Sunday, September 25, 2016

 

Issue #510, Conquering the Herschels


By “conquering,” I don’t necessarily mean you have to do what I did and observe all 2500 Herschel deep sky objects. While it is a worthy quest to Catch ‘em All, that’s not for everyone. On the other hand, what are you gonna do when you finally run out of Messiers? Sure, that list, as I’ve said in my ongoing series of articles about it, can deliver a lifetime of enjoyment, but once you’ve been through it a couple of times, you will likely want other things to see, something new, some different list to work. For more than a few of us that list is a subset of the Herschels, the Herschel 400, a best of the best.

What made me decide to not just finish the Herschel 400, but to go after over two thousand more faint fuzzies? The Herschel Project was born one autumn night in the piney woods of Louisiana when your Uncle Rod was out on the observing field of the 2009 Deep South Regional Star Gaze without a clue as to what to look at next.

I’d begun the evening with a list, Sue French’s “Deep Sky Wonders” column in the then current issue of Sky & Telescope. Alas, even though I gave each object its deserved share of eyepiece time, Sue’s dozen or so DSOs didn’t take all night to hunt up, not hardly—I was using the deadly-accurate Sky Commander digital setting circles computer on my 12-inch Dobsonian, Old Betsy. There were still plenty of hours of darkness to be filled when I finished. After some objects from a magazine article I had at hand, I turned to the showpieces, from the North America Nebula and the Swan Nebula sinking in the west, to M31 and M33 rising in the east. That was OK, but not really what I had in mind. I was becoming at least dimly aware what I wanted was new stuff.
As two a.m. came and went, I wasn’t sleepy but I was bored. I didn’t think it would ever happen, but it seemed I had finally run out of sky objects to view. That wasn’t really possible, of course, since there are thousands and thousands of deep sky objects—galaxies, nebulae, and star clusters—in range of a 12-inch telescope. I just didn’t know which of that multitude I should chase. Sure, I gloried in the Great Orion Nebula when it rose above the pine trees, but I wanted to see that new stuff. To push back my amateur astronomy frontiers. I needed some kind of project to work on.
The next morning, though not early the next morning, after a big country breakfast (those were the days when I wasn’t afraid to fill up on biscuits, gravy, and sausage) that was thankfully not served till nine, I spent quite some time thinking about what would be on Saturday evening’s observing agenda. For a while, I’d had the idea that I should do something about finishing the Herschel 400, which I’d begun years before, had returned to seriously the previous October at the Chiefland Astronomy Village, but which I still hadn’t completed.
Where the Project officially began, DSRSG 2009...
By Sunset Saturday, the die was cast: I would stop lollygagging and finish the supposedly scary Herschel 400. To do that, I’d of course need to know which 400s I still needed to see. Luckily, I still had the list from that October CAV expedition on my laptop in SkyTools 3 (the observing planning program) format, and the program showed me at a glance exactly how many I’d done, how many I still needed to do, and which of those would be available Saturday night at Deep South. Surprisingly, it turned out that I only had a generous handful of H400s left, all would be in the sky that night, and that there was a decent chance I could finish the Herschel 400 on this very evening.
The Herschel Objects
What is a Herschel object, anyhow? As you may know, Sir William Herschel, the justly famous 18th Century amateur astronomer who discovered Uranus, was also a deep sky powerhouse. Using large home-built reflecting telescopes not much different from today’s Dobsonians, he and his sister Caroline discovered the lion’s share of the objects that eventually went on to make up the NGC catalog.
Despite his objects having been subsumed into the NGC in the 19th Century, Herschel’s original observations remained available, and one of amateur astronomy’s deep sky pioneers of the last century, Father Lucian Kemble, became fascinated with them. Back in in the 1960s, Kemble compiled a corrected and re-ordered the list of all 2500 galaxies, nebulae, and clusters using Herschel’s notes. Not many amateurs undertook to observe the aitches, however. Not only was it a very long list that included some dim and difficult objects, especially for the 1960s, quite a few of the 2500 were not there at all.
I'd almost finished the 400 the previous October at CAV...
Nobody paid much attention to Kemble’s labors till the 1970s when members of Saint Augustine, Florida’s Ancient City Astronomy Club began casting about for something to “do” after the Messier and were pointed at Kemble’s Herschels by Sky & Telescope's James Mullaney. When they checked out the Herschels, it became obvious why observing these objects wasn’t more popular: nobody would want to run through the list as it was. Not only were many of the entries beyond the reach of the telescopes of the day, it was saddled with typos, duplications, non-existent objects, and objects with incorrect coordinates.
Some of these mistakes were Herschel’s and some were Kemble’s, but all needed to be corrected. In addition to many fixes, the ACAC left out the dimmer objects, almost 80% of the total. When they were finished, they were left with a list of 400 galaxies, clusters, and nebulae that would be visible in 6-inch telescopes (albeit some with difficulty), still the most popular aperture in the 1970s.
Pretty soon, amateur astronomers across the country were working what came to be called “The Herschel 400.”  The leaders of the national amateur organization, The Astronomical League, noticed and built an observing club around the H400, offering certificates and pins for observers who completed what was then thought of as a Herculean task.
That night at DSRSG, I did indeed finish the Herschel 400, and, almost unbelievably, found myself moving on to the Herschel II, the next “best” 400 objects fairly early that evening. After I’d finished the II some months later? I had so much fun with that that I was soon daring what I came to call “The Big Enchilada,” the entire 2500 object list, and was writing an extensive series of blog entries about it. Those articles, which were, I think, some of the best that have ever appeared here, were at least vaguely patterned after Julie Powell’s wonderful blog wherein she recounted her experiences with her big project, cooking all the recipes in Julia Child’s The Art of French Cooking.

