Author Topic: How many people have observed ___ ?  (Read 451 times)

Ivan Deane

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Re: How many people have observed ___ ?
« Reply #30 on: January 31, 2018, 11:45:05 AM »
I've got the Herschel 400, the little Caldwell (76), The MEssiers (and Bino Messiers), and several other lists from the Astronomical League ....

Adding up all the lists, I suspect the number of separate observations would be around 1000.

But, of course, many of the lists (Urban astronomer, for example) have objects that are already on the other lists.

I would not at all be surprised that if I were to add up all the things I have seen, I have seen fewer than 1000 different objects. And I am one of the more serious observers in my club!!!

Interesting.

Alex

Woody Boelkens

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Re: How many people have observed ___ ?
« Reply #31 on: February 02, 2018, 10:17:17 PM »
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So I don't know.. but I find the whole concept intriguing. On a personal level, the next time I am viewing taking in some 15th magnitude galaxy that's not on any special list, in the back of my mind, I will be wondering, just how many other people have seen this, 100? 1000? 10,000? More? Less?

Could it really be that I might be viewing something that less that a 10,000 people have ever seen? I have a hard time getting my head around that thought.
It would be unlikely that there are enough amateur astronomers to reach that 10,000 mark for observing that 15th magnitude galaxy.

Honestly, not a chance! Once you reach the 15th magnitude, if the magnitude figure is truly valid, then you are pretty much nearing the ragged edge of what most large amateurs scopes can pick out visually for stars. When it comes to extended objects like galaxies the challenge is a lot tougher to pick them out vs. stars of the same magnitude.

There are additional problems, too. First off, relatively few hobbyists currently have the capability of detecting galaxies that faint today since even with their larger telescopes they are being seriously hobbled by light pollution. Secondly, and perhaps even more important, until very recently such obscure objects were not ever considered the targets of 99% of active hobbyists. I might add also that, although I expect that most of today's amateurs aren't aware of it, tracking down DSO much beyond those contained in the Messier list, plus a scattering of the brighter NGC examples, was not a common pursuit among hobbyists until relatively recently. In fact, it didn't gain real prominence until the latest generation of telescopists. Scotty Houston's famed Deep Sky Wonders column in S&T was never composed of more than just a few paragraphs for decades; a sort of after thought among the Observers' Page topics. Contrast that with the topic's increasingly taking over more and more of each issue's page count of S&T today!

Something similar rings true concerning Pluto. Even when still regarded as the 9th planet, only a relatively small percentage of hobbyists could claimed to have actually tracked it down and seen it more than once. Good finder charts weren't often published (there were no planetarium programs either years back) and few hobbyists were interested in tracking down what simply looked like just another very faint star in their 6" and 8" scopes.

BrooksObs
There aren't enough large-enough telescopes for very many people to have observed a random 15th-magnitude galaxy. The numbers of such galaxies are too large. But can you imagine that if you are looking at it, that ten others have also seen it?

tidutamar

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Re: How many people have observed ___ ?
« Reply #32 on: February 08, 2018, 08:34:18 PM »
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I've got the Herschel 400, the little Caldwell (76), The MEssiers (and Bino Messiers), and several other lists from the Astronomical League ....

Adding up all the lists, I suspect the number of separate observations would be around 1000.

But, of course, many of the lists (Urban astronomer, for example) have objects that are already on the other lists.

I would not at all be surprised that if I were to add up all the things I have seen, I have seen fewer than 1000 different objects. And I am one of the more serious observers in my club!!!

Interesting.

Alex

The faintest Messier appears be galaxy M91, about 10th magnitude. Aside from those in your club known to have received the Honorary Messier Award, what might be your guess as to how many others in your club have seen it after having found it on their own?

adviconno

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Re: How many people have observed ___ ?
« Reply #33 on: February 09, 2018, 05:51:17 AM »
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<p class="citation">QuoteThe Messier and Herschel awards give solid evidence of how many people have seen all of the objects on those lists. Beyond that, we can't really assume that very many others have seen all of them, though a small number could very well have, or at least a large percentage of the objects in the lists, more for the Messiers, fewer for the Herschels. Or maybe not.


I have seen all the Messier objects but I have made no attempt to view objects on the Herschel lists because my interests and style take me elsewhere. I suspect many are like me, in this day and age, the access to large databases makes doing it your own way quite easy.

