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Messages - sgottlieb

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1
Observing Intents / OI: Lake Sonoma tonight (12/12)
« on: Yesterday at 12:30:18 PM »
Lone Rock parking lot is the spot -- weather forecast is very good.  Not sure how much the SoCal smoke will be a factor.  I plan to arrive before sunset, which is now about 4:50 PM, along with 3 others.

2
TAC Visual / Re: Visual notes on the entire NGC
« on: December 02, 2017, 10:28:44 PM »
Thanks, Mike

3
TAC Visual / Visual notes on the entire NGC
« on: December 02, 2017, 05:40:01 PM »
I've just updated my observing notes files on Adventures in Deep Space (www.astronomy-mall.com/Adventures.In.Deep.Space/) with some assistance from Mark Wagner. The latest iteration includes visual descriptions of every deep-sky object in the NGC (7840 entries) as well as 1500 more from the IC.  Some of you may find this helpful in preparing or comparing observations.

In addition, you'll find data on every object (coordinates, type, magnitude, size, position angle, etc.) as well as historical discovery information and a discussion of all contested NGC/IC identifications.

Just follow the link on the home page for "Steve Gottlieb's NGC Notes"

4
Observing Reports / Observing in Australia (Part II)
« on: November 22, 2017, 06:41:59 PM »
Over the five clear nights we had at the “Spring" OzSky Star Safari (ozsky.org), I logged over 250 objects, but the most astonishing vistas were certainly in the LMC.  In many single eyepiece fields, you find yourself gazing at a handful of emission nebulae, possibly a supernova remnant, and several clusters — some with resolved LMC stars and others unresolved knots — all superimposed on a bright, glowing background of the LMC itself!  The following is just of sampler of some of the LMC treats I observed during the week.  If this whets your appetite, you can download detailed descriptions and data on my favorite 8 “Showpiece Regions of the LMC" on the page of "Catalogs, Lists and Links” .

LMC-N59 Complex = Seagull Nebula = Dragon's Head Nebula (includes NGC 2030, 2032, 2035 and 2040)
05 35.4 -67 34.5
8’ diameter

Overall the visible structure of this complex using the 25-inch at 202x and 264 with a narrow-band filter, was comparable to the AAO-red image! (without the color, of course).

NGC 2030 is the first section in this remarkable complex (just off the upper right edge in the ESO image), though it was the faintest of three connected patches extending 5.5' from NW to SE with NGC 2032 and 2035.  The brightest portion is an elongated "bar" section ~2'x40", oriented WSW-ENE, just west of mag 12.2 HD 269810.  Fainter nebulosity spreads to the north in roughly an oval outline and includes a mag 14.5 star, so the total extent of NGC 2030 in the N-S direction is over 2.5'.  Very faint nebulosity appears to connect NGC 2030 with brighter NGC 2032 directly SE.

NGC 2032 was extremely bright, elongated SW-NE, ~2'x1', with a scalloped but sharply defined border at the brighter edge along the dust lane. A fairly prominent thin filament extends NE for ~1.5', curling a bit towards the tip.  A thin strip on the SE end (just beyond the lane) connects to NGC 2035.  The ionizing star was visible unfiltered at the eastern border, in an indentation, though it appeared fainter than the listed mag of 13.5.  A second mag 14 star was also involved at 25" to its east.  A mag 11.4 star is off the SW side and a mag 12.2 star is at the NE edge.

NGC 2035 was also extremely bright, roughly rectangular but irregular with slightly concave eastern side and lots of complex, internal structure with brighter and darker areas. A fairly thin streamer is attached on the northeast end and extends 2' NNE, similar (though slightly fainter) to a filament attached to NGC 2032!  NGC 2035 is attached or merged at the south end by a thin strip of nebulosity to NGC 2032. LMC-N59C is a fairly faint patch that is detached from NGC 2036 to its southeast.  It appeared moderately large, roundish, at least 1' diameter.  A mag 10.4 star is 2' ESE.

