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CONSTELLATION GUIDE
Last updated: 1 November 2001
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CONSTELLATION GUIDE |
"GO TO"....LEPUS - a Hare Beneath the Feet of a Great Hunter
.....home to "HINDS CRIMSON STAR"....and a BONUS: Your "GO TO" Guide to Observing CARBON STARS"
From: sherrodc@ipa.net (Clay Sherrod)
We are now deep into the winter skies of the northern hemisphere in our "GO TO" TOURS for constellation studies with computerized telescopes of all types. This 35th installment of our Constellation Guides features an oft-ignored little hare of a constellation resting beneath the feet of Orion, the mighty hunter. Orion was well covered in our last three installments of the "GO TO" TOURS, being a comprehensive three part series. LEPUS, immediately south of the Great Hunter, is often skirted over quickly after observers "ewww!" and "ahhhh" over the splendors of the magnificent bright and young stars and nebulae of Orion. However, there is a wealth of fine objects in Lepus and.....well....while you are in the neighborhood anyway....
Let's explore the relatively small but object-rich confines of LEPUS, the rabbit or "hare."
Oddly, LEPUS has little mythological reference or history. Indeed, there is no reference to the "hare" in the Greek, Arabic, nor Chinese records of antiquity. The typical assumption is that the constellation was placed - and named - where it is in reference to the Mighty Hunter, Orion. For the pitiful and fragile rabbit is poised beneath the firm footing of Orion (the bright stars Rigel and Saiph) to the north, and running away from (westward) the pursuits of Orion's hunting dogs, CANIS MAJOR and CANIS MINOR, noted to the east by the very bright stars "Sirius" and "Procyon", in Canis Major and Minor, respectively. It is interesting to me that LEPUS was included in Ptolemy's original 48 constellations established in the 2nd century A.D., for typically only the 12 constellations of the Zodiac and those with strong heritage and Greek mythological ties were included in his early list.
At any rate, the rabbit does not look one bit happy in Bode's 1603 star atlas rendering reproduced below:
In virtually all cultures the small groups of stars has remained associated with a cowering rabbit beneath Orion's feet. Early German astronomers referred to it as the "Hase," the Portuguese "Lebre," the Italians called the stars "Lepre" and the French saw "le Lievre." The Arabian starwatchers, most of the stars being named by them, imagined the four stars, alpha, beta, gamma and delta as the "Chair of the Giant" , or a place in which the great Orion could rest. Al Sufi, a 10th century A.D. Persian astronomer/astrologer,,referred to the four bright stars of Lepus as the "Thirst-slaking Camels", because of their position near the meandering Celestial River, the constellation of Eridanus (see: http://www.weasner.com/etx/ref_guides/eridanus.html ) Early Egyptians knew Lepus as the "Boat of Osiris", the god who was one of the most widely worshipped deities in Egypt and the "Judge of the Dead" and "King of the Underworld". The early Chinese skywatchers were a lot more practical with many of their star associations. Looking at these four, plainly spaced and rather symmetrical stars in a mostly void portion of dark sky, they knew the same found stars simply as Tsih, or "the Shed".
Within Lepus are NO star clusters of note with amateur instruments, one Messier Object (Messier 79), one very faint planetary nebula with a notably bright central star, about five spiral galaxies and very few bright stars. Indeed, there are TWO named stars in this rather faint constellation and one rather interesting "circlet of stars" as will be described following. In addition there are some fine double and multiple stars that we shall explore and at least one VERY fine variable star that is my favorite colored star in all the sky....."Hind's Crimson Star."
Indeed, as a "bonus" for this "GO TO" TOUR, a selected list of the 75 most famous and "reddest" of all stars - "CARBON STARS" is provided, giving the coordinates, the periods (yes, they are ALL variable stars!), the magnitude range, and the extreme "red end" spectral type of each star. Note that all the stars provided in our bonus listing are within range of almost all amateur telescopes!
Lepus (pronounced "LEAP-us") is contained within a box-like border that is barely one hour of right ascension wide (from about 5h R.A. to just past 6h R.A., some 17 degrees of sky) and barely the same extent in north-south directions. All objects within Lepus are SOUTH of the celestial equator (see the chart below) and thus have negative ("-") declinations. Lepus is due west of the much brighter (and more in the star-rich fields of the winter Milky Way) constellation Canis Major....another reason that it is often overlooked by stargazers.
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THE STARS OF LEPUS -
For a complete cross reference of named stars, Bayer and Flamsteed designations, SAO numbers and double stars along with their coordinates, I refer you to the wonderful "Star Tables" at: http://www.gatter.demon.co.uk/data/Lep.htm by British compiler and LX 200 enthusiast Robin Gatter. This particular URL is specifically targeted for Eridanus and every constellation of the sky is so cataloged in this wonderful web site. Take the time to fully explore Robin's fantastic and user-friendly constellation cross-references.
From mid-northern latitudes, the stars of Lepus rise only slightly later than do those of Orion; wherein Orion rises pretty much east for latitudes 35 degrees and below, Lepus is far to the southeast and its faint stars are not visible until much later in the evening than those of Orion. For late November, Lepus rises about 9 p.m. and is located south of overhead (culmination on the celestial meridian) the same as those of Orion, or about 1 p.m. Midnight culmination of the middle of Lepus occurs each year around December 15.
Because of the stark absence of spectacular (or even "reachable") deep sky objects in Lepus, observers are encourage to visit this celestial rabbit with "double stars in mind." There are many splendid double and multiple stars, dozens of which are observable in much detail in telescopes from 3" to 8". Unfortunately I am able to only select a few of the finest double and multiple stars to discuss in our Eridanus "GO TO" Guide; I very much encourage all telescope users to obtain the three-set copy of Burnham's Celestial Handbook for reference on each and every constellation; there is no finer reference work for deep sky viewing to be found. The discussion on the constellation LEPUS will be found in Volume Two of the Handbook.