How did I make so much progress so quickly, moving from the 400 to the 2500 in just months? Two ways. First, I cheated. I am interested in seeing, not hunting, and given our weather, I wasn’t sure I’d live long enough to finish the whole 2500 if I located objects with a finder scope and a star chart. A friend of mine, a talented observer, literally took years to finish the first 400 working manually. No, I’d use goto and digital setting circles for every segment of the project: the 400, the II, and, most of all, The Big Enchilada.

Celeste:  you don't need a huge scope for the 400...
My other problem didn’t have to do with finding, but seeing. The Herschel 400 is not at all bad in that regard. Its dimmest objects are small galaxies, and while some have faint magnitudes, they are small and not a huge challenge for an 8-inch from a decent dark site. The II is harder, however, and The Big Enchilada contains some admittedly tough DSOs (though, they, like the faintest of the H400, tend to be small and therefore not as challenging as their magnitude values suggest). Still I’d sometimes need a leg up when I was operating from my not-perfect club dark site. That leg up would be video.

I began with my old black and white Stellacam II deep sky video cam, and as the Herschel Project, as I was calling my quest (cribbed from the Julie-Julia Project, natch), proceeded, I moved on to the color Mallincam Xtreme. While these video cameras didn’t deliver DSLR or CCD quality images as far as prettiness went, they brought home the bacon when it came to the dimmest objects and to details within many of those objects. And they did that with short exposures that didn’t require guiding or precise polar alignment. In fact, I found my alt-azimuth mode NexStar 11 GPS, Big Bertha, was perfect for the Herschel Project.

Not that I didn’t do plenty of visual observing, too. When the skies were good enough for that, or I had a group of less challenging objects to tackle, I went visual. The video observing was fun, but it’s the visual looking that I tend to remember now, four years after the Project was done.

If you want to know what it was like observing all the Herschels, I refer you to my blog articles (just do a Google search on “Uncle Rod Herschel Project”). This Sunday, however, we’re not here to talk about all that, as fun as it might have been (there were some wild nights under the stars); the subject is the beginning of my Quest, the original Herschel 400.

If you’re thinking about taking this challenge yourself, the first thing you probably want to know is exactly what this observing list is like. How hard is it, really? What’s is in it? Well, to begin, it’s 400 objects, which is quite a jump for novices for whom the 110 objects (or so) of the Messier probably seemed like a lot. And, yes, the H400 also has a reputation for being much tougher than the Messier. If you look at object magnitudes in the 400 you might indeed get scared. There is, for example, NGC 6540, whose magnitude is often given as a daunting 14.6.

