THEFOqAL POilNT

The AtlantaAstronomy Club, Inc.

Vol. D( No.3 August, 1996

7947- 7997 CeTebrating Eifty Years of Astronomy in AtJ,arrta

August MeetingNotice of the went will be somewhereftom $75 to $85. The The next meeting of the Adanta Astronomy Club win be facility has a pool, tennis courts, miniture golf, glft shops held at 8:00 p.m. on August 16 at Emory University's etc. The number to the lodge is (706)695-9601. A more White Hall.Our speakerwill be Dr. Dick Miller, Professor economicalstay might be in the city Elh.yay,or Blue Ridge, of Astronomy at G€orgia State University. Dr. Miller's or in the Fort Mountain StatePark area which is about 10 miles past the overlook (Contact the Park subje€t will b; "Blazars: The Most Extreme Quasa$" Service for Blazars exhibit the greatest luminosity and variability of derails). any Quasars. As a result. they prwide an excellenttest for Directions to the Cohutta Ov€rlook: the diff€r€nt models proposedfor thes€ objects. Dr Miller There are 2 setsof directionsbelow. The Cohutta will discuss and comlnre the models which attempt to Overlook is easiestwhen aproached from Ellijay. If you dercribe Quasarsin terms of supermassiveblack holes.The don't know how to get to dori'ntownEllijay follow the first extreme profErties observed in Blazars may help us to set of instructions. If you do, then skip aheadto the second determine just what is actally going on in these very set. puzzling and very remotesystems. r) DIRECTIONS TO ELLUAY From Arlanra take I-285 10I-75 North. From I-75 North, turn onto I-575 North. Follow I-575 until you seea CalendarNotes .i@ u7hi.h .--i. FAQT Fl I rIAv" A aila ^. -^ ^^d .L^ "EAST ELLIJAY' sign, you will come across a major l0 August PerseidObeerving at CohuttaOverlook intersection. Justbefore the inters€cton you will s€ea sign 15 August Ob6ervingat EgalstonHeart Camp near on the right side ofthe road pointing to the left which reads 'ELLIJAY'. Hard Labor Creek This is for children Thereis a McDonaldson the left hand side of ag€s6 to 18 years. Ifyou would like to the road. Take a left at the intersection. After crossing help with this observing,please call over a hill you will come to a stop sign. Contirue straight (770) 227-2233. over the rail-road track until you comeacross another stop 16 August Meetrng at Emory University's Whit€ sign. A car dealershipis on the right. Take a left at the IIall stop sign. About a block ahead you will come across 24 August Public Observingat Villa Rica another intersection. There will b€ a Dairy Queenon th€ left. Take a lefr at this inters€ction. Continue on the road PerseidMeteor ShowerObserving Session for about2 miles until you reachdowntown EllUay. by DougChessei, AAC President 2) I}IRECTIONS TO TEE COEUTTA OVERLOOK The Club's Perseid Meter Shower observing From the center of downlown Ellijay take s€ssion is scheduled for August lOth at the Cohutta Highway 52 west (sigls clearly mark the road). After Overlook just northrrest of Elijay. The overlook has an about 12 to 15 miles you will see the Entrance to the incredible vista for otrerving and extremely dark skies. Cohutta Overlook on the rigbt (Just Fst Mile Marker I). Only a small s€ction to the sourh is obacured.However, Take a right hto the Entranc€ ard park next to the path there are ly'O restroomsor other facilite6 so be r*amed. The which leadsto the top. observingfield is located about 30 yards ftom the parking area, but the incline is quite steep. It will be difficult to AAC Webpage bring large/heary telescopes.Members are encouragedIo byAlex Langoussis keepit simple. Bring a loungechair, picnic dimer and kick back to $atch the shower. After starting and maintaining the Atlanta For those not wanting to dnve back after the Astronomy Club's intemet home pagefor the last year and Perseidsthere is a faidy large and well k€pt lodge about 5 a half, it is time to pass the responsibility on to someone miles past the Overlook on Highway 52. The lodge is the els€. "Cohutta Lodge & Restaunnt". Ratesfor rooms the night '| The new web page editor would need an internet hard obs€rtersin the club who love to observeat the colder connection that allows posting of a home page. One can time of the year. However, memberswho are occassional page createa with severalkinds of software. Maintenance observersare welcomedand encouragedto attend. There page of the usually takes 4-8 hours a week. But the will be no guest speakers,or talk (other than the usual rewards are many. You will find youself communicating social ones). If you erloyed our Turkey Farm event this with peoplethe world over. past Spring, you will probably nol want to miss this event . Wh€n we started early last year, we were only the either. 12* club to have a web 1nge. At last count, there are now Accomodationsare Camping. Tent camping on 103. At the time web pageswere simple, drab, mostly text. the observingfield will be permitted however,there are no Now, we have colorfrrl backgroundsand graphics, sound RV hookups. Bathroomsare locatedin facilities just off the and movrng images. Thesemore complex pagestake a lot observingfield. The club will provide Hot Bwerages and more time 10 create, time that I don't have. The club Snacksduring the nights. It will be chilly, and could get deservesa first rate web page, which is why we need somewhatcol4 so dress afrf,roFately and make sule your someonewith the time, sttlls, and desire to do the job sleepingbag is up to par. riglrt. You must register before November 1"1. To We need your creativity and comprter skills! regster just send your name, address, phone Pleasecall me or Doug if your are interestedin laking on nurnber,numberof peopleattending and how many nights, this rewarding responsibility. and a check of 5 dollars per night (Made out to the Atlanla Astronomy Club) to: SidewalkAstronomy on the 4th of July Doug Chesser by Steve " Saratoga Smitty" Smith c/o AAC 2916Appling Circle Moreland, Georgia, the birthplace of L,ewis Chanblee,GA 30341. Grizzard hosts a 4th of July bar-b-q and crafts fair. This year I was allo*ed (at no charge) to set up my telescope AAC'S Fall Picnic and table loadedwith star charts, books and magazinesfor Volunteers are needed to help out with the Club's fall general display. Many AAC information flyers were picnic scheduledfor Saturday.September l+,} in villa distributedto inquisitive onlookers,along with my personal Rica. We need I or 2 people to volunt€er to bring our AAC side$tlk astronomercards. griUs. We also needpeople to help s€tup. The picnic wil Hunqted5ui yie*s wcrcgilcu of dre Surrthough be held ilr l:sual &slu+r. The club w!! pror.idelot-dogs my scope"Starurtp Saratoga", which was equippedwith a for the grill. membeismay bring thier own steal6, chicken Thousand Oaks solar filter. Although the Sun was or other meat to