Jon

Similarfor me. I did all of the Messier's the first year I had a scope, all of the planets, all of the moons visible in that scope and would target NGC's shown in Sky Atlas 2000. I printed Herschel 400 and 2500lists and logged some, but mostly I quit logging the less interesting ones and I did not pursue these lists systematically. I have restarted logging them, but I still oftenneglect to go back and crosscheck. Once the list reaches much above a hundred, completion of it becomes challenging. Part of that is remembering to pull out the list throughout the year to fill gaps.

I tend to work a "project" area,sometimes from articles, sometimes just a page in Uranometria, sometimesDSO'ssurrounding a galaxy that has a supernova. Probably less than half of what I observe gets recorded even when I am making an effort to doso and maybe half of that doesn't make it on my Herschel lists. I spend more time chasing "squirrels" I notice along the way--15th magnitude galaxies thataren't on my charts. When I findsomething brighter andinteresting and am not sure if I have observed it in the past, I mostoften find old notes for itfrom the early days with the SCT.

While the certificates are one way to make an estimate, it is going to be difficult to come up with a multiple for those who did the lists (or most of a given list) withoutpursuing a certificate. Record keepingis an issue with the longer lists and I doubt most log frequently enough (reminding myself that I need to trudge through abacklog of several hundred galaxies observed recentlybut not yet checked against the Herschel lists.)
There might be other ways to make estimates.

Maybe 50,000 objects are visible in a 20-inch telescope?

Maybe 100 observers are inclined to go after some of the 49,000 of those that we presume most people won't look for?

They could each have 490 objects of their own.

A thousand such observers could each have 49 objects of their own, but nothing really stops them from eventually observing 490 if they choose, except maybe a shortage of 20-inch telescopes?

Nicholas Becker

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Re: How many people have observed ___ ?
« Reply #34 on: February 09, 2018, 07:18:51 AM »
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There might be other ways to make estimates.

Maybe 50,000 objects are visible in a 20-inch telescope?

Maybe 100 observers are inclined to go after some of the 49,000 of those that we presume most people won't look for?

They could each have 490 objects of their own.

A thousand such observers could each have 49 objects of their own, but nothing really stops them from eventually observing 490 if they choose, except maybe a shortage of 20-inch telescopes?

One guess is as good as another I suppose. I suspect there are quite a few large scopes out there these days, say 16" and larger. I couldn't even count the number of makers and apertures available just in the U.S. These are scopes well suited for seeing tens of thousands of galaxies.

To get some idea of how manyof these scopes there could be, my 2003 vintage Obsession has a 900's serial number. A 1990 20" f/4 is listed as #004. I see a 25" f/5 onoldAstromart ad listed as 1751 (didn't give the year.) In the time frame I ordered mine I believe the standard offerings were 12.5, 15, 18, 20, and 25--no UC's at the time. There were also several 30" and I believe four 36" scopes produced. I don't know what the distribution is of the standard production butI see a lot of 20" and 25" Obsessions listed at various times. I suspect there are overone hundred 25" alone, and probably several times asmany 20". That is just one maker.

Of the 22 current reflector classifieds that came up on Astromart (actual usedscopes for sale, not "wanted",thewrong scope type, accessories, etc.) two are 25" Obsessions, one is a 22" Obsession,one is an 18" (NGT), and there are seven 16" scopes listed of various types.

For any given dim galaxy past the NGC's/IC's, the likelihood of someone observing it probably is mostly about whether it is near anything else that draws observers or whether it has been featured in some article. A 15th magnitude galaxy off in a void and without an NGC # is unlikely to be observed even by the hardcore amateur. One that is only half a degree away from a group of NGC's, an Arp gx group, Abell, a globular or an open cluster is likely to catch a few visitor's attention along the way.

Ivan Kim

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Re: How many people have observed ___ ?
« Reply #35 on: February 09, 2018, 09:21:43 AM »
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This is a question that keeps running through my mind. How many people have observed &lt;pick your object&gt; throughout all of history? Actually observed with their own eyes, not seeing the object in a photograph...

How about the Transit of Venus? Up until the transits of 2004 and 2012, I doubt if very many had seen one (think of poor Le Gentil).

With the last two transits, the number spiked dramatically.