Also note that a wonderful program is now available for you to install on your computer to CONVERT the epoch 1950-1960 coordinates listed in the Burnham reference tables DIRECTLY to epoch 2000: http://groups.yahoo.com/group/lx90/files/Field%20References%20%26%20Techniques/Coodinates.zip which you can unzip and install within minutes....all you must do is merely type in the coordinates exactly as they appear in Burnhams and enter, with the resulting 2001 conversion done instantly for use with your Autostar or NexStar controller! This wonderful tool was made possible by a program posted on the Yahoo LX 90 site originally and offered as freeware by Meade LX 90 user Ron Gardner.
Once scanning the pages of Volume 2 of Burnhams, you will quickly see the "best multiple" and unusual stars for observations. There are no less than 100 fine multiple stars within reach of most amateur telescopes, many of which are fascinating objects. A few have been selected here as described following, some of which are wonderful and challenging targets in selected telescope sizes.
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OBSERVING THIS CONSTELLATION WITH BINOCULARS -
For those who wish to explore the regions of Lepus in binoculars I highly recommend a standard good quality 7 x 50 or 10 x 50 glass used in very dark, moonless skies away from artificial lighting. Remember to let your eyes become "dark adapted" for at least 15 minutes prior to searching out fainter objects. For a wonderful selection of binocular tour objects, visit http://www.dibonsmith.com/lep_con.htm , a tremendous guide by Richard Smith from his web page entitled "The Constellations."
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GETTING STARTED -
As with every "GO TO" TOUR guide, each GO TO object in LEPUS is discussed for your telescope regarding the type of conditions necessary for you to view it optimally for discern the very faintest details.........magnifications and aperture necessary for most objects, and much, much more. This is YOUR complete GUIDE to get you on your way to exploring the best (and few!) objects in this HUGE constellation. The chart provided above from the Arkansas Sky Observatory and the subsequent detailed listing of "BEST" objects contains the finest or most interesting from my own observing experience and preference.
Use the attached star chart shown above and the following Guide as an excellent reference for your next star party itinerary, or a beginning for further study into the thousands of objects visible in this part of the sky. To access and print the chart, double click on it and save the image to a file on your computer. Once saved, open the file and RESIZE this image to fit the normal paper format for your program and save again....then merely print out the chart on high quality paper for a field reference in this GO TO TOUR!
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OBSERVING TIPS -
Every deep sky object and every double/multiple star will have a "PERFECT MAGNIFICATION".....this is the magnification that you should use that will show the object as bright and with as much as detail with possible and still increase its size appreciably so that you can view it comfortably and unmistakably. The rule for determining "optimum magnification" is that: 1) too low power results in sky background glow detracting or diminishing the contrast against the deep sky object; 2) too high magnification darkens BOTH the sky background AND the object; 3) medium magnification can be achieved at which you have MAXIMUM contrast between the object and its darkened background sky. I have found through three decades of direct observing that about 15x per inch aperture (36x for the ETX 60/70; 55x for the ETX 90; 75x for the ETX 125; and, 125x for the LX 90).for deep sky observing is PERFECT for most objects. That being said, always remember that DOUBLE or multiple stars require whatever power you can crank out....the seeing conditions are the limiting factor here.
For my complete and comprehensive discussion regarding seeing conditions and sky transparency, see: http://www.weasner.com/etx/buyer-newuser-tips/seeing.html .
With all deep sky objects, avoid attempting to observe when the moon is in the sky, even a very thin crescent, as its brightness in the sky will overshadow the very dim contrast afforded by even the brightest deep sky object; if you see the object at all against moonlight, you will NOT see the subtle outlying areas or the full detail of what is presented.
For detail descriptive lists of the great double and variable stars within LEPUS, and as with all of the "GO TO" TOUR constellation lists, I recommend a good star atlas and/or chart which will list all the finest objects, constellation-by-constellation. One very handy reference guide is the PETERSON FIELD GUIDE TO THE STARS AND PLANETS, which features complete lists with declinations, right ascensions, magnitudes, and all pertinent information for you to expand your observing horizons beyond this brief GUIDE. For the many double and multiple stars, I again urge you to refer to the indispensable "Burnham's Celestial Handbook", Volume 2 for a complete abbreviated listing.
Truly these extensive Constellation Study Guides will most definitely put your AutoStar to work for you in the most efficient and enjoyable way possible! As a matter of fact, MANY AutoStar users are now programming their own "Tours" based on these guides, using each constellation as a separate GO TO Tour for the AutoStar library that can be added in or deleted through the main edit screen on your PC or MAC computer.
We hope you enjoy these comprehensive GUIDES to touring the constellations via your AutoStar and its computer-driven telescope. Each new installment is complete with diagrams, charts and illustrations that you will find nowhere else. Please let us hear YOUR feedback and your observations of each and every constellation after YOU have toured its vast reaches of our skies!
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YOUR LEPUS CONCISE DIRECTORY OF INTERESTING OBJECTS -
To discover more information, and learn of many, many more double and multiple stars that are within reach of your telescope, turn to your Burnham's Celestial Handbook. For a brief discussion on double star observing and their "Position Angles" refer to my brief overview in the "GO TO" TOUR guide for Lacerta: http://www.weasner.com/etx/ref_guides/lacerta.html .
The most interesting 9 targets (as well as your "GO TO" GUIDE of 75 CARBON STARS throughout the entire sky) in the constellation have been chosen for this LEPUS "GO TO" TOUR; as with all GUIDES, all objects listed below will be visible in most telescopes (some naked eye) from the ETX 60 through the LX 90; of course larger apertures may "show" an object a bit closer and "better," but frequently a wide field and low power view is more desirable than aperture for FINDING the objects initially. Indeed, I strongly encourage you first FIND the target object, or its approximate location through your GO TO function with your lowest power and then - once IDENTIFIED positively - move up slowly in steps with magnification if necessary. Remember, not all objects "like" magnification. Sometimes better "field of view" (such as the wonderful wide fields provided by the Meade ETX 60 and 70) is desired over light gathering and magnification of larger telescopes.