throw on the grills as well. The picnic w l unremarkablethat day due to no sunqrotsbeing visible (t e begin around 4pm and last till whenwer. After the curse o/ the solqr minimum! -ed.), m ny people had their cookout, when darlness arrives an obEervingsession will first good look at our nearest star. I also answeredmany begin. questionsabout our hobbyand I lnow I sfErked the interest of more than a few. AAC Expeditionto the Chielhnd Starfest A humorous side-note to this: my scope is a by DougChesser, AAC President Coult€r lo-inch Dobsonianwith a red tube. It being the 4th On the weekendof October l0e-13s, membersof of July, a few people came up to me and looking towards th€ Atlanta Astronomy Club are planning on atlending the asked about " that big rocket or fir€cracker". All part of Chiefland (FL) Starfest, hostedby the Astroscopers. This being a SidewalkAstronomer I gueris! star party featureslots of obGervingunder dark and steady Expanding the lnowledge of the public about the skies. There iue no guest speakersor tats, just plenty of universeis a great thing about Side*alk Asuonony, and it good conversationand obeerving can be done alone or in a goup, at the end of your While the Star Party is Oct. 10-13, there really is driveway, at a school or in a ctryground For more no s€t time; one can comebefore that and stay long€r (hey, information about Sidesalk Astronomv contact Larrv is this laid back or what!). The 5 acre site accommodates Higgins at 77 0 -227 -2233. canping at a cost of $5 a nigbt 1rr site. There are 2 outsideshowers, and port-a-pottiesas well.The site is about 1STANNUAL DIE HARD OBSERVERS 6 miles south of Chiefland. There are restaurantsin town . PARTY for thosewho don't care to cook out. Plus the opportunity The club will host its first annual DIE HARD to do fishing and boating in the aJea.so there is plenty to OBSERVERSparty on Friday and SaturdayNovember 8h do in the day. Only ten miles to the south lies the relnown and 9' at the Dauset Trails Natue Center near Jackon ManateePark. Georgia. For thoseplanning on going dovm on the 10' and This is a no-frills went with a focus exclusivelyon would like to participate in the carayan we will meet at (contact observing. Thrs star party is gearedmainly towardsthe die 10amat a TBD Waffle Houseon the way Doug for details).If you are interested in this outing contact Doug More on that as it happens. Chesserat 770-457-57'13 lf you have photos or even videotapeyou like to contribut€, contact Ken Poshedlyat (77O) 979-9842,ot e- AAC Meeting Minutes: July l2*, 8pm, mail to [email protected]. Fernbank Planetarium. submittedby DougChesser, AAC President From the Observer'sNotebook Members of the club enjoyed a planetarium show entitled The StarsOfAlerander. Tlte show focusedon the heavens On July 13, we had our club obsewing at Daus€t of the ancient Greeks and includ€d constellation lore, as Trails. There was a good sized group of 19 members weu as r@entdiscovedes. pres€nt with thre€ scopes and binoculars. Everyone After the meeting about 72 membersof the club attendeda attendingwas taking a gambleon the weather. Cloudsdid quick businessmeeting. roll in mth a sprinHe or two, but we all hung in there and . Doug Chessergave a presidentsreport which included obs€rvedthrcugh potholesin the clouds. Better luck nexl status rE)orts on the club's logo development progess. trme. Doug reporteda logo or seriesof logo's should be ready to be presentedat the August or Septemberclub meetingsfor On Friday, July 19, the Sidewalk Astronomy endorsementby the membership. Doug also reported on Group held an observing at the Grifrn Kiwanis the last Executive Council Meeting. This included a Fairgrounds for the Spalding County Cub Scout troop6. summary of the ObservatoryDevelopment discussioq as There were at l€ast 100+ Scouts and their parents in well as the Advanced Sites Selection, and Logo teams. attendance. They were lined up at the telescop€sfor two Doug also announcedthe club's fall picnic is tentatively solid hous. A good time was had by all, but the b€st time schedrled for Saturday, September14' in Villa Rica, as was had by AAC membersas we warchedthe excitementin well as an announcementfor the Club's expedrtionto the the facesof the scoutsand their porents. just Chiefland Starfestin FL on October l0'. You don't know what you're missing when you o Rich Jakiel gave a Conesponding Secretary'sreport don't attend these obseruings. I \vould like to thank Smitty, Phil Sacco,Keith Cox and Bill Warren for their and announcedthat the deadline for Aueust-also Focal Point submissionswould be Augusr 2d. Rich emphasized support$rth the SidewalkAstronomy Group. Comeon out join the importanceofbeing on time with submissions. and us nex time. o Larry Higgins gavethe ftserving Chairmanls report. Ee announc€severai stars could be identified As Tom that's yisible in IOUII filter photos shown in this atlas, Polakis has shown in his survey of the Local Group with a which includes some pretty inpressive stuff found in ro 33cm NeMonian (published in one of the final issuesof ordinary atlas. "Deep Sky'), the dwarf iregular galaxies also show their 4) What are surfac€ brightness limits as a firnction of HII regions clearly with and without sky-zupressing apertue? "nebula" filters. A more comprehensivesurvey could be Up until the time of TSB obcei't?tionsof my own madein ths respeclwith a bigger telescope.too. suggestedthat t[eF was a firndamentatlimit to the lowesi 2) A generalsurvey of planetarynebulae surfacebrightness one could d€t€ct, depen&nt mainly on It is certain that the 120-odd NGC and IC planetary sky brightness and otr "experience" (i.e. visual ski[). nelulae are a long way from being all of those readily Although the range of tel€scope apertures in my visible in a modesttelescope. I have seenover 400 with a obsenations was limited rhi< limil se€med to be l5cm refraclor. Jack Marling ard Steve Gottlieb made independentof aperture. I could see objeGlsof quile low good progess on a comprehensivesurvey starting in the surfacebrightness in my 7cm Pronto, as long as they were early 80s, and a few chunks of it were published as articles larg6 (e.g. NGC 147, NGC 4395). However,at TSP, yiews in "Deep Sky", "Betelgeus€", and in the "Web Society through Larry Mitchell's 9ocm telescope,which showed Q'uarterlyJoumal". A group within the Webb Societyhave things such as the faint planetaryLongmore-Tritton 5 and und€rbken another survey,but few of the observationsare the faint halo around the Ring Neh a, indicated that one being made under good conditions. It would be more could seeto quite a bit lower surfac€brightness. The limit corNincing to have a completeass€6sment done with one or with the 7cm and l5cm telecco,pesI am usedto is about V a few telescopes(sharp ones) and one or two