After the Messier List, the Herschel's are the next most observed deep-sky objects.
Most amateur astronomers know them by their
NGC or IC numbers, but they started out as a list created by British astronomer William Herschel and his sister Caroline.
From 1782 to 1790, the Herschel's conducted systematic surveys of the night sky, in search of "deep sky" objects, and discovered over 2400.
William's son John later added another 1700+ entries to the list.
Eventually, all of the Herschel objects, along with discoveries from other astronomers were combined and published in 1888 as the New General Catalogue (abbreviated NGC).
In addition to his deep-sky surveys, William Herschel also discovered the planet Uranus and two of it's moons - Titania and Oberon, along with Saturn's moons Mimas and Enceladus.
He also discovered over 800 double & multiple stars.
Caroline discovered 8 comets and was honoured by the Royal Astronomical Society.
Herschel classified his list into eight sub-categories:
Class I - Bright Nebulae;
Class II - Faint Nebulae;
Class III - Very Faint Nebulae;
Class IV - Planetary Nebulae;
Class V - Very Large Nebulae;
Class VI - Very Compressed and Rich Clusters of Stars;
Class VII - Compressed Clusters of Small and Large Stars;
Class VIII - Coarsely Scattered Clusters of Stars.
Herschel 400 map
Distribution of Herschel 400 objects, Red = Galaxies, Green = Nebulae, Yellow = Star Clusters
The Herschels and their Catalog! PDF
The idea for this 'Herschel Tour' project started back at the end of 2012, as I was wrapping up my 'Constellation Tour' survey based on the "Night Sky Observers Handbook".
I realized that my survey observations would already include a large number of the Herschel-400 objects.
So after identifying all the '400' objects that I had already observed over the years, it only took me an additional six months
to finish the 'Herschel 400' list on 6/4/2013, by video capturing the final few stragglers in Ursa Major.
I utilized the Astronomical League's "Herschel 400 by Constellation" list and their "Observe the Herschel Objects" booklet.
I then downloaded the AL's "Herschel-II" list of the next 400 objects and began hunting the objects that I hadn't already observed.
By the fall of 2016, I was down to the last 60 objects and was wondering what my next project should be.
Flipping thru some old Sky&Telescope magazines, I ran across an article from the August 2012 issue by Rod Mollise on observing the entire Herschel Catalog of 2500 objects using a video cam.
This was the inspiration (and project), that I needed, so I began a multi-year project to observe the entire Herschel Catalog.
Over the course of William and Caroline Herschel's original recording and publishing of their observations from 1786 thru 1802,
along with subsequent reprints and revisions over the 19th century, there have been a number of discrepancies over misidentified or non-existent objects.
Depending on the source, of the Herschel's 2500 objects cataloged, there are anywhere from the low 2400's to over 2500 actual objects.
Mark Bratton, in his book "The Complete Guide to the Herschel Objects", gives a good review of the issues and historical attempts to rectify Herschel's list of objects.
He eventually settles on there being only 2,435 identifiable Herschel Objects.
(I utilize his book's visual descriptions to help in comparing and confirming my personal observations).
To help tackle this project, I downloaded several lists from various websites, and after combining, distilling, and sorting,
I generated a personal spreadsheet/logbook to help in my tracking & logging.
The core data for my logbook comes from a list of 2,482 Herschel Objects by Steve Gottlieb.
If anyone is interested in using this logbook, I saved it as a PDF and you can find it on my 'Download' page.
Just be aware that I've found a few 'errors' that I've introduced in my cutting and pasting of various data.
Currently, I have either video captured or sketched 2,110 of the Herschel Objects. (from my list of 2,482)
In retrospect, over the course of this project, I have learned a lot about William and Caroline Herschel, along with the objects that they discovered.
While there are a number of nice large, bright objects including galaxies, star clusters, and nebula, the majority of Herschel's objects are small, dim, nondescript smudges.
It gives you an appreciation for the brighter Messier Objects.
Still, there is a wide variety of interesting deep sky objects for any sized telescope.
I now have a much greater appreciation for all those faint fuzzies and the work of the Herschel's!
Hope you enjoyed the visit. Come again soon!
Larry McHenry, Pittsburgh, PA. USA