But at least 12-inches of aperture is fun...
Shouldn’t the prospect of a near magnitude 15 star cluster be enough to discourage somebody who doesn’t have access to dark skies and an 18-inch scope? Nope. This little globular star cluster in Sagittarius—which is often misidentified as an open cluster—is slightly dim, but not that dim.

Yes, NGC 6540 is the faintest object in the 400 that has an even semi-reliable magnitude value assigned to it, and it is listed as 14.6 by many sources including SkyTools 3. This cluster is undoubtedly far brighter than that, however, and is probably not much dimmer than 10, since it is visible in a 6-inch Newtonian under good skies. Heck, plenty of people have seen this one with 4-inchers under decent conditions. One thing I have learned over the years is to be wary of is magnitude values. Often what’s listed for an object is actually its photographic magnitude and that can be off a lot when it comes to the object’s visual brightness, with the object looking far brighter than its supposed magnitude.

Certainly there are DSOs in the list with roughly correct magnitudes that are on the faint side, but, as mentioned above, they are usually small: little galaxies and little planetary nebulae. Even a stellar sized object isn’t always a picnic at magnitude 13 if you’re using a 6-inch, but it is doable, and, once again, most of the H objects listed at magnitude 13 are probably closer to 10 – 11. The Herschel 400 is indeed suitable for 6-inch scopes, with the usual problem with the more obscure H400 objects not being seeing them but finding them using a finder scope and star chart.

Don’t let the above give you the wrong idea about the Herschel 400, either. “Dim and difficult” just isn’t a good description of its nature. Unlike The Big Enchilada, it will not make your eyeballs bleed. In fact, the 400 is chock-full of showpieces, including over a dozen Messiers. Most of the spectacular treats from the NGC are in there, too: The E.T. Cluster, the North America Nebula, the Eskimo Nebula, the Blinking Planetary, the Blue Snowball, the Saturn Nebula, the Whale Galaxy, the Splinter Galaxy, and many more famous ones are awaiting you in the 400. If you check your observing records, you’ll probably discover you are already at least 30 or 40 objects into the Herschel without even trying.

But exactly how do you see all this goodness? What do you see all this goodness with? Yes, the Herschel 400 was composed with the idea that it would be doable with a 6-inch telescope, and it most assuredly can be finished with one. Heck, the 400 has been done with 4-inchers. However, some of the objects are semi-challenging for these smaller telescopes, and you will want a good site to make them easy/easier. NGC 2024, Orion’s Flame Nebula, is an example. You can see it with a six-inch equipped with a UHC filter, but you’ll likely need a superior suburban yard, or, better, a site in the suburban – country transition zone to see much of it with a 6-inch beyond a few wisps around Alnitak.

Breakfast time at DSRSG back in The Day...
There’s also the question of how you want to see Herschels. Do you just want to detect all the objects so you can cross ‘em off the list, or, like me, do you want to see details in these objects? If the latter, I suggest more aperture. How much more aperture? Using my old C8, Celeste, at the 2010 Deep South Regional StarGaze’s site in the dark green (light pollution) zone, I found I could tick off Herschel 2500 objects without much trouble. I was surprised I could do that with a telescope that us spoiled amateurs of today consider “small,” but I could.

While an 8-inch can be a great telescope for the 400, if you intend to do a lot of the work from a not-perfect backyard or a so-so club site, I suggest you kick things up another notch to 10 -inches. God knows, 10-inch Dobsonians are inexpensive these days, even when equipped with goto or digital setting circles—Orion’s Intelliscope 10-inch is a measly $850. The value of a 10-inch is not just that it allows you to see the dimmer objects with greater ease, but that the brighter ones become showpieces, and that sure makes for a more enjoyable experience with the H400.