observers m g. 24 Fr squarearcsecond; with Larry's telescope,we Qik€wise)ftom truedark sites in each hemisphere. Of the were readily s€eing things that I lnow have peak surface 1200 or so confirmed planefari€s,which are the onesboth brightnessno brighter than mag. 25, and as a rough guess, visible of visual inter€st (which doesl't necessarilymean ihe limit was something closer to mag. 26. Although a only the brightest ones)? How do€s each one of them mere two nagnitude gain doesnl seen like a large respond to different filters? Which of them rev€al ouler differencein going ftom a Pronio io a gocm, in fact this is haloes in large aperture? A good starting point for Fetty dann impressive, and the observing challengpsit observinghere is SteveHynes' book "Planetary N€hrlae", brings into rangeare awesomeind€ed and then progressingto the "Sta$oug-ESO Catalogueof The task of this observingproject, then, would be Galactic PlanetaryNebulae". !o make estimat€sof the surface brightness limits as a 3) [Onl or UHC suw€y of Milry Way function of apertureftom the sam€site on consistentlydark As best I can recall, this surveywas proposedfirst nights. Probablythe b€st targets for this would be any of by Alister'Ling. Here I an thinking of examining the nany galaxies for which there is prblished surface visibility of large neh ae normally consideredtoo faht for photometryin the Vband" It would not be easyto assemble ordinary viewing mainly becausethey are large. The ideal such a list, but I could help somone get a start diqging tkough the literature for it. Several of these crJuld be Galaty. Again, use of fllters would be of interest, too. Is viewed severaltimes in different telescopes, and the sizes the Gum Neh a or the gamrnaCygni complex visible as a defrnedby their extent relative to nearby field stars, which pie.e? Elsewhere in the sky, would the field be wide could then be measured on sky survey images to get the enough to get a better view of the gegenschein? other actual diameters. The resr ts would then be matchedwith "big" things, such as cometsof the Hyakuuke and tlale- the surfacebrightness profiles to see what isophote those BoE) variety will also be viewed to adyantagewith such sizescorresponded to. very-low-power optics. your gurde here would be 5) Visual surveyofneallry rich galaxy clusters Uranometriaor the Herald-Bohoff atlas. There is no pblished survey of all the brightest 7) A suvey of emission-linegalaxies probably and most nearloy rich galaxy clustets. lhe Mary of the bright Shapley-4mssgalaxies have convenientlimit for ordinary amateurtelescopes up to say prominent HII regions, which are greatly enhancedby an (16-inches) 40cm aperhre coresponds to a redshft [OIII] or UHC filter. Someof thesecan be sponedeven in velocity of about 10,000 or 12,000 tm/sec, or roughly the small alErtures on such galaxies as M33 and Ml0l. A distanceto the Herculesclusler complex. A very good start larger class of objects also exist whose light ouFut is on such a project was done from the UK tvith a 40cm greatly dominated by "stalburst' regtons buned in high- Newtonianby Walter Histon, who preparedvolume 5 of the excitation HII regionsthat are blazing-bright relatrveto the Wetb Society Observing Handbook, which dealt with rest of the galary. Such objecrs are comrnonly found galaxy clusters. This volume was certainly the best of the among lists as the Markarian and Arakelian galaxies. Webb s€ries,and Histon did about as well as he could at the lvlarkarian and his colleaguesconducted a survsy looking time as far as making chans, getting magmtudes,and so on for gala\ies with strong blue and ultraviolet signaturesin for irdivifual oqects in the clusters. However,one can lots their spectra. Their survey yielded many interestirg better now, simply becausethese clusters are now so much objects, including "H galaxies" and Sefert galaxies, Iretter exploredthFn they oncewere, and basic "observable" whose nuclei are sites of intense activity. &akelian data is availablefor all the decenttybright galaxiesin most searched simply for galaxies of unusually high surface if not all of the clusterc. brightness. As night be suspectedftom thesedescripions, This is a task for an obsessiveDurchmusterung @D) and its posirions of stars has now long silce (v2. since about successors(the southem BD, which extendeddown to -23 1990)been supercededby the PPM ald ACRS catalogues. D€ci the Cordoba Durchmusterung,from -22 to the south Both the latter catalogueshave more starsand are factors of pole; the Cape PhotographicDuchmusterung -19 to rhe srx to ten more accuratethan the creakyold SAO. Both the south pole) were done visually or photographically at a PPM and ACRS are available for free over the Net ftom time when not only were magnitudesystems themselves not data centers(details to follow). Neither cataloguecontains welldefined, but the process of getting from a photometry useflrl for oru purposes,so don't use the star photographic image to magnitudes was not understood magmtudes here either. Th6 PPM, together with its For the BD, as an exarnple,the magnitudesquoted brighter 90,000-star supplement, conlains nearly twice as many than about 9.2 are ac$ally fairly close to the "true" V stars as the SAO. Wriiers of computer "planetarium" magmtude scale when the list is consideredas a whole. softwarereally shouldabandon the SAO-they should have But the star-by-star etrors have a standard deviation of done so five years ago! And if I can 1nrt in a comment, about +/- 0.3 mag. This means that you have a -ll3 when someoneclicks on a stal (or howeverit's done)to get chanceof the BD magnrtudebeiag otr by 0.3 mag. or more. an ID, please_don't_ glve the PPM number, but inst€d Argelander, who headed up the BD effort, made an use the HD or DM name by preference(the cross-IDsare assumptionthat the little cmet-seeker used for the survey suppliedwith both the PPM and ACRS). The reasonis that showed stars only as faint as mag. 9.5, so all the faintest professionals rarely use names from the astometric starswere assign€dthat nagnitud€. This turns out to have catalogues,hrt i$tead prefer older names roughly in been quite pessimisticl the telescopeactually showedstars historical order. The hierarchy is: Bayer Greek letterg as faint as V mag. 12.5. As a result,sars calledmag. 