NGC 2040 appeared bright, very large, irregular nebula just east of NGC 2030/2032/2035 (Dragon's Head or Seagull Nebula).  The main portion is roughly triangular with one "vertex" on the south side and another on the northeast end.  It has a sharp, contrasty edge on the east side to the south tip and some internal, irregular brightness in the interior.  Unfiltered a dozen stars mag 14-15 are involved (association LH 88), with several more spreading to the south.

SNR B0536-67.6 is a supernova remnant shell on the south end of NGC 2040 and the objects are merged on the north end of the shell. Sometimes NGC 2040 itself is incorrectly called a SNR in the professional literature.  On images the shell extends ~2' in diameter, with a complex interlaced web of delicate filaments.  Visually, I could see a very faint, thin curving loop, ~45" in length, which forms the southwest end of the shell. A mag 13.5 star (O5-type) is in the interior of the shell, with the observed strip centered 40" to its WSW. This star was possibly bound to the precursor star of the SNR remnant.


LMC-N83 Complex (includes NGC 1737, 1743, 1745, 1748)
04 54 13 -69 10 40
Size: 12'

NGC 1743 = N83A is the overall brightest section of another superb HII/cluster complex including NGC 1737, 1743, 1745, 1748 and 1756.   Using 244x, along with a narrow-band filter, it appeared extremely bright, fairly large, irregular, extending ~1.5' NW-SE.  The most prominent section has a very high surface brightness and contains a mag 12.5 star.  This knot is surrounded by a fainter halo to the SE and E, along with an extension towards the NE that ends just south of NGC 1737 (nearly connected).  In the same nebulous complex (N83) is NGC 1748 ~2' NE, NGC 1745 3' NE, NGC 1737 2' NW and NGC 1756 5' SE.

NGC 1737 = N83C was fairly faint but moderately large, roughly 0.9' diameter.  A mag 14.4 star is at the center of the circular patch.  This tract of emission nebulosity is on the northwest side of the complex with NGC 1743 1.8’ SE.

NGC 1745 = N83D, on the northeast side of the complex, was also fairly faint, but easily seen as a fairly large, irregular nebulous haze, surrounding a half-dozen stars mag 14 and fainter.  Good contrast gain using a narrow-band NPB filter at 244x.

NGC 1748 = N83B is a fairly bright but fairly small round patch with a high surface brightness and a diameter of ~30".  At 397x, a 13th mag "star" was resolved at the southeast edge.  This star is classified as a high excitation H II “Blob" [HEB].  According to Iranian-born astronomer Mohammed Heydari-Malayeri , these unusual objects represent "early stages of massive stars emerging from their embryonic molecular clouds".  Unfiltered a second star (mag ~13.5) was seen closer to the center, forming a 7" double with the HEB.



NGC 2029 = LMC-N63 and LMC-N62
05 35 40.8 -66 02 06
V = 12.3;  Size 4'

I used the 30-inch to examine NGC 2029 at 202x, 264x and 429x, both with and without filters.  This is a large, fairly bright cluster (known as Shapley-Lindsay (S-L) 595) with roughly 30 stars resolved in a 3.5’ region. It includes at least 4 brighter stars from mag 12.3-13.5 and another mag 12.7 star is at the SW edge.  Moderately faint nebulous haze (LMC-N63) encompasses the cluster.  Adding a narrow-bandpass NPB filter at 264x increases the contrast with the large nebulous glow, which extended 2.5-3' diameter.  Note: this object is identified as NGC 2030 in most sources!

Henize N63A (discovered by Karl Henize in 1956), embedded slightly east of center, is a well-known compact supernova remnant and one of the first 3 extragalactic SNRs to be discovered (1966).  The SNR appeared as a small round knot, only ~12"-15" in diameter, and was faintly visible even at 202x.  It was easy to distinguish at 264x and stood out fairly prominently at 429x.  Surprisingly, I didn't notice any contrast gain adding a NPB filter (similar visibility).