Note that your AutoStar may NOT have every object listed on every constellation GO TO tour....this is intentional. You can access some of the most interesting objects of the sky directly from their coordinates. It is quite simple as you merely enter these coordinates as follows in the 10-step process:
1) Press the "MODE" key and hold down for 3 seconds and release;
2) Displayed will be the current Right Ascension and Declination of the center of field of view of where your telescope is presently pointed (assuming that you have properly aligned from "home position");
3) [NOTE: if you have the Meade electric focuser attached to any of the ETX or LX telescopes, holding down the "MODE" key will bring up the "Focus" command first....merely scroll (lower right scroll key) down one step to access the RA and DEC to enter your desired coordinates]
4) Press the "GO TO" button on AutoStar;
5) This will change the display and you will note the cursor blinking over the first digit of RIGHT ASCENSION (R.A.); merely use the number keys and dial in the R.A. of the object you are searching for;
6) When done, press "Enter;"
7) This moves the blinking cursor over the "DEC" coordinates;
8) [NOTE: the declination, unlike R.A., can be either positive or negative and you will see the "+" or "-" sign displayed depending on where your telescope is aimed at that time; if it is NOT the desired setting (plus or minus), merely use your arrow key to move the blinking cursor OVER the "+" or "-" sign and change by using either of your lower corner SCROLL KEYS;
9) Proceed to enter the DEC using number keys;
10) Press either "Enter" or "Go To" when finished and the telescope begins slewing to your desired object!!
The constellation tour Star Chart above (click on and save to a file on your PC; then open it and re-size to fit the page and print for a very handy at-the-scope star chart) will get you started on your journey for this constellation.
Following is the concise object list for your "GO TO" TOUR of ERIDANUS; you may wish to find many of the objects from the AutoStar Library (for example, you can easily go to the globular cluster Messier 79, if you pull up "Object/Deep Sky/Messier/..then type in '79'...." and then press "Enter", followed by "GO TO" to access this nice and easily resolvable star cluster. Also note that Messier 79 has the designation "NGC1904", so you can also access it that way, by keying in: "Object / Deep Sky / NGC / [type in "1904"] and press enter and then GO TO.
You will access your FIRST GOTO target - (usually the brightest star in each constellation) - via the command "SETUP / OBJECT / STAR / NAMED....and scroll to "Arneb," then press "Enter" and subsequently "GO TO" to move to one of these bright stars.
You may also access the constellation by: SETUP/OBJECT/CONSTELLATION/"Lepus".....Enter....GO TO, which will slew your telescope very near the cartographic center of this sprawling star group.
** IMPORTANT NOTE FOR AUTOSTAR, LX 200 AND NEXSTAR USERS **
As of September 2001, all COORDINATES for celestial objects in your "GO TO" TOURS will be Epoch 2001, converted from standard and pre-existing star/object data from the most recently (epoch 1950, the standard on which most current star reference guides were based). This change will make your GO TO's far more accurate in the future, as the Earth's PRECESSION in space has caused significant shifting of the apparent placement of objects within the past 50 years!
For a full and comprehensive listing, including coordinates, magnitudes, sizes and more concise information about the many NGC objects contained within the boundaries of Lepus, go to the web site: http://www.gatter.demon.co.uk/data/LepN.htm which provides wonderful tabular data on all deep sky and stellar objects in every one of the 88 constellations.
OBJECT 1:
brighter stars -
ARNEB (alpha Lep) - R.A. 05h 33' / DEC -17 49 - Mag: 2.6 - "YES!....It IS on your Autostar!"
NIHAL(beta Lep) - R.A. 05h 28' / DEC -20 46 - Mag: 2.9 - ALSO on your Autostar and a very tough double, faint companion!
OBJECT 2:
triple star - Gamma Leporis - R.A. 05h 45' / DEC -22 27 - Mags. = 3.5, 6.2 & 11 - very nice color contrast, 3rd star pretty tough
OBJECT 3:
nice double - Kappa Leporis - R.A. 05h 13' / DEC -12 57 - Mags. = 4.4 & 8.2 - very nice star for 3" and 4" scope test!
OBJECT 4: + "bonus Carbon Star Directory!"
Hind's Crimson Star - R Leporis (variable, famous "carbon star") - R.A. 04h 59 ' / DEC -14 49 - Mag. 5.9 to 11, 432 days! Wow! What color!
OBJECT 5:
difficult globular cluster - Messier 79 (ngc1904) - R.A. 05h 24' / DEC -24 31 - Mag. 8.4 - tough for northern observers!
OBJECT 6:
cluster? multiple star? - ngc2017 - R.A. 05h 39' / DEC -17 51 - six stars mag. 7 to 10.2; nice loose multiple system
OBJECT 7:
spiral galaxy - ngc1964 - R.A. 05h 33' / DEC -21 57 - Mag. 11.7, very low in southern sky; difficult except in 8" and larger
OBJECT 8:
spiral galaxy - ngc1832 - R.A. 05h 12' / DEC -15 43 - Mag. 12.0 - very faint, compact....close to mag. 10.5 star
OBJECT 9:
planetary nebula - IC418 - R.A. 05h 28' / DEC -12 42 - Mag. 11.9 - central star is mag. 10.8; good object for larger scope
OBJECT 10:
bright double star to end on! - Iota Lep (#3 Lep) - R.A. 05h 12' / DEC -11 52 - Mag. 4.2 & 10.2 - BONUS variable star RX Leporis!