9.3 Flamsteednumbers, HR (Bright Star Catalogue)numberg in the BD averagesomething like V mag. 9.8, and those then HD, BD, and "other". Use the PPM or ACRS names *9.4" cdled averagearound V mag. 10.2, and those caUed only when there is no other prwious designation. "9.5" averagesomething like 10.E. Be.ause of this Okay, off the soapbox. A completediscussion of stretching of lhe magutude scale,there is far more scatter the transformations(and errors) for many slar cataloguesto in the faint BD magnitudesthan in the brighter ones. Lest V or B magnitudesof the UBV systemcan be found in: you think modem data in alwaysbetter, I have seena paper F. Ochsenbeil 1974, "O^ the relationship between the in a refereedjoumal with photogaphic photometry of an apparent magmtudesgiven in several cataloguesand the open cluster where the systematicerrors are so bad that the LIBV system", Astron. & Asrrophys. Suppl., vol. 15, pg. BD magntudes for stars in conmon are actually closer to 215. standard V than the work in this paper. (Neither the So I've eliminated all the big catalogues,and we refereenor the editor did hiyher job in this case--and the took care of the GSC a couple of w€elrsago. Now what? author shouldn't havebothered) Wtrat is the state of photoelectric photometry for brigbt Moving forward historically, whar about the t{D stars? Actualy, for starsbrighter thrn aboutVd.5, that is, catalogue? In the orieinal volum€s, containing 225,W the 10,000sta$ in the Yal€ "Bright Star Catalogue",there stars,most of the stars were assignedmagnitudes based on is mostly-reliablephotometry for the whole sky. It may be meas:urementswith visurl photometersor on yellow-light suprising to learn that this has hapened only il the last photogaphs. Agarq the magnitude systemwas not well- ten years. Beyondthis, thingF get spotty, although things defined etc. Most (ht not all) of the photographic fie aboutto change. magnitudesare found simpty from adding a fixed value to For the northern slry do*n to -15 Dec, all_ stars the yellow-light value (€.9. K0 stars have 1.0 added). down to about V=7.0 are now welhherved This was Again, the systemalicerrorc are fairty smau, with per-star done by V. G. Komilov (SternbergInstitute in Moscow) erors arormd +/- 0.3, but oc.asional major bloopers of a a.,tda long list of collaborators,and Fblished in 1991 as magnitudeor more ill both directions. volume 63 of the Trudy Gosh.Astron. Inst. P. K. Stemberg All the major astrometric catalogues,such as the AGK Gougbly "Works of the State Astronomical Institute of P. serie6, the SAO catalogue, and others, were done on K. Sternberg"). The calalogue conlains 13,500 stars photogaphic plates, or compiled (in the caseof the SAO observedin four colors, including standardV. Becauseit is catalogue) from assembled measurements, The AGK Russian,the work is not only not well lnown in the West, magnitudesare what I call "photogaphic-blue", meaning but also is automatically(and foolishly) consideredsuspect blue-light (but not standardB) magnitudeson a relatively by professionals merely by being Russian. However, welldefined sysiemin us€ ftom rougbly the 1930s Since external comparisons show that in fact the erols are we have no colors, they are not all that useful for visual commendablysmall (lesethan0.01 mag.). There is a small s,yr*eDrficlrend jn fts V mroflihrdes, amountiflg to about A really minor by-prodrct is 0.04 over the t l range in that for the first tim€ siar colors (red starsar; a bii ton *e'ii liiiow -^aaiit linw faint), aildrlJ stirs thcic arc dorm io V but this is readily evident onl), becausethe internal mag (the 9.0 usual number bandied about of 250,000 is so small. (Much published photometry has probably .enors _are too small by a goodly percentage),and for that intemal err.orsso large that it maskssysteoratic proble*s.) matter exactly which sta$ they are. The old There's also a mammothsurvey of starsof spectral Duchmusterung catalogues,comprising some 600,000 or type A F, and G prblished by Erik Olsen in Denrt6rk. more stars,certainly include essentiallyall siars to mag. 9, This includes V magmtudes (and Stromgren colors) for but becauseof the larg€ magnitudeerrors, we don't liow over 30,000 stars brighter than about mag. 9.3 or so which starsare brighter than any parucular limit. covering the whole skv. This work is as close to perfect as _ Okay, you aslg where can I get all this good slufl one can get, partly b€cause Olsen is one of these On a star-by-starbasis, rhe be$ si;de place io look up perfectionist fiends, and also because of the first_rate photometry on the Net is in the Lausanne photometric rnstrumentatior\ and becausethe observingand reductions Database, maintained by Jean-Claude Mermilliod: were extremely thorough Olsen,s papers ar€ a model of http://obsw\nr.unige. ch/gcpd/inform. htrnl how to do photometry*right". wh€reyou simply t}?e in a star nameand ir givesyou a list Well, in about a ye3r's time all this V band (if 9f what any) photom€try is available. Right'now it,s photometrywork will be sweptaside by the releaseof final fairly picky about how you key in the name (spacesafter results from the Hipparcosspacecraft mission. In the earlv cataloguenames, e.g. HD 161239,BD +28 42llj, andonlv 1990sthis spacecraftdid a thorough inventory of the sky. accepts HD and BD names. photometry on some 7i m particular measuring positions and parallaxes of some systens rs include4 trut you want to click on either UBV_ l@,000 stars, mostly brighter than nag. 9, but includhg a UBVRI. WBVR or wty entries to get V rnagmtud€s.The few as faint as mag. 12. A separate device on the GCPD includes all the photometry mentioned above bv spacecraft,called Tycho, has measuredless-precise Out Olsen and by Kom.ilov et al (WBVR system). Do read rhi still very accuate) Insitions and obtained V and B top pageof 1lxsservice for fufiher info. photometry for maybe two million stars in a comDlete GCPD top page: http://obswvw.unige.cUgcld/gcpd"htnl inventory of the sky down to mag. 12 or so. Foi the The Komilov et al. catalogueis not on_lire as far momentthis stuff is under wrape,and folks working with it as I know. cannol telease a single datum prernaturely on penalty of To get the big photometric and asEomerric death. Obviously, the team members are trying to mt_lkthe catalogueswhole (and cataloguesgenerally), my prefened data for all it's worth beforeletting anyone else haveit, and site is the Strasbourg(France) data enter, which servesas there has been plenty of grumbling frorn folks who have a *'orldy,'irb ceni.r fol a:jtronomica!catalcgue a:chiv:ng. applications in mind (e.g. solfi-system occultation The pagesbelow are for top pag€s with descri6ions and predictions) that are not on the Hipparcos te3m,s list. formatting links to the ftp file-server,etc. N.B. beforeyou Howsver, there have been no leaks from the Hipparcos start that you'[ need somefairly big chunks of disk "Oval Office". Sace to download these; also it's best vhen doing so to suck Some summary statislics from Hiprparcos/Iycho them aqoss drring off hours lest they tate forwer. File have published been Of presentinterest is the photometric sizesare listed for eachentry below. accuacy and precision. The star-mapperin Tycho was not About ll0,00o stars have been measuredin tbe very sensitive. So