Herschel Club Introduction

Herschel 400 Club Chair: Herschel 400 logo

Brenda Branchett
515 Glen Haven Drive
Deltona, FL 32738
(407) 574-7741
E-mail: bbranchett@yahoo.com

Introduction

Observe the Herschel Objects (Astronomical League, 1980) is laid out with the objects separated into the four seasons, starting with fall (20 Hours - I Hour); winter (2 Hours - 7 Hours); spring (8 Hours - 13 Hours); summer (14 Hours - 19 Hours). Both the NGC number and the Herschel number are given. The NGC number is listed first, as very few references list objects by their Herschel number. If you are planning to use setting circles, the coordinates are for 1950, which are common to many stellar atlases. The listed magnitudes are taken from the Atlas of The Heavens Catalog, and are visual as opposed to photographic magnitudes. A few of the objects had no listed visual magnitudes, so estimates had to be made. Any discussion of visual magnitude is somewhat tricky, as different sources list different ones for the same object; and estimates can vary from person to person. Also, strongly affecting the magnitude of an object is its angular size. The larger the object is, the fainter it will appear due to the brightness being spread out over a large surface area. Many of the Herschel objects are made difficult by this effect.

It should be noted here that listed magnitudes for the diffuse nebulae in this manual and the lists on this site are strictly estimates, as no magnitude data for the nebulae themselves are ever given in references. Two of the best Herschel diffuse nebulae are NGC 7000 (The North American Nebula), in Cygnus, and NGC 2024 in Orion. Both will present distinct challenges to the visual observer. In the final analysis, the most important judgment on magnitude is whether or not the object is visible in your telescope. As we stated earlier, we feel certain any object in the lists can be seen in a six-inch telescope. However, sky conditions and observer skill are just as important as telescope size.

We wanted to stress the importance of the visual appearance of each of the objects, because this is a powerful tool in identifying the correct object in sometimes crowded and confusing situations. The two most important factors affecting visual appearance are object size and object shape. The sizes of planetary nebulae in this manual are given in seconds of arc, all other types of objects are given in minutes of arc; as with magnitudes the reference for sizes was the Atlas of The Heavens Catalog. If a galaxy is edge-on, it will appear as a streak in the eyepiece; if it is face-on, it will appear circular. In areas like Virgo and Ursa Major, this can be the only way to tell galaxies apart.

Open Clusters present an entirely different situation in terms of visual appearance. Herschel's three classes dealing with clusters do not seem to follow a rigid set of criteria for an object's placement within the classes; they are roughly based on cluster richness. The Herschel List provides a much wider selection of open clusters than the Messier List, and the observer can become aware of the beauty and diversity that these objects have to offer. Many beautiful and little- known open clusters are included, especially in the Puppis region.

Herschel's classification scheme was far from perfect; for example, several planetary nebulae (Class IV), and globular clusters (Class VI) can be found in Classes I & II. A few small diffuse nebulae will be found in Class IV (planetary nebulae); it must be kept in mind that Herschel did not have available to him the extensive knowledge of the Universe that we have today. In those days all nebulae were considered to be the same, no real distinction was made between the different types as we know today. Indeed, even the true nature of a universe strewn with countless millions of galaxies was not recognized until long after Herschel did his work. Herschel used a rather crude system of determining positions of the objects; he would note the elevation of the telescope and the time the object crossed the field of view. This resulted in one object being listed two or three times as different objects, sometimes it would even be put in a different class the second or third time.

As we stated earlier, this project is aimed at more advanced visual observers. We have not included a lot of beautiful pictures or spent a lot of time telling you how to find a particular object. We will assume that anyone undertaking this project is well aware of the sky and the constellations, as well as having some experience with the ins and outs of deep- sky observing. A few of the objects are bright and beautiful, but by far the majority of them are faint. Averted vision will be a necessity in seeing quite a few of the objects. Another trick we used to enhance the visibility of the faint ones was to rock the eyepiece field back and forth with slight movements of the telescope, this sometimes brought out an object that even averted vision would not reveal. Another point of interest; all of the objects were found without the aid of setting circles, but by the star-hopping method, which made the task much more difficult; but it also made it much more challenging and satisfying. We feel one of the most important reasons for undertaking a project like this is to increase your observing skills and to attain a good knowledge of the sky. Star-hopping to find these objects can serve these goals very well.

The Herschel Club is similar to the Messier Club, with a few important differences. First of all, we have done away with a preliminary certificate. A special certificate will be awarded after all of the 400 objects have been observed. This certificate will be in accordance with the magnitude of having completed this difficult project.

-Paul Jones

The Herschel 400 Club - The Rules.

The Astronomical League offers special recognition in the form of a Herschel 400 Club Certificate for those that have observed all 400 of the listed Herschel objects. To qualify you must either be a Member-at-Large or be a member of an astronomical society which is affiliated with the League. To obtain an award you must observe the following rules:

Rule 1:

Observe all the 400 Herschel objects listed and keep a record of your observations. Your notes must show:

a. Date of observation;
b. Time of observation;
c. Seeing conditions;
d. Aperture size of telescope;
e. Power used;
f. A short note describing your observation of the object.

Rule 2:

Have your notebook or record examined by an officer of your Society or a suitably qualified second party if you are not a member of a society and have this party forward a letter to the effect that you have made the necessary number of observations. This letter should be addressed to:

Brenda Branchett
515 Glen Haven Drive
Deltona, FL 32738
(407) 574-7741

Only non-society members need to actually mail their observing log to Ms. Branchett. A Certificate of Membership in the Herschel 400 Club and award pin will be forwarded to your Society for presentation at a meeting. The letter should specify the address to which the Certificate should be mailed. The certificate will be suitable for framing.

Herschel Club Introduction

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