before we could locate the G fragment.

Dave

Melusine
2006-Apr-20, 04:37 AM
A fellow ASH member and I were able to observe Comet 73P/Schwassmann-Wachmann 3 Fragment B from the Naylor Observatory last night. I'd already located the C fragment the previous night. After a few minutes of searching with an 18" f/5 Obsession, we tracked down B to the north of Psi Bootis.

Fragment B was rather ghostly looking and was obviously fainter than C, with a well-defined if somewhat dim tail. The ASH 17" f/15 classical Cassegrain provided a good view at 162x. I could see the B fragment through the scope's 5" f/5 finder and a 13mm Ploessl.

Earlier we observed the C fragment through another member's 10" f/10 Meade LX200, the 17" classical Cassegrain, and the 18" Obsession. The C fragment was visible through the Obsession's finder scope, a 66mm Williams Optics refractor.

I had to leave before we could locate the G fragment.

Dave
I'm glad I've saved all my S&Ts, because comets are something I've admittedly glazed over, being partial to asteroids firstly. But in March's issue, David Levy refers to his article in December's issue, neither of which discusses this comet, and I'm thoroughly flustered over the A,B,C's of fragments. No images? :)

BTW, also mentioned in said S&T, is Levy's Deep Sky Objects: The Best And Brightest from Four Decades of Comet Chasing (http://www.amazon.com/gp/product/1591023610/sr=8-1/qid=1145506742/ref=pd_bbs_1/104-4252304-0528718?%5Fencoding=UTF8). Have you read it or reviewed it, Dave? Even though I might not be up to speed on comets, I have read enough (which is not a lot) of Levy's articles to know he can be an enthusiastic writer. Maybe others are familiar with this book as well.

Comets indeed make prettier images than asteroids, for sure.

Dave Mitsky
2006-Apr-21, 06:58 AM
Over 25 comets have been known to fragment, Comet Shoemaker-Levy 9 being undoubtedly the most famous example.

http://www.solarviews.com/eng/comet/frag.htm

Capturing a decent image of an eighth to ninth magnitude diffuse object really requires a dedicated CCD camera and a darker sky than we have at the increasingly light polluted Naylor Observatory.

http://www.ne.jp/asahi/stellar/scenes/comet_e/sw3_060331.htm

http://www.austskyandtel.com.au/Comet73P.htm

I recently checked that book out of a local library but haven't had a chance to read much of it yet. Since the bogus Caldwell Catalogue came into being, it's de rigueur to name a list of well-known deep-sky objects after oneself I suppose. ;) I do own a number of David Levy's many other books.

I first met David at the 1995 Winter Star Party and have heard him speak at Stellafane and a number of other venues since then. He's a prolific writer but can be just a bit too earnest, especially while speaking, for my tastes at times.

Dave Mitsky

Melusine
2006-Apr-21, 07:50 AM
Over 25 comets have been known to fragment, Comet Shoemaker-Levy 9 being undoubtedly the most famous example.

http://www.solarviews.com/eng/comet/frag.htm
http://www.ne.jp/asahi/stellar/scenes/comet_e/sw3_060331.htm
http://www.austskyandtel.com.au/Comet73P.htm

Thanks, Dave, those are three links that are new to me, and the first one is "dangerous" in a good, though distracting, way. I saw "Puzzles" and made the mistake of clicking on it. I need a monitor with a cord (no, not a laptop), so I can read in bed. I didn't even realize there was an Aussie S&T...the www is expanding rapidly. :wall:



I recently checked that book out of a local library but haven't had a chance to read much of it yet. Since the bogus Caldwell Catalogue came into being, it's de rigueur to name a list of well-known deep-sky objects after oneself I suppose. ;)

Hmm, well, personally, two asteroids here were named after benefactors to the observatory, and considering the number of asteroids, I have no problem with self-naming asteroids. I don't really understand the nature of your comment, though, regarding deep-sky objects. I just know that if I hung out at the observatory enough, fooled around with the PC while the AA went to the bathroom or something, then snuck into their house to read the downloads, I could possibly* find an asteroid and want to name it after myself (my real name). Seriously, I would like to learn how to do that...I like the whole method of looking for them. BOT, I am looking at http://www.seds.org/messier/xtra/similar/caldwell.html and am further confused by your comment. The "bogus" part of it. :think:


but can be just a bit too earnest, especially while speaking, for my tastes at times.

...at least he said comets are like cats...that's not too earnest. :eh: <---that's a Canadian "eh?" symbol, meaning the cat comment was OK by me.

*"Possible" has a lot of latitude.

Dave Mitsky
2006-Apr-21, 01:51 PM
Melusine,

Comets are the only astronomical objects that are officially named after their discoverers. People who discover asteroids are permitted to suggest a name, which must meet with the approval of the IAU's Committee on Small Body Nomenclature. Some rather odd monikers have been the result such as James Bond, Mr. Spock, and Cheshirecat.

http://www.johnstonsarchive.net/astro/names.html

http://www.ss.astro.umd.edu/IAU/csbn/

http://wc.arizona.edu/papers/96/108/01_2.html

http://cfa-www.harvard.edu/iau/lists/MPNames.html

The so-called Caldwell Catalog(ue) is really essentially a marketing device and not an astronomical catalog like the Messier Catalog(ue), the NGC, or the Uppsala General Catalog(ue) of Galaxies. (See http://www.maa.agleia.de/Cat/listing.html and http://cdsweb.u-strasbg.fr/cats/cats.html for many, many more.) Sir Patrick Moore (Caldwell-Moore) submitted a list of deep-sky objects to Sky & Telescope and before you know it - $$$ka-ching$$$ - the Caldwell Catalog(ue) was for sale. Moore was justifiably famous for his lunar observing, his many books, and his British television program but was never known as a deep-sky observer and actually expressed some disdain for DSO observing before it became fashionable according to author Phil Harrington. The Dobsonian revolution changed the nature of amateur observing by making large aperture scopes affordable to many amateur astronomers and soon the Moon and double stars were passe and the deep-sky ruled.

Many dedicated deep-sky observers have strong reservations about the Caldwell Catalog(ue). Moore neither discovered any of the objects on his list (and that's all it is, a list of objects that without the cache of Moore's name would be just like any other of the many DSO lists that existed prior to the Caldwell Catalog(ue)*) nor did he do professional level research on any of them.

http://members.aol.com/anonglxy/lingmoor.htm

From the Astronomy Magazine web site:

DEEP-SKY OBSERVING
The Caldwell Catalog
When British astronomer Sir Patrick Moore published his list of deep-sky objects in 1995, many people cried foul, while others erupted in praise. Regardless of which side you’re on, the Caldwell Catalog is here to stay. MICHAEL E. BAKICH

If anyone deserves an honorary deep-sky catalog, it's Walter Scott Houston, who through his "Deep Sky Wonders" column did more to promote DSO observing than anyone else in amateur astronomy.

http://ottawa.rasc.ca/astronotes/1994/an9402p6.html

http://infinity.my-expressions.com/archives/2368_1035328070/102851

* see http://www.seds.org/messier/xtra/similar/catalogs.html

Dave Mitsky

Dave Mitsky
2006-Apr-21, 02:59 PM
Returning to the subject of the fractured comet, I was at the Naylor Observatory on Wednesday night to help out with the observing portion of the ASH spring astronomy class. The B fragment seemed even more difficult to see through the 17" classical Cassegrain than it did the previous night.

Dave Mitsky