even for mag. 8 stars, the per- IIBV syslem,and about 60,000 stals are obcervedin lhe observation errors are already at 0.1 mag., and rise to 0.4 Stromgen system(which usually includes a V magnitude). mag. by mag 10. This doesn't look very good until you Mermilliod haspblished summarycatalogues for the UBV realize most stats were ob6erveds€veral dozen times. So system. The fim goes up to 1985, and ircludes data for the errors of the meanswill be somdhing like +/- 0.01 at 87,000 sta$; the second goqs to 1992 and adds 25,000 mag. 8, rising to about 0.1 mag. at rnag. 10, and worse more stars: fainter than this. It doesmean that the data will not reveal UBV (1953-1985, 13Mb): http:i/astro.u-stra$g.ft/cgi- many new variables ex@ among naked-eyestars, since binlc,;t?Ill22Bl the enors of observationwill nask any true variability in UBV (19E6-1992,l.4Mb): http://astro.u-strasbg.fr/cgi- the stars, Sincebona fide standardstars are included in the binlCat'tIJ/l93/ obB€rving,the external errors (how well they match the The third edition of Mermilliod's catalogueof photometry, standardsystem) should tr under control and pretty snall. specfal tpes, and star identificationsin opencluslers iE: So we should have quite good V magnitudes and B-V open cluster stars (2lvlb): http://astro.u-stsasbg.fr/cgi- colors lor most stars brighter than lod in about a year or b'lJ./Ca{llY124N published so. The summaries indicate there are stars Erik Olsen's Stromgren photomerry catalogues are observed only a few times, and these \yill have to be availablein severalfleces: remeasuredfrom the ground on an indrvidual hsis oncgwe Olsen 1983 (l.5Mb): http://asrro.u-strasbg.fr/cgi- know which starsthey arc(!). bin/CdTlllgol The Hipparcos/Tycho data will rwolutionize Olsen 1992 (l.2Mb): http://astro.u-srrasbg.&/cgi- severalareas of astronomy. bl/Cat?J/A+AS/ 102/89/ Ols€n 1994a (475Kb): http://astro.u-strasbg.fr/cg- observingalone in rural areas.Reading these posts jared a binl Car?U A+ ASI I O4 / 422/ few weird memoriesof my own (750Kb): Olsen 1994b http://astro.u-stlasbg.frlcgr- Back about l0 years ago, I movedfrom the frozen binl Cl,t?I I A+ ASI 106I 257| shoresof Westem New York to teach high school science The chunks ("Positions proper of the PPM and Motions,,) in Adanta. I was a high-mi:rdd save-the-worldliberal and cataloguesare at: quite naive 10the waysof the rural South.It took sometime PPM North (47Mb): http://astro.u-srrasbg.fr/cgi- for me to get used to grits (..which don't come from *gnt-plant"!), ft€ binlCat'lV146l let alone collard greensand chithns (which I PPM South (51Mb): htF://as[o.u-strasbg.fr/cgi- stil/ refi$e to eat!). My trips to the Villa Rica WafrleHouse binlCar?Ul93l were truly insplrattonal,and I learnedthe proper way to eai PPM bright stars supplement (48Kb): http://asto.u- gnts, plus make ob,servationsof the deficient dentition of stasbg.ft/cgr-bin/Cat?U206l most of the waiuesses. PPM 90,000 starc suppknent (llMb): http://astro.u- During thosedays, my "southern cultual mentor" stasbg.frlcgi+ir/Cat?V208/ was Rick Clarlc, a former New JerseyYankee now firlly Ifyou're into sheerstar count, the PPM wins: the acculturated in ways of the southern gentleman(???). three main lists above total some 470,000 stars, versus Ahem, ...yeahright. Rick was a former AAC memberand 320,000 for the ACRS and 259,000 for the SAO. The one of the origlnal "Deep Sky Zombies" whom I often "bright star supplemenf' has just 275 stars brighter than obseryedwith into the wee (I always wondered about the mag, 7.5 that were omitted from the main PPM catalogu€s origin of this sa''lng....) hoursof the night. for various reasons,usually becausethey are double and On one unremarkable early spring evening in havecrummy astrometrichistory. 19E9, I witnessedone of the more "interesting' rites of If you are interestedin adding more spectraltypes rural manhood,Rick and I were doing the usual searchfor to your files for ploning by color, etc., have a look also at the "small, round and dim' with the club's 20-inch scope an astrometrically-imprwed version of the I{DE catalogue, when we heard the sharp crack of rifle-fire and spotted which includesabout E9,00Ostars beyond lhe origrnal HD: ligha highlighting the tops of large tre€s itqoss the swamp HDE (5.3Mb): http://astro.u-strasbg.ftlcgt-binlcat?\U1821 located near the obsenatory. The sounds of distant The ACRS ("Astrographic Catalogue Reference shoutingfilled the air. Rick wasn't taking any chances,and Stars") was createdby the USNO for use in re-redrcing the removed the .45 from under the car seat and jammed a old Asrogaphic Catalogue./Cartedu Ciel data from early loaded clip into it. After a time, the rifle fue stoppedand in this century. The overall precision and accuracy :re the woods becamevery qruet., so we went back 10 the nearly identical to the PPlvI,hrt it doesnot include as many pusuit of the deadlydim frrzies. faint stars. The USNO people have claimed in print that The peacewas broken by the raucouslaughter and the ACRS is much better than the PPM, ht third parties raw conversationof several southern "gentlemen', befier 'lednecks" have sho$! that neither is the last word on the subject. lno$a as the of Jeff Foxworthy fame. ..."Hey 'him Mean errors for both cataloguesare about 0".3 at the Jim-bob,it was s'ulefun to watch scamperup dat tlee. curent epoch,much smaller than most of us need aryryay. Did yah seeda way I shot him7' "Hell, I sure did! You 'dat The ACRS can be obtainedeither from the Strasbowgdata plugged coon right between the ey€sl" Christ, I cenler..,. thought, they musl ba,tekilled somepoor black manl This ACRS (60Mb): http://astro.u-sEa$9.ftlcgt]olnlcat'tVt7l must be a lynching party! Before I could spout my ....or from the USNO directly. The USNO "recommended ignorance to the worl4 Rick chimed in " Hmm, just a catalogues"page has quite a lot of useflrl major catalogues, bunch of stupid (rac)coonhunters, nothing to get worried and they evend€ign to offer the PPM: about." Another lessonin rual living for me. http://aries.usno.nary. mivad_homdstd_cats_rec.htrnl After nearly ten years, I nolv drive a pick-up Note that the USNO lists the SAO under the truch have a closet firll of rifles, wear a variety of hats, "obfolete calalogues" h€adingl Also of interest are theit become a card-carrying conservative and spe3k with a redrctions ofthe AstrographicCatalogues, several of which modest southern accenl (at least thafs wbat my Yankee are postedhere, ag:arnwilh sone major megalryte-agetaken friends tell m6!). But I still don't like grits that much and up with dorr oading. Okay, all for now. I'11 entertain I'll be darnnedif I'll evereat somechitlins! questionsvia e-mail. (f you hrve some weird/unxsual stoies about observing, Brian Skiff ([email protected]) pleasesend them in! - editor)