Roughly 14’ SSW of NGC 2029 is N62A. I observed this HII region with a 14-inch using a NPB filter.  It appeared very bright, very elongated ~E-W, relatively large, ~1.5'x0.4'.  The shape is a bit irregular, but has a sharply defined northern edge, while the southern edge weaker and more ill-defined.  Visible unfiltered but excellent response to the NPB.  A couple of very faint stars are visible with averted.  BSDL 2348, an LMC cluster perhaps associated with the nebula, is ~2' W and contains a  half-dozen mag 14-15 stars in a 1.5' knot, along with a mag 12.5 star on the west end.



"Lionel Murphy" Supernova = LMC-N86 = SNR B0456-68.7
04 55 49 -68 38 30
Size 3.5'

In 1977, Mike Dopita, Don Mathewson & Vince Ford, working at the Mt Stromlo Observatory in Canberra, published a paper titled "Optical emission from shock waves. III. Abundances in supernova remnants.”  It included a photograph taken at the 150-inch prime focus [of the Anglo-Australian telescope at Siding Spring] that is labeled the "Lionel-Murphy" SNR.  Aussie Steve Mencinsky told me he was working as a night assistant at the time on the 74-inch at Mt Stromlo (later destroyed in a bush fire) in early 1976 as a "vacation scholar”.  One day a few astronomers were taking a break and looking at some of the prints of nebulae in the Magellanic clouds.  Steve looked at this SNR image and said "That looks like Lionel Murphy!”.  Who, you say?  Murphy was a politician, former Attorney General turned Judge of Australia's High Court, who is later life got mixed up in a corruption scandal — and apparently had a rather distinctive nose.  The Wikipedia page on Murphy (https://en.wikipedia.org/wiki/Lionel_Murphy) states ""Murphy normally rejected public honours (such as a knighthood) but accepted this [nickname] because of the symbolic resemblance to his own impact on human rights in Australian law and its lasting significance as a "signpost" to space travelers. Murphy asked for a large mounted photo of SNR N86 from the scientific paper and placed it in his High Court chambers in the place where the other High Court justices usually hung a portrait of the Queen.”

With the 25-inch (unfiltered) at 244x, this LMC supernova remnant appeared as a large, low surface brightness hazy region, just south of a mag 11.8 star.  A couple of 14th mag stars appear involved with the haze.  The mag 11.8 star forms the eastern vertex of an isosceles triangle with a mag 11.5 star 5.6' NW and a mag 10 star 6' SW.  There was a weak contrast gain adding a NPB filter, with the most evident section ~1' diameter [centered 1.2' S of the mag 11.8 star] and slightly brighter on the east side.

Images in H-alpha, [O III] and [S II] reveal a relatively well defined shell of over 3' diameter, rich in internal filamentary structure, and a large jetlike stream of filaments extending 2' further north that appear to break out into the interstellar medium.



NGC 2103 = LMC-N214C
05 41 40 -71 19 56
V = 10.8;  Size 3'x2'

This unusual nebulous cluster was observed using the 25-inch at 244x.  If found it a fairly bright, very large, roundish glow surrounding a central star (12.7-magnitude O2-type Sk -71°51) with a bright quasi-stellar knot at the north edge (that strange-looking pinkish Pac-Man object on the image above).  Increasing the magnification to 397x, at least 8 stars were involved with the nebula (part of OB-association LH 110), which was clearly elongated NNW-SSE (tapering on the SSE end) and brighter along a central spine.  The addition of a NPB filter at 244x produced an excellent contrast gain and the nebula appeared very bright with an irregular surface brightness.  The small knot at the north edge (a high excitation HII blob or HEB) was prominently visible.

The central “star” (and nearly centered in the ESO image above) is unusually hot and bright and has been resolved by the HST into a compact cluster of at least 6 components in a 4 arc-second region!  The HEB at the north edge is typical of small dense regions, usually "only" 4 to 9 light-years wide, that sometimes form adjacent to or inside giant H II regions and represent "early stages of massive stars (O-type) emerging from their embryonic molecular clouds.