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YOUR VISUAL GUIDE TO DEEP SKY OBJECTS IN LEPUS
Object 1 - Our "Starting" Brighter Stars - ARNEB (alpha Lep - pronounced "ar-NEEB") and NIHAL (beta Lep - pronounced "KNEE-hal")
ARNEB:
Also known in Arabic as "Arsh", this 2.7 magnitude star is nearly 920 light years distant and far more luminous than our own sun. This rather uninteresting star is very close to another object on our "GO TO" TOUR, ngc2017 (below) which is officially cataloged as a galactic cluster, but is in reality nothing more than a 6-component multiple star system. Arneb is a solar-type yellow star and there is a very faint (magnitude 11.1) star some 36" arc southeast (Position Angle 156 degrees); this is a tough target for most telescopes even with that distance (comparable to almost the size of Jupiter in the same medium power....about 15-20x per inch aperture), since the brightness of the primary star outshines the very faint one. This star is most likely NOT a true gravitational companion to Arneb, but merely a more distant object aligned to our line of sight. Look for the nice color contrast: Arneb is distinctly yellow, while the faint star almost appears a blue-green color at medium-high power. At third fainter (12th magnitude) star is located about THREE TIMES the distance between these two; look for the third "optical double" nearly in line with Arneb and the other star, but slightly more to the south, three times the same distance as the 11.1 star.
NIHLA:
This is a MUCH closer star to us than is Arneb. At only 115 light years it is obviously not as luminous a star as Arneb, since its magnitude is nearly the same: 2.8.This is a true TRIPLE star, but is among the most difficult of all for amateur telescopes. It is comparable to attempting to see the companion to the bright star Sirius (see my discussion about attempting to see such doubles at: http://www.weasner.com/etx/ref_guides/sirius.html ), where the primary star is so overshadowingly bright that the companion star is masked from the glare. This is particularly true with this star. However, I can barely see the stars if I use a crosshair eyepiece fitted into at least an 8" scope (I think that a keen-eye person should be able to spot this in a 5" or 6" on a steady clear night); I use one crosshair to "hide" the bright star just enough to expose the elusive fainter star!
However, the first companion, magnitude 11.1 is VERY close...about 2.5" arc, (see the chart above) and just northwest (Position Angle of 336 degrees) of the bright star; so in the Maksutov or Schmidt-Cassegrain telescope with the diagonal in place, the finder chart above is oriented correctly for your field of view. This will be a challenge for ALL telescopes and observers to see this star. If you give up, try the THIRD member of the group, another 11th magnitude star exactly southeast (Position Angle 145 degrees) of Nihla quite a distance (64" arc) away. This faint star is most definitely "seeable" with the 4" and larger aperture telescopes.
Object 2 - The Fine Double Star Gamma Leporis
This is a quite nice double star with enough magnitude difference in the two stars to "make it interesting" for all size telescopes. With a whopping 1.2' arc (that's "minute"....not "second") this is a fabulous star for small telescopes. The primary star is magnitude 3.6 and its companion - just a bit west of due south from the brighter star - is a much fainter 6.2. However, with this nice spacing between the two stars, the glare from the brighter star does not prevent even the smallest of telescopes form enjoying this fine double. This is one of the closest stars to our own solar system, only 26 light years away, and it moves through space somewhat in concert with the brightest star of the sky, nearby Sirius. Because this star rests so close to (just west of) the winter Milky Way, the star field surrounding Gamma Leporis is a spectacular sight for low power instruments; even at the lowest magnification look for the distinct difference in color of these two stars: Gamma itself is a true yellow "F" spectral type star, while the companion is anything but. Color estimates for the fainter star, even with experienced observers, range from blue-green, the ivy green, to purple! Take a look and see what color YOU see....to me in smaller telescopes the color appears somewhat greyish green. In slightly larger telescopes look for yet a third star in this collection, but this one is NOT actually a gravitationally-bound member of the Gamma Leporis group. This 11th magnitude star is almost exactly in the same line as the two stars, but located almost exactly half-way between Gamma and its 6th magnitude companion...quite a sight!
Object 3 - Another Very Nice Double Star - Kappa Leporis.....tough on a 3" scope but "do-able!"
Like Gamma, Kappa Leporis offers a wonderful - though more difficult - contrast in magnitudes. Kappa is a relatively bright magnitude 4.2 while its much fainter companion (and MUCH closer than that of Kappa!) is only magnitude 8.1. Now that is plenty bright enough to spot in a 3" or 4" telescope, but it is not that easy; since the two are separated ONLY 2.5" apart, the star is a tough one for small telescope, due primarily to the overpowering glare of the 4th magnitude star; use medium (15x per inch aperture and up) power and my "trick" of putting a crosshair eyepiece to position one reticle as a mask to block the light of the brighter star. Then look for its faint companion exactly DUE NORTH from the brighter star! This is a nice target for larger telescopes; Kappa looks bright white to me, while its faint companion is distinctly yellowish.
Object 4 - A Colorful Variable Star - "HIND'S CRIMSON STAR" - R Leporis - YOUR CARBON STAR "GO TO" DIRECTORY
All of the "carbon stars" - such as the remarkably blood-red "Hind's Crimson Star" in Lepus - are variable stars; incredible and interesting red stars with spectral types that indicate the "latest" of all stars known, perhaps spending what precious little fuel remains unused and that in the form of atomic Carbon. It is likely that all of the primordial hydrogen and helium that first powered these scarlet stars is now spent, combined from nuclear fusion first from hydrogen....to helium...to lithium....and ultimate to Carbon.
The Carbon Stars and all variables are named according to variable star nomenclature. The first variable that was discovered in a constellation was named "R," followed by the name of the constellation in "genitive" form. The more "common" form of the name, "R Lepus," is NOT used.....rather it is called "R Leporis" in a more gentlemanly form. The second variable in every constellation is named "S," then T,U,V,...Z. Then the naming continues with RR, RS, RT,...,RZ. It continues with SS (not SR to keep things from getting confusing!) through SZ, TT through TZ, and continuing in this fashion through ZZ. This standard method of variable star designations covers the first 334 variables that were cataloged in all 88 constellations....but obviously there are more than that: thousands more. Most such variables after the "first 334" are named V335, then V336, V337. In addition, many of the brighter variable stars are known by a common name, such as Polaris and Alcor, and thus are merely referred to by the more common name and no "variable star designation."