"Tales From The Drrk Site" By Nctwrd Jakiel Ahut one month ago, there was an interesting "thread' or topic on the usenet newsgroup sci.astlo.amateur. Tided "Observing Alone Concerns", many posters described a variety of encounters while Beginner'sStar-Hops; August, 1996 ByArt Russell

Augusl normally heraldsthe "Dog Days" of Summerand brings the hopethat cooler daysmay be ahead. For astronomers,this August brings other things as well. This will be a $eat month for vie*'lng the Perseidmeteor shower. The meteorshow will peak at about2 AM on the morning of 13 August, but expeclthat we may get geat views arytime that previousweekend as well. Comeon out to the Adanta Asuonomy Club's PerseidMeteor ShowerViewing eventon the eveningof l0 August to sharethe occasionwith other club members. This eventwill take place at the CahuttaOverlook which providesa panoramic view of the horizon so bring your binoculars,picnic dinner, lounge chair, and stay for a while. August also marks your last opportunity to obsewethe greatestconcentradon ofeasy to observeMESSIER ('M) objectsas the constellationsScomius. ODhiuchus,Saqrttarius, and Scutumslip passthe zenith and begin their inevitabledescent into the weslem horizon, not to be s€enuntil n€xt year. I encouage anyoneinterested in getting a running start at their MESSIER CERTIFICATE to get out this month and scourthese constellations for their 29 (of 110) MESSIER obje{ts.Plese give me a call ifyou are interestedin working on your MESSIER CERTIFICATE. Our Begimers' Sessionswill focuson observingthe MESSIER objectswith small scopesas a project for the next year. How many memberscan we get certifted brythe end of next Summer? Give me a call if you are interested (404-373-{ll9)! Incidentally, ar the sametime you are working on your MESSIER GERTIFICATE, you can also work on the club's Visual Impressions Program, sinceyou'll seemany of its targetsat the sametime!

