The Caldwell and Herschel lists and difficulty

[Admiral Crispy]

Hi there,

with me progressing through the Messier list, I was wondering if it would be worthwhile having a go at trying to find objects on the Caldwell and Herschel lists at the same time, on a constellation by constellation basis?

Are the objects on these lists much more difficult than the Messier list? And if so, would you still expect the objects to be possible to see in my 10 inch Dob in magnitude 4.8-5 skies?

Chris

[swamp thing]

Hi Chris

A 10" scope is a very powerful deep sky tool and both the Caldwell and Herschel catalogues make excellent challenges for a scope of this size.

I have owned a 10" scope for......many years and am nowhere near exhausting it's potential.

TBH most of the time it's my limits as an observer that's reached long before the capability of the scope.

Go for it buddy and don't forget to post your results.

Regards Steve

[Mark at Beaufort]

Hello Chris - both the Caldwell and Herschel 400 list are within the reach of your 10" scope.

As you can see from my signature I have finished the Messier list. I then started on other lists.

If you want to view DSOs on a constellation basis you might find this website useful. It covers the best 666 DSOs of which about 600 are visible in the UK.

Illustrated DSO guide - Deep Sky Watch

Mark

[acey]

I think it would be a nice idea to start the Caldwell and Herschel lists simultaneously on a constellation-by-constellation basis. There is a degree of overlap, which helps.

The Caldwell lists contains quite a few showpieces, though also a some obscure objects (difficult or just plain uninteresting) whose inclusion is a bit questionable. Same goes for the Herschel list, which like the Caldwell is a modern "best of" selection, with all the pros and cons that entails. To be honest I got bored with the Herschel selection and went back to the great man's original list: if you cut out the Class II and Class III objects you get a list of about 600.

The downside of following a Herschel agenda is that he didn't cover the whole northern sky (e.g. he missed out the polar region).

The first post-Messier list I tried, and which I can still recommend, is the Royal Astronomical Society of Canada's "best NGC" list.

http://seds.org/messier/xtra/similar/rasc-ngc.html

http://astronomy-mall.com/Adventures.In.Deep.Space/catalogs.htm

[Admiral Crispy]

Thanks for all of your advice guys, I will make an attempt at some of the Caldwell and Herschel lists the next time! Thanks also for the links, they are all extremely useful and now in my favourites! Its nice to get an idea of what the objects will actually look like through the EP too!

[michael.h.f.wilkinson]

I have finished Messier, and am ploughing through the Caldwell and Herschel 400 lists at an almost alarming rate with my C8 (and 15x70 bins in the southern hemisphere). Your 10" scope should easily better that. Having said that, the Caldwell list is a mixed bag, some objects being very easy, but others very hard. C1 is a very faint scattering of stars, whereas the Hyades is a naked eye object. I think C3 (NGC 4236) was one of the hardest ones I found to date: a very low surface brightness edge-on galaxy.

[Admiral Crispy]

Already found the Hyades, so I guess I'm up and running already! Though I got to say, how on Earth did Messier not see that one? Are some of the Caldwell and Herschel objects Southern Hemisphere only then?

[acey]

Messier set out to list objects that could be mistaken for comets. He wanted round numbers so topped up his list with a couple of evident non-comets, notably the Pleiades, but didn't bother to include the Hyades.

The Caldwell list covers the whole sky, north and south hemisphere (and is ordered by declination, starting with the most northerly), so the only way to see them all is to travel south (I don't think you actually need to cross the equator but that would help). So many people just set themselves the challenge of observing all the objects that rise above their horizon. Furthest south I've observed from is the Canaries and I've managed down to 80-something.

[bish]

Hi there,

with me progressing through the Messier list, I was wondering if it would be worthwhile having a go at trying to find objects on the Caldwell and Herschel lists at the same time, on a constellation by constellation basis?

Are the objects on these lists much more difficult than the Messier list? And if so, would you still expect the objects to be possible to see in my 10 inch Dob in magnitude 4.8-5 skies?

Chris

Try not to get too distracted with the Messier list. It's a good way to start finding your way around but there is so much more up there to see.

[mdstuart]

Chris

I have a ten inch scope and have been working through the galaxies out there. I am up to about 400 now from a semi rural location.

I have created a web site with objects. The galaxies all have a brightness indicator. I would go for any marked with 2 or higher initially to get a feel for these elusive objects.

PDA LIST OF NIGHT SKY OBJECTS

I find that when you start out it is hard to see even the category 2 objects and it takes time and patience a good detailed map and averted vision to pick up those marked as 0.5!

Let me know how my difficulty assessments compare with your experience!

Regards

Mark

[acey]

Herschel's own visibility scale is also very useful in judging which objects to view: this is seen in the Herschel number of the object, which is H followed by a Roman numeral followed by a number, e.g. H I 57, H II 125 etc. I means "bright", II means "faint" and III means "very faint". There are also Roman numerals that denote "planetary", "very large" and different types of cluster.

As I mentioned before, if you remove the objects designated "faint" and "very faint" (classes II and III) you get a list of about 600 objects, which formed the basis for various deep-sky surveys in the 19th and early 20th centuries.

The numbers can be found in the column WH in the "Herschel 2500" spreadsheet at the site I linked to previously (Adventures in Deep Space), the prefix H having been omitted. If you reorder the spreadsheet by that column you can easily filter out the reduced list. In fact that list was advocated by James Mullaney some years before the Herschel Club created its 400 list. Mullaney has written a nice book which provides a guide to his "Herschel 600".

http://www.amazon.co.uk/Herschel-Objects-How-Observe-Them/dp/0387681248

[bish]

Chris

I have a ten inch scope and have been working through the galaxies out there. I am up to about 400 now from a semi rural location.

Regards

Mark

That's an incredible amount of galaxies.

[Admiral Crispy]

Thanks for your suggetsions and links guys, they are very greatly appreciated! Mark, I have to say that I generally agree with your assessments, although I do have more difficulty with M78 than I do for say M109! Don't know if that's a sign that my observing site is unusual, or maybe my eyesight! Though I will have an O-III filter for xmas!

[swamp thing]

Chris, remember an O-III filter is only useful on emission Nebulae. It won't help with reflection nebula like M78.

It may help with extragalactic nebula but not the Galaxy itself.

[mdstuart]

Chris

The star ratings on the web site are more of a WOW factor. Only the galaxies have a difficulty rating with M109 getting 0.5 so I rate this a very tough..

Odd for a Messier but I struggled with it for years. I can pull it out with the 10 inch on a good night but its tough..M78 is pretty easy even in my 20 x 80mm bins...

I must try again my ratings are only very amateur estimates, perhaps I have been a bit harsh on M109..Will try it with my 80mm bins again..

Mark

[michael.h.f.wilkinson]

I found M109 hard, but M78 (lower in the sky) was harder in my C8. Much depends on sky conditions, as noted before.

[Admiral Crispy]

Yep, maybe that is the case! I found M78 much easier than M109 to observe, but finding M78 was a nightmare in the skyglow of my backyard. I guess a lot of the observing experiences people have must be fairly subjective! I don't tend to get much contrast in the sky for M33 or M109, but do for globular clusters in general, so that must say more about the light pollution in my backyard, I would have thought!