LMC-N11 Complex = Bean Nebula
04 56 45 -66 24 36
Size 5'x3'

The Bean Nebula complex (LHA 120-N11) is the second largest stellar nursery in the LMC after the Tarantula Nebula.  I showed off this tasty piece of eye-candy treat to the other OzSky participants using the 30” at 244x and this inspired Tony Tanner to image the field above.  I’ve viewed this region several times and the following notes were taken through the same scope a few years ago.  The showpiece is certainly NGC 1763, which sits near the center of a stunning field of emission nebulae and clusters including NGC 1760 7' S, NGC 1761 3' S, NGC 1769 6.5' SE, NGC 1773 8' ENE and NGC 1776 11' E.  NGC 1763 is a very bright, very large irregular nebula, shaped like a kidney-bean or a fetus. The main body extends 5'x3', elongated SW-NE with a bulbous portion on the northeast side and an indentation (weaker nebulosity) on the south side.  Overall the surface brightness is very high, though uneven, and much fainter haze and filaments flow out from the Bean in most directions.  Within the main body, the nebula is brightest in a loop on the southwest side and secondly in a section on the northeast side.

Involved with NGC 1763 is a large cluster catalogued as OB-association LH 10 (the youngest cluster in the LMC-N11 complex), with roughly two dozen resolved stars.  This cluster includes a number of 12-13 mag stars (several of which are massive O3-type stars), many in an elongated 1' group on the southwestern side.  At the northeast edge is mag 11.3 HD 268726 and 45" further east is LMC-N11A = IC 2116, a high surface brightness knot of ~15" diameter.  Very faint haze at the NE side of NGC 1763 bulges towards N11A.  This compact, discrete object is also classified as an HEB (High Excitation Blob), distinguished by high excitation, small size, high density and tightly linked to early states of massive star formation. The surrounding field is rich in stars between the individual objects with some locally brighter patches of nebulosity.

NGC 1761 is a bright, large cluster sandwiched between the Bean Nebula (NGC 1763) to the north and NGC 1760 to the south.  There are roughly 80 stars mag 11 to 16 in a 3.5' irregularly shaped group over some background haze.  The stars are fairly even distributed except for a detached 1.3' group of 10-12 stars off the NW side.  Including this detached section, the overall size of this star cloud (association LH 9) is 5’ x 3.5'.  A close bright double star (h3716 = 10.2/10.9 at 5") is on the NW side of the main group.

NGC 1760 appears as a string of a half-dozen stars, nearly 2’ in length, over fairly bright nebulosity.  The emission haze is brightest just south of the string and extending to the west of the string a couple of arc minutes.  Irregular nebulosity also branches out to the south of the string for another 2' and involves a mag 12 star.  Another 2' string of N-S stars is on the west side of the haze.

NGC 1769 is a bright, large oval nebula oriented SW-NE, roughly 3’ x 2'.  At the center is a mag 11.5 star (Sk -66 41), with three mag 14-14.5 companions, the closest 15" SE.  A small, bright knot (~10" diameter) is embedded on the south side of the nebula, just 0.9' S of the central star.  Sk-66 41 was once thought to be one of the most single massive and luminous stars in the LMC but has been shown to be a very compact cluster with over a dozen components.  The companion to the SE (an O3-class star) is actually the ionizing source of the nebula.  The bright knot on the south side was also discovered to be a compact cluster of very faint stars in 1987 and is identified as HNT 1 in SIMBAD.

NGC 1773 is a fairly large, bright glow, elongated 3:2 ~N-S, 2.2’ x 1.5'.  On first glance, two brighter mag 12/13 stars are offset southwest of the geometric center and separated by 17".  But on closer inspection the more central star (0-type supergiant SK -66 43), resolved into a very close double. In additional a couple of fainter mag 15/15.5 stars are superimposed on the north side of the glow.  The nebulosity is slightly irregular in surface brightness and brighter along the rim, particularly on the southwest side.  This emission nebula is located at the northeast end of the Bean Nebula complex.

NGC 1776, located on the east edge of the N11 complex, is a moderately bright cluster, fairly small, well concentrated with a small bright core surrounded by a 50" halo.  A couple of extremely faint stars are just visible in the halo.