Almost as important as your telescope is your software. By that, I don’t mean you must have a laptop connected to your telescope to send it on gotos. That can speed things up, and is what I usually did during the Herschel Project, but what I am actually talking about is software to keep you organized. When you are dealing with 400 targets, that is vital. You need to be able to easily determine which you have seen/need to see, and when you can see the DSOs still on your want list. The way you do that is with an observing planning program.

For the balance of the Herschel Project, I used SkyTools 3, mentioned earlier, and you can’t go wrong with that. During the latter phase of the Project, however, I mostly used Deep Sky Planner, which I found had some important strengths for me. If I were just doing the H400, I would no doubt have found Deepsky quite sufficient as well. Unfortunately, that program is limited in the number of objects you can put in a list. I couldn’t cram 2500 into it and so couldn’t use it on The Big Enchilada. One other planner I used was Eye and Telescope, and it was excellent. Astroplanner is a favorite with the Macintosh troops and is a natural if you do your astronomy computing the Apple way.

SkyTools 3 has a built in star atlas, so I didn’t need other software to fulfill that function when I was using it. Many other planners, like Eye and Telescope, also have charting engines, but they tend to be fairly minimalist in nature and I generally used those planners along side planetarium programs (Deep Sky Planner doesn’t do charts at all, using built-in links to many 3rd party planetariums for its charting instead) When I needed star maps and was not using SkyTools, what I used most was either TheSky or Cartes du Ciel. I love Cartes du Ciel, and it is free, so if you don’t have a planetarium you think is up to the task of doing the H400, that’s what I suggest you glom onto.

A dark star party is the perfect place to chase aitches!
Other resources to help you, like books? There is the booklet offered by the Astronomical League, Observe the Herschel Objects, but what I recommend book-wise are Stephen O’Meara’s Herschel 400 Observing Guide, and Mark Bratton’s The Complete Guide to the Herschel Objects.

The O’Meara book is well written, and I enjoyed it. Unfortunately, it has once big strike against it. Mr. O’Meara chose to do all his observing with a 4-inch refractor. While getting through the list with such a small scope, even given his superior Hawaiian skies, is an impressive feat, it makes the book a little less valuable for those of us using larger aperture.

When I was observing the 400 that October in Chiefland, I was using the O’Meara book to help me, but soon found his descriptions didn’t tally well with what I was in the eyepiece of my 12-inch Dob. Even though my skies were not nearly as good as what he must have had when doing the 400, I was seeing so many more details in many aitches that I would occasionally wonder if I were on the correct object. Still, a good book, and if you’ve got an 8-inch in the backyard, his descriptions may match yours.

The Bratton book has, several big advantages. Firstly, Mark used a variety of telescopes from an 8-inch to a 15-inch (and occasionally larger). Also, the book includes plenty of sketches, something I think is vital for a visual observing book. Photos, like the many in the O’Meara book, can be a help, but nothing is more informative about what you can/should see of an object than a sketch done by a fellow observer. Finally, the book covers all the Herschels, so if you intend to go on to the HII or the Big Enchilada, it will still be there to help you on your way.

“But Uncle Rod, we thought you were going to do a Herschel book?” That was the plan, Stan. I intended to begin it in 2012 right after the Project was done. Alas, beyond some very preliminary work, not much has been accomplished. If Mark hadn’t written his guide, there’d have been a little more impetus and I probably would have gritted my teeth and done the Herschel Project book, but he did and he wrote a fine one. My book could still happen, I suppose, but if it does it will undoubtedly be a lot more like Julie Powell’s Julie and Julia: 365 Days, 524 Recipes, 1 Tiny Apartment Kitchen than it will be like a serious observing handbook.

And there you have it. All that remains is for you to get into the backyard or out to the club dark site and get started. Oh! how I envy you! You get to tour the heavens with this magical observing list and see tons of crazy good objects for the first time. Not that my Herschel observing is completely done. I’ve been wanting something new to do—I seem to be in the observing project doldrums again. What if I went through the H400 again? This time with a small(er) telescope?