This variable star is different than nearly all of the "carbon stars": these very "late" R- and N-type spectral "cold" stars are normally part of the interesting and yet-to-be-understood "Semi-Regular" stars; such stars demonstrate a "suspected or slight" regular period between brightening, dimming and then re-brightening again, but are characterized during that period by sometimes major fluctuations....unexpected dimming or brightening....long periods at maximum or minimum....very rapid brightness increases followed perhaps by extremely slow fading....and so on. On the other had, many of the carbon stars are pure "irregular" and change brightness without pattern nor notice! Hence the need for YOUR observations of such stars. They should be observed at least once weekly when possible. For a complete discussion on this classification of variable and methods for observing variable stars, see my guide at: http://www.weasner.com/etx/ref_guides/variable_stars.html.
R Leporis on the other hand demonstrates a fairly regular period of 432 days, fluctuating from a fairly bright magnitude 5.9 to a dim 11.2 to even 12.0 in half that period. Many times it will fluctuate near halfway from minimum to maximum (see the graph below) and is very interesting to monitor during that period.
This is an incredible star just to "look at," as the British J.R. Hind agreed in 1845 when he first happened upon this apparently unseen object until then. Although the star raised considerable attention among astronomers at the time, many of them English noblemen and not "professional" as we think today, it was not until seven years later that anyone even noticed that this blood-colored star was even variable! Indeed, its variations are so great that within one year, the star will nearly appear to the naked eye for nearly 40 days and slowly fade to such a faint object that Mr. Hind's modest telescope would likely not be able to even find it!
The carbon stars are the most intensely RED of any know, and for good reason. They have spent all their lighter element nuclear fuel: hydrogen, helium and lithium and have fused what is left into an atomic carbon form, burning very slowly and very cool compared to younger and more energetic stars. The color of the star is much like the color of a flame here on Earth: WHITE is the hottest (brightest) as we would expect from the flames of the efficient and incredibly hot acetylene torch; next would be BLUE, like the intensely hot flame from natural gas; YELLOW is a cooler flame that the first two, much like the "gentle heat" given up by a rapidly burning log fire or the wick of a healthy candle; the flame (and star) gets cooler as it burns on less efficient fuel, gobbling its resources in a most efficient way and rendering an ORANGE flame; then of course - like the RED coals simmering in the bed of your campfire from the previously hotter and yellow-colored flames - the flame is the coolest and will provide a much "slower burning" environment with a less energetic output of heat and light.
It is just the same for the colors of stars. R Leporis is about 1500 light years away, curiously at the same distance as the many bright, young and conversely HOT stars of the constellation of Orion!
Be sure to observe this star when at MAXIMUM to appreciate its brilliant scarlet color...it is like nothing else in the sky; although still appearing red even when at faintest, the color is truly remarkable when at its peak. The 4" telescopes can handle this star all the way through its 432 changes in brightness; however, the 3" and smaller scopes can appreciate it at all times except during its "valley" at dimmest. I have noticed that long focal ratio telescopes (such as f/10 to f/15) will show the color of R Leporis far more intensely than very short Newtonian (f/4 to f/8) instruments. Likewise, the color is enriched in a traditional refracting telescope over compound telescopes of any type.
R Leporis is an excellent target for continued wintertime viewing for all observers....it is likewise very easy to locate. For free observing and finder charts for ALL variable stars, observers need only go to the American Association of Variable Star Observers (AAVSO) web site at: www.aavso.org for complete observing information and packets to get started; in addition nearly every major variable star "worth observing" is mapped in their convenient variable star charts. You can find the proper chart (low power and wide field, but to magnitudes less than 11) at charts.aavso.org/standard/ORI/W_ORI/WORI-AB.GIF , which is actually the chart for another variable star "W Orionis." Nonetheless, R Leporis is found on this chart as well. Once located, refer to the "reversed chart" charts.aavso.org/standard/LEP/R_LEP/RLEP-A.GIF expressly for R Leporis. The reversed image is for users of Maksutovs and Schmidt Cassegrains with the field like a mirror image, or with NORTH up and EAST to the right in your field of view.
A wonderful observing project for astronomers with small, medium and large instruments is to monitor the complete "GO TO" directory of Carbon Stars provided below. The coordinates provided are epoch 2000, so you need only key in the RA and DEC of each star to locate. However, if you want your "telescope to do the walking" you can download the wonderful tour: http://groups.yahoo.com/group/lx90/files/Autostar%20Guided%20Tours/CarbonStars.mtf which provides these in R.A. sequence and in the proper format ready to load onto your Autostar in its Tour Library!
One caution about observing the variability of Carbon Stars and actually MOST variable star since they typically are leaning into the "red" spectral range. There is a well known and documented effect, known as the "Purkinje Effect" in which two mis-estimations can occur when looking at very reddish stars:
1) the observer with more red-sensitive eyes will always note a reddish star brighter than it really is; and,
2) the longer ANY observer stares at a reddish object, particularly a star, the brighter its light will appear to the receptors of the eye.
CARBON STARS:
STAR NAME COORDINATES MAG. PERIOD SPECTRAL TYPE
R.A. DEC.
VX And 00:19:51 44:42:00 8.0-9.5 367 N7
T Aql 18:45:42 08:44:14 8.8-10.0 Irr M5
V Aql 19:04:22 -05:41:27 6.6-8.1 350 N6
Y CVn 12:45:09 45:26:35 5.0-6.4 158 N3
W CMa 07:08:02 -11:55:33 7.0-8 Irr C6
R Cap 20:11:18 -14:16:00 9.4-14 345 Ne
RT Cap 20:17:02 -21:19:40 6.5-8.1 395 N3
X Cas 01:56:40 59:15:40 9.5-13 423 Ne
WW Cas 01:33:33 57:45:24 9.1-11.7 Irr N?