5
Observing Reports / Re: Some recent ! and !! doubles, and a question
« on: October 31, 2017, 06:25:43 PM »
I really enjoyed reading your results, Mark!  You've really taken on the challenge of close, unequal doubles.  Great job!!

Are these doubles you ran across using the Interstellarum Deep Sky Atlas or from another source?

6
Observing Reports / Re: Observing in Australia October 15-22
« on: October 26, 2017, 11:15:00 PM »
In 1978 I was in full swing with Edmund 6" on a fork mount and did most of the Messiers, but my notes were pretty primitive.  Before that in 1976 I was just poking around the sky with a 60mm refractor in Lafayette.  In the summer I'd point and scan around the Milky Way (yes, there was a Milky Way in Lafayette back then) and "discovered" the showpiece emission nebulae and clusters in Sagittarius and Scorpius.  I thought they were awesome in that little scope.

BTW, I'll post my visual descriptions soon for the entire NGC, but except for the missing 34, they're available now at http://www.astronomy-mall.com/Adventures.In.Deep.Space/steve.ngc.htm

7
Observing Reports / Observing in Australia October 15-22
« on: October 26, 2017, 09:28:58 PM »
During the October new moon period I hopped on the 15-hour flight from SFO to attend the week-long Spring OzSky Star Safari (ozsky.org/spring.asp), which took place on the 6300 acre Markdale Homestead (https://tinyurl.com/yd9ju9q5), a 3 to 3 1/2 hour drive west of Sydney in the Central Tablelands (https://en.wikipedia.org/wiki/Central_Tablelands).  I know several TACos have participated in these fantastic star parties (this one was my 4th, out of a total of 8 pilgrimages to the southern hemisphere), but here's the background.

A group of Sydney amateurs, in conjunction with the Three River Foundation (3RF) Australia (www.3rf.com.au/) offer this twice-a-year event, with the main star party hosting 3 dozen or so attendees in the Fall (that's around March-April downunder) at Coonabarabran NSW, near the Warrumbungles National Park and the Siding Springs Observatory.  It's mostly attended by U.S. amateurs and I'd guess half are repeaters, who are itching for more of the same.  What's the draw?  If you've been to the southern hemisphere, you know it beats the north, hands down, in terms of open clusters, globular clusters, emission nebulae and the single most impressive external galaxy in the sky -- the Large Magellanic Cloud.  And experiencing the center of the Milky Way at the zenith (with typical skies ~21.8+ SQM) and the jet-black dark nebulae forming the Aboriginal "Emu in the sky" is flat-out jaw-dropping.

The locals, led by Lachlan McDonald and Tony Buckley, provide the telescopes -- ranging in size from 14.5" to 30" (that's me on the ladder of the 30" on the first link), equipped with Argo Navis and Servocats if you don't want to star hop in unfamiliar skies, as well as a collection of Televue eyepieces.  Really all you need to do to prepare is sign-up in advance, download some of their showpiece observing lists, pack your clothes and join the party!

Two years ago we had a very small, private event.  Only three Californians (John Hoey, Kemer Thomson and myself) attended the Aussie Spring event, which took place at Markdale -- a large working sheep ranch and country estate with a beautiful Heritage garden.  Last October there was closer to 16 attendees, including locals Bob Douglas and Dennis Beckley, but this year we were back to another small group with just 4 U.S. amateurs (a 5th dropped out at the last minute).  That matched the number of scopes that Lachlan carried to the site in his trailer -- two 18's, a 25 and a 30", a one-to-one ratio!  Lodging was in two stone guest cottages, built in the late 1800's.

In mid-October, the galaxy-rich constellations of Fornax, Pisces Austrinus, Sculptor, Phoenix and Horologium pass nearly overhead from Australia and eye-candy galaxies in Pavo, Dorado,  and Reticulum are well placed.  But Sagittarius is still higher than we see it from home, and once you get used to seeing the constellation's Teapot outline completely upside down, its easy to track down obscure globulars and even Sagittarius galaxies that would be difficult from home.  But the biggest treat for me is the LMC, as there is absolutely nothing remotely comparable in the northern sky -- as well as the magnificent globular 47 Tucanae, which must be seen to be believed at high power.