This month's star hopswill indulge my passionfor globular clusters. Of the 142 glohrlar clustersI ktrow of, theii geatest concentation is in the constollationsOohiuchus and Sasittarius. This month, we'll concentrateon Ophiuchuswhich lies above both Sasittariusand ScorDius.We'll start off the summernext year w'lth the MESSIER objectsin Saeittarius. A tip to easy observationofthese objectsis to view from the darkestskies possible and usethe lowestpower eyepleceyou have. All ofthese objectsare visible in binoculars,so don't hesitateto useyours if you haveth€m as well!

Star-hoo #1. M62, NGC 6266. We begin our tour ofOohiuchus' globular cluster by $anirg in the constellationSc.onrius, First locatethe starAntares ("The Rival ofMars"),Alpha (a),Scorpii. Then locatethe next star in the custellations figwe to the south, Tau (O Scoui. Beginning at Zaa Scorpii, extendan imaginary line to the star 45 Ophiuchi. M62 is locatedabout half way along, and southof '.his line. 11162afryears veq'compa.;t and disk slalre4 ijnf riic statr:are resolvel,,insnaller telescopes.

Star-hop #2. M19, NGC 6273. Our nex stop is Ml9. To find M19, return your scopeto Tou Scorpii and,theneiend an imaginary line to the st?trThetu (e) Ophizcti. M19 lies a little more than half way along and south of this lirc, about60% of the way to ThetaOphiucht. Like M62, M19 also appearsvery compactwith no resolvedstars in smallg{"telescopes.

Star-hop#3. M9, NGC 6333.Constellation Ophiuchus, SrarUng ar the starTheta Ophiuchi.the ne* sfarto the nonh in the constellationis 44 Oprircri. E*end an imaginary line ftom 44 Ophiuchi to lhe slar Sabik,Eta (ry)Ophtrclri. M9 is located about halfoay along andjust eastof the line. M9 appearsas a falnt, but distitrct, unresolvedsmudge in smaller telescopes.