Mu Cep 21:43:32 58:46:49 3.7-5.0 Irr M2e
S Cep 21:35:14 78:37:31 7.4-12.9 487 N8e
V CrB 15:49:29 39:33:55 6.9-12.5 358 N2
V Cyg 20:41:17 48:08:33 7.8-13.8 420 Npe
RR Cyg 20:46:04 44:52:07 6.6-9.4 417 Npe
RV Cyg 21:43:16 38:00:48 7.1-9.3 300 N5
RY Cyg 20:10:23 35:56:57 8.5-10 Irr C4
TT Cyg 19:40:55 32:37:04 7.8-9.1 118 N3e
WX Cyg 20:18:34 37:26:27 8.8-13.2 411 N3e
V460 Cyg 21:42:01 35:30:45 6.1-7.0 Irr N1
V778 Cyg 20:36:10 60:05:17 9.4-11 ?
SY Eri 05:09:46 -05:30.16 9.0-10 96 N0
R For 02:29:14 -26:05.39 7.5-13.0 387 Ne
VW Gem 06:42:08 31:27:04 8.7-9.1 Irr C5
RT Gem 06:46:34 18:36:54 9.9-15 350 N?
TU Gem 06:10:55 26:01:19 7.5-8.4 230 N3
CR Gem 06:34:23 16:04:36 8.5-9.5 Irr C8
U Hya 10:37:34 -13:22:38 4.7-6.2 Irr N2
V Hya 10:51:38 -21:14:58 6.5-12 533 N6e
Y Hya 09:51:07 -23:01:06 6.9-9 303 N3
CZ Hya 10:27:21 -25:33:20 8.5-14 442 Ne
TV Lac 22:56:08 54:13:04 9.9-11 N3
R Lep 04:59:35 -14:48:34 5.9-11 432 N5e
T Lyn 08:22:40 33:31:20 8.0-12 419 N0e
T Lyr 18:32:20 36:59:58 7.5-9.3 Irr R6
U Lyr 19:20:09 37:52:40 8.3-13 457 N0e
W Mon 06:52:20 -07:08:42 9.0-13 Irr C4
RV Mon 06:58:23 06:09:53 7.0-8.9 132 C4
BG Mon 06:56:24 07:04:01 9.2-10.4 30 C5
GY Mon 06:53:11 -04:34:46 7.7-8.9 Irr N3
V Oph 16:26:44 -12:25:43 7.3-11.5 298 N3e
TY Oph 18:31:23 04:22:12 9.5-11.0 Irr N?
R Ori 04:59:01 08:07:30 9.0-13.5 378 Ne
W Ori 05:05:23 01:11:02 6.5-10 210 N5
RT Ori 05:33:12 07:09:03 8.0-8.9 320 N3
BL Ori 06:25:28 14:43:30 6.3-7.0 Irr N3
GK Ori 06:17:42 08:31:06 9.5-11 236 C4
V431 Ori 05:15:57 11:57:48 9.3-11.1 122 C5
RX Peg 21:56:25 22:51:19 8.0-9.5 630 C4
RZ Peg 22:05:55 33:30:40 7.7-13.5 439 C9
Y Per 03:27:43 44:10:25 8.1-10.9 252 N?
SY Per 04:16:35 50:37:25 9.5-12.5 476 Ne
19 Psc 23:46:22 03:29:42 5.5-6.0 Irr N0
Z Psc 01:16:08 25:45:51 7.0-7.9 144 N0
RT Pup 08:05:19 -38:46:38 8.5-9.2 100 C6
RU Pup 08:07:29 -22:54:55 8.9-11.1 425 C5
AC Pup 08:22:43 -15:54:42 8.9-10 Irr C5
X Sge 20:05:06 20:38:37 8.7-9.7 196 N3
BF Sge 20:02:24 21:05:27 8.5-10 Irr N3
SS Sgr 18:30:24 -16:53:54 9.0-10 Irr N3
SZ Sgr 17:44:57 -18:39:12 9.0-10 73 C7
AQ Sgr 19:34:16 -16:22:24 6.6-7.7 200 N3
V1942 Sgr 19:19:10 -15:54:26 6.7-7.1 Irr C6
SU Sco 16:40:38 -32:22:47 8.0-9.4 414 NO
SX Sco 17:47:28 -35:42:02 8.5-9.5 Irr N3
R Scl 01:27:00 -32:32:26 6.1-8.8 363 N3p
S Scl 18:50:19 -07:54:27 7.3-9 148 N3
T Sct 18:55:25 -08:11:05 8.9-10 122 N3
RX Sct 18:37:00 -07:36:25 9.0-11 Irr N3
W Sex 09:50:57 -02:02:06 9.0-10 40 C6
Y Tau 05:45:41 20:41:09 7.1-9.5 241 N2
TT Tau 04:51:33 28:32:02 8.0-10 166 N3
RT UMa 09:18:23 51:24:21 8.6-9.6 Irr C4
VY UMa 10:45:51 67:24:19 6.0-6.6 Irr N0
SS Vir 12:25:16 00:46:22 6.0-9.6 355 Ne
BD Vul 20:37:18 26:28:48 9.3-12.7 430 Ne
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Object 5 - A Far South and Difficult Globular Cluster - Messier 79
This is a very difficult object to resolve in any size amateur telescope from the northern hemisphere except perhaps Florida, and the southern tip of Texas. At the far-south declination of nearly minus 25 degrees, the atmopshere plays havoc with your telescope's ability to resolve this otherwise bright cluster into the hundreds of stars that should be visible. It was discovered by the French comet-hunter Pierre Mechain in October of 1780 when he recorded in his observing log: "...a nebula without star, situated below Lepus, and on the same parallel (Right Ascension) as a star of sixth magnitude..." By December, Charles Messier, the countryman and somewhat adversary of Mechain, located the object saying:
"....this nebula is most beautiful, the center brilliant, the nebulosity a little diffuse, its position being determined by Epsilon Leporis....a star of the fourth magnitude."