We were pretty fortunate with the weather - 4 straight all-nighters to start the week, then 2 nights of clouds, and a clear 7th night.  So, 5 for 7 overall and enough observing time to log about 250 objects.  I came prepared with a list of 300 deep sky targets, but a subset of 34 NGCs had a special meaning.  These were the only ones I had remaining to observe and record out of the 7840 entries in the 1888 New General Catalogue.  Not sure if the entire catalog (covering +89 to -89 dec) has been attempted or previously completed by other obsessed amateurs. This huge project been percolating a long time -- I've been slowly working on it (along with many others such as Hicksons, Arps, Palomar globulars, Flat galaxies, Abell planetaries, rich galaxy clusters, etc. etc.) for quite awhile -- 37 years to be precise!  And along the way, the instruments evolved from a 6" f/5 Edmund, C-8 Schmidt-Cass, 13.1" Odyssey I, 17.5" Sky Designs (early truss-tube dob), 18" f/4.3 Starmaster and 24" f/3.7 Starstructure, along with a little help from Jimi Lowrey's 48-inch  ;).

Four or five years ago I finished all the NGCs accessible from northern California (down to -40° declination), but there was still over 300 remaining far southern objects.  After a couple more trips to Oz that number was whittled down to 34, of which 32 were well placed this time of year (that's why I missed them a year and a half ago from Coonabarabran).  The final two would have to be caught low in the sky either at dusk or dawn, but I knew they would be doable.  But first a bit of background on the NGC...

Roughly 2500 deep sky objects in the NGC were discovered by musician-turned-astronomer William Herschel from England and another 1700 by his son John, at Slough, England and later the Cape of Good Hope in South Africa.  Their discoveries were made with 18.7-inch speculum reflectors -- roughly equivalent in light-grasp to a modern 14- or 15-inch.  The next largest contributors in terms of visual discoveries were Albert Marth (over 500 using a 48-inch speculum reflector on the island of Malta), Lewis Swift (over 450 galaxies from Rochester, NY and southern CA using a 16-inch Clark refractor) and Edouard Stephan (over 400 from Marseilles using a 31-inch silver-on-glass reflector).  The largest scope that contributed to the NGC was Lord Rosse's 72-inch Leviathan and the discoveries made with this scope go down to mag 16.5V.  Within the next few years after the publication of the NGC, the golden era of visual deep sky discovery would wind down as long-exposure photographic plates revealed thousands of dim galaxies beyond visual reach and which now have IC (Index Catalogue) designations.

During the first two nights I logged 33 of the remaining objects (mostly galaxies in Phoenix and Tucana) using the 25" f/5 Obsession, leaving only one target remaining for the third night -- NGC 2932 -- which is nothing more than a Milky Way star cloud in Vela that captured John Herschel's attention.  He called it "an enormous cluster of 1 deg or 1.5 deg, very rich in stars of all magnitudes, from 8m downwards, which merits registry as a sort of telescope Praesape.  It may be regarded as a detached portion of the milky way."  With so many more mouth-watering targets nearby, most amateurs would probably put NGC 2932 in the "Why bother?" bin. But this one was a little more special to me.

I tracked down the field after 3:00 AM on the third night using an 18-inch Obsession at 79x (1° field of view).  I looked up and noticed Orion was 50° up and of course, turned topsy-turvy on its head!  Sirius and Canopus, the two brightest stars in the sky, hovered at 60° altitude and dominated the eastern skies. Truthfully I didn't find the star field of NGC 2932 very exciting, but I carefully examined it and a 1/4 degree richer section caught my eye as appearing more cluster-like.  The next day I checked the online SIMBAD database and was pleased to find this collection was catalogued as the 1,694th Milky Way cluster in a 2012 compilation (https://tinyurl.com/yb37vzva). So perhaps a real cluster is actually embedded in Herschel's star field.

