Special Interest Group (SIGs)

Messier Observing List SIG

Messier Object Field Observation Tips

By Greg Haubrich
Dec. 22, 2001

The purpose of the Messier SIG is to bring members together to share thoughts and ideas and to encourage one another in observing and logging all 110 Messier Objects for the end goal of obtaining their Astronomical League's Messier Club Certificate.

Below are a few thoughts of mine that I'd like to share with you. It's a few items that I've picked up so far. Please share your ideas and observing tips with the SIG too.

Constellation Recognition:

Because the Messier Club Certificate requires the use of "star-hopping" to find the Messier Objects (i.e. manually pointing your telescope without any artificial aids other than "Telrads" or magnified finder scopes), some basic familiarity with at least 1/4 the constellations as readily seen from the northern hemisphere helps tremendously. Once you can identify the big and easy constellations, the dimmer, lesser known constellations are easily learned with a "planisphere" under the stars. However, it does help to learn the constellations before searching for Messier Objects in them.

Your Telescope:

Get familiar with your telescope. Just like driving a new car, the more that you use it, the better an operator/driver you become. Eventually, it almost becomes a natural extension to your reflexes and senses.

It helps to have a passing understanding of the terms: field-of-view, focal length, focal ratio, magnification, exit-pupil, and magnitude as they pertain to your telescope and observing. Check out the attachments enclosed for descriptions of these important concepts.

Being able to point your telescope via the finder is a must (I would highly recommend using a Telrad or Telrad-like 1:1 reflex finder - - they are so much more effective and easier to use than magnified finders).

Human Vision (and your vision personally):

It also helps to understand human eye dark adaptation, personal entrance/exit-pupil (vs. eyepiece focal length and telescope focal length), averted vision, and "wiggling the scope" in viewing faint Deep-Sky Objects.

Visual Observations:

Color

Full color Hubble pictures are a fallacy as far as what one sees with visual telescope observing. Most Deep Sky Objects (Galaxies, nebula, and most star clusters) will show no color (except maybe the Orion Nebula, which to me looks slightly green tinted). They simply do not have the light intensity necessary to turn on our color vision (the "cone" cells in our eyes). However, individual stars will definitely show color.

Brightness and Detail

Additionally, as first glance, most Deep Sky Objects appear dim and diffuse. Only with training one's eyes and mind will details start to appear after the object is studied long enough by the observer. Many times adjusting the magnification will affect the details seen by the observer.

Knowing what to expect

It's usually much easier to find and identify the objects once you have seen them before. Having a good idea of what you are looking for can help speed up finding and identifying objects considerably. Also do not be fooled by the overall "magnitude" (brightness) listed for Deep Sky Objects; the size of an object is equally important. The way magnitude is measured, one can take a star of the same listed magnitude and "defocus" it to cover the entire object's area. Thus larger objects have much lower surface brightness, or brightness per unit area (i.e. M33 is notoriously difficult to see for a magnitude 5.7 Galaxy). Surface brightness is the key factor in the contrast that allows objects to be visible against the night sky. Light pollution can lower this contrast significantly and make the lower surface brightness objects invisible in urban/suburban light pollution if they are too close to the horizon.

Seeing Conditions

The transparency and stability (seeing) of the atmosphere can have a great affect on what is observed at the eyepiece. The seeing in Minnesota usually limits the maximum amount of magnification that can be practically used on most nights. Additionally, subtle details can be lost, or whole objects missed if the seeing is poor enough. Objects that are visually "jaw droppers" on nights of good seeing can turn into "ho-hum" diffuse blurs on nights of poor seeing (or be missed altogether). Light pollution effects make sky transparency even more critical. For example, while in the vacuum of space, Hubble observes during the "day"; conversely as atmospheric transparency degrades, more light pollution is scattered making light pollution's effects much worse during nights of poor transparency.

If you've seen the Messier Objects only once, unless it was under ideal seeing conditions and at various magnifications, you will see more almost each time you re-observe them (i.e. you don't have to feel guilty about looking at the same objects over and over, as long as you see something new just about every time!)

Hunting for and Identifying Objects:

Patience, and "practice makes perfect": Patience and a some knowledge of the night sky is necessary to find objects. My first Messier Object (M57) took me 45 minutes to find. But it was all down-hill from there! After carefully taking about a year and a half to go through the Messier Club Certificate, I was able to go through 102 Messier Objects in one night at this past year's MAS Messier Marathon via star hopping. Hint: Start out with a low-power eyepiece giving a wide 1 degree field-of-view or more, and then switch over to a higher power eyepiece if desired (much smaller field-of-view) after the object has been found.