John Herschel, observing from his huge observatory near Cape Town, South Africa years later noted that Messier 79 was ".....a globular, pretty large, extremely rich; extremely compress and well resolved." in his giant 20-foot reflecting telescope. On the other hand, you can see that this is not a very spectacular not large globular from the photograph below taken with the 200" Palomar telescope, providing photographs normally commanding a gasp of air or a sudden swoon.
Without a doubt Messier 79 is the most difficult globular cluster for discerning viewers of all the Messier objects. This is due to two factors: 1) the cluster is located very far south in the skies for northern hemisphere observers and atmospheric extinction blocks much of the subtle detail and contrast of the very faint stars within it; and, 2) the stars within this cluster are primarily magnitude 14 and fainter and thus beyond the resolution of smaller amateur instruments. On very dark nights an observer with an 8" telescope might begin to see some stars sprinkled around the perimeter of this small cluster. My 12" has difficulty with individual stars on average nights but present a very beautiful view of "stardust" throughout the cluster when the skies are deep and dark. NEVER hesitate to use high magnification on nights of very good steadiness. For a complete discussion regarding how "seeing" and air transparency affects your viewing, go to my discussion at: http://www.weasner.com/etx/buyer-newuser-tips/seeing.html. I routinely use over 50x per inch aperture to observer planets and doubles stars when the conditions are favorable; the old myth that higher powers are useless on telescopes are not true with today's Null-figured optics and excellently corrected eyepieces.....it is the AIR around us that limits the "power potential" of your telescope. I have learned that higher powers (up to around 200x to 250x) are not necessarily detrimental to observing the MOST in globular clusters! Through the power of space and an unfettered view through the emptiness of the cosmos, NASA astronauts aboard the Shuttle were able to capture the beautiful infrared image shown below:
The magnitude of the cluster is about 8.9, and its size measure nearly 8' arc; hence its distance of over 50,000 lights years is partly responsible for the poor views afforded of this cluster. However, it is also a physically smaller cluster than many of the showcase objects such as Messier 13 and those throughout Ophiuchus.
Object 6 - NGC 2017 (Herschel's 3780) - You tell ME what this is.... a nice multiple star or a very poor galactic cluster?
Here is an object that has (probably in error) been classified as a very sparse and loose galactic star cluster. Six Stars....galactic cluster. So it's not the richest star-packed cluster in all the sky...but it IS six stars all at the same distance bound to one-another gravitationally, so is it actually a "cluster" or a very healthy "multiple star?" This is much like the now-famous "is Pluto a planet?" debate.
Let's study the small double star locator graphic I have prepared above. This chart has NORTH up and EAST to the right, which is the proper field orientation of your Maksutov or Schmidt Cassegrain telescope with the diagonal mirror installed. The primary brightness of this object ("cluster") is about magnitude 7, yet the object is NOT commonly referred to in many catalogs of NGC objects. Nonetheless, it IS designated as "2017" while William Herschel merely noted it as "object 3780" and did not distinguish as anything but a celestial object. Most of the brightness is the combined light of two very close stars - "A" and "B", magnitudes 7.1 and 8.2, respectively - which are only 0.9" arc apart. This equal-magnitude double can make a wonderful test for the "perfect" 5 inch or 6 inch telescope, but it will be quite a challenge with either; I have found most times it is difficult to split with even an 8", although the 10" and 12" size telescopes does a nice job showing black sky between two very nice disks. The lesser star, "B", is located SOUTHEAST (Position Angle 147 degrees) from the brighter star; make sure to use at least 25x per inch aperture to even get close to resolving these first two members of the group.
Now look for star "C" almost in a STRAIGHT LINE from these two, also further southeast from "A", but a considerable distance....89" arc, or two Jupiter diameters. Nonetheless, this star should be quite easy to identify, as it is only slightly dimmer (magnitude 9.3) than star "B" and in the same direction (SE) from the brightest star....so this "string of stars" should be quite a nice sight for larger telescopes. Even if you do not see "B", be sure and look for "C"; in fact, I have often used "C" as an angle marker denoting the exactly location "next to" the brighter star where the star "B" might be found.
Nearly due NORTH and a bit to the east (Position Angle 7 degrees) is star "D" of this six-star system, almost the same distance from "A" that is "C". This star is brighter than "C", at magnitude 8.4.
The fifth star ("E") of the group is about the same magnitude as "D" (8.3) but oriented almost exactly northwest (Position Angle 330 degrees) from the bright star "A". It is nearly 2/3 farther away in your field (129" arc) than are either "C" or "D". This star, likewise, is an easy target in even small telescopes.
The last star is "F" and it is a bit harder to see as it is only magnitude 10.1; it is still visible in the 3" and 4" telescope range however; look for "F" about 60" arc to the northeast (Position Angle 49 degrees) from the brightest star.
All-in-all, this is a nice object for all telescopes to study. It is a pretty sight and a challenge for medium size instruments if you want to see all six members; "A" and "B" will always be a challenge, but a total of at least five stars should be detected in most telescopes. Except to split the A-B pair, use medium-low (about 10x per inch aperture) to view this nice little group against a beautiful winter star field.
Object 7 - A Faint but Observable Spiral Galaxy - ngc1964
The "ringed effect" of this distant galaxy, magnitude 11.6 visually, is clearly shown in the 200" Palomar photo shown above; with telescope of 10" or less, all that is visible is a very tiny star-like smudge of light that measure 5' x 1' arc at best. It is a very difficult object, but a 5-6" scope on a very dark night and about 25x per inch CAN see the diffuse nature of this tilted spiral galaxy. In a 12" on the darkest of nights, some suggestion of the "ring" (actually merely clumping of stars within the galactic arms) can be glimpsed using averted vision. This ring is distinct and very interesting in detail in a 24" scope.