I am not (entirely) a masochist, so I wouldn’t go as low as a 4-inch given my skies and my weather, but how about a 6-inch? I might cheat a little and use a 6-inch refractor instead of the 6-inch reflector the H400 was intended for, but that’s still a small scope as such things are judged in these latter days. What will I see of the Herschel 400 with a 6-inch? How will one do on the Herschel II? Stay tuned!

Comments:
I've decided to do a Herschel 2500 viewing list - but a combination of visual and using short exposure stacking from the house. My skies are ok for suburban 5.2-.3, but my older eyes and C8 need some help from home. Getting a AVX/Skysense/wifi and I use an m43 camera that gives you a 10 times or so refresh of the images as it builds. While to get a "good" image I need 60 or so stacked images of 7331 and friends, I can after just 5 to 10 images identify them easily. With the wifi adapter I will control the scope and do the same with the camera from inside. The real fun begins after I take the images and do as much research on each object on the Net. I have Mark's book and an old copy of DeepSky (2010) that I am using to record my expedition's findings. When I go to one of the clubs deep sites, it will be a visual hunt. Given my limited view from my yard, I have about 1100 Herschel's to see. So I have about half to see at the clubs dark site and half at home - should keep me busy for a while. Of course I got this idea when you did your project and started it several years ago, but then quite. (about 200 Herschel's done visually).
 
Rod,

Your assessment of the H400 pretty much mirrors my experience. I took a LONG time to get it all done (several years, maybe mid-90s to 2004 or so?) and I used a 4" TV Genesis, 10" Dob and 14.5" Dob (I think, here and there) to complete it, mostly the 10". My main concern turned out to be unfounded... I was afraid of open clusters in the galactic core region, afraid that Herschel would classify two stars as a cluster. :-) But it wasn't that bad.

I don't recall for sure, but although my usage of SkyTools overlaps with my H400 time, I think I finished the majority of the H400 before adopting ST.

I started the HII slightly but got only (maybe?) 20 or 30 into it.
 
Hi Unk,

Don't you mean NGC6540? NGC4560 is a galaxy. NGC6540 is a globular cluster whose published magnitude gave me angst until I actually found it with my 1980's era Super C8.

Regards,
Paul Lennous

 
Thanks, Paul. I am lucky to have such attentive readers!
 
Hi Rod....can you define "aitches" please? Thanks....just curious.

 
Great post. I started the Herschel 400 a few months ago, using both my 4-inch refractor and 8-inch SCT. The smaller scope with it's wide field (2 degrees) is actually great for snapping up lots of the open and globular clusters quickly, and in my Bortle 3 backyard galaxies down to mag 13 are not desperately difficult either (although they are a LOT easier in the 8-inch).

I do get distracted easily by other objects though, and frequently wander off to scrounge up nearby goodies that are not on the list--especially if they are galaxies. Also, SOME of the H400 objects (like sparse, loose open clusters) are not that interesting, but are just viewed to check them off the list.

Congrats on finishing all 2500 objects. That is a wonderful feat!
 
Thanks, Rod for another attention holding blog. I'm actually doing the 400 right now, in nearly 40 years of observing, I've never set out to accomplish an observing list, so it's about time. During the Black Forest Star Party 3 weeks back, I was using a Sky Watcher 100 Pro ED and could see nothing of NGC 1444 from this "dark blue" site. We could see little more in the 7" Starmaster my wife was using, and it took a 10 inch to actually verify the "cluster nature" of the object. The transparency wasn't perfect, but not bad either. I've been working on the H400 for two years, but lake effect clouds from Lake Erie frustrate those of us in NW Pennsylvania.

By all means, take the list on with your 6" glass and have fun!

John O'Hara
Oil City, PA

 
Hey Rodster, I wanted to correct one thing in this weekend's blog. There is no current requirement to not use DSOs or GOTO. I know this as I'm the H400 coordinator for the AL. I just went to the website to verify this. Perhaps it used to be that way but not now. I believe the only AL certificate currently that requires star hoping is the Messier program.
 
HI Jack:

Thanks for setting me straight on that...I'll admit I haven't visited the AL website in a while. :)
 
Anonymous: "aitches" = "Hs" ;)
 
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