During the daytime we toured the property, panned for gold, and watched mobs of 'roos bounding across as the fields when we drove by (actually this was a serious road hazard whenever we returned to the estate at twilight) and closely examined some of the other natives (two attached).  A bit scary, though, was a visitor who slithered very close to the observing field in the late afternoon -- an Eastern Brown snake, the second most venomous in the world!  For some false sense of security, I took all of my notes that night (some highlights will follow) at the shelf on the top of a tall ladder, instead of my usual observing table  ;D



8
Observing Reports / Re: Lake Sonoma 10/21/17
« on: October 25, 2017, 08:05:14 PM »
Dan's referring to a little project I completed -- more on that later.

9
Observing Reports / Re: Dinosaur Point Saturday night, 21 October
« on: October 25, 2017, 08:04:07 PM »
I'll give a downunder report soon -- always fun seeing Orion rising with standing on its head

10
Observing Reports / Re: Lake Sonoma 10/21/17
« on: October 23, 2017, 07:08:53 PM »
Glad to hear you and Ray are out observing again!  I hope to join you in the next couple of months.

I just got back from the OzSky star party in Australia.  We had 5 clear nights out of 7, so needless to say I'm exhausted and it'll take awhile before entering all my notes.  But I'll post a report as soon as I can.

Steve

11
Observing Reports / Re: Globular Cluster hunting -- in Barnard's Galaxy!
« on: August 06, 2017, 03:36:48 PM »
NGC 1049 = Fornax 3 is the brightest globular, then Fornax 4 and 5 a bit smaller and fainter.  Fornax 2 is the faintest of the main 4, which are all visible in a 10-inch or 12-inch.

I would be surprised if you could pick up Fornax 6 as I called it "extremely faint" in the 48-inch, but Uwe Glahn writes that he glimpsed it a 18" from Namibia.  My full description was "extremely faint, small, very low surface brightness spot, ~0.3' diameter.  Located 7' due north of globular Fornax 4.  Pinpointing the location, a mag 15.8 star is 1.6' W and a mag 16.5 star is 2.1' WNW."   But Fornax 6 isn't a globular anyways -- it's either a group of extremely faint stars (~21st mag) or even distant galaxies!

There is a 5th globular, though -- Fornax 1, which is much fainter than the other 4 (perhaps close to 16th mag).  Perhaps this is the one you looked for?

12
Observing Reports / Re: Globular Cluster hunting -- in Barnard's Galaxy!
« on: August 05, 2017, 09:49:00 PM »
For next fall, I was just approved for an observing article in Sky & Tel on Local Group globular clusters, so I certainly hope to get a look at SC 6!

13
Thanks Mark and Marko for the comments and posting the finder chart.  SC 6 is already on my observing list as it's only a 1/2 magnitude fainter than SC 7, but I didn't take a look at Grandview.  Maybe next month.  For the record, here are the coordinates of these two exotic objects.

SC 6   19 45 37.0 -14 41 10.8
SC 7   19 46 00.7 -14 32 35.0

A 2005 study titled "The Globular Cluster System of NGC 6822" (https://arxiv.org/pdf/1506.00951.pdf) gives the following magnitudes (rounded to nearest tenth):

SC 6  15.4V
SC 7  14.8V

Let us know if anyone gives these a try.


14
Observing Reports / Globular Cluster hunting -- in Barnard's Galaxy!
« on: July 28, 2017, 06:01:55 PM »
For the July new moon I observed for 4 nights in the White Mountains above Bishop (Grandview Campground at 8500 ft), just below the Ancient Bristlecone Pine Forest.  Our group included Paul and Debbie Alsing, Kemer Thomson, John Hoey (all from the San Diego area), Jimi and Connie Lowrey (from west Texas but drove from Florida) and bay area locals Carter Scholz and Rick Linden.  The weather turned out great and the Detwiler fire southwest of Yosemite didn't impact us, though I drove through the smoke in Yosemite to reach the site.  SQM readings were generally in the 21.6-21.8 range, though occasionally below 21.5.  The largest scope was Rick's 32", which nearly dwarfed my 24" Starstructure.