Object 8 - Another Faint Galaxy - ngc1832
Normally I would not even put a 12.2 magnitude galaxy in here as a "GO TO" TOUR object, but this one might be interesting to test your telescope's light gathering ability. Many observers with small-to-medium sized telescopes simply "refuse" to search out faint galaxies and for a justifiable reason: many times an "impression" or suggestion of an object might be there and the observer is wondering whether or not the object was actually SEEN or IMAGINED. If you are like me, this leaves more frustration than satisfaction. NGC 1832's image is very "tight" and compact in a telescope, the light of this galaxy compressed nearly all into its very central region that measure only 2.1' by 1' arc across; thus, even though it is a visual 12.3 magnitude, all of its light is fairly packed into a small area....a 4" or 5" telescope CAN see this galaxy, but barely, given perfect dark sky conditions. With ngc1832, you have an excellent "guide" to this star, for in the same low power field of view, just about due south of this tiny smudge of light is the bright star "mu Leporis (see the Palomar photo below, digitally re-oriented to match the reversed view of your telescope). If you will look about 1/2 degree NORTH and just a bit west of mu (magnitude 3.3) , you should be able to lock onto this galaxy. If you have dark enough skies and at least a 4" telescope when Lepus is highest in the southern sky, then YOU can claim bragging rights to a 12.3 magnitude galaxy among your observing trophies!
Object 9 - A Faint Planetary Nebula with a Brighter Central Star - IC 418
This one is not in the custom "Planetary Nebula" tour that I provide, nor is it listed among your Autostar Library NGC objects....it doesn't even have an "NGC" designation! IC 418 is a very difficult nebula to make out...BUT the central star that exploded millions of years ago to create it is still there at magnitude 10.8, visible in even a 3" scope, but perhaps more easily in the 4" and larger apertures. The "ring" of stellar gases in this planetary nebula has a brightenss of 12.0 and with its tiny size of 14" x 11" arc, the concentrated brightness is easy to spot in a 5" and certainly an 8" telescope. However, note that the star itself is far brighter than the planetary nebula which is many times the case in some of the fainter and more compact objects of this class. On a very dark night, medium power (about 20x per inch minimum) to search for the faint cloud around the star; the keen-eyed should spot this very subtly surrounding this star in a good 4" glass.
Object 10 - Taking You Out on a High Note - The Challenging and Bright Double Star - Iota Leporis ("3 Lep") and the Variable RX Leporis
Here is a nice way to end out "GO TO" list of objects in Lepus....normally I try to end the segments with some spectacular deep sky object, but since you have suffered through the miserably difficult and faint objects in this "wascally-wabbit", this should come as a breath of fresh air. The bright (magnitude 4.2) star Iota Leporis has a very faint (magnitude 10.4) companion star AND a nice brighter (5.7) VARIABLE STAR immediately south of it! Iota Leporis is about 277 light years distant and the faint star can be found (note the finder chart above) nearly northwest of the primary star about 12.8" arc; the pair should be able to be seen in a good 4" telescope and possibly in a 3" under very dark skies and medium-high magnification (about 25x per inch aperture). This pair has a period of rotation around one-another about every 33 years (we think!). Note that there is a nice and relatively bright (magnitude 6.1) star immediately WEST of Iota which makes a very nice grouping in any telescope.
Only 3 degrees to the south and a bit west of Iota Lep is the variable RX Leporis, an irregular variable star with a brightness range from magnitudes 5.7 to a bit less than 11, with NO particular cyclic period. Thus, the entire range of light changes in this unpredictable star can be monitored easily in a 4" and larger telescope. Note its location in my locator chart above which has a field of view oriented properly for your Maksutov or Schmidt-Cassegrain telescope. Unfortunately there is no AAVSO locator (not needed here!) nor comparison star chart available, but observers can make relative estimates via the 8th, 9th and 10th magnitude stars stars within the field of view. It is worth keeping up with, as are any irregular variable stars!
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WANDERING ABOUT....YOUR NEW "USER OBJECT" IN LEPUS
There is simply no other option to consider here. Since this is a remarkable object to view over and over again and a wonderful star to share with those at public star parties or within your observing group, NO telescope should be without "Hind's Crimson Star" on its User List. Not only is it a splendid sight like none you have ever seen, but it is a great variable for nearly all telescopes to monitor!
This wonderful object is the Rosette Stone among the Carbon Stars featured previously; it should be in your Autostar library without question.
On AutoStar, go to: "Select/Object [enter]...." scroll down to "User Object" [ enter]. Now enter the coordinates given above for R LEPORIS using the number keys on AutoStar. After entering the coordinates and pressing "Enter" yet again, scroll down one and you can list the magnitude of the object as "6" [Enter].
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Your next constellation is a trip not only into space, but into a realm of mythology and memories of your own as we explore the wondrous boundaries of the constellation ORION, the Hunter.....the Hero....the Legend....the sparkling revelation of stars that virtually announce the grandeur of winter and its crisp and cold skies. ORION is NOT to be taken lightly, both the legend of the man nor the constellation pattern and the boundaries that contain it. For within the man is mythology that encompasses all cultures, all times and all of mankind. Within the bright pattern of stars are virtual stellar nurseries that harbor the first life of newborn stars, vast clouds of nebulous gases that hold the keys to the very advent of our sun, our planet and our lives. Countless beautiful and colorful multiple stars grace the constellation as the intriguingly mysterious winter clouds of the Milky Way sink from the hunter's raised club in hand, past the fiery red signal of Betelgeuse and down into the realm of the Diamond of the Sky, Sirius.
Because of the countless objects....the far-reaching and fascinating mythology and legends....the beauty of nearly each and every naked eye star and asterism... I am offering the "GO TO" TOUR version of the Orion Constellation Guide in THREE parts:
ORION: Part I - The Constellation, Making a Mark in the Sky and in Legends for Mankind ORION: Part II - Observing and Understand Messier 42 - The Great Orion Nebula ORION: Part III - Revealing the Treasures Within - Your "GO TO" TOUR
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Good Observing and may the stars serve as your sentries as you explore the frontiers of space!
P. Clay Sherrod
Arkansas Sky Observatory
Conway / Petit Jean Mountain
Arkansas
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