Navigating the Night Sky: Geometric Dead-Reckoning

Once you know the constellations, it is relatively easy to point the telescope close (within a degree and a half of the object of interest). One can increase the initial pointing accuracy by imagining geometric shapes consisting of stars at each vertex (i.e. triangles, rectangles, pentagons, etc.) but leaving one imaginary vertex which is where the object of interest is located in the sky. This can often times get one to within a couple of telescope fields-of-view, it's just that you don't know what direction to go from there without looking at a star chart. Thus, look through the eyepiece and begin searching. A star chart is then used to unambiguously identify the surrounding star field and thus the object of interest (brighter stars tend to form discernable patterns relative to the object of interest).

Star-hopping

Start at a "bright star" and by using a star chart as a map, hop from one "bright" star, or star pattern, to the next until you get near the object of interest. Verify the star field and object per above. Navigating the night sky is an acquired skill, don't be too frustrated, be patient with yourself. Before too long you will have it mastered.

Star Charts

Computers

While mentioned above, this deserves extra attention. Planetarium programs can display star fields as faint as most telescopes can view visually (down to 16th magnitude). Newtonian Telescopes invert (180 degree flip) the image and their actual field-of-view can be simulated easily and surprisingly accurately by these planetarium programs (other telescopes also have predictable field rotation). The Messier Object locations are also displayed (often size and orientation as well). One can easily print out a zoomed-out (approximately 45 degree sky view), and a zoomed-in telescope field-of-view for each Messier Object (approximately 2 degree field-of-view). I put mine in a 3-ring binder. Alternately, if a laptop computer can have it's display covered with a dark red filter, it can made into a very flexible and dynamic "star chart".

Books

Uranometria, Millenium, and other fine star charts/ sky atlases also work well.

Miscellaneous Support Equipment and Member Support:

Equipment

In addition to the obvious (telescope, eyepieces, finders, de-dewing equipment, detailed finder star charts, red flashlight, and counterbalance weights), I would recommend the following: A portable table (for charts/or laptop computer, eyepieces, observing log, binoculars, etc.), a small micro-cassette recorder for logging in the dark, a pencil in addition to a pen, a snack with water, and a chair. Dressing for at least 10 degrees colder than actual conditions is usually a good idea due to the lack of physical activity during observing.

"Observing Buddies"

Even though the Messier Club Certificate is a solo effort for finding, observing and logging the Messier Objects, teaming up with a like-minded Messier Hunter/ Messier SIG Member(s) is a very good idea. In addition to not having to observe alone, you can encourage each other, swap observing hints, and even provide eyepiece "sanity checks" when you think you have the Messier Object Identified (depending on the size of your telescope, and the quality of the skies, you may be inadvertently observing one of 10000+ NGC or IC objects attainable with amateur instruments). You can even run informal competitions among Observing Buddies/SIG members.

Have Fun and don't hurry through it!

The fun is in the journey as much as, or more than, in the end-goal . Enjoy!

It took me a year and a half to go through the Messier List and I considered myself highly driven. My observation log was strictly via words. Others have even drawn sketches of each object. Please read the Astronomical League logging requirements before you begin to log seriously.

Re-Observing the Messier Objects:

Even though I've seen almost all of the Messier Objects at least a few times (some probably hundreds of times), I find myself trying different magnifications, and hoping for better seeing conditions. Some surprises I've found from re-observing my old favorites under different magnifications (certainly not seeing this every night!):

The clear spiral structure in M51, M101, M81.
The central star of M27.
The "eyes" in the "Owl" Planetary Nebula, M97.
The multitude of galaxies visible in with the same 1 degree FOV as M84 and M86 (at least 7!).
Dust Lanes and an embedded NGC object, (NGC205), in M31.
A planetary nebula (NGC2438) clearly visible inside M46.
A double open cluster of M38 & NGC1907.

After you've "seen them all" and want an additional challenge, try the annual MAS Messier Marathon in mid-March to early-April. Here it's possible to see 109 of the 110 Messier Objects in one night! I only managed 102 star hopping so far. But this gives me reason to try again!

See you at the SIG!