Star-hon ll4. Mt07, NGC 6171. To locateM107, we onceagain retum to the constellationScorpius for our starting poirt. First, locatethe star Beta (fl Scorpii recognrzedas the highest ofeasily seen"Clows ofthe Scorpion." Frcm Beta Scorpii,lhe next star higher in the constellationis l& (u) Scorpii. Exlend an imaginary line fiom,ly'aScorpii to tlre starZeta (QOfiiuchi. Ml07 lies 3/4 of the way ftom Nu Scorpii to Zeta Ophiuchi Ltrdjust to the eastof this line. In the club's 20 inch tel€scope, M107 app€red as a moderatesized gloh ar with many resolvedstars. A numberof outlying starswere conc€ntrated toward the west side ofthe cluster.

Star-hop n5. M12, NC,C62f8. Slart at the star Zeta Ophiuchi andextendan imagimry line to the statKappa (9 Ophiuchi. M12 lies a little lesstban ha|f w€y ftom Zeta Ophiuchi to Kappa Ophiuchi ^nd jvstto the eastof this line. In the club's 20 inch telescope,M12 appe3rsas a moderatesized globular cluster with many resolvedstars. There appearedto be a main concentrationof starswith a lessorganized patch apparentlyin the backgound to the northwestof lhe nucleusof the cluster.

Star-hop tt6. M10, NGC 6254. Starting onceagain at t!.e starZeta Ophilcri, e$end an iftrginary line to the starAlpha (a) Ophiuchi. M10 lies about l/3 of the way ftom Zeta Ophiuchi to Alpha Ophiuchi mdjust to the eastof this line. In the club's 20 inch telescope,M10 appearedas a relatively b'nght, moderatesiz€d globular cluster. Howwer, the clusler did not appesr well orgamzedand had many starstrailing away from its nucleus.

to Star-hoD #7. M1'{' NGc 6!102. To locate Mlil, extendan irnaginary line ftom the star ,sarift, Eta (D ophiuchi,and rhe s1"r Cheleb,"TheShepherd's Dog," (p) Beta Ophiuchi. M14 is localednot quite2/3 alongthe wayfrombta'ophiuchi to Beta ophiuchi andjust , to the eastof that line. In the club's 20 inch telescope,Mt+ appeaiedas a;ma[ to moderatesized globular cluster' Its stars wele not well resolved but the cluster seemedweu organized. Addirionaly, a uery faint arm of stars.appeared to trail offto the northwest.

Sb/"c/',6//'tto{-evgJ/|i/1rgotll Angust l$oteposrf'on ot Corflet tlate{,opp

SCar+ops' ftlag*rary lftes We'rehere to help! Here'show to reachus: Addressfor NeryMembsships, Renelvats, Magazine Subscriptions, and BookOrders: Atlanta Astronorny Club 3595Canton Road. SuttGA9306 Madetta,cA 30066

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DougChesser President 770!57-574€ [email protected] JerryArmstrong VP,ProgramChairman 770-9..2424€ [email protected] LarryHiggins VP, ObservingChairman 77tU-T3 PhilBracken Treasurer,Subscriptions, Books 770€41-617 [email protected] RichJakiel Ne'dslelterEditor, VIP Pr€ram zpzf362{816 [email protected] JackWamer RecordingSecretary /O4-€3e6&a EnaShelton Boerd,Obs€watory Design Chairman T70€64,2a37 [email protected] Tom Buchanan Bo€rd,Light Pollution Chairman 779sa74n4 TusharThrivikaman Board,Meeting Logisii6 T1ol70A742 [email protected] LennyAbbey Board,Asst. ProgramChairman 4443+1W labbey@mindsp{ing.com SteveGilbreath Board zo€1915 [email protected] GinnyMintz HospitalityChairman TTU2-7ffi GinnyMauuin-Kinney Informaiion Line 77U4149€3 [email protected] Ken Poshedly Publicity,Peach State Star caze r/G9BS42 [email protected]@compuserve.com Art Russell Library,Beginner's lnteresl Group 4L3734'119 [email protected] KenWalbum ClubGraphios 77096+9442

THEFOqAL POilNT Newsletterof The Atlanta AstronomvClub. Inc.

FROM: Richard and Jennifer Jakiel 1101Collier Road Apt. Q-l Atlanta, Georgia 30318 First Class The A dfa A.gfoorny Club Isc., the Sodhh Irrged od olded adronornicalsocidy, meds at 8:00 p.!r. a rhe ttird Fridsy of eod rncnrh at Elnory Univdsity's Vrhite Hall 6 occ$iGally sl dh€ locaticns(deck the hd line for ddails). Med$€fSb is Cp€trto all. Annu.l duesare $20 ($10 for studsrts). Dscourted sub{crid.ims10 A$qrorny (S20), asd SLy & Tel€"cope (S24) magazin€s are available S€dddu€3 to: Thc AO|nt| Arb.otromy Club, Inc., 3595 Csnton Ro.d, Soitc A9-30i Mrdctls, Gr.3(x|66.

Hd Lioe: Timely iDformatim €il lh€ niglrt sky ard adrorpmy in the Allanta a.eab availableqr a twe$ty-fourhour basisqr the A arfa Asrmomy Club hil line. 17G4L2s6l

Chs-* o|i our ASTRO disorssiod list on lhe Irtefird: AsTRo@Mind+ringcom. Also visit our Iriemet hom+page: http:/hvww.ndndlpdry..on/-deko/r0$tro.hbnl

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