Instead of posting a long list of observations (I logged 125 objects), I'll mention just one -- a Sagittarius globular that actually resides in Barnard's Galaxy (NGC 6822).  Edwin Hubble was the first to investigate Barnard's Galaxy in detail in 1925 (http://cdsads.u-strasbg.fr/full/1925ApJ....62..409H).  His study included a table of 10 nebulous objects within Barnard's Galaxy.  Most of these turned out to be HII regions (including 2 great visual targets), but Hubble VII turned out to be the first confirmed ancient globular in this galaxy.  The location, though, creates a problem -- its a tiny 16th magnitude speck superimposed on the glow of the galaxy and a very nasty visual target.  I was successful observing it twice from GSSP back in 2010 with my 18", though it was quite challenging (barely non stellar and lost in a maze of other dim stars within the galaxy).  I figured that was the last GC I'd see in Barnard's Galaxy

Four new globular discoveries in this dwarf galaxy were announced in 2011 but these seemed too faint for visual targets.  Then in 2013 three more were identified (so the current total is 8 ) and globular #7 (coincidentally the same number as Hubble's object) seemed a reasonable target for my 24".  When I added it to my observing list, I had no idea what to expect as I've never read of amateur observations of these globulars. You can read the discovery paper at http://adsabs.harvard.edu/abs/2013MNRAS.429.1039H, where it's called SC 7 (Star Cluster 7)

SC 7 is in the outskirts of Barnard's Galaxy, 22' NE of the center of the galaxy and well outside the visual extent -- that makes identification much easier!  Once the general field was centered using the 6mm Delos (375x), both Jimi Lowrey and I were surprised to quickly notice a non-stellar glow without first examining an image of the galaxy.  SC 7 was faint in my 24-inch, but clearly non-stellar, roughly 6"-8" diameter and 15-16th magnitude.  The globular could be held steadily when we backed the magnification down to 282x and possibly had a brighter stellar nucleus.

If you're curious about the distance, Barnard's Galaxy is ~1.6 million light years away.  For comparison, the most distant Milky Way globulars are 300 to 400,000 l.y. away, so this one is at least 4 times that distance!  I believe an 18" scope should catch this object from a dark site, if you know the precise location.

-- Steve 



15
Observing Reports / Re: Speaking of subtle...
« on: July 27, 2017, 10:22:09 PM »
Great set of targets, Mark!!

As far as GN 18.32.5 = PNG 27.0 +1.5, it's definitely a planetary neb and not a reflection nebula -- SIMBAD is wrong, wrong, wrong.

Check out this page from the MASH catalogue:  http://vizier.cfa.harvard.edu/viz-bin/vizExec/.show?V/127A&G027.0%2b01.5.  Perhaps I mentioned this one to you before?

I made two observations 9 years back with my 18" ---  I noted the planetary wasn't symmetric around the central star (as you also commented).

18" (7/31/08 and 8/1/08): At 175x unfiltered a mag 13 star was visible and a small ill-defined halo was highly suspected surrounding the star knowing the exact location.  Adding an OIII filter, the halo brightened nicely and the edge sharpened to a 20" disc.  The involved star appeared offset to the north side.

For comparison, here are a few more observations ---

Alvin Huey (22" @184, 255 and 328x): Considerably faint round glow with defined edge with a very bright central star.   Estimated magnitude of the central star is about 11.5.  Not visible without filter.  Ultrablock brings it out pretty well and a similar response with O-III filter.  About 0.5' across.

Kent Wallace (20" @134X and 169X): could see the star superimposed on the northern side of the PN as shown in the SuperCOSMOS blue image. Using the O-III filter and averted vision, a blob forms on the southern side of the star. Good response to the O-III filter. Fair response to the UHC filter. No response to the H-Beta filter. The image is best at 169X. At 254X, the image isn't very good. Identified the field in the AP finder chart. This is a first known visual sighting.

Kent Blackwell (25"): Easy to find because of its involvement with an 11.4 magnitude star.   Even in bright moonlight I could still see it. Once I sighted the nebulosity with the filter I could see it without a filter. It responds so well to the OIII the nebula nearly outshines the involved 11.4 magnitude star.

-- Steve




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